diff --git a/cranelift/bforest/src/path.rs b/cranelift/bforest/src/path.rs
index 1df66b7ef7..a55de6b2ae 100644
--- a/cranelift/bforest/src/path.rs
+++ b/cranelift/bforest/src/path.rs
@@ -49,7 +49,7 @@ impl<F: Forest> Path<F> {
         key: F::Key,
         root: Node,
         pool: &NodePool<F>,
-        comp: &Comparator<F::Key>,
+        comp: &dyn Comparator<F::Key>,
     ) -> Option<F::Value> {
         let mut node = root;
         for level in 0.. {
diff --git a/cranelift/codegen/meta/src/gen_legalizer.rs b/cranelift/codegen/meta/src/gen_legalizer.rs
index 45221b1ffd..149e29f926 100644
--- a/cranelift/codegen/meta/src/gen_legalizer.rs
+++ b/cranelift/codegen/meta/src/gen_legalizer.rs
@@ -410,7 +410,7 @@ fn gen_transform_group<'a>(
         fmt.line("inst: crate::ir::Inst,");
         fmt.line("func: &mut crate::ir::Function,");
         fmt.line("cfg: &mut crate::flowgraph::ControlFlowGraph,");
-        fmt.line("isa: &crate::isa::TargetIsa,");
+        fmt.line("isa: &dyn crate::isa::TargetIsa,");
     });
     fmtln!(fmt, ") -> bool {");
 
diff --git a/cranelift/codegen/src/binemit/memorysink.rs b/cranelift/codegen/src/binemit/memorysink.rs
index 170e1a95e9..b70b4a2c86 100644
--- a/cranelift/codegen/src/binemit/memorysink.rs
+++ b/cranelift/codegen/src/binemit/memorysink.rs
@@ -34,8 +34,8 @@ pub struct MemoryCodeSink<'a> {
     data: *mut u8,
     /// Offset is isize because its major consumer needs it in that form.
     offset: isize,
-    relocs: &'a mut RelocSink,
-    traps: &'a mut TrapSink,
+    relocs: &'a mut dyn RelocSink,
+    traps: &'a mut dyn TrapSink,
     /// Information about the generated code and read-only data.
     pub info: CodeInfo,
 }
@@ -45,7 +45,11 @@ impl<'a> MemoryCodeSink<'a> {
     ///
     /// This function is unsafe since `MemoryCodeSink` does not perform bounds checking on the
     /// memory buffer, and it can't guarantee that the `data` pointer is valid.
-    pub unsafe fn new(data: *mut u8, relocs: &'a mut RelocSink, traps: &'a mut TrapSink) -> Self {
+    pub unsafe fn new(
+        data: *mut u8,
+        relocs: &'a mut dyn RelocSink,
+        traps: &'a mut dyn TrapSink,
+    ) -> Self {
         Self {
             data,
             offset: 0,
diff --git a/cranelift/codegen/src/binemit/relaxation.rs b/cranelift/codegen/src/binemit/relaxation.rs
index d1b5815e7c..1e84f2f4b9 100644
--- a/cranelift/codegen/src/binemit/relaxation.rs
+++ b/cranelift/codegen/src/binemit/relaxation.rs
@@ -40,7 +40,7 @@ use log::debug;
 /// Relax branches and compute the final layout of EBB headers in `func`.
 ///
 /// Fill in the `func.offsets` table so the function is ready for binary emission.
-pub fn relax_branches(func: &mut Function, isa: &TargetIsa) -> CodegenResult<CodeInfo> {
+pub fn relax_branches(func: &mut Function, isa: &dyn TargetIsa) -> CodegenResult<CodeInfo> {
     let _tt = timing::relax_branches();
 
     let encinfo = isa.encoding_info();
@@ -174,7 +174,7 @@ fn relax_branch(
     offset: CodeOffset,
     dest_offset: CodeOffset,
     encinfo: &EncInfo,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) -> CodeOffset {
     let inst = cur.current_inst().unwrap();
     debug!(
diff --git a/cranelift/codegen/src/binemit/shrink.rs b/cranelift/codegen/src/binemit/shrink.rs
index b3cfdfa6d1..281a93ae31 100644
--- a/cranelift/codegen/src/binemit/shrink.rs
+++ b/cranelift/codegen/src/binemit/shrink.rs
@@ -13,7 +13,7 @@ use crate::timing;
 use log::debug;
 
 /// Pick the smallest valid encodings for instructions.
-pub fn shrink_instructions(func: &mut Function, isa: &TargetIsa) {
+pub fn shrink_instructions(func: &mut Function, isa: &dyn TargetIsa) {
     let _tt = timing::shrink_instructions();
 
     let encinfo = isa.encoding_info();
diff --git a/cranelift/codegen/src/cfg_printer.rs b/cranelift/codegen/src/cfg_printer.rs
index 6a9932febe..e3ce37e731 100644
--- a/cranelift/codegen/src/cfg_printer.rs
+++ b/cranelift/codegen/src/cfg_printer.rs
@@ -23,14 +23,14 @@ impl<'a> CFGPrinter<'a> {
     }
 
     /// Write the CFG for this function to `w`.
-    pub fn write(&self, w: &mut Write) -> Result {
+    pub fn write(&self, w: &mut dyn Write) -> Result {
         self.header(w)?;
         self.ebb_nodes(w)?;
         self.cfg_connections(w)?;
         writeln!(w, "}}")
     }
 
-    fn header(&self, w: &mut Write) -> Result {
+    fn header(&self, w: &mut dyn Write) -> Result {
         writeln!(w, "digraph \"{}\" {{", self.func.name)?;
         if let Some(entry) = self.func.layout.entry_block() {
             writeln!(w, "    {{rank=min; {}}}", entry)?;
@@ -38,7 +38,7 @@ impl<'a> CFGPrinter<'a> {
         Ok(())
     }
 
-    fn ebb_nodes(&self, w: &mut Write) -> Result {
+    fn ebb_nodes(&self, w: &mut dyn Write) -> Result {
         for ebb in &self.func.layout {
             write!(w, "    {} [shape=record, label=\"{{{}", ebb, ebb)?;
             // Add all outgoing branch instructions to the label.
@@ -62,7 +62,7 @@ impl<'a> CFGPrinter<'a> {
         Ok(())
     }
 
-    fn cfg_connections(&self, w: &mut Write) -> Result {
+    fn cfg_connections(&self, w: &mut dyn Write) -> Result {
         for ebb in &self.func.layout {
             for BasicBlock { ebb: parent, inst } in self.cfg.pred_iter(ebb) {
                 writeln!(w, "    {}:{} -> {}", parent, inst, ebb)?;
diff --git a/cranelift/codegen/src/context.rs b/cranelift/codegen/src/context.rs
index 369b956a67..64c382cb23 100644
--- a/cranelift/codegen/src/context.rs
+++ b/cranelift/codegen/src/context.rs
@@ -96,10 +96,10 @@ impl Context {
     /// Returns information about the function's code and read-only data.
     pub fn compile_and_emit(
         &mut self,
-        isa: &TargetIsa,
+        isa: &dyn TargetIsa,
         mem: &mut Vec<u8>,
-        relocs: &mut RelocSink,
-        traps: &mut TrapSink,
+        relocs: &mut dyn RelocSink,
+        traps: &mut dyn TrapSink,
     ) -> CodegenResult<CodeInfo> {
         let info = self.compile(isa)?;
         let old_len = mem.len();
@@ -117,7 +117,7 @@ impl Context {
     /// code sink.
     ///
     /// Returns information about the function's code and read-only data.
-    pub fn compile(&mut self, isa: &TargetIsa) -> CodegenResult<CodeInfo> {
+    pub fn compile(&mut self, isa: &dyn TargetIsa) -> CodegenResult<CodeInfo> {
         let _tt = timing::compile();
         self.verify_if(isa)?;
 
@@ -164,10 +164,10 @@ impl Context {
     /// Returns information about the emitted code and data.
     pub unsafe fn emit_to_memory(
         &self,
-        isa: &TargetIsa,
+        isa: &dyn TargetIsa,
         mem: *mut u8,
-        relocs: &mut RelocSink,
-        traps: &mut TrapSink,
+        relocs: &mut dyn RelocSink,
+        traps: &mut dyn TrapSink,
     ) -> CodeInfo {
         let _tt = timing::binemit();
         let mut sink = MemoryCodeSink::new(mem, relocs, traps);
@@ -199,7 +199,7 @@ impl Context {
     }
 
     /// Run the locations verifier on the function.
-    pub fn verify_locations(&self, isa: &TargetIsa) -> VerifierResult<()> {
+    pub fn verify_locations(&self, isa: &dyn TargetIsa) -> VerifierResult<()> {
         let mut errors = VerifierErrors::default();
         let _ = verify_locations(isa, &self.func, None, &mut errors);
 
@@ -211,7 +211,7 @@ impl Context {
     }
 
     /// Run the locations verifier only if the `enable_verifier` setting is true.
-    pub fn verify_locations_if(&self, isa: &TargetIsa) -> CodegenResult<()> {
+    pub fn verify_locations_if(&self, isa: &dyn TargetIsa) -> CodegenResult<()> {
         if isa.flags().enable_verifier() {
             self.verify_locations(isa)?;
         }
@@ -226,20 +226,20 @@ impl Context {
     }
 
     /// Perform pre-legalization rewrites on the function.
-    pub fn preopt(&mut self, isa: &TargetIsa) -> CodegenResult<()> {
+    pub fn preopt(&mut self, isa: &dyn TargetIsa) -> CodegenResult<()> {
         do_preopt(&mut self.func, &mut self.cfg);
         self.verify_if(isa)?;
         Ok(())
     }
 
     /// Perform NaN canonicalizing rewrites on the function.
-    pub fn canonicalize_nans(&mut self, isa: &TargetIsa) -> CodegenResult<()> {
+    pub fn canonicalize_nans(&mut self, isa: &dyn TargetIsa) -> CodegenResult<()> {
         do_nan_canonicalization(&mut self.func);
         self.verify_if(isa)
     }
 
     /// Run the legalizer for `isa` on the function.
-    pub fn legalize(&mut self, isa: &TargetIsa) -> CodegenResult<()> {
+    pub fn legalize(&mut self, isa: &dyn TargetIsa) -> CodegenResult<()> {
         // Legalization invalidates the domtree and loop_analysis by mutating the CFG.
         // TODO: Avoid doing this when legalization doesn't actually mutate the CFG.
         self.domtree.clear();
@@ -249,7 +249,7 @@ impl Context {
     }
 
     /// Perform post-legalization rewrites on the function.
-    pub fn postopt(&mut self, isa: &TargetIsa) -> CodegenResult<()> {
+    pub fn postopt(&mut self, isa: &dyn TargetIsa) -> CodegenResult<()> {
         do_postopt(&mut self.func, isa);
         self.verify_if(isa)?;
         Ok(())
@@ -284,7 +284,7 @@ impl Context {
     }
 
     /// Perform LICM on the function.
-    pub fn licm(&mut self, isa: &TargetIsa) -> CodegenResult<()> {
+    pub fn licm(&mut self, isa: &dyn TargetIsa) -> CodegenResult<()> {
         do_licm(
             isa,
             &mut self.func,
@@ -305,13 +305,13 @@ impl Context {
     }
 
     /// Run the register allocator.
-    pub fn regalloc(&mut self, isa: &TargetIsa) -> CodegenResult<()> {
+    pub fn regalloc(&mut self, isa: &dyn TargetIsa) -> CodegenResult<()> {
         self.regalloc
             .run(isa, &mut self.func, &self.cfg, &mut self.domtree)
     }
 
     /// Insert prologue and epilogues after computing the stack frame layout.
-    pub fn prologue_epilogue(&mut self, isa: &TargetIsa) -> CodegenResult<()> {
+    pub fn prologue_epilogue(&mut self, isa: &dyn TargetIsa) -> CodegenResult<()> {
         isa.prologue_epilogue(&mut self.func)?;
         self.verify_if(isa)?;
         self.verify_locations_if(isa)?;
@@ -319,7 +319,7 @@ impl Context {
     }
 
     /// Run the instruction shrinking pass.
-    pub fn shrink_instructions(&mut self, isa: &TargetIsa) -> CodegenResult<()> {
+    pub fn shrink_instructions(&mut self, isa: &dyn TargetIsa) -> CodegenResult<()> {
         shrink_instructions(&mut self.func, isa);
         self.verify_if(isa)?;
         self.verify_locations_if(isa)?;
@@ -328,7 +328,7 @@ impl Context {
 
     /// Run the branch relaxation pass and return information about the function's code and
     /// read-only data.
-    pub fn relax_branches(&mut self, isa: &TargetIsa) -> CodegenResult<CodeInfo> {
+    pub fn relax_branches(&mut self, isa: &dyn TargetIsa) -> CodegenResult<CodeInfo> {
         let info = relax_branches(&mut self.func, isa)?;
         self.verify_if(isa)?;
         self.verify_locations_if(isa)?;
@@ -336,7 +336,10 @@ impl Context {
     }
 
