[turbofan] Unify Math.floor / Math.ceil optimization.

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

Index: src/compiler/x64/code-generator-x64.cc
diff --git a/src/compiler/x64/code-generator-x64.cc b/src/compiler/x64/code-generator-x64.cc
index f8c439faa833b9ab763adf6bedb8193229dffcd2..9d946b8094291b1e2143f241d2fa9531189e309d 100644
--- a/src/compiler/x64/code-generator-x64.cc
+++ b/src/compiler/x64/code-generator-x64.cc
@@ -748,22 +748,11 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
         __ sqrtsd(i.OutputDoubleRegister(), i.InputOperand(0));
       }
       break;
-    case kSSEFloat64Floor: {
+    case kSSEFloat64Round: {
       CpuFeatureScope sse_scope(masm(), SSE4_1);
-      __ roundsd(i.OutputDoubleRegister(), i.InputDoubleRegister(0),
-                 v8::internal::Assembler::kRoundDown);
-      break;
-    }
-    case kSSEFloat64Ceil: {
-      CpuFeatureScope sse_scope(masm(), SSE4_1);
-      __ roundsd(i.OutputDoubleRegister(), i.InputDoubleRegister(0),
-                 v8::internal::Assembler::kRoundUp);
-      break;
-    }
-    case kSSEFloat64RoundTruncate: {
-      CpuFeatureScope sse_scope(masm(), SSE4_1);
-      __ roundsd(i.OutputDoubleRegister(), i.InputDoubleRegister(0),
-                 v8::internal::Assembler::kRoundToZero);
+      RoundingMode const mode =
+          static_cast<RoundingMode>(MiscField::decode(instr->opcode()));
+      __ roundsd(i.OutputDoubleRegister(), i.InputDoubleRegister(0), mode);
       break;
     }
     case kSSECvtss2sd: