Relax --debug-code checks that runtime returns are not the hole

src/ia32/code-stubs-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
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@@ skipping 5020 matching lines @@
   __ mov(Operand(esp, 1 * kPointerSize), esi);  // argv.
   __ mov(Operand(esp, 2 * kPointerSize),
          Immediate(ExternalReference::isolate_address()));
   __ call(ebx);
   // Result is in eax or edx:eax - do not destroy these registers!
 
   if (always_allocate_scope) {
     __ dec(Operand::StaticVariable(scope_depth));
   }
 
-  // Make sure we're not trying to return 'the hole' from the runtime
-  // call as this may lead to crashes in the IC code later.
+  // Most runtime functions should not return 'the hole'.  Allowing it to escape
+  // may lead to crashes in the IC code later.
   if (FLAG_debug_code) {
     Label okay;
     __ cmp(eax, masm->isolate()->factory()->the_hole_value());
     __ j(not_equal, &okay, Label::kNear);
+    // However, it is expected that SuspendJSGeneratorObject returns the hole.

[Michael Starzinger, 2013/04/25 10:39:57]

I am fine with landing this white-listing for now to make tests pass. But can we
add a TODO here to use another sentinel (e.g. a Harmony symbol) instead? This
has really low priority, it would just be "nice to have".

+    __ cmp(ebx, Immediate(ExternalReference(
+        Runtime::kSuspendJSGeneratorObject, masm->isolate())));
+    __ j(equal, &okay, Label::kNear);
     __ int3();
     __ bind(&okay);
   }
 
   // Check for failure result.
   Label failure_returned;
   STATIC_ASSERT(((kFailureTag + 1) & kFailureTagMask) == 0);
   __ lea(ecx, Operand(eax, 1));
   // Lower 2 bits of ecx are 0 iff eax has failure tag.
   __ test(ecx, Immediate(kFailureTagMask));
@@ skipping 2652 matching lines @@
   // Restore ecx.
   __ pop(ecx);
   __ ret(0);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32