     /// Builds ranges and location for specified value labels.
-    pub fn build_value_labels_ranges(&self, isa: &TargetIsa) -> CodegenResult<ValueLabelsRanges> {
+    pub fn build_value_labels_ranges(
+        &self,
+        isa: &dyn TargetIsa,
+    ) -> CodegenResult<ValueLabelsRanges> {
         Ok(build_value_labels_ranges::<ComparableSourceLoc>(
             &self.func,
             &self.regalloc,
diff --git a/cranelift/codegen/src/cursor.rs b/cranelift/codegen/src/cursor.rs
index ba7bc92b13..dbb459ed7a 100644
--- a/cranelift/codegen/src/cursor.rs
+++ b/cranelift/codegen/src/cursor.rs
@@ -657,12 +657,12 @@ pub struct EncCursor<'f> {
     pub func: &'f mut ir::Function,
 
     /// The target ISA that will be used to encode instructions.
-    pub isa: &'f TargetIsa,
+    pub isa: &'f dyn TargetIsa,
 }
 
 impl<'f> EncCursor<'f> {
     /// Create a new `EncCursor` pointing nowhere.
-    pub fn new(func: &'f mut ir::Function, isa: &'f TargetIsa) -> Self {
+    pub fn new(func: &'f mut ir::Function, isa: &'f dyn TargetIsa) -> Self {
         Self {
             pos: CursorPosition::Nowhere,
             srcloc: Default::default(),
diff --git a/cranelift/codegen/src/ir/dfg.rs b/cranelift/codegen/src/ir/dfg.rs
index 362a6cd772..d26abaa3e7 100644
--- a/cranelift/codegen/src/ir/dfg.rs
+++ b/cranelift/codegen/src/ir/dfg.rs
@@ -426,7 +426,7 @@ impl DataFlowGraph {
     }
 
     /// Returns an object that displays `inst`.
-    pub fn display_inst<'a, I: Into<Option<&'a TargetIsa>>>(
+    pub fn display_inst<'a, I: Into<Option<&'a dyn TargetIsa>>>(
         &'a self,
         inst: Inst,
         isa: I,
@@ -909,7 +909,7 @@ impl EbbData {
 }
 
 /// Object that can display an instruction.
-pub struct DisplayInst<'a>(&'a DataFlowGraph, Option<&'a TargetIsa>, Inst);
+pub struct DisplayInst<'a>(&'a DataFlowGraph, Option<&'a dyn TargetIsa>, Inst);
 
 impl<'a> fmt::Display for DisplayInst<'a> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
diff --git a/cranelift/codegen/src/ir/entities.rs b/cranelift/codegen/src/ir/entities.rs
index a0b694ad84..2c05fbc84b 100644
--- a/cranelift/codegen/src/ir/entities.rs
+++ b/cranelift/codegen/src/ir/entities.rs
@@ -238,7 +238,7 @@ impl fmt::Display for AnyEntity {
 
 impl fmt::Debug for AnyEntity {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        (self as &fmt::Display).fmt(f)
+        (self as &dyn fmt::Display).fmt(f)
     }
 }
 
diff --git a/cranelift/codegen/src/ir/function.rs b/cranelift/codegen/src/ir/function.rs
index 6a1d4cdd0d..f4b62dc59c 100644
--- a/cranelift/codegen/src/ir/function.rs
+++ b/cranelift/codegen/src/ir/function.rs
@@ -155,7 +155,10 @@ impl Function {
     }
 
     /// Return an object that can display this function with correct ISA-specific annotations.
-    pub fn display<'a, I: Into<Option<&'a TargetIsa>>>(&'a self, isa: I) -> DisplayFunction<'a> {
+    pub fn display<'a, I: Into<Option<&'a dyn TargetIsa>>>(
+        &'a self,
+        isa: I,
+    ) -> DisplayFunction<'a> {
         DisplayFunction(self, isa.into().into())
     }
 
@@ -202,13 +205,13 @@ impl Function {
     }
 
     /// Wrapper around `encode` which assigns `inst` the resulting encoding.
-    pub fn update_encoding(&mut self, inst: ir::Inst, isa: &TargetIsa) -> Result<(), Legalize> {
+    pub fn update_encoding(&mut self, inst: ir::Inst, isa: &dyn TargetIsa) -> Result<(), Legalize> {
         self.encode(inst, isa).map(|e| self.encodings[inst] = e)
     }
 
     /// Wrapper around `TargetIsa::encode` for encoding an existing instruction
     /// in the `Function`.
-    pub fn encode(&self, inst: ir::Inst, isa: &TargetIsa) -> Result<Encoding, Legalize> {
+    pub fn encode(&self, inst: ir::Inst, isa: &dyn TargetIsa) -> Result<Encoding, Legalize> {
         isa.encode(&self, &self.dfg[inst], self.dfg.ctrl_typevar(inst))
     }
 
@@ -221,7 +224,7 @@ impl Function {
 /// Additional annotations for function display.
 pub struct DisplayFunctionAnnotations<'a> {
     /// Enable ISA annotations.
-    pub isa: Option<&'a TargetIsa>,
+    pub isa: Option<&'a dyn TargetIsa>,
 
     /// Enable value labels annotations.
     pub value_ranges: Option<&'a ValueLabelsRanges>,
@@ -237,8 +240,8 @@ impl<'a> DisplayFunctionAnnotations<'a> {
     }
 }
 
-impl<'a> From<Option<&'a TargetIsa>> for DisplayFunctionAnnotations<'a> {
-    fn from(isa: Option<&'a TargetIsa>) -> DisplayFunctionAnnotations {
+impl<'a> From<Option<&'a dyn TargetIsa>> for DisplayFunctionAnnotations<'a> {
+    fn from(isa: Option<&'a dyn TargetIsa>) -> DisplayFunctionAnnotations {
         DisplayFunctionAnnotations {
             isa,
             value_ranges: None,
diff --git a/cranelift/codegen/src/ir/globalvalue.rs b/cranelift/codegen/src/ir/globalvalue.rs
index b67c26e1a2..6c7b62aab9 100644
--- a/cranelift/codegen/src/ir/globalvalue.rs
+++ b/cranelift/codegen/src/ir/globalvalue.rs
@@ -76,7 +76,7 @@ impl GlobalValueData {
     }
 
     /// Return the type of this global.
-    pub fn global_type(&self, isa: &TargetIsa) -> Type {
+    pub fn global_type(&self, isa: &dyn TargetIsa) -> Type {
         match *self {
             GlobalValueData::VMContext { .. } | GlobalValueData::Symbol { .. } => {
                 isa.pointer_type()
diff --git a/cranelift/codegen/src/ir/libcall.rs b/cranelift/codegen/src/ir/libcall.rs
index 3617f906d6..275e22a91f 100644
--- a/cranelift/codegen/src/ir/libcall.rs
+++ b/cranelift/codegen/src/ir/libcall.rs
@@ -107,7 +107,7 @@ pub fn get_libcall_funcref(
     libcall: LibCall,
     func: &mut Function,
     inst: Inst,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) -> FuncRef {
     find_funcref(libcall, func).unwrap_or_else(|| make_funcref_for_inst(libcall, func, inst, isa))
 }
@@ -119,7 +119,7 @@ pub fn get_probestack_funcref(
     func: &mut Function,
     reg_type: Type,
     arg_reg: RegUnit,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) -> FuncRef {
     find_funcref(LibCall::Probestack, func)
         .unwrap_or_else(|| make_funcref_for_probestack(func, reg_type, arg_reg, isa))
@@ -147,7 +147,7 @@ fn make_funcref_for_probestack(
     func: &mut Function,
     reg_type: Type,
     arg_reg: RegUnit,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) -> FuncRef {
     let mut sig = Signature::new(CallConv::Probestack);
     let rax = AbiParam::special_reg(reg_type, ArgumentPurpose::Normal, arg_reg);
@@ -163,7 +163,7 @@ fn make_funcref_for_inst(
     libcall: LibCall,
     func: &mut Function,
     inst: Inst,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) -> FuncRef {
     let mut sig = Signature::new(isa.default_call_conv());
     for &v in func.dfg.inst_args(inst) {
@@ -177,7 +177,12 @@ fn make_funcref_for_inst(
 }
 
 /// Create a funcref for `libcall`.
-fn make_funcref(libcall: LibCall, func: &mut Function, sig: Signature, isa: &TargetIsa) -> FuncRef {
+fn make_funcref(
+    libcall: LibCall,
+    func: &mut Function,
+    sig: Signature,
+    isa: &dyn TargetIsa,
+) -> FuncRef {
     let sigref = func.import_signature(sig);
 
     func.import_function(ExtFuncData {
diff --git a/cranelift/codegen/src/isa/arm32/mod.rs b/cranelift/codegen/src/isa/arm32/mod.rs
index 7bede88f3c..d4e2f32255 100644
--- a/cranelift/codegen/src/isa/arm32/mod.rs
+++ b/cranelift/codegen/src/isa/arm32/mod.rs
@@ -40,7 +40,7 @@ fn isa_constructor(
     triple: Triple,
     shared_flags: shared_settings::Flags,
     builder: shared_settings::Builder,
-) -> Box<TargetIsa> {
+) -> Box<dyn TargetIsa> {
     let level1 = match triple.architecture {
         Architecture::Thumbv6m | Architecture::Thumbv7em | Architecture::Thumbv7m => {
             &enc_tables::LEVEL1_T32[..]
@@ -119,7 +119,7 @@ impl TargetIsa for Isa {
         func: &ir::Function,
         inst: ir::Inst,
         divert: &mut regalloc::RegDiversions,
-        sink: &mut CodeSink,
+        sink: &mut dyn CodeSink,
     ) {
         binemit::emit_inst(func, inst, divert, sink)
     }
diff --git a/cranelift/codegen/src/isa/arm64/mod.rs b/cranelift/codegen/src/isa/arm64/mod.rs
index 84277301c3..c24be19f69 100644
--- a/cranelift/codegen/src/isa/arm64/mod.rs
+++ b/cranelift/codegen/src/isa/arm64/mod.rs
@@ -39,7 +39,7 @@ fn isa_constructor(
     triple: Triple,
     shared_flags: shared_settings::Flags,
     builder: shared_settings::Builder,
-) -> Box<TargetIsa> {
+) -> Box<dyn TargetIsa> {
     Box::new(Isa {
         triple,
         isa_flags: settings::Flags::new(&shared_flags, builder),
@@ -106,7 +106,7 @@ impl TargetIsa for Isa {
         func: &ir::Function,
         inst: ir::Inst,
         divert: &mut regalloc::RegDiversions,
-        sink: &mut CodeSink,
+        sink: &mut dyn CodeSink,
     ) {
         binemit::emit_inst(func, inst, divert, sink)
     }
diff --git a/cranelift/codegen/src/isa/mod.rs b/cranelift/codegen/src/isa/mod.rs
index b3e4d81421..eb6b4d2650 100644
--- a/cranelift/codegen/src/isa/mod.rs
+++ b/cranelift/codegen/src/isa/mod.rs
@@ -141,13 +141,13 @@ pub enum LookupError {
 pub struct Builder {
     triple: Triple,
     setup: settings::Builder,
-    constructor: fn(Triple, settings::Flags, settings::Builder) -> Box<TargetIsa>,
+    constructor: fn(Triple, settings::Flags, settings::Builder) -> Box<dyn TargetIsa>,
 }
 
 impl Builder {
     /// Combine the ISA-specific settings with the provided ISA-independent settings and allocate a
     /// fully configured `TargetIsa` trait object.
-    pub fn finish(self, shared_flags: settings::Flags) -> Box<TargetIsa> {
+    pub fn finish(self, shared_flags: settings::Flags) -> Box<dyn TargetIsa> {
         (self.constructor)(self.triple, shared_flags, self.setup)
     }
 }
@@ -167,7 +167,7 @@ impl settings::Configurable for Builder {
 ///
 /// The `Encodings` iterator returns a legalization function to call.
 pub type Legalize =
-    fn(ir::Inst, &mut ir::Function, &mut flowgraph::ControlFlowGraph, &TargetIsa) -> bool;
+    fn(ir::Inst, &mut ir::Function, &mut flowgraph::ControlFlowGraph, &dyn TargetIsa) -> bool;
 
 /// This struct provides information that a frontend may need to know about a target to
 /// produce Cranelift IR for the target.
@@ -367,7 +367,7 @@ pub trait TargetIsa: fmt::Display + Sync {
         func: &ir::Function,
         inst: ir::Inst,
         divert: &mut regalloc::RegDiversions,
-        sink: &mut binemit::CodeSink,
+        sink: &mut dyn binemit::CodeSink,
     );
 
     /// Emit a whole function into memory.
diff --git a/cranelift/codegen/src/isa/riscv/mod.rs b/cranelift/codegen/src/isa/riscv/mod.rs
index 60154cf162..3096ff69aa 100644
--- a/cranelift/codegen/src/isa/riscv/mod.rs
+++ b/cranelift/codegen/src/isa/riscv/mod.rs
@@ -40,7 +40,7 @@ fn isa_constructor(
     triple: Triple,
     shared_flags: shared_settings::Flags,
     builder: shared_settings::Builder,
-) -> Box<TargetIsa> {
+) -> Box<dyn TargetIsa> {
     let level1 = match triple.pointer_width().unwrap() {
         PointerWidth::U16 => panic!("16-bit RISC-V unrecognized"),
         PointerWidth::U32 => &enc_tables::LEVEL1_RV32[..],
@@ -113,7 +113,7 @@ impl TargetIsa for Isa {
         func: &ir::Function,
         inst: ir::Inst,
         divert: &mut regalloc::RegDiversions,
-        sink: &mut CodeSink,
+        sink: &mut dyn CodeSink,
     ) {
         binemit::emit_inst(func, inst, divert, sink)
     }
@@ -133,7 +133,7 @@ mod tests {
     use std::string::{String, ToString};
     use target_lexicon::triple;
 
