MIPS: DoNumberTagD performance improvement

Port r12711 (a8d45ac2)

Original commit message:
Allocate heap entry untagged and tag at end to avoid having to subtract off
the tag offset before storing the value.

BUG=
TEST=

Review URL: https://codereview.chromium.org/11280106
Patch from Akos Palfi <palfia@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13087 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/lithium-codegen-mips.cc

@@ -4245,7 +4245,7 @@ void LCodeGen::DoDeferredNumberTagI(LInstruction* instr,
 
   if (FLAG_inline_new) {
     __ LoadRoot(t2, Heap::kHeapNumberMapRootIndex);
-    __ AllocateHeapNumber(t1, a3, t0, t2, &slow);
+    __ AllocateHeapNumber(t1, a3, t0, t2, &slow, DONT_TAG_RESULT);
     __ Move(dst, t1);
     __ Branch(&done);
   }
@@ -4259,11 +4259,13 @@ void LCodeGen::DoDeferredNumberTagI(LInstruction* instr,
   __ StoreToSafepointRegisterSlot(zero_reg, dst);
   CallRuntimeFromDeferred(Runtime::kAllocateHeapNumber, 0, instr);
   __ Move(dst, v0);
+  __ Subu(dst, dst, kHeapObjectTag);
 
   // Done. Put the value in dbl_scratch into the value of the allocated heap
   // number.
   __ bind(&done);
-  __ sdc1(dbl_scratch, FieldMemOperand(dst, HeapNumber::kValueOffset));
+  __ sdc1(dbl_scratch, MemOperand(dst, HeapNumber::kValueOffset));
+  __ Addu(dst, dst, kHeapObjectTag);
   __ StoreToSafepointRegisterSlot(dst, dst);
 }
 
@@ -4288,12 +4290,16 @@ void LCodeGen::DoNumberTagD(LNumberTagD* instr) {
   DeferredNumberTagD* deferred = new(zone()) DeferredNumberTagD(this, instr);
   if (FLAG_inline_new) {
     __ LoadRoot(scratch, Heap::kHeapNumberMapRootIndex);
-    __ AllocateHeapNumber(reg, temp1, temp2, scratch, deferred->entry());
+    // We want the untagged address first for performance
+    __ AllocateHeapNumber(reg, temp1, temp2, scratch, deferred->entry(),
+                          DONT_TAG_RESULT);
   } else {
     __ Branch(deferred->entry());
   }
   __ bind(deferred->exit());
-  __ sdc1(input_reg, FieldMemOperand(reg, HeapNumber::kValueOffset));
+  __ sdc1(input_reg, MemOperand(reg, HeapNumber::kValueOffset));
+  // Now that we have finished with the object's real address tag it
+  __ Addu(reg, reg, kHeapObjectTag);
 }
 
 
@@ -4306,6 +4312,7 @@ void LCodeGen::DoDeferredNumberTagD(LNumberTagD* instr) {
 
   PushSafepointRegistersScope scope(this, Safepoint::kWithRegisters);
   CallRuntimeFromDeferred(Runtime::kAllocateHeapNumber, 0, instr);
+  __ Subu(v0, v0, kHeapObjectTag);
   __ StoreToSafepointRegisterSlot(v0, reg);
 }
 

src/mips/macro-assembler-mips.cc

@@ -3234,7 +3234,8 @@ void MacroAssembler::AllocateHeapNumber(Register result,
                                         Register scratch1,
                                         Register scratch2,
                                         Register heap_number_map,
-                                        Label* need_gc) {
+                                        Label* need_gc,
+                                        TaggingMode tagging_mode) {
   // Allocate an object in the heap for the heap number and tag it as a heap
   // object.
   AllocateInNewSpace(HeapNumber::kSize,
@@ -3242,11 +3243,16 @@ void MacroAssembler::AllocateHeapNumber(Register result,
                      scratch1,
                      scratch2,
                      need_gc,
-                     TAG_OBJECT);
+                     tagging_mode == TAG_RESULT ? TAG_OBJECT :
+                                                  NO_ALLOCATION_FLAGS);
 
