[v8-dev] Small refactor to KeyedStoreIC::GenerateGeneric to make it slightly faster. (issue 8008016)

[yangguo]

Reviewers: Rico,

Message:
Please take a look.
Checking for smi before checking for non-smi array should make storing smi
values slightly faster.

Description:
Small refactor to KeyedStoreIC::GenerateGeneric to make it slightly faster.


Please review this at http://codereview.chromium.org/8008016/

SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge

Affected files:
  M src/arm/ic-arm.cc
  M src/ia32/ic-ia32.cc


Index: src/arm/ic-arm.cc
diff --git a/src/arm/ic-arm.cc b/src/arm/ic-arm.cc
index  
9932125a719baedf5b1712fb22bf8e2e4099cbc2..cadddf3895da4a7679f7271616824bba69dd5273  
100644
--- a/src/arm/ic-arm.cc
+++ b/src/arm/ic-arm.cc
@@ -1360,28 +1360,26 @@ void KeyedStoreIC::GenerateGeneric(MacroAssembler*  
masm,
   __ bind(&fast);
   Register scratch_value = r4;
   Register address = r5;
+
+  Label non_smi_value;
+  __ JumpIfNotSmi(value, &non_smi_value);
+  // It's irrelevant whether array is smi-only or not when writing a smi.
+  __ add(address, elements,
+         Operand(FixedArray::kHeaderSize - kHeapObjectTag));
+  __ add(address, address, Operand(key, LSL, kPointerSizeLog2 -  
kSmiTagSize));
+  __ str(value, MemOperand(address));
+  __ Ret();
+
+  __ bind(&non_smi_value);
   if (FLAG_smi_only_arrays) {
-    Label not_smi_only;
     // Make sure the elements are smi-only.
     __ ldr(scratch_value, FieldMemOperand(receiver,  
HeapObject::kMapOffset));
-    __ CheckFastSmiOnlyElements(scratch_value, scratch_value,  
&not_smi_only);
-    // Non-smis need to call into the runtime if the array is smi only.
-    __ JumpIfNotSmi(value, &slow);
-    __ add(address, elements,
-           Operand(FixedArray::kHeaderSize - kHeapObjectTag));
-    __ add(address, address, Operand(key, LSL, kPointerSizeLog2 -  
kSmiTagSize));
-    __ str(value, MemOperand(address));
-    __ Ret();
-    __ bind(&not_smi_only);
+    __ CheckFastObjectElements(scratch_value, scratch_value, &slow);
   }
-  // Fast case, store the value to the elements backing store.
+  // Fast elements array, store the value to the elements backing store.
   __ add(address, elements, Operand(FixedArray::kHeaderSize -  
kHeapObjectTag));
   __ add(address, address, Operand(key, LSL, kPointerSizeLog2 -  
kSmiTagSize));
   __ str(value, MemOperand(address));
-  // Skip write barrier if the written value is a smi.
-  __ tst(value, Operand(kSmiTagMask));
-  __ Ret(eq);
-
   // Update write barrier for the elements array address.
   __ mov(scratch_value, value);  // Preserve the value which is returned.
   __ RecordWrite(elements,
@@ -1391,7 +1389,6 @@ void KeyedStoreIC::GenerateGeneric(MacroAssembler*  
masm,
                  kDontSaveFPRegs,
                  EMIT_REMEMBERED_SET,
                  OMIT_SMI_CHECK);
-
   __ Ret();
 }

Index: src/ia32/ic-ia32.cc
diff --git a/src/ia32/ic-ia32.cc b/src/ia32/ic-ia32.cc
index  
c2181e7134f3838a9d1dafc70d2c596f0c6635c1..50ea5416075670d7ee0dba1bd47efb3c7c251dd4  
100644
--- a/src/ia32/ic-ia32.cc
+++ b/src/ia32/ic-ia32.cc
@@ -811,23 +811,23 @@ void KeyedStoreIC::GenerateGeneric(MacroAssembler*  
masm,
   // edx: receiver
   // edi: FixedArray receiver->elements

+  Label non_smi_value;
+  __ JumpIfNotSmi(eax, &non_smi_value);
+  // It's irrelevant whether array is smi-only or not when writing a smi.
+  __ mov(CodeGenerator::FixedArrayElementOperand(edi, ecx), eax);
+  __ ret(0);
+
+  __ bind(&non_smi_value);
   if (FLAG_smi_only_arrays) {
-    Label not_smi_only;
-    // Make sure the elements are smi-only.
     __ mov(ebx, FieldOperand(edx, HeapObject::kMapOffset));
-    __ CheckFastSmiOnlyElements(ebx, &not_smi_only, Label::kNear);
-    // Non-smis need to call into the runtime if the array is smi only.
-    __ JumpIfNotSmi(eax, &slow);
-    __ mov(CodeGenerator::FixedArrayElementOperand(edi, ecx), eax);
-    __ ret(0);
-    __ bind(&not_smi_only);
+    __ CheckFastObjectElements(ebx, &slow, Label::kNear);
   }
-
+  // Fast elements array, store the value to the elements backing store.
   __ mov(CodeGenerator::FixedArrayElementOperand(edi, ecx), eax);
-
   // Update write barrier for the elements array address.
   __ mov(edx, Operand(eax));  // Preserve the value which is returned.
-  __ RecordWriteArray(edi, edx, ecx, kDontSaveFPRegs);
+  __ RecordWriteArray(
+      edi, edx, ecx, kDontSaveFPRegs, EMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
   __ ret(0);
 }



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