[turbofan] Add support for reinterpreting integers as floating point and vice versa.

src/compiler/ia32/code-generator-ia32.cc

Index: src/compiler/ia32/code-generator-ia32.cc
diff --git a/src/compiler/ia32/code-generator-ia32.cc b/src/compiler/ia32/code-generator-ia32.cc
index c21cc2df2497ecac875e6105c90f76d46cff510b..e9b3a9949a28cf00ea484b84708e5e8131d574ab 100644
--- a/src/compiler/ia32/code-generator-ia32.cc
+++ b/src/compiler/ia32/code-generator-ia32.cc
@@ -840,6 +840,20 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
         __ movss(operand, i.InputDoubleRegister(index));
       }
       break;
+    case kIA32BitcastFI:
+      if (instr->InputAt(0)->IsDoubleStackSlot()) {
+        __ mov(i.OutputRegister(), i.InputOperand(0));
+      } else {
+        __ movd(i.OutputRegister(), i.InputDoubleRegister(0));
+      }
+      break;
+    case kIA32BitcastIF:
+      if (instr->InputAt(0)->IsRegister()) {
+        __ movd(i.OutputDoubleRegister(), i.InputRegister(0));
+      } else {
+        __ movss(i.OutputDoubleRegister(), i.InputOperand(0));
+      }
+      break;
     case kIA32Lea: {
       AddressingMode mode = AddressingModeField::decode(instr->opcode());
       // Shorten "leal" to "addl", "subl" or "shll" if the register allocation