-    fn encstr(isa: &isa::TargetIsa, enc: Result<isa::Encoding, isa::Legalize>) -> String {
+    fn encstr(isa: &dyn isa::TargetIsa, enc: Result<isa::Encoding, isa::Legalize>) -> String {
         match enc {
             Ok(e) => isa.encoding_info().display(e).to_string(),
             Err(_) => "no encoding".to_string(),
diff --git a/cranelift/codegen/src/isa/x86/abi.rs b/cranelift/codegen/src/isa/x86/abi.rs
index 37d9ffb257..549ec644c7 100644
--- a/cranelift/codegen/src/isa/x86/abi.rs
+++ b/cranelift/codegen/src/isa/x86/abi.rs
@@ -199,7 +199,7 @@ pub fn allocatable_registers(_func: &ir::Function, triple: &Triple) -> RegisterS
 }
 
 /// Get the set of callee-saved registers.
-fn callee_saved_gprs(isa: &TargetIsa, call_conv: CallConv) -> &'static [RU] {
+fn callee_saved_gprs(isa: &dyn TargetIsa, call_conv: CallConv) -> &'static [RU] {
     match isa.triple().pointer_width().unwrap() {
         PointerWidth::U16 => panic!(),
         PointerWidth::U32 => &[RU::rbx, RU::rsi, RU::rdi],
@@ -227,7 +227,7 @@ fn callee_saved_gprs(isa: &TargetIsa, call_conv: CallConv) -> &'static [RU] {
 }
 
 /// Get the set of callee-saved registers that are used.
-fn callee_saved_gprs_used(isa: &TargetIsa, func: &ir::Function) -> RegisterSet {
+fn callee_saved_gprs_used(isa: &dyn TargetIsa, func: &ir::Function) -> RegisterSet {
     let mut all_callee_saved = RegisterSet::empty();
     for reg in callee_saved_gprs(isa, func.signature.call_conv) {
         all_callee_saved.free(GPR, *reg as RegUnit);
@@ -269,7 +269,7 @@ fn callee_saved_gprs_used(isa: &TargetIsa, func: &ir::Function) -> RegisterSet {
     used
 }
 
-pub fn prologue_epilogue(func: &mut ir::Function, isa: &TargetIsa) -> CodegenResult<()> {
+pub fn prologue_epilogue(func: &mut ir::Function, isa: &dyn TargetIsa) -> CodegenResult<()> {
     match func.signature.call_conv {
         // For now, just translate fast and cold as system_v.
         CallConv::Fast | CallConv::Cold | CallConv::SystemV => {
@@ -281,7 +281,7 @@ pub fn prologue_epilogue(func: &mut ir::Function, isa: &TargetIsa) -> CodegenRes
     }
 }
 
-fn baldrdash_prologue_epilogue(func: &mut ir::Function, isa: &TargetIsa) -> CodegenResult<()> {
+fn baldrdash_prologue_epilogue(func: &mut ir::Function, isa: &dyn TargetIsa) -> CodegenResult<()> {
     debug_assert!(
         !isa.flags().probestack_enabled(),
         "baldrdash does not expect cranelift to emit stack probes"
@@ -302,7 +302,7 @@ fn baldrdash_prologue_epilogue(func: &mut ir::Function, isa: &TargetIsa) -> Code
 
 /// Implementation of the fastcall-based Win64 calling convention described at [1]
 /// [1] https://msdn.microsoft.com/en-us/library/ms235286.aspx
-fn fastcall_prologue_epilogue(func: &mut ir::Function, isa: &TargetIsa) -> CodegenResult<()> {
+fn fastcall_prologue_epilogue(func: &mut ir::Function, isa: &dyn TargetIsa) -> CodegenResult<()> {
     if isa.triple().pointer_width().unwrap() != PointerWidth::U64 {
         panic!("TODO: windows-fastcall: x86-32 not implemented yet");
     }
@@ -374,7 +374,7 @@ fn fastcall_prologue_epilogue(func: &mut ir::Function, isa: &TargetIsa) -> Codeg
 }
 
 /// Insert a System V-compatible prologue and epilogue.
-fn system_v_prologue_epilogue(func: &mut ir::Function, isa: &TargetIsa) -> CodegenResult<()> {
+fn system_v_prologue_epilogue(func: &mut ir::Function, isa: &dyn TargetIsa) -> CodegenResult<()> {
     // The original 32-bit x86 ELF ABI had a 4-byte aligned stack pointer, but
     // newer versions use a 16-byte aligned stack pointer.
     let stack_align = 16;
@@ -435,7 +435,7 @@ fn insert_common_prologue(
     stack_size: i64,
     reg_type: ir::types::Type,
     csrs: &RegisterSet,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) {
     if stack_size > 0 {
         // Check if there is a special stack limit parameter. If so insert stack check.
diff --git a/cranelift/codegen/src/isa/x86/enc_tables.rs b/cranelift/codegen/src/isa/x86/enc_tables.rs
index dd7bf02c86..474ef3c544 100644
--- a/cranelift/codegen/src/isa/x86/enc_tables.rs
+++ b/cranelift/codegen/src/isa/x86/enc_tables.rs
@@ -115,7 +115,7 @@ fn expand_sdivrem(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    isa: &isa::TargetIsa,
+    isa: &dyn isa::TargetIsa,
 ) {
     let (x, y, is_srem) = match func.dfg[inst] {
         ir::InstructionData::Binary {
@@ -225,7 +225,7 @@ fn expand_udivrem(
     inst: ir::Inst,
     func: &mut ir::Function,
     _cfg: &mut ControlFlowGraph,
-    isa: &isa::TargetIsa,
+    isa: &dyn isa::TargetIsa,
 ) {
     let (x, y, is_urem) = match func.dfg[inst] {
         ir::InstructionData::Binary {
@@ -278,7 +278,7 @@ fn expand_minmax(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    _isa: &isa::TargetIsa,
+    _isa: &dyn isa::TargetIsa,
 ) {
     let (x, y, x86_opc, bitwise_opc) = match func.dfg[inst] {
         ir::InstructionData::Binary {
@@ -370,7 +370,7 @@ fn expand_fcvt_from_uint(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    _isa: &isa::TargetIsa,
+    _isa: &dyn isa::TargetIsa,
 ) {
     let x;
     match func.dfg[inst] {
@@ -441,7 +441,7 @@ fn expand_fcvt_to_sint(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    _isa: &isa::TargetIsa,
+    _isa: &dyn isa::TargetIsa,
 ) {
     use crate::ir::immediates::{Ieee32, Ieee64};
 
@@ -536,7 +536,7 @@ fn expand_fcvt_to_sint_sat(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    _isa: &isa::TargetIsa,
+    _isa: &dyn isa::TargetIsa,
 ) {
     use crate::ir::immediates::{Ieee32, Ieee64};
 
@@ -655,7 +655,7 @@ fn expand_fcvt_to_uint(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    _isa: &isa::TargetIsa,
+    _isa: &dyn isa::TargetIsa,
 ) {
     use crate::ir::immediates::{Ieee32, Ieee64};
 
@@ -736,7 +736,7 @@ fn expand_fcvt_to_uint_sat(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    _isa: &isa::TargetIsa,
+    _isa: &dyn isa::TargetIsa,
 ) {
     use crate::ir::immediates::{Ieee32, Ieee64};
 
diff --git a/cranelift/codegen/src/isa/x86/mod.rs b/cranelift/codegen/src/isa/x86/mod.rs
index acefe0e786..c71e97410a 100644
--- a/cranelift/codegen/src/isa/x86/mod.rs
+++ b/cranelift/codegen/src/isa/x86/mod.rs
@@ -42,7 +42,7 @@ fn isa_constructor(
     triple: Triple,
     shared_flags: shared_settings::Flags,
     builder: shared_settings::Builder,
-) -> Box<TargetIsa> {
+) -> Box<dyn TargetIsa> {
     let level1 = match triple.pointer_width().unwrap() {
         PointerWidth::U16 => unimplemented!("x86-16"),
         PointerWidth::U32 => &enc_tables::LEVEL1_I32[..],
@@ -123,7 +123,7 @@ impl TargetIsa for Isa {
         func: &ir::Function,
         inst: ir::Inst,
         divert: &mut regalloc::RegDiversions,
-        sink: &mut CodeSink,
+        sink: &mut dyn CodeSink,
     ) {
         binemit::emit_inst(func, inst, divert, sink)
     }
diff --git a/cranelift/codegen/src/legalizer/boundary.rs b/cranelift/codegen/src/legalizer/boundary.rs
index c4bbcc9db6..8912743dd5 100644
--- a/cranelift/codegen/src/legalizer/boundary.rs
+++ b/cranelift/codegen/src/legalizer/boundary.rs
@@ -35,7 +35,7 @@ use std::vec::Vec;
 /// This changes all signatures to be ABI-compliant with full `ArgumentLoc` annotations. It doesn't
 /// change the entry block arguments, calls, or return instructions, so this can leave the function
 /// in a state with type discrepancies.
-pub fn legalize_signatures(func: &mut Function, isa: &TargetIsa) {
+pub fn legalize_signatures(func: &mut Function, isa: &dyn TargetIsa) {
     legalize_signature(&mut func.signature, true, isa);
     for sig_data in func.dfg.signatures.values_mut() {
         legalize_signature(sig_data, false, isa);
@@ -49,14 +49,14 @@ pub fn legalize_signatures(func: &mut Function, isa: &TargetIsa) {
 
 /// Legalize the libcall signature, which we may generate on the fly after
 /// `legalize_signatures` has been called.
-pub fn legalize_libcall_signature(signature: &mut Signature, isa: &TargetIsa) {
+pub fn legalize_libcall_signature(signature: &mut Signature, isa: &dyn TargetIsa) {
     legalize_signature(signature, false, isa);
 }
 
 /// Legalize the given signature.
 ///
 /// `current` is true if this is the signature for the current function.
-fn legalize_signature(signature: &mut Signature, current: bool, isa: &TargetIsa) {
+fn legalize_signature(signature: &mut Signature, current: bool, isa: &dyn TargetIsa) {
     isa.legalize_signature(signature, current);
 }
 
diff --git a/cranelift/codegen/src/legalizer/call.rs b/cranelift/codegen/src/legalizer/call.rs
index 6122937f3c..4321dbb90b 100644
--- a/cranelift/codegen/src/legalizer/call.rs
+++ b/cranelift/codegen/src/legalizer/call.rs
@@ -14,7 +14,7 @@ pub fn expand_call(
     inst: ir::Inst,
     func: &mut ir::Function,
     _cfg: &mut ControlFlowGraph,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) {
     // Unpack the instruction.
     let (func_ref, old_args) = match func.dfg[inst] {
diff --git a/cranelift/codegen/src/legalizer/globalvalue.rs b/cranelift/codegen/src/legalizer/globalvalue.rs
index 344a8b8d0f..97ef58c2bb 100644
--- a/cranelift/codegen/src/legalizer/globalvalue.rs
+++ b/cranelift/codegen/src/legalizer/globalvalue.rs
@@ -13,7 +13,7 @@ pub fn expand_global_value(
     inst: ir::Inst,
     func: &mut ir::Function,
     _cfg: &mut ControlFlowGraph,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) {
     // Unpack the instruction.
     let gv = match func.dfg[inst] {
@@ -90,7 +90,7 @@ fn load_addr(
     offset: ir::immediates::Offset32,
     global_type: ir::Type,
     readonly: bool,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) {
     // We need to load a pointer from the `base` global value, so insert a new `global_value`
     // instruction. This depends on the iterative legalization loop. Note that the IR verifier
@@ -123,7 +123,7 @@ fn load_addr(
 }
 
 /// Expand a `global_value` instruction for a symbolic name global.
-fn symbol(inst: ir::Inst, func: &mut ir::Function, gv: ir::GlobalValue, isa: &TargetIsa) {
+fn symbol(inst: ir::Inst, func: &mut ir::Function, gv: ir::GlobalValue, isa: &dyn TargetIsa) {
     let ptr_ty = isa.pointer_type();
     func.dfg.replace(inst).symbol_value(ptr_ty, gv);
 }
diff --git a/cranelift/codegen/src/legalizer/heap.rs b/cranelift/codegen/src/legalizer/heap.rs
index 19217a8af9..33f37155ee 100644
--- a/cranelift/codegen/src/legalizer/heap.rs
+++ b/cranelift/codegen/src/legalizer/heap.rs
@@ -14,7 +14,7 @@ pub fn expand_heap_addr(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    _isa: &TargetIsa,
+    _isa: &dyn TargetIsa,
 ) {
     // Unpack the instruction.
     let (heap, offset, access_size) = match func.dfg[inst] {
diff --git a/cranelift/codegen/src/legalizer/libcall.rs b/cranelift/codegen/src/legalizer/libcall.rs
index c4cbac30ee..01ff630f01 100644
--- a/cranelift/codegen/src/legalizer/libcall.rs
+++ b/cranelift/codegen/src/legalizer/libcall.rs
@@ -7,7 +7,7 @@ use crate::legalizer::boundary::legalize_libcall_signature;
 use std::vec::Vec;
 
