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Unified Diff: src/arm/full-codegen-arm.cc

Issue 10909007: Sharing of descriptor arrays. (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: Addressed comments Created 8 years, 3 months ago
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Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index 85e94f29649dacf999f1fbf7afd4415a6f48bfb0..54dc5a1da7c0ba9ad2a21ea212f9b279fdd4cf73 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -2729,26 +2729,31 @@ void FullCodeGenerator::EmitIsStringWrapperSafeForDefaultValueOf(
__ b(eq, if_false);
// Look for valueOf symbol in the descriptor array, and indicate false if
- // found. The type is not checked, so if it is a transition it is a false
- // negative.
- __ LoadInstanceDescriptors(r1, r4, r3);
- __ ldr(r3, FieldMemOperand(r4, FixedArray::kLengthOffset));
- // r4: descriptor array
- // r3: length of descriptor array
- // Calculate the end of the descriptor array.
+ // found. Since we omit an enumeration index check, if it is added via a
+ // transition that shares its descriptor array, this is a false positive.
+ Label entry, loop, done;
+
+ // Skip loop if no descriptors are valid.
+ __ NumberOfOwnDescriptors(r3, r1);
+ __ cmp(r3, Operand(0));
+ __ b(eq, &done);
+
+ __ LoadInstanceDescriptors(r1, r4, r2);
+ // r4: descriptor array.
+ // r3: valid entries in the descriptor array.
STATIC_ASSERT(kSmiTag == 0);
STATIC_ASSERT(kSmiTagSize == 1);
STATIC_ASSERT(kPointerSize == 4);
- __ add(r2, r4, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
+ __ mov(ip, Operand(DescriptorArray::kDescriptorSize));
+ __ mul(r3, r3, ip);
+ // Calculate location of the first key name.
+ __ add(r4, r4, Operand(DescriptorArray::kFirstOffset - kHeapObjectTag));
+ // Calculate the end of the descriptor array.
+ __ mov(r2, r4);
__ add(r2, r2, Operand(r3, LSL, kPointerSizeLog2 - kSmiTagSize));
- // Calculate location of the first key name.
- __ add(r4,
- r4,
- Operand(DescriptorArray::kFirstOffset - kHeapObjectTag));
// Loop through all the keys in the descriptor array. If one of these is the
// symbol valueOf the result is false.
- Label entry, loop;
// The use of ip to store the valueOf symbol asumes that it is not otherwise
// used in the loop below.
__ mov(ip, Operand(FACTORY->value_of_symbol()));
@@ -2762,7 +2767,8 @@ void FullCodeGenerator::EmitIsStringWrapperSafeForDefaultValueOf(
__ cmp(r4, Operand(r2));
__ b(ne, &loop);
- // If a valueOf property is not found on the object check that it's
+ __ bind(&done);
+ // If a valueOf property is not found on the object check that its
// prototype is the un-modified String prototype. If not result is false.
__ ldr(r2, FieldMemOperand(r1, Map::kPrototypeOffset));
__ JumpIfSmi(r2, if_false);
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