[wasm][asm.js] Make asm.js -> wasm message allocations predictable.

src/asmjs/asm-js.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/asmjs/asm-js.h"
 
 #include "src/api-natives.h"
 #include "src/api.h"
 #include "src/asmjs/asm-typer.h"
 #include "src/asmjs/asm-wasm-builder.h"
@@ skipping 194 matching lines @@
   result->set(kWasmDataCompiledModule, *compiled.ToHandleChecked());
   result->set(kWasmDataForeignGlobals, *foreign_globals);
   result->set(kWasmDataUsesArray, *uses_array);
   result->set(kWasmDataScript, *info->script());
   result->set(kWasmDataScriptPosition,
               Smi::FromInt(info->literal()->position()));
 
   MessageLocation location(info->script(), info->literal()->position(),
                            info->literal()->position());
   char text[100];
-  int length = base::OS::SNPrintF(
-      text, arraysize(text), "success, asm->wasm: %0.3f ms, compile: %0.3f ms",
-      asm_wasm_time, compile_time);
+  int length;
+  if (FLAG_predictable) {
+    length = base::OS::SNPrintF(text, arraysize(text), "success");
+  } else {
+    length =
+        base::OS::SNPrintF(text, arraysize(text),
+                           "success, asm->wasm: %0.3f ms, compile: %0.3f ms",
+                           asm_wasm_time, compile_time);
+  }
   DCHECK_NE(-1, length);
   USE(length);
   Handle<String> stext(info->isolate()->factory()->InternalizeUtf8String(text));
   Handle<JSMessageObject> message = MessageHandler::MakeMessageObject(
       info->isolate(), MessageTemplate::kAsmJsCompiled, &location, stext,
       Handle<JSArray>::null());
   message->set_error_level(v8::Isolate::kMessageInfo);
   if (!FLAG_suppress_asm_messages && FLAG_trace_asm_time) {
     MessageHandler::ReportMessage(info->isolate(), &location, message);
   }
@@ skipping 86 matching lines @@
     return single_function;
   }
 
   i::Handle<i::Script> script(i::Script::cast(wasm_data->get(kWasmDataScript)));
   int32_t position = 0;
   if (!wasm_data->get(kWasmDataScriptPosition)->ToInt32(&position)) {
     UNREACHABLE();
   }
   MessageLocation location(script, position, position);
   char text[50];
-  int length =
-      base::OS::SNPrintF(text, arraysize(text), "success, %0.3f ms",
-                         instantiate_timer.Elapsed().InMillisecondsF());
+  int length;
+  if (FLAG_predictable) {
+    length = base::OS::SNPrintF(text, arraysize(text), "success");
+  } else {
+    length = base::OS::SNPrintF(text, arraysize(text), "success, %0.3f ms",
+                                instantiate_timer.Elapsed().InMillisecondsF());
+  }
   DCHECK_NE(-1, length);
   USE(length);
   Handle<String> stext(isolate->factory()->InternalizeUtf8String(text));
   Handle<JSMessageObject> message = MessageHandler::MakeMessageObject(
       isolate, MessageTemplate::kAsmJsInstantiated, &location, stext,
       Handle<JSArray>::null());
   message->set_error_level(v8::Isolate::kMessageInfo);
   if (!FLAG_suppress_asm_messages && FLAG_trace_asm_time) {
     MessageHandler::ReportMessage(isolate, &location, message);
   }
 
   return module_object;
 }
 
 }  // namespace internal
 }  // namespace v8