 /// Try to expand `inst` as a library call, returning true is successful.
-pub fn expand_as_libcall(inst: ir::Inst, func: &mut ir::Function, isa: &TargetIsa) -> bool {
+pub fn expand_as_libcall(inst: ir::Inst, func: &mut ir::Function, isa: &dyn TargetIsa) -> bool {
     // Does the opcode/ctrl_type combo even have a well-known runtime library name.
     let libcall = match ir::LibCall::for_inst(func.dfg[inst].opcode(), func.dfg.ctrl_typevar(inst))
     {
diff --git a/cranelift/codegen/src/legalizer/mod.rs b/cranelift/codegen/src/legalizer/mod.rs
index 2e1db93d42..0a59f0d1b5 100644
--- a/cranelift/codegen/src/legalizer/mod.rs
+++ b/cranelift/codegen/src/legalizer/mod.rs
@@ -41,7 +41,7 @@ fn legalize_inst(
     inst: ir::Inst,
     pos: &mut FuncCursor,
     cfg: &mut ControlFlowGraph,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) -> bool {
     let opcode = pos.func.dfg[inst].opcode();
 
@@ -83,7 +83,7 @@ fn legalize_inst(
 /// - Transform any instructions that don't have a legal representation in `isa`.
 /// - Fill out `func.encodings`.
 ///
-pub fn legalize_function(func: &mut ir::Function, cfg: &mut ControlFlowGraph, isa: &TargetIsa) {
+pub fn legalize_function(func: &mut ir::Function, cfg: &mut ControlFlowGraph, isa: &dyn TargetIsa) {
     let _tt = timing::legalize();
     debug_assert!(cfg.is_valid());
 
@@ -129,7 +129,7 @@ fn expand_cond_trap(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    _isa: &TargetIsa,
+    _isa: &dyn TargetIsa,
 ) {
     // Parse the instruction.
     let trapz;
@@ -179,7 +179,7 @@ fn expand_br_table(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) {
     if isa.flags().jump_tables_enabled() {
         expand_br_table_jt(inst, func, cfg, isa);
@@ -193,7 +193,7 @@ fn expand_br_table_jt(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) {
     use crate::ir::condcodes::IntCC;
 
@@ -239,7 +239,7 @@ fn expand_br_table_conds(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    _isa: &TargetIsa,
+    _isa: &dyn TargetIsa,
 ) {
     use crate::ir::condcodes::IntCC;
 
@@ -280,7 +280,7 @@ fn expand_select(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    _isa: &TargetIsa,
+    _isa: &dyn TargetIsa,
 ) {
     let (ctrl, tval, fval) = match func.dfg[inst] {
         ir::InstructionData::Ternary {
@@ -315,7 +315,7 @@ fn expand_br_icmp(
     inst: ir::Inst,
     func: &mut ir::Function,
     cfg: &mut ControlFlowGraph,
-    _isa: &TargetIsa,
+    _isa: &dyn TargetIsa,
 ) {
     let (cond, a, b, destination, ebb_args) = match func.dfg[inst] {
         ir::InstructionData::BranchIcmp {
@@ -350,7 +350,7 @@ fn expand_fconst(
     inst: ir::Inst,
     func: &mut ir::Function,
     _cfg: &mut ControlFlowGraph,
-    _isa: &TargetIsa,
+    _isa: &dyn TargetIsa,
 ) {
     let ty = func.dfg.value_type(func.dfg.first_result(inst));
     debug_assert!(!ty.is_vector(), "Only scalar fconst supported: {}", ty);
@@ -378,7 +378,7 @@ fn expand_stack_load(
     inst: ir::Inst,
     func: &mut ir::Function,
     _cfg: &mut ControlFlowGraph,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) {
     let ty = func.dfg.value_type(func.dfg.first_result(inst));
     let addr_ty = isa.pointer_type();
@@ -410,7 +410,7 @@ fn expand_stack_store(
     inst: ir::Inst,
     func: &mut ir::Function,
     _cfg: &mut ControlFlowGraph,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) {
     let addr_ty = isa.pointer_type();
 
diff --git a/cranelift/codegen/src/legalizer/table.rs b/cranelift/codegen/src/legalizer/table.rs
index 14da52612f..0c4385e96b 100644
--- a/cranelift/codegen/src/legalizer/table.rs
+++ b/cranelift/codegen/src/legalizer/table.rs
@@ -15,7 +15,7 @@ pub fn expand_table_addr(
     inst: ir::Inst,
     func: &mut ir::Function,
     _cfg: &mut ControlFlowGraph,
-    _isa: &TargetIsa,
+    _isa: &dyn TargetIsa,
 ) {
     // Unpack the instruction.
     let (table, index, element_offset) = match func.dfg[inst] {
diff --git a/cranelift/codegen/src/licm.rs b/cranelift/codegen/src/licm.rs
index 14c4630dc7..2af4ef3244 100644
--- a/cranelift/codegen/src/licm.rs
+++ b/cranelift/codegen/src/licm.rs
@@ -17,7 +17,7 @@ use std::vec::Vec;
 /// loop-invariant instructions out of them.
 /// Changes the CFG and domtree in-place during the operation.
 pub fn do_licm(
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
     func: &mut Function,
     cfg: &mut ControlFlowGraph,
     domtree: &mut DominatorTree,
@@ -64,7 +64,7 @@ pub fn do_licm(
 // Insert a pre-header before the header, modifying the function layout and CFG to reflect it.
 // A jump instruction to the header is placed at the end of the pre-header.
 fn create_pre_header(
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
     header: Ebb,
     func: &mut Function,
     cfg: &mut ControlFlowGraph,
diff --git a/cranelift/codegen/src/postopt.rs b/cranelift/codegen/src/postopt.rs
index a82a3e59d3..ef027f6f25 100644
--- a/cranelift/codegen/src/postopt.rs
+++ b/cranelift/codegen/src/postopt.rs
@@ -45,7 +45,7 @@ fn optimize_cpu_flags(
     pos: &mut EncCursor,
     inst: Inst,
     last_flags_clobber: Option<Inst>,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) {
     // Look for compare and branch patterns.
     // This code could be considerably simplified with non-lexical lifetimes.
@@ -179,7 +179,7 @@ struct MemOpInfo {
     offset: Offset32,
 }
 
-fn optimize_complex_addresses(pos: &mut EncCursor, inst: Inst, isa: &TargetIsa) {
+fn optimize_complex_addresses(pos: &mut EncCursor, inst: Inst, isa: &dyn TargetIsa) {
     // Look for simple loads and stores we can optimize.
     let info = match pos.func.dfg[inst] {
         InstructionData::Load {
@@ -357,7 +357,7 @@ fn optimize_complex_addresses(pos: &mut EncCursor, inst: Inst, isa: &TargetIsa)
 //
 // The main post-opt pass.
 
-pub fn do_postopt(func: &mut Function, isa: &TargetIsa) {
+pub fn do_postopt(func: &mut Function, isa: &dyn TargetIsa) {
     let _tt = timing::postopt();
     let mut pos = EncCursor::new(func, isa);
     while let Some(_ebb) = pos.next_ebb() {
diff --git a/cranelift/codegen/src/print_errors.rs b/cranelift/codegen/src/print_errors.rs
index 2d09845c92..a18b5d6955 100644
--- a/cranelift/codegen/src/print_errors.rs
+++ b/cranelift/codegen/src/print_errors.rs
@@ -17,8 +17,8 @@ use std::vec::Vec;
 /// Pretty-print a verifier error.
 pub fn pretty_verifier_error<'a>(
     func: &ir::Function,
-    isa: Option<&TargetIsa>,
-    func_w: Option<Box<FuncWriter + 'a>>,
+    isa: Option<&dyn TargetIsa>,
+    func_w: Option<Box<dyn FuncWriter + 'a>>,
     errors: VerifierErrors,
 ) -> String {
     let mut errors = errors.0;
@@ -44,14 +44,14 @@ pub fn pretty_verifier_error<'a>(
     w
 }
 
-struct PrettyVerifierError<'a>(Box<FuncWriter + 'a>, &'a mut Vec<VerifierError>);
+struct PrettyVerifierError<'a>(Box<dyn FuncWriter + 'a>, &'a mut Vec<VerifierError>);
 
 impl<'a> FuncWriter for PrettyVerifierError<'a> {
     fn write_ebb_header(
         &mut self,
-        w: &mut Write,
+        w: &mut dyn Write,
         func: &Function,
-        isa: Option<&TargetIsa>,
+        isa: Option<&dyn TargetIsa>,
         ebb: Ebb,
         indent: usize,
     ) -> fmt::Result {
@@ -60,10 +60,10 @@ impl<'a> FuncWriter for PrettyVerifierError<'a> {
 
     fn write_instruction(
         &mut self,
-        w: &mut Write,
+        w: &mut dyn Write,
         func: &Function,
         aliases: &SecondaryMap<Value, Vec<Value>>,
-        isa: Option<&TargetIsa>,
+        isa: Option<&dyn TargetIsa>,
         inst: Inst,
         indent: usize,
     ) -> fmt::Result {
@@ -72,10 +72,10 @@ impl<'a> FuncWriter for PrettyVerifierError<'a> {
 
     fn write_entity_definition(
         &mut self,
-        w: &mut Write,
+        w: &mut dyn Write,
         func: &Function,
         entity: AnyEntity,
-        value: &fmt::Display,
+        value: &dyn fmt::Display,
     ) -> fmt::Result {
         pretty_preamble_error(w, func, entity, value, &mut *self.0, self.1)
     }
@@ -83,12 +83,12 @@ impl<'a> FuncWriter for PrettyVerifierError<'a> {
 
 /// Pretty-print a function verifier error for a given EBB.
 fn pretty_ebb_header_error(
-    w: &mut Write,
+    w: &mut dyn Write,
     func: &Function,
-    isa: Option<&TargetIsa>,
+    isa: Option<&dyn TargetIsa>,
     cur_ebb: Ebb,
     indent: usize,
-    func_w: &mut FuncWriter,
+    func_w: &mut dyn FuncWriter,
     errors: &mut Vec<VerifierError>,
 ) -> fmt::Result {
     let mut s = String::new();
@@ -121,13 +121,13 @@ fn pretty_ebb_header_error(
 
 /// Pretty-print a function verifier error for a given instruction.
 fn pretty_instruction_error(
-    w: &mut Write,
+    w: &mut dyn Write,
     func: &Function,
     aliases: &SecondaryMap<Value, Vec<Value>>,
-    isa: Option<&TargetIsa>,
+    isa: Option<&dyn TargetIsa>,
     cur_inst: Inst,
     indent: usize,
-    func_w: &mut FuncWriter,
+    func_w: &mut dyn FuncWriter,
     errors: &mut Vec<VerifierError>,
 ) -> fmt::Result {
     let mut s = String::new();
@@ -159,11 +159,11 @@ fn pretty_instruction_error(
 }
 
 fn pretty_preamble_error(
-    w: &mut Write,
+    w: &mut dyn Write,
     func: &Function,
     entity: AnyEntity,
-    value: &fmt::Display,
-    func_w: &mut FuncWriter,
+    value: &dyn fmt::Display,
+    func_w: &mut dyn FuncWriter,
     errors: &mut Vec<VerifierError>,
 ) -> fmt::Result {
     let mut s = String::new();
@@ -195,7 +195,7 @@ fn pretty_preamble_error(
 
 /// Prints:
 ///    ;   ^~~~~~
-fn print_arrow(w: &mut Write, entity: &str) -> fmt::Result {
+fn print_arrow(w: &mut dyn Write, entity: &str) -> fmt::Result {
     write!(w, ";")?;
 
     let indent = entity.len() - entity.trim_start().len();
@@ -212,13 +212,13 @@ fn print_arrow(w: &mut Write, entity: &str) -> fmt::Result {
 
 /// Prints:
 ///    ; error: [ERROR BODY]
-fn print_error(w: &mut Write, err: VerifierError) -> fmt::Result {
+fn print_error(w: &mut dyn Write, err: VerifierError) -> fmt::Result {
     writeln!(w, "; error: {}", err.to_string())?;
     Ok(())
 }
 
 /// Pretty-print a Cranelift error.
-pub fn pretty_error(func: &ir::Function, isa: Option<&TargetIsa>, err: CodegenError) -> String {
+pub fn pretty_error(func: &ir::Function, isa: Option<&dyn TargetIsa>, err: CodegenError) -> String {
     if let CodegenError::Verifier(e) = err {
         pretty_verifier_error(func, isa, None, e)
     } else {
diff --git a/cranelift/codegen/src/regalloc/affinity.rs b/cranelift/codegen/src/regalloc/affinity.rs
index bbd29f8f2e..7eea98ab8a 100644
--- a/cranelift/codegen/src/regalloc/affinity.rs
+++ b/cranelift/codegen/src/regalloc/affinity.rs
@@ -48,7 +48,7 @@ impl Affinity {
     }
 
