Simplify DoubleRegister for the ia32 port.

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index 1da0866b3c2333778e5433da9dd69c6d30604fd8..c4b26cd1bf5d7002a2762ddfd77e45c4fbd4fb0d 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -971,10 +971,11 @@ void MacroAssembler::EnterExitFramePrologue() {
 void MacroAssembler::EnterExitFrameEpilogue(int argc, bool save_doubles) {
   // Optionally save all XMM registers.
   if (save_doubles) {
-    int space = XMMRegister::kNumRegisters * kDoubleSize + argc * kPointerSize;
+    int space = XMMRegister::kMaxNumRegisters * kDoubleSize +
+                argc * kPointerSize;
     sub(esp, Immediate(space));
     const int offset = -2 * kPointerSize;
-    for (int i = 0; i < XMMRegister::kNumRegisters; i++) {
+    for (int i = 0; i < XMMRegister::kMaxNumRegisters; i++) {
       XMMRegister reg = XMMRegister::from_code(i);
       movsd(Operand(ebp, offset - ((i + 1) * kDoubleSize)), reg);
     }
@@ -1017,7 +1018,7 @@ void MacroAssembler::LeaveExitFrame(bool save_doubles) {
   // Optionally restore all XMM registers.
   if (save_doubles) {
     const int offset = -2 * kPointerSize;
-    for (int i = 0; i < XMMRegister::kNumRegisters; i++) {
+    for (int i = 0; i < XMMRegister::kMaxNumRegisters; i++) {
       XMMRegister reg = XMMRegister::from_code(i);
       movsd(reg, Operand(ebp, offset - ((i + 1) * kDoubleSize)));
     }