[wasm] Also print relative position for compiled frames

This helps debugging wasm crashes. {WasmCompiledFrame::Print} should
also print the position inside the current function, additional to the
absolute position in the wasm module. The source positions encoded in
wasm code are also function-relative, so with the additional output
it's easier to match them.

R=ahaas@chromium.org

Change-Id: I40f99e75e3ba25fdfd24943ea96e49868b91844f
Reviewed-on: https://chromium-review.googlesource.com/1138053Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54458}

src/frames.cc

@@ -1772,9 +1772,14 @@ void WasmCompiledFrame::Print(StringStream* accumulator, PrintMode mode,
   int func_name_len = std::min(kMaxPrintedFunctionName, raw_func_name.length());
   memcpy(func_name, raw_func_name.start(), func_name_len);
   func_name[func_name_len] = '\0';
-  accumulator->Add("], function #%u ('%s'), pc=%p (+0x%x), pos=%d\n",
-                   function_index(), func_name, reinterpret_cast<void*>(pc()),
-                   static_cast<int>(pc() - instruction_start), position());
+  int pos = position();
+  const wasm::WasmModule* module = wasm_instance()->module_object()->module();
+  int func_index = function_index();
+  int func_code_offset = module->functions[func_index].code.offset();
+  accumulator->Add("], function #%u ('%s'), pc=%p (+0x%x), pos=%d (+%d)\n",
+                   func_index, func_name, reinterpret_cast<void*>(pc()),
+                   static_cast<int>(pc() - instruction_start), pos,
+                   pos - func_code_offset);
   if (mode != OVERVIEW) accumulator->Add("\n");
 }