     /// Create an affinity that matches an ABI argument for `isa`.
-    pub fn abi(arg: &AbiParam, isa: &TargetIsa) -> Self {
+    pub fn abi(arg: &AbiParam, isa: &dyn TargetIsa) -> Self {
         match arg.location {
             ArgumentLoc::Unassigned => Affinity::Unassigned,
             ArgumentLoc::Reg(_) => Affinity::Reg(isa.regclass_for_abi_type(arg.value_type).into()),
diff --git a/cranelift/codegen/src/regalloc/coalescing.rs b/cranelift/codegen/src/regalloc/coalescing.rs
index 401b795eea..4ba19ebbf4 100644
--- a/cranelift/codegen/src/regalloc/coalescing.rs
+++ b/cranelift/codegen/src/regalloc/coalescing.rs
@@ -66,7 +66,7 @@ pub struct Coalescing {
 
 /// One-shot context created once per invocation.
 struct Context<'a> {
-    isa: &'a TargetIsa,
+    isa: &'a dyn TargetIsa,
     encinfo: EncInfo,
 
     func: &'a mut Function,
@@ -108,7 +108,7 @@ impl Coalescing {
     /// Convert `func` to Conventional SSA form and build virtual registers in the process.
     pub fn conventional_ssa(
         &mut self,
-        isa: &TargetIsa,
+        isa: &dyn TargetIsa,
         func: &mut Function,
         cfg: &ControlFlowGraph,
         domtree: &DominatorTree,
diff --git a/cranelift/codegen/src/regalloc/coloring.rs b/cranelift/codegen/src/regalloc/coloring.rs
index 12ef018329..4e584b5a64 100644
--- a/cranelift/codegen/src/regalloc/coloring.rs
+++ b/cranelift/codegen/src/regalloc/coloring.rs
@@ -118,7 +118,7 @@ impl Coloring {
     /// Run the coloring algorithm over `func`.
     pub fn run(
         &mut self,
-        isa: &TargetIsa,
+        isa: &dyn TargetIsa,
         func: &mut Function,
         domtree: &DominatorTree,
         liveness: &mut Liveness,
diff --git a/cranelift/codegen/src/regalloc/context.rs b/cranelift/codegen/src/regalloc/context.rs
index a12a09dee1..cb4b4245f4 100644
--- a/cranelift/codegen/src/regalloc/context.rs
+++ b/cranelift/codegen/src/regalloc/context.rs
@@ -75,7 +75,7 @@ impl Context {
     /// location that is consistent with instruction encoding constraints.
     pub fn run(
         &mut self,
-        isa: &TargetIsa,
+        isa: &dyn TargetIsa,
         func: &mut Function,
         cfg: &ControlFlowGraph,
         domtree: &mut DominatorTree,
diff --git a/cranelift/codegen/src/regalloc/liveness.rs b/cranelift/codegen/src/regalloc/liveness.rs
index 0befe50bf3..7b31aedd54 100644
--- a/cranelift/codegen/src/regalloc/liveness.rs
+++ b/cranelift/codegen/src/regalloc/liveness.rs
@@ -195,7 +195,7 @@ type LiveRangeSet = SparseMap<Value, LiveRange>;
 fn get_or_create<'a>(
     lrset: &'a mut LiveRangeSet,
     value: Value,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
     func: &Function,
     encinfo: &EncInfo,
 ) -> &'a mut LiveRange {
@@ -389,7 +389,7 @@ impl Liveness {
 
     /// Compute the live ranges of all SSA values used in `func`.
     /// This clears out any existing analysis stored in this data structure.
-    pub fn compute(&mut self, isa: &TargetIsa, func: &mut Function, cfg: &ControlFlowGraph) {
+    pub fn compute(&mut self, isa: &dyn TargetIsa, func: &mut Function, cfg: &ControlFlowGraph) {
         let _tt = timing::ra_liveness();
         self.ranges.clear();
 
diff --git a/cranelift/codegen/src/regalloc/pressure.rs b/cranelift/codegen/src/regalloc/pressure.rs
index 2db3ec3d03..3b15a1c6e2 100644
--- a/cranelift/codegen/src/regalloc/pressure.rs
+++ b/cranelift/codegen/src/regalloc/pressure.rs
@@ -281,7 +281,7 @@ mod tests {
     use target_lexicon::triple;
 
     // Make an arm32 `TargetIsa`, if possible.
-    fn arm32() -> Option<Box<TargetIsa>> {
+    fn arm32() -> Option<Box<dyn TargetIsa>> {
         use crate::isa;
         use crate::settings;
 
@@ -294,7 +294,7 @@ mod tests {
     }
 
     // Get a register class by name.
-    fn rc_by_name(isa: &TargetIsa, name: &str) -> RegClass {
+    fn rc_by_name(isa: &dyn TargetIsa, name: &str) -> RegClass {
         isa.register_info()
             .classes
             .iter()
diff --git a/cranelift/codegen/src/regalloc/reload.rs b/cranelift/codegen/src/regalloc/reload.rs
index 11c1a5513d..fb6b61ec6f 100644
--- a/cranelift/codegen/src/regalloc/reload.rs
+++ b/cranelift/codegen/src/regalloc/reload.rs
@@ -65,7 +65,7 @@ impl Reload {
     /// Run the reload algorithm over `func`.
     pub fn run(
         &mut self,
-        isa: &TargetIsa,
+        isa: &dyn TargetIsa,
         func: &mut Function,
         domtree: &DominatorTree,
         liveness: &mut Liveness,
@@ -466,7 +466,7 @@ fn handle_abi_args(
     abi_types: &[AbiParam],
     var_args: &[Value],
     offset: usize,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
     liveness: &Liveness,
 ) {
     debug_assert_eq!(abi_types.len(), var_args.len());
diff --git a/cranelift/codegen/src/regalloc/solver.rs b/cranelift/codegen/src/regalloc/solver.rs
index 96ccdd2841..0d6a816dcb 100644
--- a/cranelift/codegen/src/regalloc/solver.rs
+++ b/cranelift/codegen/src/regalloc/solver.rs
@@ -406,7 +406,7 @@ impl fmt::Display for Move {
 
 impl fmt::Debug for Move {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let as_display: &fmt::Display = self;
+        let as_display: &dyn fmt::Display = self;
         as_display.fmt(f)
     }
 }
@@ -1139,7 +1139,7 @@ mod tests {
     use target_lexicon::triple;
 
     // Make an arm32 `TargetIsa`, if possible.
-    fn arm32() -> Option<Box<TargetIsa>> {
+    fn arm32() -> Option<Box<dyn TargetIsa>> {
         use crate::isa;
         use crate::settings;
 
diff --git a/cranelift/codegen/src/regalloc/spilling.rs b/cranelift/codegen/src/regalloc/spilling.rs
index 9065566003..f45dd41c94 100644
--- a/cranelift/codegen/src/regalloc/spilling.rs
+++ b/cranelift/codegen/src/regalloc/spilling.rs
@@ -91,7 +91,7 @@ impl Spilling {
     /// Run the spilling algorithm over `func`.
     pub fn run(
         &mut self,
-        isa: &TargetIsa,
+        isa: &dyn TargetIsa,
         func: &mut Function,
         domtree: &DominatorTree,
         liveness: &mut Liveness,
diff --git a/cranelift/codegen/src/settings.rs b/cranelift/codegen/src/settings.rs
index 6da73076e4..748484b10c 100644
--- a/cranelift/codegen/src/settings.rs
+++ b/cranelift/codegen/src/settings.rs
@@ -346,7 +346,7 @@ pub struct FlagsOrIsa<'a> {
     pub flags: &'a Flags,
 
     /// The ISA may not be present.
-    pub isa: Option<&'a TargetIsa>,
+    pub isa: Option<&'a dyn TargetIsa>,
 }
 
 impl<'a> From<&'a Flags> for FlagsOrIsa<'a> {
@@ -355,8 +355,8 @@ impl<'a> From<&'a Flags> for FlagsOrIsa<'a> {
     }
 }
 
-impl<'a> From<&'a TargetIsa> for FlagsOrIsa<'a> {
-    fn from(isa: &'a TargetIsa) -> FlagsOrIsa {
+impl<'a> From<&'a dyn TargetIsa> for FlagsOrIsa<'a> {
+    fn from(isa: &'a dyn TargetIsa) -> FlagsOrIsa {
         FlagsOrIsa {
             flags: isa.flags(),
             isa: Some(isa),
diff --git a/cranelift/codegen/src/value_label.rs b/cranelift/codegen/src/value_label.rs
index d70d6258fa..8dab92b892 100644
--- a/cranelift/codegen/src/value_label.rs
+++ b/cranelift/codegen/src/value_label.rs
@@ -81,7 +81,7 @@ where
 pub fn build_value_labels_ranges<T>(
     func: &Function,
     regalloc: &Context,
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
 ) -> ValueLabelsRanges
 where
     T: From<SourceLoc> + Deref<Target = SourceLoc> + Ord + Copy,
diff --git a/cranelift/codegen/src/verifier/flags.rs b/cranelift/codegen/src/verifier/flags.rs
index 9be8d48280..43a235def5 100644
--- a/cranelift/codegen/src/verifier/flags.rs
+++ b/cranelift/codegen/src/verifier/flags.rs
@@ -24,7 +24,7 @@ use crate::verifier::{VerifierErrors, VerifierStepResult};
 pub fn verify_flags(
     func: &ir::Function,
     cfg: &ControlFlowGraph,
-    isa: Option<&isa::TargetIsa>,
+    isa: Option<&dyn isa::TargetIsa>,
     errors: &mut VerifierErrors,
 ) -> VerifierStepResult<()> {
     let _tt = timing::verify_flags();
diff --git a/cranelift/codegen/src/verifier/liveness.rs b/cranelift/codegen/src/verifier/liveness.rs
index 9556ae3703..c396a46803 100644
--- a/cranelift/codegen/src/verifier/liveness.rs
+++ b/cranelift/codegen/src/verifier/liveness.rs
@@ -23,7 +23,7 @@ use core::cmp::Ordering;
 /// We don't verify that live ranges are minimal. This would require recomputing live ranges for
 /// all values.
 pub fn verify_liveness(
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
     func: &Function,
     cfg: &ControlFlowGraph,
     liveness: &Liveness,
@@ -42,7 +42,7 @@ pub fn verify_liveness(
 }
 
 struct LivenessVerifier<'a> {
-    isa: &'a TargetIsa,
+    isa: &'a dyn TargetIsa,
     func: &'a Function,
     cfg: &'a ControlFlowGraph,
     liveness: &'a Liveness,
diff --git a/cranelift/codegen/src/verifier/locations.rs b/cranelift/codegen/src/verifier/locations.rs
index 26e5edfaf1..bcf006e7f5 100644
--- a/cranelift/codegen/src/verifier/locations.rs
+++ b/cranelift/codegen/src/verifier/locations.rs
@@ -19,7 +19,7 @@ use crate::verifier::{VerifierErrors, VerifierStepResult};
 /// If a liveness analysis is provided, it is used to verify that there are no active register
 /// diversions across control flow edges.
 pub fn verify_locations(
-    isa: &isa::TargetIsa,
+    isa: &dyn isa::TargetIsa,
     func: &ir::Function,
     liveness: Option<&Liveness>,
     errors: &mut VerifierErrors,
@@ -37,7 +37,7 @@ pub fn verify_locations(
 }
 
 struct LocationVerifier<'a> {
-    isa: &'a isa::TargetIsa,
+    isa: &'a dyn isa::TargetIsa,
     func: &'a ir::Function,
     reginfo: isa::RegInfo,
     encinfo: isa::EncInfo,
diff --git a/cranelift/codegen/src/verifier/mod.rs b/cranelift/codegen/src/verifier/mod.rs
index 38a52f0934..fc1a38ed99 100644
--- a/cranelift/codegen/src/verifier/mod.rs
+++ b/cranelift/codegen/src/verifier/mod.rs
@@ -266,7 +266,7 @@ struct Verifier<'a> {
     func: &'a Function,
     expected_cfg: ControlFlowGraph,
     expected_domtree: DominatorTree,
-    isa: Option<&'a TargetIsa>,
+    isa: Option<&'a dyn TargetIsa>,
 }
 
