Optimize KeyedStoreGeneric for Smi arrays.

src/ia32/ic-ia32.cc

Index: src/ia32/ic-ia32.cc
diff --git a/src/ia32/ic-ia32.cc b/src/ia32/ic-ia32.cc
index 65ecaeced037e1e2e069d6e6be92a0365de0866f..61db9d3fc83d1da18cf8fdc398a4b40c7e8d6a01 100644
--- a/src/ia32/ic-ia32.cc
+++ b/src/ia32/ic-ia32.cc
@@ -734,7 +734,9 @@ void KeyedStoreIC::GenerateGeneric(MacroAssembler* masm,
   //  -- edx    : receiver
   //  -- esp[0] : return address
   // -----------------------------------
-  Label slow, fast, array, extra;
+  Label slow, fast_object_with_map_check, fast_object_without_map_check;
+  Label fast_double_with_map_check, fast_double_without_map_check;
+  Label check_extra_double, array, extra;

[Rico, 2011/09/27 12:57:53]

check_extra_double -> check_is_fast_double_array?

[danno, 2011/09/27 16:14:57]

Done.

 
   // Check that the object isn't a smi.
   __ JumpIfSmi(edx, &slow);
@@ -761,11 +763,10 @@ void KeyedStoreIC::GenerateGeneric(MacroAssembler* masm,
   // eax: value
   // edx: JSObject
   // ecx: key (a smi)
-  __ mov(edi, FieldOperand(edx, JSObject::kElementsOffset));
+  __ mov(ebx, FieldOperand(edx, JSObject::kElementsOffset));
   // Check that the object is in fast mode and writable.
-  __ CheckMap(edi, FACTORY->fixed_array_map(), &slow, DONT_DO_SMI_CHECK);
-  __ cmp(ecx, FieldOperand(edi, FixedArray::kLengthOffset));
-  __ j(below, &fast);
+  __ cmp(ecx, FieldOperand(ebx, FixedArray::kLengthOffset));
+  __ j(below, &fast_object_with_map_check);
 
   // Slow case: call runtime.
   __ bind(&slow);
@@ -778,16 +779,24 @@ void KeyedStoreIC::GenerateGeneric(MacroAssembler* masm,
   // eax: value
   // edx: receiver, a JSArray
   // ecx: key, a smi.
-  // edi: receiver->elements, a FixedArray
+  // ebx: receiver->elements, a FixedArray
   // flags: compare (ecx, edx.length())
   // do not leave holes in the array:
   __ j(not_equal, &slow);
-  __ cmp(ecx, FieldOperand(edi, FixedArray::kLengthOffset));
+  __ cmp(ecx, FieldOperand(ebx, FixedArray::kLengthOffset));
   __ j(above_equal, &slow);
   // Add 1 to receiver->length, and go to fast array write.

[Rico, 2011/09/27 12:57:53]

Update comment

[danno, 2011/09/27 16:14:57]

Done.

+  __ CheckMap(ebx, FACTORY->fixed_array_map(),
+              &check_extra_double, DONT_DO_SMI_CHECK);
   __ add(FieldOperand(edx, JSArray::kLengthOffset),
          Immediate(Smi::FromInt(1)));
-  __ jmp(&fast);
+  __ jmp(&fast_object_without_map_check);
+
+  __ bind(&check_extra_double);
+  __ CheckMap(ebx, FACTORY->fixed_double_array_map(), &slow, DONT_DO_SMI_CHECK);
+  __ add(FieldOperand(edx, JSArray::kLengthOffset),
+         Immediate(Smi::FromInt(1)));
+  __ jmp(&fast_double_without_map_check);
 
   // Array case: Get the length and the elements array from the JS

[Rico, 2011/09/27 12:57:53]

This comment seems outdated now, please update to reflect what we do now

[danno, 2011/09/27 16:14:57]

Done.

   // array. Check that the array is in fast mode (and writable); if it
@@ -796,8 +805,7 @@ void KeyedStoreIC::GenerateGeneric(MacroAssembler* masm,
   // eax: value
   // edx: receiver, a JSArray
   // ecx: key, a smi.
-  __ mov(edi, FieldOperand(edx, JSObject::kElementsOffset));
-  __ CheckMap(edi, FACTORY->fixed_array_map(), &slow, DONT_DO_SMI_CHECK);
+  __ mov(ebx, FieldOperand(edx, JSObject::kElementsOffset));
 
   // Check the key against the length in the array, compute the
   // address to store into and fall through to fast case.
@@ -805,30 +813,49 @@ void KeyedStoreIC::GenerateGeneric(MacroAssembler* masm,
   __ j(above_equal, &extra);
 
   // Fast case: Do the store.

[Rico, 2011/09/27 12:57:53]

This comment is also slightly misleading now, since we will not necessarily
actuallty do the store here, we might jump to fast_double case and through there
even go to runtime 

[danno, 2011/09/27 16:14:57]

Done.

-  __ bind(&fast);
+  __ bind(&fast_object_with_map_check);
   // eax: value
   // ecx: key (a smi)
   // edx: receiver
-  // edi: FixedArray receiver->elements
-
+  // ebx: FixedArray receiver->elements
+  __ CheckMap(ebx, FACTORY->fixed_array_map(),
+              &fast_double_with_map_check, DONT_DO_SMI_CHECK);
+  __ bind(&fast_object_without_map_check);
+  // Smi stores don't require further checks.
   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);
+  __ mov(CodeGenerator::FixedArrayElementOperand(ebx, ecx), eax);
   __ ret(0);
 
   __ bind(&non_smi_value);
   if (FLAG_smi_only_arrays) {
     // Escape to slow case when writing non-smi into smi-only array.
-    __ mov(ebx, FieldOperand(edx, HeapObject::kMapOffset));
-    __ CheckFastObjectElements(ebx, &slow, Label::kNear);
+    __ CheckFastObjectElements(edi, &slow, Label::kNear);

[Rico, 2011/09/27 12:57:53]

Could we add something like the following to (all) the registrer overviews:
// edi: receiver map
this is loaded way back.
Also, maybe add comment saying why we will not bailout here if we have a fast
double array (we already jumped over this if we did)

[danno, 2011/09/27 16:14:57]

Done.

   }
+
   // Fast elements array, store the value to the elements backing store.
-  __ mov(CodeGenerator::FixedArrayElementOperand(edi, ecx), eax);
+  __ mov(CodeGenerator::FixedArrayElementOperand(ebx, 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, EMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
+      ebx, edx, ecx, kDontSaveFPRegs, EMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
+  __ ret(0);
+
+  __ bind(&fast_double_with_map_check);
+  // Check for fast double array case. If this fails, call through to the
+  // runtime.
+  __ CheckMap(ebx, FACTORY->fixed_double_array_map(), &slow, DONT_DO_SMI_CHECK);
+  __ bind(&fast_double_without_map_check);
+  // If the value is a number, store it as a double in the FastDoubleElements
+  // array.
+  __ StoreNumberToDoubleElements(eax,
+                                 ebx,
+                                 ecx,
+                                 edx,
+                                 xmm0,
+                                 &slow,
+                                 false);
   __ ret(0);
 }