[v8-dev] MIPS: Minor optimizations in Builtins::Generate_ArgumentsAdaptorTrampoline. (issue 9618013)

[kalmard]

Reviewers: danno, Paul Lind, kisg,

Description:
MIPS: Minor optimizations in Builtins::Generate_ArgumentsAdaptorTrampoline.
The branch delay slot is now utilized in a few loops.
This is the cleanup of an old TODO.

BUG=
TEST=


Please review this at http://codereview.chromium.org/9618013/

Affected files:
  M src/mips/builtins-mips.cc


Index: src/mips/builtins-mips.cc
diff --git a/src/mips/builtins-mips.cc b/src/mips/builtins-mips.cc
index  
715ff95102730f8d7d842ae5117556908beaec6f..09a99243872014c09aea4000d214fb0e6c7eecec  
100644
--- a/src/mips/builtins-mips.cc
+++ b/src/mips/builtins-mips.cc
@@ -1735,8 +1735,6 @@ void  
Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {
     __ bind(&too_few);
     EnterArgumentsAdaptorFrame(masm);

-    // TODO(MIPS): Optimize these loops.
-
     // Calculate copy start address into a0 and copy end address is fp.
     // a0: actual number of arguments as a smi
     // a1: function
@@ -1758,9 +1756,10 @@ void  
Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {
     Label copy;
     __ bind(&copy);
     __ lw(t0, MemOperand(a0));  // Adjusted above for return addr and  
receiver.
-    __ push(t0);
+    __ Subu(sp, sp, kPointerSize);
     __ Subu(a0, a0, kPointerSize);
-    __ Branch(&copy, ne, a0, Operand(t3));
+    __ Branch(USE_DELAY_SLOT, &copy, ne, a0, Operand(t3));
+    __ sw(t0, MemOperand(sp));  // In the delay slot.

     // Fill the remaining expected arguments with undefined.
     // a1: function
@@ -1773,8 +1772,9 @@ void  
Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {

     Label fill;
     __ bind(&fill);
-    __ push(t0);
-    __ Branch(&fill, ne, sp, Operand(a2));
+    __ Subu(sp, sp, kPointerSize);
+    __ Branch(USE_DELAY_SLOT, &fill, ne, sp, Operand(a2));
+    __ sw(t0, MemOperand(sp));
   }

   // Call the entry point.


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