Remove unnecessary check in RegExpExecStub.

R=ulan@chromium.org
BUG=v8:592
LOG=N

Review URL: https://codereview.chromium.org/363313002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22202 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/code-stubs-arm.cc

@@ -2516,17 +2516,12 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
   __ cmp(r0, Operand(NativeRegExpMacroAssembler::EXCEPTION));
   // If not exception it can only be retry. Handle that in the runtime system.
   __ b(ne, &runtime);
-  // Result must now be exception. If there is no pending exception already a
-  // stack overflow (on the backtrack stack) was detected in RegExp code but
-  // haven't created the exception yet. Handle that in the runtime system.
-  // TODO(592): Rerunning the RegExp to get the stack overflow exception.
+
+  // Result must now be exception.
   __ mov(r1, Operand(isolate()->factory()->the_hole_value()));
   __ mov(r2, Operand(ExternalReference(Isolate::kPendingExceptionAddress,
                                        isolate())));
   __ ldr(r0, MemOperand(r2, 0));
-  __ cmp(r0, r1);
-  __ b(eq, &runtime);
-
   __ str(r1, MemOperand(r2, 0));  // Clear pending exception.
 
   // Check if the exception is a termination. If so, throw as uncatchable.

src/arm64/code-stubs-arm64.cc

@@ -2855,17 +2855,12 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
 
   __ Bind(&exception);
   Register exception_value = x0;
-  // A stack overflow (on the backtrack stack) may have occured
-  // in the RegExp code but no exception has been created yet.
-  // If there is no pending exception, handle that in the runtime system.
+  // Result must now be exception.
   __ Mov(x10, Operand(isolate()->factory()->the_hole_value()));
   __ Mov(x11,
          Operand(ExternalReference(Isolate::kPendingExceptionAddress,
                                    isolate())));
   __ Ldr(exception_value, MemOperand(x11));
-  __ Cmp(x10, exception_value);
-  __ B(eq, &runtime);
-
   __ Str(x10, MemOperand(x11));  // Clear pending exception.
 
   // Check if the exception is a termination. If so, throw as uncatchable.

src/ia32/code-stubs-ia32.cc

@@ -1596,19 +1596,14 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
   __ cmp(eax, NativeRegExpMacroAssembler::EXCEPTION);
   // If not exception it can only be retry. Handle that in the runtime system.
   __ j(not_equal, &runtime);
-  // Result must now be exception. If there is no pending exception already a
-  // stack overflow (on the backtrack stack) was detected in RegExp code but
-  // haven't created the exception yet. Handle that in the runtime system.
-  // TODO(592): Rerunning the RegExp to get the stack overflow exception.
+
+  // Result must now be exception.
   ExternalReference pending_exception(Isolate::kPendingExceptionAddress,
                                       isolate());
   __ mov(edx, Immediate(isolate()->factory()->the_hole_value()));
   __ mov(eax, Operand::StaticVariable(pending_exception));
-  __ cmp(edx, eax);
-  __ j(equal, &runtime);
-  // For exception, throw the exception again.
 
-  // Clear the pending exception variable.
+  // Clear pending exception.
   __ mov(Operand::StaticVariable(pending_exception), edx);
 
   // Special handling of termination exceptions which are uncatchable

src/x64/code-stubs-x64.cc

@@ -1574,19 +1574,14 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
   __ ret(REG_EXP_EXEC_ARGUMENT_COUNT * kPointerSize);
 
   __ bind(&exception);
-  // Result must now be exception. If there is no pending exception already a
-  // stack overflow (on the backtrack stack) was detected in RegExp code but
-  // haven't created the exception yet. Handle that in the runtime system.
-  // TODO(592): Rerunning the RegExp to get the stack overflow exception.
+  // Result must now be exception.
   ExternalReference pending_exception_address(
       Isolate::kPendingExceptionAddress, isolate());
   Operand pending_exception_operand =
       masm->ExternalOperand(pending_exception_address, rbx);
-  __ movp(rax, pending_exception_operand);
   __ LoadRoot(rdx, Heap::kTheHoleValueRootIndex);
-  __ cmpp(rax, rdx);
-  __ j(equal, &runtime);
-  __ movp(pending_exception_operand, rdx);
+  __ movp(rax, pending_exception_operand);
+  __ movp(pending_exception_operand, rdx);  // Clear pending exception.
 
   __ CompareRoot(rax, Heap::kTerminationExceptionRootIndex);
   Label termination_exception;

test/mjsunit/regexp-stack-overflow.js

+// Copyright 2014 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.
+
+// Flags: --stack-size=100
+
+var result = null;
+var type = true;
+var re = /\w/;
+re.test("a");  // Trigger regexp compile.
+
+function rec() {
+  try {
+    return rec();
+  } catch (e) {
+    if (!(e instanceof RangeError)) type = false;
+    return re.test("b");
+  }
+}
+
+assertTrue(rec());
+assertTrue(type);