 impl<'a> Verifier<'a> {
diff --git a/cranelift/codegen/src/write.rs b/cranelift/codegen/src/write.rs
index f1810524d8..cf44fa8aca 100644
--- a/cranelift/codegen/src/write.rs
+++ b/cranelift/codegen/src/write.rs
@@ -22,9 +22,9 @@ pub trait FuncWriter {
     /// Write the extended basic block header for the current function.
     fn write_ebb_header(
         &mut self,
-        w: &mut Write,
+        w: &mut dyn Write,
         func: &Function,
-        isa: Option<&TargetIsa>,
+        isa: Option<&dyn TargetIsa>,
         ebb: Ebb,
         indent: usize,
     ) -> fmt::Result;
@@ -32,10 +32,10 @@ pub trait FuncWriter {
     /// Write the given `inst` to `w`.
     fn write_instruction(
         &mut self,
-        w: &mut Write,
+        w: &mut dyn Write,
         func: &Function,
         aliases: &SecondaryMap<Value, Vec<Value>>,
-        isa: Option<&TargetIsa>,
+        isa: Option<&dyn TargetIsa>,
         inst: Inst,
         indent: usize,
     ) -> fmt::Result;
@@ -43,7 +43,7 @@ pub trait FuncWriter {
     /// Write the preamble to `w`. By default, this uses `write_entity_definition`.
     fn write_preamble(
         &mut self,
-        w: &mut Write,
+        w: &mut dyn Write,
         func: &Function,
         regs: Option<&RegInfo>,
     ) -> Result<bool, fmt::Error> {
@@ -53,7 +53,7 @@ pub trait FuncWriter {
     /// Default impl of `write_preamble`
     fn super_preamble(
         &mut self,
-        w: &mut Write,
+        w: &mut dyn Write,
         func: &Function,
         regs: Option<&RegInfo>,
     ) -> Result<bool, fmt::Error> {
@@ -108,10 +108,10 @@ pub trait FuncWriter {
     /// Write an entity definition defined in the preamble to `w`.
     fn write_entity_definition(
         &mut self,
-        w: &mut Write,
+        w: &mut dyn Write,
         func: &Function,
         entity: AnyEntity,
-        value: &fmt::Display,
+        value: &dyn fmt::Display,
     ) -> fmt::Result {
         self.super_entity_definition(w, func, entity, value)
     }
@@ -120,10 +120,10 @@ pub trait FuncWriter {
     #[allow(unused_variables)]
     fn super_entity_definition(
         &mut self,
-        w: &mut Write,
+        w: &mut dyn Write,
         func: &Function,
         entity: AnyEntity,
-        value: &fmt::Display,
+        value: &dyn fmt::Display,
     ) -> fmt::Result {
         writeln!(w, "    {} = {}", entity, value)
     }
@@ -135,10 +135,10 @@ pub struct PlainWriter;
 impl FuncWriter for PlainWriter {
     fn write_instruction(
         &mut self,
-        w: &mut Write,
+        w: &mut dyn Write,
         func: &Function,
         aliases: &SecondaryMap<Value, Vec<Value>>,
-        isa: Option<&TargetIsa>,
+        isa: Option<&dyn TargetIsa>,
         inst: Inst,
         indent: usize,
     ) -> fmt::Result {
@@ -147,9 +147,9 @@ impl FuncWriter for PlainWriter {
 
     fn write_ebb_header(
         &mut self,
-        w: &mut Write,
+        w: &mut dyn Write,
         func: &Function,
-        isa: Option<&TargetIsa>,
+        isa: Option<&dyn TargetIsa>,
         ebb: Ebb,
         indent: usize,
     ) -> fmt::Result {
@@ -160,7 +160,7 @@ impl FuncWriter for PlainWriter {
 /// Write `func` to `w` as equivalent text.
 /// Use `isa` to emit ISA-dependent annotations.
 pub fn write_function(
-    w: &mut Write,
+    w: &mut dyn Write,
     func: &Function,
     annotations: &DisplayFunctionAnnotations,
 ) -> fmt::Result {
@@ -184,7 +184,7 @@ fn alias_map(func: &Function) -> SecondaryMap<Value, Vec<Value>> {
 /// pretty_function_error is passed as 'closure' to add error decoration.
 pub fn decorate_function<FW: FuncWriter>(
     func_w: &mut FW,
-    w: &mut Write,
+    w: &mut dyn Write,
     func: &Function,
     annotations: &DisplayFunctionAnnotations,
 ) -> fmt::Result {
@@ -210,7 +210,7 @@ pub fn decorate_function<FW: FuncWriter>(
 //
 // Function spec.
 
-fn write_spec(w: &mut Write, func: &Function, regs: Option<&RegInfo>) -> fmt::Result {
+fn write_spec(w: &mut dyn Write, func: &Function, regs: Option<&RegInfo>) -> fmt::Result {
     write!(w, "{}{}", func.name, func.signature.display(regs))
 }
 
@@ -218,7 +218,12 @@ fn write_spec(w: &mut Write, func: &Function, regs: Option<&RegInfo>) -> fmt::Re
 //
 // Basic blocks
 
-fn write_arg(w: &mut Write, func: &Function, regs: Option<&RegInfo>, arg: Value) -> fmt::Result {
+fn write_arg(
+    w: &mut dyn Write,
+    func: &Function,
+    regs: Option<&RegInfo>,
+    arg: Value,
+) -> fmt::Result {
     write!(w, "{}: {}", arg, func.dfg.value_type(arg))?;
     let loc = func.locations[arg];
     if loc.is_assigned() {
@@ -235,9 +240,9 @@ fn write_arg(w: &mut Write, func: &Function, regs: Option<&RegInfo>, arg: Value)
 ///    ebb10(v4: f64, v5: b1):
 ///
 pub fn write_ebb_header(
-    w: &mut Write,
+    w: &mut dyn Write,
     func: &Function,
-    isa: Option<&TargetIsa>,
+    isa: Option<&dyn TargetIsa>,
     ebb: Ebb,
     indent: usize,
 ) -> fmt::Result {
@@ -263,7 +268,7 @@ pub fn write_ebb_header(
     writeln!(w, "):")
 }
 
-fn write_valueloc(w: &mut Write, loc: &ValueLoc, regs: &RegInfo) -> fmt::Result {
+fn write_valueloc(w: &mut dyn Write, loc: &ValueLoc, regs: &RegInfo) -> fmt::Result {
     match loc {
         ValueLoc::Reg(r) => write!(w, "{}", regs.display_regunit(*r)),
         ValueLoc::Stack(ss) => write!(w, "{}", ss),
@@ -272,7 +277,7 @@ fn write_valueloc(w: &mut Write, loc: &ValueLoc, regs: &RegInfo) -> fmt::Result
 }
 
 fn write_value_range_markers(
-    w: &mut Write,
+    w: &mut dyn Write,
     val_ranges: &ValueLabelsRanges,
     regs: &RegInfo,
     offset: u32,
@@ -306,7 +311,7 @@ fn write_value_range_markers(
 
 fn decorate_ebb<FW: FuncWriter>(
     func_w: &mut FW,
-    w: &mut Write,
+    w: &mut dyn Write,
     func: &Function,
     aliases: &SecondaryMap<Value, Vec<Value>>,
     annotations: &DisplayFunctionAnnotations,
@@ -385,7 +390,7 @@ fn type_suffix(func: &Function, inst: Inst) -> Option<Type> {
 
 /// Write out any aliases to the given target, including indirect aliases
 fn write_value_aliases(
-    w: &mut Write,
+    w: &mut dyn Write,
     aliases: &SecondaryMap<Value, Vec<Value>>,
     target: Value,
     indent: usize,
@@ -402,10 +407,10 @@ fn write_value_aliases(
 }
 
 fn write_instruction(
-    w: &mut Write,
+    w: &mut dyn Write,
     func: &Function,
     aliases: &SecondaryMap<Value, Vec<Value>>,
-    isa: Option<&TargetIsa>,
+    isa: Option<&dyn TargetIsa>,
     inst: Inst,
     indent: usize,
 ) -> fmt::Result {
@@ -472,9 +477,9 @@ fn write_instruction(
 
 /// Write the operands of `inst` to `w` with a prepended space.
 pub fn write_operands(
-    w: &mut Write,
+    w: &mut dyn Write,
     dfg: &DataFlowGraph,
-    isa: Option<&TargetIsa>,
+    isa: Option<&dyn TargetIsa>,
     inst: Inst,
 ) -> fmt::Result {
     let pool = &dfg.value_lists;
@@ -687,7 +692,7 @@ pub fn write_operands(
 }
 
 /// Write EBB args using optional parantheses.
-fn write_ebb_args(w: &mut Write, args: &[Value]) -> fmt::Result {
+fn write_ebb_args(w: &mut dyn Write, args: &[Value]) -> fmt::Result {
     if args.is_empty() {
         Ok(())
     } else {
diff --git a/cranelift/entity/src/lib.rs b/cranelift/entity/src/lib.rs
index 8d5579000b..57287d6c79 100644
--- a/cranelift/entity/src/lib.rs
+++ b/cranelift/entity/src/lib.rs
@@ -126,7 +126,7 @@ macro_rules! entity_impl {
 
         impl $crate::__core::fmt::Debug for $entity {
             fn fmt(&self, f: &mut $crate::__core::fmt::Formatter) -> $crate::__core::fmt::Result {
-                (self as &$crate::__core::fmt::Display).fmt(f)
+                (self as &dyn $crate::__core::fmt::Display).fmt(f)
             }
         }
     };
diff --git a/cranelift/faerie/src/backend.rs b/cranelift/faerie/src/backend.rs
index 29f3c0480d..57dc21376a 100644
--- a/cranelift/faerie/src/backend.rs
+++ b/cranelift/faerie/src/backend.rs
@@ -27,10 +27,10 @@ pub enum FaerieTrapCollection {
 
 /// A builder for `FaerieBackend`.
 pub struct FaerieBuilder {
-    isa: Box<TargetIsa>,
+    isa: Box<dyn TargetIsa>,
     name: String,
     collect_traps: FaerieTrapCollection,
-    libcall_names: Box<Fn(ir::LibCall) -> String>,
+    libcall_names: Box<dyn Fn(ir::LibCall) -> String>,
 }
 
 impl FaerieBuilder {
@@ -48,10 +48,10 @@ impl FaerieBuilder {
     /// floating point instructions, and for stack probes. If you don't know what to use for this
     /// argument, use `cranelift_module::default_libcall_names()`.
     pub fn new(
-        isa: Box<TargetIsa>,
+        isa: Box<dyn TargetIsa>,
         name: String,
         collect_traps: FaerieTrapCollection,
-        libcall_names: Box<Fn(ir::LibCall) -> String>,
+        libcall_names: Box<dyn Fn(ir::LibCall) -> String>,
     ) -> ModuleResult<Self> {
         if !isa.flags().is_pic() {
             return Err(ModuleError::Backend(
@@ -71,10 +71,10 @@ impl FaerieBuilder {
 ///
 /// See the `FaerieBuilder` for a convenient way to construct `FaerieBackend` instances.
 pub struct FaerieBackend {
-    isa: Box<TargetIsa>,
+    isa: Box<dyn TargetIsa>,
     artifact: faerie::Artifact,
     trap_manifest: Option<FaerieTrapManifest>,
-    libcall_names: Box<Fn(ir::LibCall) -> String>,
+    libcall_names: Box<dyn Fn(ir::LibCall) -> String>,
 }
 
 pub struct FaerieCompiledFunction {
@@ -117,7 +117,7 @@ impl Backend for FaerieBackend {
         }
     }
 
-    fn isa(&self) -> &TargetIsa {
+    fn isa(&self) -> &dyn TargetIsa {
         &*self.isa
     }
 
@@ -361,7 +361,7 @@ struct FaerieRelocSink<'a> {
     artifact: &'a mut faerie::Artifact,
     name: &'a str,
     namespace: &'a ModuleNamespace<'a, FaerieBackend>,
-    libcall_names: &'a Fn(ir::LibCall) -> String,
+    libcall_names: &'a dyn Fn(ir::LibCall) -> String,
 }
 
 impl<'a> RelocSink for FaerieRelocSink<'a> {
diff --git a/cranelift/filetests/src/lib.rs b/cranelift/filetests/src/lib.rs
index 6284e945fa..fbd069bcb5 100644
--- a/cranelift/filetests/src/lib.rs
+++ b/cranelift/filetests/src/lib.rs
@@ -110,7 +110,7 @@ pub fn run_passes(
 ///
 /// This function knows how to create all of the possible `test <foo>` commands that can appear in
 /// a `.clif` test file.
-fn new_subtest(parsed: &TestCommand) -> subtest::SubtestResult<Box<subtest::SubTest>> {
+fn new_subtest(parsed: &TestCommand) -> subtest::SubtestResult<Box<dyn subtest::SubTest>> {
     match parsed.command {
         "binemit" => test_binemit::subtest(parsed),
         "cat" => test_cat::subtest(parsed),
diff --git a/cranelift/filetests/src/runone.rs b/cranelift/filetests/src/runone.rs
index 323442d4b5..3a69c37c4e 100644
--- a/cranelift/filetests/src/runone.rs
+++ b/cranelift/filetests/src/runone.rs
@@ -102,10 +102,10 @@ pub fn run(path: &Path, passes: Option<&[String]>, target: Option<&str>) -> Test
 
 // Given a slice of tests, generate a vector of (test, flags, isa) tuples.
 fn test_tuples<'a>(
-    tests: &'a [Box<SubTest>],
+    tests: &'a [Box<dyn SubTest>],
     isa_spec: &'a IsaSpec,
     no_isa_flags: &'a Flags,
-) -> SubtestResult<Vec<(&'a SubTest, &'a Flags, Option<&'a TargetIsa>)>> {
+) -> SubtestResult<Vec<(&'a dyn SubTest, &'a Flags, Option<&'a dyn TargetIsa>)>> {
     let mut out = Vec::new();
     for test in tests {
         if test.needs_isa() {
@@ -131,7 +131,7 @@ fn test_tuples<'a>(
 }
 
 fn run_one_test<'a>(
-    tuple: (&'a SubTest, &'a Flags, Option<&'a TargetIsa>),
+    tuple: (&'a dyn SubTest, &'a Flags, Option<&'a dyn TargetIsa>),
     func: Cow<Function>,
     context: &mut Context<'a>,
 ) -> SubtestResult<()> {
diff --git a/cranelift/filetests/src/subtest.rs b/cranelift/filetests/src/subtest.rs
index 4400561cc8..0264169e4c 100644
--- a/cranelift/filetests/src/subtest.rs
+++ b/cranelift/filetests/src/subtest.rs
@@ -25,7 +25,7 @@ pub struct Context<'a> {
 
