Preserve global wasm module offset in SourceLoc.

cranelift/wasm/src/environ/dummy.rs

@@ -458,7 +458,11 @@ impl<'data> ModuleEnvironment<'data> for DummyEnvironment {
         self.info.start_func = Some(func_index);
     }
 
-    fn define_function_body(&mut self, body_bytes: &'data [u8]) -> WasmResult<()> {
+    fn define_function_body(
+        &mut self,
+        body_bytes: &'data [u8],
+        body_offset: usize,
+    ) -> WasmResult<()> {
         let func = {
             let mut func_environ = DummyFuncEnvironment::new(&self.info, self.return_mode);
             let func_index =
@@ -467,7 +471,7 @@ impl<'data> ModuleEnvironment<'data> for DummyEnvironment {
             let sig = func_environ.vmctx_sig(self.get_func_type(func_index));
             let mut func = ir::Function::with_name_signature(name, sig);
             self.trans
-                .translate(body_bytes, &mut func, &mut func_environ)?;
+                .translate(body_bytes, body_offset, &mut func, &mut func_environ)?;
             func
         };
         self.func_bytecode_sizes.push(body_bytes.len());

cranelift/wasm/src/environ/spec.rs

@@ -343,7 +343,11 @@ pub trait ModuleEnvironment<'data> {
     ///
     /// Note there's no `reserve_function_bodies` function because the number of
     /// functions is already provided by `reserve_func_types`.
-    fn define_function_body(&mut self, body_bytes: &'data [u8]) -> WasmResult<()>;
+    fn define_function_body(
+        &mut self,
+        body_bytes: &'data [u8],
+        body_offset: usize,
+    ) -> WasmResult<()>;
 
     /// Provides the number of data initializers up front. By default this does nothing, but
     /// implementations can use this to preallocate memory if desired.

cranelift/wasm/src/func_translator.rs

@@ -54,10 +54,15 @@ impl FuncTranslator {
     pub fn translate<FE: FuncEnvironment + ?Sized>(
         &mut self,
         code: &[u8],
+        code_offset: usize,
         func: &mut ir::Function,
         environ: &mut FE,
     ) -> WasmResult<()> {
-        self.translate_from_reader(BinaryReader::new(code), func, environ)
+        self.translate_from_reader(
+            BinaryReader::new_with_offset(code, code_offset),
+            func,
+            environ,
+        )
     }
 
     /// Translate a binary WebAssembly function from a `BinaryReader`.
@@ -222,11 +227,9 @@ fn parse_function_body<FE: FuncEnvironment + ?Sized>(
 
 /// Get the current source location from a reader.
 fn cur_srcloc(reader: &BinaryReader) -> ir::SourceLoc {
-    // We record source locations as byte code offsets relative to the beginning of the function.
+    // We record source locations as byte code offsets relative to the beginning of the file.
-    // This will wrap around of a single function's byte code is larger than 4 GB, but a) the
+    // This will wrap around if byte code is larger than 4 GB.
-    // WebAssembly format doesn't allow for that, and b) that would hit other Cranelift
+    ir::SourceLoc::new(reader.original_position() as u32)
-    // implementation limits anyway.
-    ir::SourceLoc::new(reader.current_position() as u32)
 }
 
 #[cfg(test)]
@@ -270,7 +273,7 @@ mod tests {
         ctx.func.signature.returns.push(ir::AbiParam::new(I32));
 
         trans
-            .translate(&BODY, &mut ctx.func, &mut runtime.func_env())
+            .translate(&BODY, 0, &mut ctx.func, &mut runtime.func_env())
             .unwrap();
         debug!("{}", ctx.func.display(None));
         ctx.verify(&flags).unwrap();
@@ -308,7 +311,7 @@ mod tests {
         ctx.func.signature.returns.push(ir::AbiParam::new(I32));
 
         trans
-            .translate(&BODY, &mut ctx.func, &mut runtime.func_env())
+            .translate(&BODY, 0, &mut ctx.func, &mut runtime.func_env())
             .unwrap();
         debug!("{}", ctx.func.display(None));
         ctx.verify(&flags).unwrap();
@@ -354,7 +357,7 @@ mod tests {
         ctx.func.signature.returns.push(ir::AbiParam::new(I32));
 
         trans
-            .translate(&BODY, &mut ctx.func, &mut runtime.func_env())
+            .translate(&BODY, 0, &mut ctx.func, &mut runtime.func_env())
             .unwrap();
         debug!("{}", ctx.func.display(None));
         ctx.verify(&flags).unwrap();

cranelift/wasm/src/sections_translator.rs

@@ -295,7 +295,8 @@ pub fn parse_code_section<'data>(
     for body in code {
         let mut reader = body?.get_binary_reader();
         let size = reader.bytes_remaining();
-        environ.define_function_body(reader.read_bytes(size)?)?;
+        let offset = reader.original_position();
+        environ.define_function_body(reader.read_bytes(size)?, offset)?;
     }
     Ok(())
 }