Handle OOM failures correctly in the CEntryStub when embedders set V8::IgnoreOutOfMemoryException()

src/x64/code-stubs-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4134 matching lines @@
 
   Label retry;
   // If the returned exception is RETRY_AFTER_GC continue at retry label
   STATIC_ASSERT(Failure::RETRY_AFTER_GC == 0);
   __ testl(rax, Immediate(((1 << kFailureTypeTagSize) - 1) << kFailureTagSize));
   __ j(zero, &retry, Label::kNear);
 
   // Special handling of out of memory exceptions.
   JumpIfOOM(masm, rax, kScratchRegister, throw_out_of_memory_exception);
 
-  // Retrieve the pending exception and clear the variable.
+  // Retrieve the pending exception.
   ExternalReference pending_exception_address(
       Isolate::kPendingExceptionAddress, masm->isolate());
   Operand pending_exception_operand =
       masm->ExternalOperand(pending_exception_address);
   __ movq(rax, pending_exception_operand);
+
+  // See if we just retrieved an OOM exception.
+  JumpIfOOM(masm, rax, kScratchRegister, throw_out_of_memory_exception);
+
+  // Clear the pending exception.
+  pending_exception_operand =
+      masm->ExternalOperand(pending_exception_address);

[Michael Starzinger, 2013/04/16 12:09:45]

nit: Do we really need to recompute the operand here? Can't we just use the same
operand twice?

[Jakob Kummerow, 2013/04/16 12:13:11]

Yes, we need to, because the call to masm->ExternalOperand() also emits a move
instruction that modifies kScratchRegister. Obvious, no? :-P

   __ LoadRoot(rdx, Heap::kTheHoleValueRootIndex);
   __ movq(pending_exception_operand, rdx);
 
   // Special handling of termination exceptions which are uncatchable
   // by javascript code.
   __ CompareRoot(rax, Heap::kTerminationExceptionRootIndex);
   __ j(equal, throw_termination_exception);
 
   // Handle normal exception.
   __ jmp(throw_normal_exception);
@@ skipping 2537 matching lines @@
 #endif
 
   __ Ret();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64