MIPS: Make TestJSArrayForAllocationMemento less awkward.

Port r17220 (be968d52)

Original commit message:
Generated code ended up having two conditional jump statements in a
row. Also introduce JumpIfJSArrayHasAllocationMemento which handles
most cases more simply.

BUG=
R=gergely@homejinni.com

Review URL: https://codereview.chromium.org/27421002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17225 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/codegen-mips.cc

@@ -156,8 +156,7 @@ void ElementsTransitionGenerator::GenerateMapChangeElementsTransition(
   // -----------------------------------
   if (mode == TRACK_ALLOCATION_SITE) {
     ASSERT(allocation_memento_found != NULL);
-    masm->TestJSArrayForAllocationMemento(a2, t0, eq,
-                                          allocation_memento_found);
+    __ JumpIfJSArrayHasAllocationMemento(a2, t0, allocation_memento_found);
   }
 
   // Set transitioned map.
@@ -188,7 +187,7 @@ void ElementsTransitionGenerator::GenerateSmiToDouble(
   Register scratch = t6;
 
   if (mode == TRACK_ALLOCATION_SITE) {
-    masm->TestJSArrayForAllocationMemento(a2, t0, eq, fail);
+    __ JumpIfJSArrayHasAllocationMemento(a2, t0, fail);
   }
 
   // Check for empty arrays, which only require a map transition and no changes
@@ -316,7 +315,7 @@ void ElementsTransitionGenerator::GenerateDoubleToObject(
   Label entry, loop, convert_hole, gc_required, only_change_map;
 
   if (mode == TRACK_ALLOCATION_SITE) {
-    masm->TestJSArrayForAllocationMemento(a2, t0, eq, fail);
+    __ JumpIfJSArrayHasAllocationMemento(a2, t0, fail);
   }
 
   // Check for empty arrays, which only require a map transition and no changes

src/mips/lithium-codegen-mips.cc

@@ -4466,10 +4466,11 @@ void LCodeGen::DoTransitionElementsKind(LTransitionElementsKind* instr) {
 void LCodeGen::DoTrapAllocationMemento(LTrapAllocationMemento* instr) {
   Register object = ToRegister(instr->object());
   Register temp = ToRegister(instr->temp());
-  Label fail;
-  __ TestJSArrayForAllocationMemento(object, temp, ne, &fail);
+  Label no_memento_found;
+  __ TestJSArrayForAllocationMemento(object, temp, &no_memento_found,
+                                     ne, &no_memento_found);
   DeoptimizeIf(al, instr->environment());
-  __ bind(&fail);
+  __ bind(&no_memento_found);
 }
 
 

src/mips/macro-assembler-mips.cc

@@ -5570,23 +5570,24 @@ void MacroAssembler::ClampDoubleToUint8(Register result_reg,
 void MacroAssembler::TestJSArrayForAllocationMemento(
     Register receiver_reg,
     Register scratch_reg,
+    Label* no_memento_found,
     Condition cond,
     Label* allocation_memento_present) {
-  Label no_memento_available;
   ExternalReference new_space_start =
       ExternalReference::new_space_start(isolate());
   ExternalReference new_space_allocation_top =
       ExternalReference::new_space_allocation_top_address(isolate());
   Addu(scratch_reg, receiver_reg,
        Operand(JSArray::kSize + AllocationMemento::kSize - kHeapObjectTag));
-  Branch(&no_memento_available, lt, scratch_reg, Operand(new_space_start));
+  Branch(no_memento_found, lt, scratch_reg, Operand(new_space_start));
   li(at, Operand(new_space_allocation_top));
   lw(at, MemOperand(at));
-  Branch(&no_memento_available, gt, scratch_reg, Operand(at));
+  Branch(no_memento_found, gt, scratch_reg, Operand(at));
   lw(scratch_reg, MemOperand(scratch_reg, -AllocationMemento::kSize));
-  Branch(allocation_memento_present, cond, scratch_reg,
-         Operand(isolate()->factory()->allocation_memento_map()));
-  bind(&no_memento_available);
+  if (allocation_memento_present) {
+    Branch(allocation_memento_present, cond, scratch_reg,
+           Operand(isolate()->factory()->allocation_memento_map()));
+  }
 }
 
 

src/mips/macro-assembler-mips.h

@@ -1520,11 +1520,22 @@ class MacroAssembler: public Assembler {
   // to another type.
   // On entry, receiver_reg should point to the array object.
   // scratch_reg gets clobbered.
-  // If allocation info is present, jump to allocation_info_present
-  void TestJSArrayForAllocationMemento(Register receiver_reg,
-                                       Register scratch_reg,
-                                       Condition cond,
-                                       Label* allocation_memento_present);
+  // If allocation info is present, jump to allocation_memento_present.
+  void TestJSArrayForAllocationMemento(
+      Register receiver_reg,
+      Register scratch_reg,
+      Label* no_memento_found,
+      Condition cond = al,
+      Label* allocation_memento_present = NULL);
+
+  void JumpIfJSArrayHasAllocationMemento(Register receiver_reg,
+                                         Register scratch_reg,
+                                         Label* memento_found) {
+    Label no_memento_found;
+    TestJSArrayForAllocationMemento(receiver_reg, scratch_reg,
+                                    &no_memento_found, eq, memento_found);
+    bind(&no_memento_found);
+  }
 
  private:
   void CallCFunctionHelper(Register function,