   // Store heap number map in the allocated object.
   AssertRegisterIsRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
+  if (tagging_mode == TAG_RESULT) {
     sw(heap_number_map, FieldMemOperand(result, HeapObject::kMapOffset));
+  } else {
+    sw(heap_number_map, MemOperand(result, HeapObject::kMapOffset));
+  }
 }
 
 

src/mips/macro-assembler-mips.h

@@ -65,6 +65,14 @@ enum AllocationFlags {
   SIZE_IN_WORDS = 1 << 2
 };
 
+// Flags used for AllocateHeapNumber
+enum TaggingMode {
+  // Tag the result.
+  TAG_RESULT,
+  // Don't tag
+  DONT_TAG_RESULT
+};
+
 // Flags used for the ObjectToDoubleFPURegister function.
 enum ObjectToDoubleFlags {
   // No special flags.
@@ -536,7 +544,8 @@ class MacroAssembler: public Assembler {
                           Register scratch1,
                           Register scratch2,
                           Register heap_number_map,
-                          Label* gc_required);
+                          Label* gc_required,
+                          TaggingMode tagging_mode = TAG_RESULT);
   void AllocateHeapNumberWithValue(Register result,
                                    FPURegister value,
                                    Register scratch1,

src/mips/stub-cache-mips.cc

@@ -3847,20 +3847,27 @@ void KeyedLoadStubCompiler::GenerateLoadExternalArray(
     __ Ret();
 
     __ bind(&box_int);
+
+    if (CpuFeatures::IsSupported(FPU)) {
+      CpuFeatures::Scope scope(FPU);
       // Allocate a HeapNumber for the result and perform int-to-double
       // conversion.
       // The arm version uses a temporary here to save r0, but we don't need to
       // (a0 is not modified).
       __ LoadRoot(t1, Heap::kHeapNumberMapRootIndex);
-    __ AllocateHeapNumber(v0, a3, t0, t1, &slow);
+      __ AllocateHeapNumber(v0, a3, t0, t1, &slow, DONT_TAG_RESULT);
-
-    if (CpuFeatures::IsSupported(FPU)) {
-      CpuFeatures::Scope scope(FPU);
       __ mtc1(value, f0);
       __ cvt_d_w(f0, f0);
-      __ sdc1(f0, FieldMemOperand(v0, HeapNumber::kValueOffset));
+      __ sdc1(f0, MemOperand(v0, HeapNumber::kValueOffset));
+      __ Addu(v0, v0, kHeapObjectTag);
       __ Ret();
     } else {
+      // Allocate a HeapNumber for the result and perform int-to-double
+      // conversion.
+      // The arm version uses a temporary here to save r0, but we don't need to
+      // (a0 is not modified).
+      __ LoadRoot(t1, Heap::kHeapNumberMapRootIndex);
+      __ AllocateHeapNumber(v0, a3, t0, t1, &slow, TAG_RESULT);
       Register dst1 = t2;
       Register dst2 = t3;
       FloatingPointHelper::Destination dest =
@@ -3897,7 +3904,7 @@ void KeyedLoadStubCompiler::GenerateLoadExternalArray(
       // conversion. Don't use a0 and a1 as AllocateHeapNumber clobbers all
       // registers - also when jumping due to exhausted young space.
       __ LoadRoot(t6, Heap::kHeapNumberMapRootIndex);
-      __ AllocateHeapNumber(v0, t2, t3, t6, &slow);
+      __ AllocateHeapNumber(v0, t2, t3, t6, &slow, DONT_TAG_RESULT);
 
       // This is replaced by a macro:
       // __ mtc1(value, f0);     // LS 32-bits.
@@ -3906,8 +3913,9 @@ void KeyedLoadStubCompiler::GenerateLoadExternalArray(
 
       __ Cvt_d_uw(f0, value, f22);
 
-      __ sdc1(f0, FieldMemOperand(v0, HeapNumber::kValueOffset));
+      __ sdc1(f0, MemOperand(v0, HeapNumber::kValueOffset));
 
