Expose precise offset information in wasmtime::FrameInfo (#1495)

* Consolidate trap/frame information

This commit removes `TrapRegistry` in favor of consolidating this
information in the `FRAME_INFO` we already have in the `wasmtime` crate.
This allows us to keep information generally in one place and have one
canonical location for "map this PC to some original wasm stuff". The
intent for this is to next update with enough information to go from a
program counter to a position in the original wasm file.

* Expose module offset information in `FrameInfo`

This commit implements functionality for `FrameInfo`, the wasm stack
trace of a `Trap`, to return the module/function offset. This allows
knowing the precise wasm location of each stack frame, instead of only
the main trap itself. The intention here is to provide more visibility
into the wasm source when something traps, so you know precisely where
calls were and where traps were, in order to assist in debugging.
Eventually we might use this information for mapping back to native
source languages as well (given sufficient debug information).

This change makes a previously-optional artifact of compilation always
computed on the cranelift side of things. This `ModuleAddressMap` is
then propagated to the same store of information other frame information
is stored within. This also removes the need for passing a `SourceLoc`
with wasm traps or to wasm trap creation, since the backtrace's wasm
frames will be able to infer their own `SourceLoc` from the relevant
program counters.

crates/runtime/src/instance.rs

@@ -14,7 +14,6 @@ use crate::vmcontext::{
     VMGlobalDefinition, VMGlobalImport, VMMemoryDefinition, VMMemoryImport, VMSharedSignatureIndex,
     VMTableDefinition, VMTableImport, VMTrampoline,
 };
-use crate::TrapRegistration;
 use crate::{ExportFunction, ExportGlobal, ExportMemory, ExportTable};
 use memoffset::offset_of;
 use more_asserts::assert_lt;
@@ -111,10 +110,6 @@ pub(crate) struct Instance {
     /// Handler run when `SIGBUS`, `SIGFPE`, `SIGILL`, or `SIGSEGV` are caught by the instance thread.
     pub(crate) signal_handler: Cell<Option<Box<SignalHandler>>>,
 
-    /// Handle to our registration of traps so signals know what trap to return
-    /// when a segfault/sigill happens.
-    pub(crate) trap_registration: TrapRegistration,
-
     /// Additional context used by compiled wasm code. This field is last, and
     /// represents a dynamically-sized array that extends beyond the nominal
     /// end of the struct (similar to a flexible array member).
@@ -603,7 +598,6 @@ impl Instance {
         dst: u32,
         src: u32,
         len: u32,
-        source_loc: ir::SourceLoc,
     ) -> Result<(), Trap> {
         // https://webassembly.github.io/bulk-memory-operations/core/exec/instructions.html#exec-table-init
 
@@ -619,7 +613,7 @@ impl Instance {
             .map_or(true, |n| n as usize > elem.len())
             || dst.checked_add(len).map_or(true, |m| m > table.size())
         {
-            return Err(Trap::wasm(source_loc, ir::TrapCode::TableOutOfBounds));
+            return Err(Trap::wasm(ir::TrapCode::TableOutOfBounds));
         }
 
         // TODO(#983): investigate replacing this get/set loop with a `memcpy`.
@@ -654,7 +648,6 @@ impl Instance {
         dst: u32,
         src: u32,
         len: u32,
-        source_loc: ir::SourceLoc,
     ) -> Result<(), Trap> {
         // https://webassembly.github.io/reference-types/core/exec/instructions.html#exec-memory-copy
 
@@ -667,7 +660,7 @@ impl Instance {
                 .checked_add(len)
                 .map_or(true, |m| m as usize > memory.current_length)
         {
-            return Err(Trap::wasm(source_loc, ir::TrapCode::HeapOutOfBounds));
+            return Err(Trap::wasm(ir::TrapCode::HeapOutOfBounds));
         }
 
         let dst = usize::try_from(dst).unwrap();
@@ -691,14 +684,13 @@ impl Instance {
         dst: u32,
         src: u32,
         len: u32,
-        source_loc: ir::SourceLoc,
     ) -> Result<(), Trap> {
         let import = self.imported_memory(memory_index);
         unsafe {
             let foreign_instance = (&*import.vmctx).instance();
             let foreign_memory = &*import.from;
             let foreign_index = foreign_instance.memory_index(foreign_memory);
-            foreign_instance.defined_memory_copy(foreign_index, dst, src, len, source_loc)
+            foreign_instance.defined_memory_copy(foreign_index, dst, src, len)
         }
     }
 
