[turbofan] Add the TruncateFloat32ToInt32 operator to turbofan.

src/compiler/wasm-compiler.cc

 // Copyright 2015 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/wasm-compiler.h"
 
 #include "src/isolate-inl.h"
 
 #include "src/base/platform/platform.h"
 
@@ skipping 1103 matching lines @@
       wasm::kAstF64, left,
       right_gt_left.Phi(wasm::kAstF64, right,
                         left_is_not_nan.Phi(wasm::kAstF64, right, left)));
 }
 
 
 Node* WasmGraphBuilder::BuildI32SConvertF32(Node* input) {
   MachineOperatorBuilder* m = jsgraph()->machine();
   // Truncation of the input value is needed for the overflow check later.
   Node* trunc = Unop(wasm::kExprF32Trunc, input);
-  // TODO(titzer): two conversions
-  Node* f64_trunc = graph()->NewNode(m->ChangeFloat32ToFloat64(), trunc);
-  Node* result = graph()->NewNode(m->ChangeFloat64ToInt32(), f64_trunc);
+  Node* result = graph()->NewNode(m->TruncateFloat32ToInt32(), trunc);
 
   // Convert the result back to f64. If we end up at a different value than the
   // truncated input value, then there has been an overflow and we trap.
-  Node* check = Unop(wasm::kExprF64SConvertI32, result);
-  Node* overflow = Binop(wasm::kExprF64Ne, f64_trunc, check);
+  Node* check = Unop(wasm::kExprF32SConvertI32, result);
+  Node* overflow = Binop(wasm::kExprF32Ne, trunc, check);
   trap_->AddTrapIfTrue(kTrapFloatUnrepresentable, overflow);
 
   return result;
 }
 
 
 Node* WasmGraphBuilder::BuildI32SConvertF64(Node* input) {
   MachineOperatorBuilder* m = jsgraph()->machine();
   // Truncation of the input value is needed for the overflow check later.
   Node* trunc = Unop(wasm::kExprF64Trunc, input);
@@ skipping 880 matching lines @@
     code->Disassemble(buffer.start(), os);
   }
 #endif
   return code;
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8