Reviewers: fschneider, danno, Paul Lind, kisg,
Description:
MIPS: Improve performance of keyed loads/stores which have a HeapNumber
index.
Port r11282 (bd2ab07).
Original commit message:
Some GWT compiled code results in array access that has a heap number (e.g.
-0)
as an index. Until now this would result in a generic IC.
For example:
a[-0] === a[0] or
a[0.25 * 4] === a[1]
This change detects heap numbers that are representable as a smi
and converts them. As a result we can still use the fast keyed monomorphic
ICs. Optimized code already handles keyed access with a double-key
efficiently.
As a result the frame rate on the reported benchmark improves by roughly 2x.
BUG=
TEST=
Please review this at http://codereview.chromium.org/10068012/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/mips/stub-cache-mips.cc
Index: src/mips/stub-cache-mips.cc
diff --git a/src/mips/stub-cache-mips.cc b/src/mips/stub-cache-mips.cc
index
4d18c942db86b0d185e3fc6cf3d50e8dc32dbbfd..a319011d0fa809344e3d311956b804102118e4ff
100644
--- a/src/mips/stub-cache-mips.cc
+++ b/src/mips/stub-cache-mips.cc
@@ -3371,6 +3371,45 @@ static bool IsElementTypeSigned(ElementsKind
elements_kind) {
}
+static void GenerateSmiKeyCheck(MacroAssembler* masm,
+ Register key,
+ Register scratch0,
+ Register scratch1,
+ FPURegister double_scratch0,
+ Label* fail) {
+ if (CpuFeatures::IsSupported(FPU)) {
+ CpuFeatures::Scope scope(FPU);
+ Label key_ok;
+ // Check for smi or a smi inside a heap number. We convert the heap
+ // number and check if the conversion is exact and fits into the smi
+ // range.
+ __ JumpIfSmi(key, &key_ok);
+ __ CheckMap(key,
+ scratch0,
+ Heap::kHeapNumberMapRootIndex,
+ fail,
+ DONT_DO_SMI_CHECK);
+ __ ldc1(double_scratch0, FieldMemOperand(key,
HeapNumber::kValueOffset));
+ __ EmitFPUTruncate(kRoundToZero,
+ double_scratch0,
+ double_scratch0,
+ scratch0,
+ scratch1,
+ kCheckForInexactConversion);
+
+ __ Branch(fail, ne, scratch1, Operand(zero_reg));
+
+ __ mfc1(scratch0, double_scratch0);
+ __ SmiTagCheckOverflow(key, scratch0, scratch1);
+ __ BranchOnOverflow(fail, scratch1);
+ __ bind(&key_ok);
+ } else {
+ // Check that the key is a smi.
+ __ JumpIfNotSmi(key, fail);
+ }
+}
+
+
void KeyedLoadStubCompiler::GenerateLoadExternalArray(
MacroAssembler* masm,
ElementsKind elements_kind) {
@@ -3387,8 +3426,8 @@ void KeyedLoadStubCompiler::GenerateLoadExternalArray(
// This stub is meant to be tail-jumped to, the receiver must already
// have been verified by the caller to not be a smi.
- // Check that the key is a smi.
- __ JumpIfNotSmi(key, &miss_force_generic);
+ // Check that the key is a smi or a heap number convertible to a smi.
+ GenerateSmiKeyCheck(masm, key, t0, t1, f2, &miss_force_generic);
__ lw(a3, FieldMemOperand(receiver, JSObject::kElementsOffset));
// a3: elements array
@@ -3726,8 +3765,8 @@ void
KeyedStoreStubCompiler::GenerateStoreExternalArray(
// This stub is meant to be tail-jumped to, the receiver must already
// have been verified by the caller to not be a smi.
- // Check that the key is a smi.
- __ JumpIfNotSmi(key, &miss_force_generic);
+ // Check that the key is a smi or a heap number convertible to a smi.
+ GenerateSmiKeyCheck(masm, key, t0, t1, f2, &miss_force_generic);
__ lw(a3, FieldMemOperand(receiver, JSObject::kElementsOffset));
@@ -4106,9 +4145,8 @@ void
KeyedLoadStubCompiler::GenerateLoadFastElement(MacroAssembler* masm) {
// This stub is meant to be tail-jumped to, the receiver must already
// have been verified by the caller to not be a smi.
- // Check that the key is a smi.
- __ JumpIfNotSmi(a0, &miss_force_generic, at, USE_DELAY_SLOT);
- // The delay slot can be safely used here, a1 is an object pointer.
+ // Check that the key is a smi or a heap number convertible to a smi.
+ GenerateSmiKeyCheck(masm, a0, t0, t1, f2, &miss_force_generic);
// Get the elements array.
__ lw(a2, FieldMemOperand(a1, JSObject::kElementsOffset));
@@ -4158,8 +4196,8 @@ void
KeyedLoadStubCompiler::GenerateLoadFastDoubleElement(
// This stub is meant to be tail-jumped to, the receiver must already
// have been verified by the caller to not be a smi.
- // Check that the key is a smi.
- __ JumpIfNotSmi(key_reg, &miss_force_generic);
+ // Check that the key is a smi or a heap number convertible to a smi.
+ GenerateSmiKeyCheck(masm, key_reg, t0, t1, f2, &miss_force_generic);
// Get the elements array.
__ lw(elements_reg,
@@ -4233,8 +4271,8 @@ void KeyedStoreStubCompiler::GenerateStoreFastElement(
// This stub is meant to be tail-jumped to, the receiver must already
// have been verified by the caller to not be a smi.
- // Check that the key is a smi.
- __ JumpIfNotSmi(key_reg, &miss_force_generic);
+ // Check that the key is a smi or a heap number convertible to a smi.
+ GenerateSmiKeyCheck(masm, key_reg, t0, t1, f2, &miss_force_generic);
if (elements_kind == FAST_SMI_ONLY_ELEMENTS) {
__ JumpIfNotSmi(value_reg, &transition_elements_kind);
@@ -4400,7 +4438,9 @@ void
KeyedStoreStubCompiler::GenerateStoreFastDoubleElement(
// This stub is meant to be tail-jumped to, the receiver must already
// have been verified by the caller to not be a smi.
- __ JumpIfNotSmi(key_reg, &miss_force_generic);
+
+ // Check that the key is a smi or a heap number convertible to a smi.
+ GenerateSmiKeyCheck(masm, key_reg, t0, t1, f2, &miss_force_generic);
__ lw(elements_reg,
FieldMemOperand(receiver_reg, JSObject::kElementsOffset));
--
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