X87: [turbofan] Add the RoundInt32ToFloat32 operator to turbofan.

  port e06f7d78 (r33347)

  original commit message:
  The new operator converts an int32 input to float32. If the input cannot
  be represented exactly in float32, the value is rounded using the
  round-ties-even rounding mode (the default rounding mode).

  I provide implementations of the new operator for x64, ia32, arm, arm64,
  mips, mips64, ppc, and ppc64.

BUG=

Review URL: https://codereview.chromium.org/1597403002

Cr-Commit-Position: refs/heads/master@{#33351}

src/compiler/x87/code-generator-x87.cc

@@ -972,6 +972,20 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       __ lea(esp, Operand(esp, kDoubleSize));
       break;
     }
+    case kX87Int32ToFloat32: {
+      InstructionOperand* input = instr->InputAt(0);
+      DCHECK(input->IsRegister() || input->IsStackSlot());
+      __ fstp(0);
+      if (input->IsRegister()) {
+        Register input_reg = i.InputRegister(0);
+        __ push(input_reg);
+        __ fild_s(Operand(esp, 0));
+        __ pop(input_reg);
+      } else {
+        __ fild_s(i.InputOperand(0));
+      }
+      break;
+    }
     case kX87Int32ToFloat64: {
       InstructionOperand* input = instr->InputAt(0);
       DCHECK(input->IsRegister() || input->IsStackSlot());

src/compiler/x87/instruction-codes-x87.h

@@ -53,6 +53,7 @@ namespace compiler {
   V(X87Float64Max)                 \
   V(X87Float64Min)                 \
   V(X87Float64Abs)                 \
+  V(X87Int32ToFloat32)             \
   V(X87Int32ToFloat64)             \
   V(X87Float32ToFloat64)           \
   V(X87Uint32ToFloat64)            \

src/compiler/x87/instruction-selector-x87.cc

@@ -656,7 +656,9 @@ void InstructionSelector::VisitChangeFloat32ToFloat64(Node* node) {
 
 
 void InstructionSelector::VisitRoundInt32ToFloat32(Node* node) {
-  UNIMPLEMENTED();
+  X87OperandGenerator g(this);
+  Emit(kX87Int32ToFloat32, g.DefineAsFixed(node, stX_0),
+       g.Use(node->InputAt(0)));
 }