+      __ Addu(v0, v0, kHeapObjectTag);
       __ Ret();
     } else {
       // Check whether unsigned integer fits into smi.
@@ -3940,7 +3948,7 @@ void KeyedLoadStubCompiler::GenerateLoadExternalArray(
       // clobbers all registers - also when jumping due to exhausted young
       // space.
       __ LoadRoot(t6, Heap::kHeapNumberMapRootIndex);
-      __ AllocateHeapNumber(t2, t3, t5, t6, &slow);
+      __ AllocateHeapNumber(t2, t3, t5, t6, &slow, TAG_RESULT);
 
       __ sw(hiword, FieldMemOperand(t2, HeapNumber::kExponentOffset));
       __ sw(loword, FieldMemOperand(t2, HeapNumber::kMantissaOffset));
@@ -3957,17 +3965,19 @@ void KeyedLoadStubCompiler::GenerateLoadExternalArray(
       // AllocateHeapNumber clobbers all registers - also when jumping due to
       // exhausted young space.
       __ LoadRoot(t6, Heap::kHeapNumberMapRootIndex);
-      __ AllocateHeapNumber(v0, t3, t5, t6, &slow);
+      __ AllocateHeapNumber(v0, t3, t5, t6, &slow, DONT_TAG_RESULT);
       // The float (single) value is already in fpu reg f0 (if we use float).
       __ cvt_d_s(f0, f0);
-      __ sdc1(f0, FieldMemOperand(v0, HeapNumber::kValueOffset));
+      __ sdc1(f0, MemOperand(v0, HeapNumber::kValueOffset));
+
+      __ Addu(v0, v0, kHeapObjectTag);
       __ Ret();
     } else {
       // Allocate a HeapNumber for the result. Don't use a0 and a1 as
       // AllocateHeapNumber clobbers all registers - also when jumping due to
       // exhausted young space.
       __ LoadRoot(t6, Heap::kHeapNumberMapRootIndex);
-      __ AllocateHeapNumber(v0, t3, t5, t6, &slow);
+      __ AllocateHeapNumber(v0, t3, t5, t6, &slow, TAG_RESULT);
       // FPU is not available, do manual single to double conversion.
 
       // a2: floating point value (binary32).
@@ -4022,16 +4032,18 @@ void KeyedLoadStubCompiler::GenerateLoadExternalArray(
       // AllocateHeapNumber clobbers all registers - also when jumping due to
       // exhausted young space.
       __ LoadRoot(t6, Heap::kHeapNumberMapRootIndex);
-      __ AllocateHeapNumber(v0, t3, t5, t6, &slow);
+      __ AllocateHeapNumber(v0, t3, t5, t6, &slow, DONT_TAG_RESULT);
       // The double value is already in f0
-      __ sdc1(f0, FieldMemOperand(v0, HeapNumber::kValueOffset));
+      __ sdc1(f0, MemOperand(v0, HeapNumber::kValueOffset));
+
+      __ Addu(v0, v0, kHeapObjectTag);
       __ Ret();
     } else {
       // Allocate a HeapNumber for the result. Don't use a0 and a1 as
       // AllocateHeapNumber clobbers all registers - also when jumping due to
       // exhausted young space.
       __ LoadRoot(t6, Heap::kHeapNumberMapRootIndex);
-      __ AllocateHeapNumber(v0, t3, t5, t6, &slow);
+      __ AllocateHeapNumber(v0, t3, t5, t6, &slow, TAG_RESULT);
 
       __ sw(a2, FieldMemOperand(v0, HeapNumber::kMantissaOffset));
       __ sw(a3, FieldMemOperand(v0, HeapNumber::kExponentOffset));
@@ -4549,7 +4561,7 @@ void KeyedLoadStubCompiler::GenerateLoadFastDoubleElement(
   // Non-NaN. Allocate a new heap number and copy the double value into it.
   __ LoadRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
   __ AllocateHeapNumber(heap_number_reg, scratch2, scratch3,
-                        heap_number_map, &slow_allocate_heapnumber);
+                        heap_number_map, &slow_allocate_heapnumber, TAG_RESULT);
 
   // Don't need to reload the upper 32 bits of the double, it's already in
   // scratch.