     /// Target ISA to test against. Only guaranteed to be present for sub-tests whose `needs_isa`
     /// method returned `true`. For other sub-tests, this is set if the test file has a unique ISA.
-    pub isa: Option<&'a TargetIsa>,
+    pub isa: Option<&'a dyn TargetIsa>,
 }
 
 impl<'a> Context<'a> {
diff --git a/cranelift/filetests/src/test_binemit.rs b/cranelift/filetests/src/test_binemit.rs
index a80b3aefe6..0b1e838795 100644
--- a/cranelift/filetests/src/test_binemit.rs
+++ b/cranelift/filetests/src/test_binemit.rs
@@ -18,7 +18,7 @@ use std::fmt::Write;
 
 struct TestBinEmit;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "binemit");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_cat.rs b/cranelift/filetests/src/test_cat.rs
index 88ebadf11e..756b5e5700 100644
--- a/cranelift/filetests/src/test_cat.rs
+++ b/cranelift/filetests/src/test_cat.rs
@@ -13,7 +13,7 @@ use std::borrow::Cow;
 /// The result is verified by filecheck.
 struct TestCat;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "cat");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_compile.rs b/cranelift/filetests/src/test_compile.rs
index fee681d609..e9150a73ee 100644
--- a/cranelift/filetests/src/test_compile.rs
+++ b/cranelift/filetests/src/test_compile.rs
@@ -13,7 +13,7 @@ use std::borrow::Cow;
 
 struct TestCompile;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "compile");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_dce.rs b/cranelift/filetests/src/test_dce.rs
index 2b07654f64..b7b72d2a77 100644
--- a/cranelift/filetests/src/test_dce.rs
+++ b/cranelift/filetests/src/test_dce.rs
@@ -14,7 +14,7 @@ use std::borrow::Cow;
 
 struct TestDCE;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "dce");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_domtree.rs b/cranelift/filetests/src/test_domtree.rs
index e8aeca9bfa..05c7dc31e5 100644
--- a/cranelift/filetests/src/test_domtree.rs
+++ b/cranelift/filetests/src/test_domtree.rs
@@ -25,7 +25,7 @@ use std::fmt::{self, Write};
 
 struct TestDomtree;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "domtree");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_legalizer.rs b/cranelift/filetests/src/test_legalizer.rs
index cb9ab8858c..ec182f4092 100644
--- a/cranelift/filetests/src/test_legalizer.rs
+++ b/cranelift/filetests/src/test_legalizer.rs
@@ -12,7 +12,7 @@ use std::borrow::Cow;
 
 struct TestLegalizer;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "legalizer");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_licm.rs b/cranelift/filetests/src/test_licm.rs
index 32360cadc7..31385f8081 100644
--- a/cranelift/filetests/src/test_licm.rs
+++ b/cranelift/filetests/src/test_licm.rs
@@ -14,7 +14,7 @@ use std::borrow::Cow;
 
 struct TestLICM;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "licm");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_postopt.rs b/cranelift/filetests/src/test_postopt.rs
index e7919b13ca..5d5486e912 100644
--- a/cranelift/filetests/src/test_postopt.rs
+++ b/cranelift/filetests/src/test_postopt.rs
@@ -11,7 +11,7 @@ use std::borrow::Cow;
 
 struct TestPostopt;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "postopt");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_preopt.rs b/cranelift/filetests/src/test_preopt.rs
index 2da3005df6..7e0e23475a 100644
--- a/cranelift/filetests/src/test_preopt.rs
+++ b/cranelift/filetests/src/test_preopt.rs
@@ -15,7 +15,7 @@ use std::borrow::Cow;
 
 struct TestPreopt;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "preopt");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_print_cfg.rs b/cranelift/filetests/src/test_print_cfg.rs
index 7053234dc3..4483c23939 100644
--- a/cranelift/filetests/src/test_print_cfg.rs
+++ b/cranelift/filetests/src/test_print_cfg.rs
@@ -13,7 +13,7 @@ use cranelift_reader::TestCommand;
 /// Object implementing the `test print-cfg` sub-test.
 struct TestPrintCfg;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "print-cfg");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_regalloc.rs b/cranelift/filetests/src/test_regalloc.rs
index a813b43e2f..5a316c022f 100644
--- a/cranelift/filetests/src/test_regalloc.rs
+++ b/cranelift/filetests/src/test_regalloc.rs
@@ -14,7 +14,7 @@ use std::borrow::Cow;
 
 struct TestRegalloc;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "regalloc");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_shrink.rs b/cranelift/filetests/src/test_shrink.rs
index 2cbd2b614f..d32da3c384 100644
--- a/cranelift/filetests/src/test_shrink.rs
+++ b/cranelift/filetests/src/test_shrink.rs
@@ -14,7 +14,7 @@ use std::borrow::Cow;
 
 struct TestShrink;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "shrink");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_simple_gvn.rs b/cranelift/filetests/src/test_simple_gvn.rs
index 3752129a92..831a632951 100644
--- a/cranelift/filetests/src/test_simple_gvn.rs
+++ b/cranelift/filetests/src/test_simple_gvn.rs
@@ -14,7 +14,7 @@ use std::borrow::Cow;
 
 struct TestSimpleGVN;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "simple-gvn");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_simple_preopt.rs b/cranelift/filetests/src/test_simple_preopt.rs
index 4d2e7a7414..286a86ba23 100644
--- a/cranelift/filetests/src/test_simple_preopt.rs
+++ b/cranelift/filetests/src/test_simple_preopt.rs
@@ -11,7 +11,7 @@ use std::borrow::Cow;
 
 struct TestSimplePreopt;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "simple_preopt");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/filetests/src/test_verifier.rs b/cranelift/filetests/src/test_verifier.rs
index 7e057248fb..e8d3ffb3ef 100644
--- a/cranelift/filetests/src/test_verifier.rs
+++ b/cranelift/filetests/src/test_verifier.rs
@@ -19,7 +19,7 @@ use std::fmt::Write;
 
 struct TestVerifier;
 
-pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<dyn SubTest>> {
     assert_eq!(parsed.command, "verifier");
     if !parsed.options.is_empty() {
         Err(format!("No options allowed on {}", parsed))
diff --git a/cranelift/frontend/src/frontend.rs b/cranelift/frontend/src/frontend.rs
index 407d03fec4..82a3a09f1a 100644
--- a/cranelift/frontend/src/frontend.rs
+++ b/cranelift/frontend/src/frontend.rs
@@ -571,7 +571,7 @@ impl<'a> FunctionBuilder<'a> {
     /// Useful for debug purposes. Use it with `None` for standard printing.
     // Clippy thinks the lifetime that follows is needless, but rustc needs it
     #[cfg_attr(feature = "cargo-clippy", allow(clippy::needless_lifetimes))]
-    pub fn display<'b, I: Into<Option<&'b TargetIsa>>>(&'b self, isa: I) -> DisplayFunction {
+    pub fn display<'b, I: Into<Option<&'b dyn TargetIsa>>>(&'b self, isa: I) -> DisplayFunction {
         self.func.display(isa)
     }
 }
diff --git a/cranelift/module/src/backend.rs b/cranelift/module/src/backend.rs
index fa23d24f01..316c0a3e2b 100644
--- a/cranelift/module/src/backend.rs
+++ b/cranelift/module/src/backend.rs
@@ -53,7 +53,7 @@ where
     fn new(_: Self::Builder) -> Self;
 
     /// Return the `TargetIsa` to compile for.
-    fn isa(&self) -> &TargetIsa;
+    fn isa(&self) -> &dyn TargetIsa;
 
     /// Declare a function.
     fn declare_function(&mut self, name: &str, linkage: Linkage);
@@ -135,7 +135,7 @@ where
 
 /// Default names for `ir::LibCall`s. A function by this name is imported into the object as
 /// part of the translation of a `ir::ExternalName::LibCall` variant.
-pub fn default_libcall_names() -> Box<Fn(ir::LibCall) -> String> {
+pub fn default_libcall_names() -> Box<dyn Fn(ir::LibCall) -> String> {
     Box::new(move |libcall| match libcall {
         ir::LibCall::Probestack => "__cranelift_probestack".to_owned(),
         ir::LibCall::CeilF32 => "ceilf".to_owned(),
diff --git a/cranelift/module/src/module.rs b/cranelift/module/src/module.rs
index 5d8f3c5f60..33a13b7f9a 100644
--- a/cranelift/module/src/module.rs
+++ b/cranelift/module/src/module.rs
@@ -690,7 +690,7 @@ where
     }
 
     /// Return the target isa
-    pub fn isa(&self) -> &isa::TargetIsa {
+    pub fn isa(&self) -> &dyn isa::TargetIsa {
         self.backend.isa()
     }
 
diff --git a/cranelift/preopt/src/lib.rs b/cranelift/preopt/src/lib.rs
index 310d1ba614..e8cf7be321 100644
--- a/cranelift/preopt/src/lib.rs
+++ b/cranelift/preopt/src/lib.rs
@@ -37,7 +37,7 @@ use cranelift_codegen::{isa::TargetIsa, settings::FlagsOrIsa, CodegenResult, Con
 /// Since this can be resource intensive (and code-size inflating),
 /// it is separated from `Context::compile` to allow DCE to remove it
 /// if it's not used.
-pub fn optimize(ctx: &mut Context, isa: &TargetIsa) -> CodegenResult<()> {
+pub fn optimize(ctx: &mut Context, isa: &dyn TargetIsa) -> CodegenResult<()> {
     ctx.verify_if(isa)?;
     fold_constants(ctx, isa)?;
 
diff --git a/cranelift/reader/src/isaspec.rs b/cranelift/reader/src/isaspec.rs
index 6aefce354a..140eb8324b 100644
--- a/cranelift/reader/src/isaspec.rs
+++ b/cranelift/reader/src/isaspec.rs
@@ -19,12 +19,12 @@ pub enum IsaSpec {
 
     /// The parsed file does contain `isa` commands.
     /// Each `isa` command is used to configure a `TargetIsa` trait object.
-    Some(Vec<Box<TargetIsa>>),
+    Some(Vec<Box<dyn TargetIsa>>),
 }
 
 impl IsaSpec {
     /// If the `IsaSpec` contains exactly 1 `TargetIsa` we return a reference to it
-    pub fn unique_isa(&self) -> Option<&TargetIsa> {
+    pub fn unique_isa(&self) -> Option<&dyn TargetIsa> {
         if let IsaSpec::Some(ref isa_vec) = *self {
             if isa_vec.len() == 1 {
                 return Some(&*isa_vec[0]);
@@ -35,7 +35,11 @@ impl IsaSpec {
 }
 
 /// Parse an iterator of command line options and apply them to `config`.
-pub fn parse_options<'a, I>(iter: I, config: &mut Configurable, loc: Location) -> ParseResult<()>
+pub fn parse_options<'a, I>(
+    iter: I,
+    config: &mut dyn Configurable,
+    loc: Location,
+) -> ParseResult<()>
 where
     I: Iterator<Item = &'a str>,
 {
diff --git a/cranelift/reader/src/parser.rs b/cranelift/reader/src/parser.rs
index 42dfd55f01..037ed2acce 100644
--- a/cranelift/reader/src/parser.rs
+++ b/cranelift/reader/src/parser.rs
@@ -113,11 +113,11 @@ struct Context<'a> {
     /// information. This is only `Some` if exactly one set of `isa` directives were found in the
     /// prologue (it is valid to have directives for multiple different targets, but in that case
     /// we couldn't know which target the provided encodings are intended for)
-    unique_isa: Option<&'a TargetIsa>,
+    unique_isa: Option<&'a dyn TargetIsa>,
 }
 
 impl<'a> Context<'a> {
-    fn new(f: Function, unique_isa: Option<&'a TargetIsa>) -> Self {
+    fn new(f: Function, unique_isa: Option<&'a dyn TargetIsa>) -> Self {
         Self {
             function: f,
             map: SourceMap::new(),
@@ -720,7 +720,7 @@ impl<'a> Parser<'a> {
     }
 
