MIPS: Some assembler-level optimizations on ARM.

src/mips/lithium-codegen-mips.cc

Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index 13057347f4f6af4058a529854ce09b37f32f6789..428da02e702d7f4dfb1b87f573e4d8d19de22b2c 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -3844,7 +3844,7 @@ void LCodeGen::EmitNumberUntagD(Register input_reg,
   Label load_smi, heap_number, done;
 
   // Smi check.
-  __ JumpIfSmi(input_reg, &load_smi);
+  __ UntagAndJumpIfSmi(scratch, input_reg, &load_smi);
 
   // Heap number map check.
   __ lw(scratch, FieldMemOperand(input_reg, HeapObject::kMapOffset));
@@ -3877,7 +3877,7 @@ void LCodeGen::EmitNumberUntagD(Register input_reg,
 
   // Smi to double register conversion
   __ bind(&load_smi);
-  __ SmiUntag(scratch, input_reg);  // Untag smi before converting to float.
+  // scratch: untagged value of input_reg
   __ mtc1(scratch, result_reg);
   __ cvt_d_w(result_reg, result_reg);
   __ bind(&done);
@@ -4160,7 +4160,7 @@ void LCodeGen::DoClampTToUint8(LClampTToUint8* instr) {
   Label is_smi, done, heap_number;
 
   // Both smi and heap number cases are handled.
-  __ JumpIfSmi(input_reg, &is_smi);
+  __ UntagAndJumpIfSmi(scratch, input_reg, &is_smi);
 
   // Check for heap number
   __ lw(scratch, FieldMemOperand(input_reg, HeapObject::kMapOffset));
@@ -4180,9 +4180,7 @@ void LCodeGen::DoClampTToUint8(LClampTToUint8* instr) {
   __ ClampDoubleToUint8(result_reg, double_scratch0(), temp_reg);
   __ jmp(&done);
 
-  // smi
   __ bind(&is_smi);
-  __ SmiUntag(scratch, input_reg);
   __ ClampUint8(result_reg, scratch);
 
   __ bind(&done);