[x64] Make xmm0 allocatable and use xmm15 as scratch register instead.

src/compiler/x64/code-generator-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/code-generator.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/osr.h"
 #include "src/x64/assembler-x64.h"
 #include "src/x64/macro-assembler-x64.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 #define __ masm()->
 
-
-#define kScratchDoubleReg xmm0
-
-
 // Adds X64 specific methods for decoding operands.
 class X64OperandConverter : public InstructionOperandConverter {
  public:
   X64OperandConverter(CodeGenerator* gen, Instruction* instr)
       : InstructionOperandConverter(gen, instr) {}
 
   Immediate InputImmediate(size_t index) {
     return ToImmediate(instr_->InputAt(index));
   }
 
@@ skipping 2185 matching lines @@
       Operand dst = g.ToOperand(destination);
       __ Movsd(dst, src);
     }
   } else if (source->IsFPStackSlot()) {
     DCHECK(destination->IsFPRegister() || destination->IsFPStackSlot());
     Operand src = g.ToOperand(source);
     if (destination->IsFPRegister()) {
       XMMRegister dst = g.ToDoubleRegister(destination);
       __ Movsd(dst, src);
     } else {
-      // We rely on having xmm0 available as a fixed scratch register.
       Operand dst = g.ToOperand(destination);
-      __ Movsd(xmm0, src);
-      __ Movsd(dst, xmm0);
+      __ Movsd(kScratchDoubleReg, src);
+      __ Movsd(dst, kScratchDoubleReg);
     }
   } else {
     UNREACHABLE();
   }
 }
 
 
 void CodeGenerator::AssembleSwap(InstructionOperand* source,
                                  InstructionOperand* destination) {
   X64OperandConverter g(this, nullptr);
@@ skipping 23 matching lines @@
     Operand dst = g.ToOperand(destination);
     __ movq(tmp, dst);
     __ pushq(src);
     frame_access_state()->IncreaseSPDelta(1);
     src = g.ToOperand(source);
     __ movq(src, tmp);
     frame_access_state()->IncreaseSPDelta(-1);
     dst = g.ToOperand(destination);
     __ popq(dst);
   } else if (source->IsFPRegister() && destination->IsFPRegister()) {
-    // XMM register-register swap. We rely on having xmm0
-    // available as a fixed scratch register.
+    // XMM register-register swap.
     XMMRegister src = g.ToDoubleRegister(source);
     XMMRegister dst = g.ToDoubleRegister(destination);
-    __ Movapd(xmm0, src);
+    __ Movapd(kScratchDoubleReg, src);
     __ Movapd(src, dst);
-    __ Movapd(dst, xmm0);
+    __ Movapd(dst, kScratchDoubleReg);
   } else if (source->IsFPRegister() && destination->IsFPStackSlot()) {
-    // XMM register-memory swap.  We rely on having xmm0
-    // available as a fixed scratch register.
+    // XMM register-memory swap.
     XMMRegister src = g.ToDoubleRegister(source);
     Operand dst = g.ToOperand(destination);
-    __ Movsd(xmm0, src);
+    __ Movsd(kScratchDoubleReg, src);
     __ Movsd(src, dst);
-    __ Movsd(dst, xmm0);
+    __ Movsd(dst, kScratchDoubleReg);
   } else {
     // No other combinations are possible.
     UNREACHABLE();
   }
 }
 
 
 void CodeGenerator::AssembleJumpTable(Label** targets, size_t target_count) {
   for (size_t index = 0; index < target_count; ++index) {
     __ dq(targets[index]);
@@ skipping 14 matching lines @@
     int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     __ Nop(padding_size);
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8