diff --git a/lib/cretonne/src/ir/dfg.rs b/lib/cretonne/src/ir/dfg.rs
index 9178aeeb38..63ae3a5e97 100644
--- a/lib/cretonne/src/ir/dfg.rs
+++ b/lib/cretonne/src/ir/dfg.rs
@@ -26,7 +26,7 @@ pub struct DataFlowGraph {
     /// Data about all of the instructions in the function, including opcodes and operands.
     /// The instructions in this map are not in program order. That is tracked by `Layout`, along
     /// with the EBB containing each instruction.
-    pub insts: EntityMap<Inst, InstructionData>,
+    insts: EntityMap<Inst, InstructionData>,
 
     /// Memory pool of value lists referenced by instructions in `insts`.
     pub value_lists: ValueListPool,
@@ -77,6 +77,11 @@ impl DataFlowGraph {
         self.insts.len()
     }
 
+    /// Returns `true` if the given instruction reference is valid.
+    pub fn inst_is_valid(&self, inst: Inst) -> bool {
+        self.insts.is_valid(inst)
+    }
+
     /// Get the total number of extended basic blocks created in this function, whether they are
     /// currently inserted in the layout or not.
     ///
diff --git a/lib/cretonne/src/ir/instructions.rs b/lib/cretonne/src/ir/instructions.rs
index f48cbcae6f..626c130740 100644
--- a/lib/cretonne/src/ir/instructions.rs
+++ b/lib/cretonne/src/ir/instructions.rs
@@ -376,6 +376,19 @@ impl InstructionData {
         }
     }
 
+    /// Get a mutable reference to the single destination of this branch instruction, if it is a
+    /// single destination branch or jump.
+    ///
+    /// Multi-destination branches like `br_table` return `None`.
+    pub fn branch_destination_mut(&mut self) -> Option<&mut Ebb> {
+        match *self {
+            InstructionData::Jump { ref mut destination, .. } => Some(destination),
+            InstructionData::Branch { ref mut destination, .. } => Some(destination),
+            InstructionData::BranchIcmp { ref mut destination, .. } => Some(destination),
+            _ => None,
+        }
+    }
+
     /// Return information about a call instruction.
     ///
     /// Any instruction that can call another function reveals its call signature here.
diff --git a/lib/cretonne/src/verifier.rs b/lib/cretonne/src/verifier.rs
index 371ada0440..ace83235df 100644
--- a/lib/cretonne/src/verifier.rs
+++ b/lib/cretonne/src/verifier.rs
@@ -337,7 +337,7 @@ impl<'a> Verifier<'a> {
         match dfg.value_def(v) {
             ValueDef::Res(def_inst, _) => {
                 // Value is defined by an instruction that exists.
-                if !dfg.insts.is_valid(def_inst) {
+                if !dfg.inst_is_valid(def_inst) {
                     return err!(loc_inst,
                                 "{} is defined by invalid instruction {}",
                                 v,
diff --git a/lib/reader/src/parser.rs b/lib/reader/src/parser.rs
index a0302a1a30..a5c3b4244c 100644
--- a/lib/reader/src/parser.rs
+++ b/lib/reader/src/parser.rs
@@ -213,71 +213,10 @@ impl<'a> Context<'a> {
         for ebb in self.function.layout.ebbs() {
             for inst in self.function.layout.ebb_insts(ebb) {
                 let loc = inst.into();
-                let value_lists = &mut self.function.dfg.value_lists;
-                match self.function.dfg.insts[inst] {
-                    InstructionData::Nullary { .. } |
-                    InstructionData::UnaryImm { .. } |
-                    InstructionData::UnaryIeee32 { .. } |
-                    InstructionData::UnaryIeee64 { .. } |
-                    InstructionData::StackLoad { .. } => {}
-
-                    InstructionData::BinaryImm { ref mut arg, .. } |
-                    InstructionData::BranchTable { ref mut arg, .. } |
-                    InstructionData::ExtractLane { ref mut arg, .. } |
-                    InstructionData::IntCompareImm { ref mut arg, .. } |
-                    InstructionData::Unary { ref mut arg, .. } |
-                    InstructionData::UnarySplit { ref mut arg, .. } |
-                    InstructionData::StackStore { ref mut arg, .. } |
-                    InstructionData::HeapLoad { ref mut arg, .. } |
-                    InstructionData::Load { ref mut arg, .. } => {
-                        self.map.rewrite_value(arg, loc)?;
-                    }
-
-                    // `args: Value[2]`
-                    InstructionData::Binary { ref mut args, .. } |
-                    InstructionData::BinaryOverflow { ref mut args, .. } |
-                    InstructionData::InsertLane { ref mut args, .. } |
-                    InstructionData::IntCompare { ref mut args, .. } |
-                    InstructionData::FloatCompare { ref mut args, .. } |
-                    InstructionData::HeapStore { ref mut args, .. } |
-                    InstructionData::Store { ref mut args, .. } => {
-                        self.map.rewrite_values(args, loc)?;
-                    }
-
-                    InstructionData::Ternary { ref mut args, .. } => {
-                        self.map.rewrite_values(args, loc)?;
-                    }
-
-                    InstructionData::MultiAry { ref mut args, .. } => {
-                        self.map
-                            .rewrite_values(args.as_mut_slice(value_lists), loc)?;
-                    }
-
-                    InstructionData::Jump {
-                        ref mut destination,
-                        ref mut args,
-                        ..
-                    } |
-                    InstructionData::Branch {
-                        ref mut destination,
-                        ref mut args,
-                        ..
-                    } |
-                    InstructionData::BranchIcmp {
-                        ref mut destination,
-                        ref mut args,
-                        ..
-                    } => {
-                        self.map.rewrite_ebb(destination, loc)?;
-                        self.map
-                            .rewrite_values(args.as_mut_slice(value_lists), loc)?;
-                    }
-
-                    InstructionData::Call { ref mut args, .. } |
-                    InstructionData::IndirectCall { ref mut args, .. } => {
-                        self.map
-                            .rewrite_values(args.as_mut_slice(value_lists), loc)?;
-                    }
+                self.map
+                    .rewrite_values(self.function.dfg.inst_args_mut(inst), loc)?;
+                if let Some(dest) = self.function.dfg[inst].branch_destination_mut() {
+                    self.map.rewrite_ebb(dest, loc)?;
                 }
             }
         }