@@ -713,7 +705,6 @@ impl Instance {
         dst: u32,
         val: u32,
         len: u32,
-        source_loc: ir::SourceLoc,
     ) -> Result<(), Trap> {
         let memory = self.memory(memory_index);
 
@@ -721,7 +712,7 @@ impl Instance {
             .checked_add(len)
             .map_or(true, |m| m as usize > memory.current_length)
         {
-            return Err(Trap::wasm(source_loc, ir::TrapCode::HeapOutOfBounds));
+            return Err(Trap::wasm(ir::TrapCode::HeapOutOfBounds));
         }
 
         let dst = isize::try_from(dst).unwrap();
@@ -748,14 +739,13 @@ impl Instance {
         dst: u32,
         val: u32,
         len: u32,
-        source_loc: ir::SourceLoc,
     ) -> Result<(), Trap> {
         let import = self.imported_memory(memory_index);
         unsafe {
             let foreign_instance = (&*import.vmctx).instance();
             let foreign_memory = &*import.from;
             let foreign_index = foreign_instance.memory_index(foreign_memory);
-            foreign_instance.defined_memory_fill(foreign_index, dst, val, len, source_loc)
+            foreign_instance.defined_memory_fill(foreign_index, dst, val, len)
         }
     }
 
@@ -773,7 +763,6 @@ impl Instance {
         dst: u32,
         src: u32,
         len: u32,
-        source_loc: ir::SourceLoc,
     ) -> Result<(), Trap> {
         // https://webassembly.github.io/bulk-memory-operations/core/exec/instructions.html#exec-memory-init
 
@@ -790,7 +779,7 @@ impl Instance {
                 .checked_add(len)
                 .map_or(true, |m| m as usize > memory.current_length)
         {
-            return Err(Trap::wasm(source_loc, ir::TrapCode::HeapOutOfBounds));
+            return Err(Trap::wasm(ir::TrapCode::HeapOutOfBounds));
         }
 
         let src_slice = &data[src as usize..(src + len) as usize];
@@ -859,7 +848,6 @@ impl InstanceHandle {
     /// safety.
     pub unsafe fn new(
         module: Arc<Module>,
-        trap_registration: TrapRegistration,
         finished_functions: BoxedSlice<DefinedFuncIndex, *mut [VMFunctionBody]>,
         trampolines: HashMap<VMSharedSignatureIndex, VMTrampoline>,
         imports: Imports,
@@ -906,7 +894,6 @@ impl InstanceHandle {
                 dbg_jit_registration,
                 host_state,
                 signal_handler: Cell::new(None),
-                trap_registration,
                 vmctx: VMContext {},
             };
             let layout = instance.alloc_layout();
@@ -1256,7 +1243,6 @@ fn initialize_tables(instance: &Instance) -> Result<(), InstantiationError> {
             .map_or(true, |end| end > table.size() as usize)
         {
             return Err(InstantiationError::Trap(Trap::wasm(
-                ir::SourceLoc::default(),
                 ir::TrapCode::HeapOutOfBounds,
             )));
         }
@@ -1332,7 +1318,6 @@ fn initialize_memories(
             .map_or(true, |end| end > memory.current_length)
         {
             return Err(InstantiationError::Trap(Trap::wasm(
-                ir::SourceLoc::default(),
                 ir::TrapCode::HeapOutOfBounds,
             )));
         }
@@ -1407,9 +1392,9 @@ pub enum InstantiationError {
 
     /// A trap ocurred during instantiation, after linking.
     #[error("Trap occurred during instantiation")]
-    Trap(#[source] Trap),
+    Trap(Trap),
 
     /// A compilation error occured.
     #[error("Trap occurred while invoking start function")]
-    StartTrap(#[source] Trap),
+    StartTrap(Trap),
 }