     // Match and consume a register unit either by number `%15` or by name `%rax`.
-    fn match_regunit(&mut self, isa: Option<&TargetIsa>) -> ParseResult<RegUnit> {
+    fn match_regunit(&mut self, isa: Option<&dyn TargetIsa>) -> ParseResult<RegUnit> {
         if let Some(Token::Name(name)) = self.token() {
             self.consume();
             match isa {
@@ -891,7 +891,7 @@ impl<'a> Parser<'a> {
     /// This is the top-level parse function matching the whole contents of a file.
     pub fn parse_function_list(
         &mut self,
-        unique_isa: Option<&TargetIsa>,
+        unique_isa: Option<&dyn TargetIsa>,
     ) -> ParseResult<Vec<(Function, Details<'a>)>> {
         let mut list = Vec::new();
         while self.token().is_some() {
@@ -911,7 +911,7 @@ impl<'a> Parser<'a> {
     //
     fn parse_function(
         &mut self,
-        unique_isa: Option<&TargetIsa>,
+        unique_isa: Option<&dyn TargetIsa>,
     ) -> ParseResult<(Function, Details<'a>)> {
         // Begin gathering comments.
         // Make sure we don't include any comments before the `function` keyword.
@@ -999,7 +999,7 @@ impl<'a> Parser<'a> {
     //
     // signature ::=  * "(" [paramlist] ")" ["->" retlist] [callconv]
     //
-    fn parse_signature(&mut self, unique_isa: Option<&TargetIsa>) -> ParseResult<Signature> {
+    fn parse_signature(&mut self, unique_isa: Option<&dyn TargetIsa>) -> ParseResult<Signature> {
         // Calling convention defaults to `fast`, but can be changed.
         let mut sig = Signature::new(CallConv::Fast);
 
@@ -1033,7 +1033,7 @@ impl<'a> Parser<'a> {
     //
     fn parse_abi_param_list(
         &mut self,
-        unique_isa: Option<&TargetIsa>,
+        unique_isa: Option<&dyn TargetIsa>,
     ) -> ParseResult<Vec<AbiParam>> {
         let mut list = Vec::new();
 
@@ -1050,7 +1050,7 @@ impl<'a> Parser<'a> {
     }
 
     // Parse a single argument type with flags.
-    fn parse_abi_param(&mut self, unique_isa: Option<&TargetIsa>) -> ParseResult<AbiParam> {
+    fn parse_abi_param(&mut self, unique_isa: Option<&dyn TargetIsa>) -> ParseResult<AbiParam> {
         // abi-param ::= * type { flag } [ argumentloc ]
         let mut arg = AbiParam::new(self.match_type("expected parameter type")?);
 
@@ -1079,7 +1079,7 @@ impl<'a> Parser<'a> {
     // Parse an argument location specifier; either a register or a byte offset into the stack.
     fn parse_argument_location(
         &mut self,
-        unique_isa: Option<&TargetIsa>,
+        unique_isa: Option<&dyn TargetIsa>,
     ) -> ParseResult<ArgumentLoc> {
         // argumentloc ::= '[' regname | uimm32 ']'
         if self.optional(Token::LBracket) {
@@ -1426,7 +1426,7 @@ impl<'a> Parser<'a> {
     //
     fn parse_signature_decl(
         &mut self,
-        unique_isa: Option<&TargetIsa>,
+        unique_isa: Option<&dyn TargetIsa>,
     ) -> ParseResult<(SigRef, Signature)> {
         let sig = self.match_sig("expected signature number: sig«n»")?;
         self.match_token(Token::Equal, "expected '=' in signature decl")?;
diff --git a/cranelift/simplejit/src/backend.rs b/cranelift/simplejit/src/backend.rs
index 3786e3e964..c182ada674 100644
--- a/cranelift/simplejit/src/backend.rs
+++ b/cranelift/simplejit/src/backend.rs
@@ -23,9 +23,9 @@ const READONLY_DATA_ALIGNMENT: u8 = 0x1;
 
 /// A builder for `SimpleJITBackend`.
 pub struct SimpleJITBuilder {
-    isa: Box<TargetIsa>,
+    isa: Box<dyn TargetIsa>,
     symbols: HashMap<String, *const u8>,
-    libcall_names: Box<Fn(ir::LibCall) -> String>,
+    libcall_names: Box<dyn Fn(ir::LibCall) -> String>,
 }
 
 impl SimpleJITBuilder {
@@ -35,7 +35,7 @@ impl SimpleJITBuilder {
     /// enum to symbols. LibCalls are inserted in the IR as part of the legalization for certain
     /// floating point instructions, and for stack probes. If you don't know what to use for this
     /// argument, use `cranelift_module::default_libcall_names()`.
-    pub fn new(libcall_names: Box<Fn(ir::LibCall) -> String>) -> Self {
+    pub fn new(libcall_names: Box<dyn Fn(ir::LibCall) -> String>) -> Self {
         let flag_builder = settings::builder();
         let isa_builder = cranelift_native::builder().unwrap_or_else(|msg| {
             panic!("host machine is not supported: {}", msg);
@@ -56,7 +56,10 @@ impl SimpleJITBuilder {
     /// enum to symbols. LibCalls are inserted in the IR as part of the legalization for certain
     /// floating point instructions, and for stack probes. If you don't know what to use for this
     /// argument, use `cranelift_module::default_libcall_names()`.
-    pub fn with_isa(isa: Box<TargetIsa>, libcall_names: Box<Fn(ir::LibCall) -> String>) -> Self {
+    pub fn with_isa(
+        isa: Box<dyn TargetIsa>,
+        libcall_names: Box<dyn Fn(ir::LibCall) -> String>,
+    ) -> Self {
         debug_assert!(!isa.flags().is_pic(), "SimpleJIT requires non-PIC code");
         let symbols = HashMap::new();
         Self {
@@ -108,9 +111,9 @@ impl SimpleJITBuilder {
 ///
 /// See the `SimpleJITBuilder` for a convenient way to construct `SimpleJITBackend` instances.
 pub struct SimpleJITBackend {
-    isa: Box<TargetIsa>,
+    isa: Box<dyn TargetIsa>,
     symbols: HashMap<String, *const u8>,
-    libcall_names: Box<Fn(ir::LibCall) -> String>,
+    libcall_names: Box<dyn Fn(ir::LibCall) -> String>,
     code_memory: Memory,
     readonly_memory: Memory,
     writable_memory: Memory,
@@ -205,7 +208,7 @@ impl<'simple_jit_backend> Backend for SimpleJITBackend {
         }
     }
 
-    fn isa(&self) -> &TargetIsa {
+    fn isa(&self) -> &dyn TargetIsa {
         &*self.isa
     }
 
diff --git a/cranelift/src/disasm.rs b/cranelift/src/disasm.rs
index 65fb33ec06..d7ba0dca6b 100644
--- a/cranelift/src/disasm.rs
+++ b/cranelift/src/disasm.rs
@@ -85,7 +85,7 @@ cfg_if! {
         use capstone::prelude::*;
         use target_lexicon::Architecture;
 
-        fn get_disassembler(isa: &TargetIsa) -> Result<Capstone, String> {
+        fn get_disassembler(isa: &dyn TargetIsa) -> Result<Capstone, String> {
             let cs = match isa.triple().architecture {
                 Architecture::Riscv32 | Architecture::Riscv64 => {
                     return Err(String::from("No disassembler for RiscV"))
@@ -117,7 +117,7 @@ cfg_if! {
             cs.map_err(|err| err.to_string())
         }
 
-        pub fn print_disassembly(isa: &TargetIsa, mem: &[u8]) -> Result<(), String> {
+        pub fn print_disassembly(isa: &dyn TargetIsa, mem: &[u8]) -> Result<(), String> {
             let mut cs = get_disassembler(isa)?;
 
             println!("\nDisassembly of {} bytes:", mem.len());
@@ -156,7 +156,7 @@ cfg_if! {
             Ok(())
         }
     } else {
-        pub fn print_disassembly(_: &TargetIsa, _: &[u8]) -> Result<(), String> {
+        pub fn print_disassembly(_: &dyn TargetIsa, _: &[u8]) -> Result<(), String> {
             println!("\nNo disassembly available.");
             Ok(())
         }
@@ -164,7 +164,7 @@ cfg_if! {
 }
 
 pub fn print_all(
-    isa: &TargetIsa,
+    isa: &dyn TargetIsa,
     mem: &[u8],
     code_size: u32,
     rodata_size: u32,
diff --git a/cranelift/src/utils.rs b/cranelift/src/utils.rs
index a05c0ac3b0..908b310007 100644
--- a/cranelift/src/utils.rs
+++ b/cranelift/src/utils.rs
@@ -42,7 +42,7 @@ pub fn read_to_end<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
 /// Like `FlagsOrIsa`, but holds ownership.
 pub enum OwnedFlagsOrIsa {
     Flags(settings::Flags),
-    Isa(Box<TargetIsa>),
+    Isa(Box<dyn TargetIsa>),
 }
 
 impl OwnedFlagsOrIsa {
diff --git a/cranelift/wasm/src/module_translator.rs b/cranelift/wasm/src/module_translator.rs
index 1cf0f4cd2d..72f257acea 100644
--- a/cranelift/wasm/src/module_translator.rs
+++ b/cranelift/wasm/src/module_translator.rs
@@ -13,7 +13,7 @@ use wasmparser::{ModuleReader, SectionCode};
 /// [`Function`](../codegen/ir/function/struct.Function.html).
 pub fn translate_module<'data>(
     data: &'data [u8],
-    environ: &mut ModuleEnvironment<'data>,
+    environ: &mut dyn ModuleEnvironment<'data>,
 ) -> WasmResult<()> {
     let _tt = timing::wasm_translate_module();
     let mut reader = ModuleReader::new(data)?;
diff --git a/cranelift/wasm/src/sections_translator.rs b/cranelift/wasm/src/sections_translator.rs
index 929114984a..e3dacc1b38 100644
--- a/cranelift/wasm/src/sections_translator.rs
+++ b/cranelift/wasm/src/sections_translator.rs
@@ -27,7 +27,7 @@ use wasmparser::{
 /// Parses the Type section of the wasm module.
 pub fn parse_type_section(
     types: TypeSectionReader,
-    environ: &mut ModuleEnvironment,
+    environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
     environ.reserve_signatures(types.get_count());
 
@@ -60,7 +60,7 @@ pub fn parse_type_section(
 /// Parses the Import section of the wasm module.
 pub fn parse_import_section<'data>(
     imports: ImportSectionReader<'data>,
-    environ: &mut ModuleEnvironment<'data>,
+    environ: &mut dyn ModuleEnvironment<'data>,
 ) -> WasmResult<()> {
     environ.reserve_imports(imports.get_count());
 
@@ -122,7 +122,7 @@ pub fn parse_import_section<'data>(
 /// Parses the Function section of the wasm module.
 pub fn parse_function_section(
     functions: FunctionSectionReader,
-    environ: &mut ModuleEnvironment,
+    environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
     environ.reserve_func_types(functions.get_count());
 
@@ -137,7 +137,7 @@ pub fn parse_function_section(
 /// Parses the Table section of the wasm module.
 pub fn parse_table_section(
     tables: TableSectionReader,
-    environ: &mut ModuleEnvironment,
+    environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
     environ.reserve_tables(tables.get_count());
 
@@ -159,7 +159,7 @@ pub fn parse_table_section(
 /// Parses the Memory section of the wasm module.
 pub fn parse_memory_section(
     memories: MemorySectionReader,
-    environ: &mut ModuleEnvironment,
+    environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
     environ.reserve_memories(memories.get_count());
 
@@ -178,7 +178,7 @@ pub fn parse_memory_section(
 /// Parses the Global section of the wasm module.
 pub fn parse_global_section(
     globals: GlobalSectionReader,
-    environ: &mut ModuleEnvironment,
+    environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
     environ.reserve_globals(globals.get_count());
 
@@ -215,7 +215,7 @@ pub fn parse_global_section(
 /// Parses the Export section of the wasm module.
 pub fn parse_export_section<'data>(
     exports: ExportSectionReader<'data>,
-    environ: &mut ModuleEnvironment<'data>,
+    environ: &mut dyn ModuleEnvironment<'data>,
 ) -> WasmResult<()> {
     environ.reserve_exports(exports.get_count());
 
@@ -243,7 +243,7 @@ pub fn parse_export_section<'data>(
 }
 
 /// Parses the Start section of the wasm module.
-pub fn parse_start_section(index: u32, environ: &mut ModuleEnvironment) -> WasmResult<()> {
+pub fn parse_start_section(index: u32, environ: &mut dyn ModuleEnvironment) -> WasmResult<()> {
     environ.declare_start_func(FuncIndex::from_u32(index));
     Ok(())
 }
@@ -251,7 +251,7 @@ pub fn parse_start_section(index: u32, environ: &mut ModuleEnvironment) -> WasmR
 /// Parses the Element section of the wasm module.
 pub fn parse_element_section<'data>(
     elements: ElementSectionReader<'data>,
-    environ: &mut ModuleEnvironment,
+    environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
     environ.reserve_table_elements(elements.get_count());
 
@@ -292,7 +292,7 @@ pub fn parse_element_section<'data>(
 /// Parses the Code section of the wasm module.
 pub fn parse_code_section<'data>(
     code: CodeSectionReader<'data>,
-    environ: &mut ModuleEnvironment<'data>,
+    environ: &mut dyn ModuleEnvironment<'data>,
 ) -> WasmResult<()> {
     for body in code {
         let mut reader = body?.get_binary_reader();
@@ -306,7 +306,7 @@ pub fn parse_code_section<'data>(
 /// Parses the Data section of the wasm module.
 pub fn parse_data_section<'data>(
     data: DataSectionReader<'data>,
-    environ: &mut ModuleEnvironment<'data>,
+    environ: &mut dyn ModuleEnvironment<'data>,
 ) -> WasmResult<()> {
     environ.reserve_data_initializers(data.get_count());