Remove unused last_pc_ in AssemblerX64.

Remove unneeded checks for SSE2 in X64 code.
Remove an unneeded check for SSE3 where the X64 code doesn't use SSE3 features.

Review URL: http://codereview.chromium.org/6793040

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7508 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/assembler-x64.h

@@ -1589,8 +1589,6 @@ class Assembler : public AssemblerBase {
   RelocInfoWriter reloc_info_writer;
 
   List< Handle<Code> > code_targets_;
-  // push-pop elimination
-  byte* last_pc_;
 
   PositionsRecorder positions_recorder_;
 

src/x64/code-stubs-x64.cc

@@ -2961,8 +2961,6 @@ void NumberToStringStub::GenerateLookupNumberStringCache(MacroAssembler* masm,
                          times_1,
                          FixedArray::kHeaderSize));
     __ JumpIfSmi(probe, not_found);
-    ASSERT(CpuFeatures::IsSupported(SSE2));
-    CpuFeatures::Scope fscope(SSE2);
     __ movsd(xmm0, FieldOperand(object, HeapNumber::kValueOffset));
     __ movsd(xmm1, FieldOperand(probe, HeapNumber::kValueOffset));
     __ ucomisd(xmm0, xmm1);

src/x64/deoptimizer-x64.cc

@@ -600,7 +600,6 @@ void Deoptimizer::DoComputeFrame(TranslationIterator* iterator,
 
 void Deoptimizer::EntryGenerator::Generate() {
   GeneratePrologue();
-  CpuFeatures::Scope scope(SSE2);
 
   // Save all general purpose registers before messing with them.
   const int kNumberOfRegisters = Register::kNumRegisters;

src/x64/lithium-x64.cc

@@ -1613,10 +1613,8 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
       LOperand* value = UseRegister(instr->value());
       bool needs_check = !instr->value()->type().IsSmi();
       if (needs_check) {
-        LOperand* xmm_temp =
-            (instr->CanTruncateToInt32() && CpuFeatures::IsSupported(SSE3))
-            ? NULL
-            : FixedTemp(xmm1);
+        LOperand* xmm_temp = instr->CanTruncateToInt32() ? NULL
+                                                         : FixedTemp(xmm1);
         LTaggedToI* res = new LTaggedToI(value, xmm_temp);
         return AssignEnvironment(DefineSameAsFirst(res));
       } else {

src/x64/macro-assembler-x64.cc

@@ -2202,7 +2202,6 @@ void MacroAssembler::EnterExitFrameEpilogue(int arg_stack_space,
 #endif
   // Optionally save all XMM registers.
   if (save_doubles) {
-    CpuFeatures::Scope scope(SSE2);
     int space = XMMRegister::kNumRegisters * kDoubleSize +
         arg_stack_space * kPointerSize;
     subq(rsp, Immediate(space));