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

src/compiler/arm64/instruction-selector-arm64.cc

Index: src/compiler/arm64/instruction-selector-arm64.cc
diff --git a/src/compiler/arm64/instruction-selector-arm64.cc b/src/compiler/arm64/instruction-selector-arm64.cc
index a27bd88733ee56e9ce8cdcfa40a7d4af3e63d114..b8805078138c45e02077f90228d62b90ef301eba 100644
--- a/src/compiler/arm64/instruction-selector-arm64.cc
+++ b/src/compiler/arm64/instruction-selector-arm64.cc
@@ -1033,6 +1033,20 @@ void InstructionSelector::VisitFloat64Add(Node* node) {
 
 
 void InstructionSelector::VisitFloat64Sub(Node* node) {
+  Arm64OperandGenerator g(this);
+  Float64BinopMatcher m(node);
+  if (m.left().IsMinusZero() && m.right().IsFloat64RoundDown() &&
+      CanCover(m.node(), m.right().node())) {
+    if (m.right().InputAt(0)->opcode() == IrOpcode::kFloat64Sub &&
+        CanCover(m.right().node(), m.right().InputAt(0))) {
+      Float64BinopMatcher mright0(m.right().InputAt(0));
+      if (mright0.left().IsMinusZero()) {
+        Emit(kArm64Float64RoundUp, g.DefineAsRegister(node),
+             g.UseRegister(mright0.right().node()));
+        return;
+      }
+    }
+  }
   VisitRRRFloat64(this, kArm64Float64Sub, node);
 }
 
@@ -1060,13 +1074,8 @@ void InstructionSelector::VisitFloat64Sqrt(Node* node) {
 }
 
 
-void InstructionSelector::VisitFloat64Floor(Node* node) {
-  VisitRRFloat64(this, kArm64Float64Floor, node);
-}
-
-
-void InstructionSelector::VisitFloat64Ceil(Node* node) {
-  VisitRRFloat64(this, kArm64Float64Ceil, node);
+void InstructionSelector::VisitFloat64RoundDown(Node* node) {
+  VisitRRFloat64(this, kArm64Float64RoundDown, node);
 }
 
 
@@ -1613,8 +1622,7 @@ void InstructionSelector::VisitFloat64InsertHighWord32(Node* node) {
 // static
 MachineOperatorBuilder::Flags
 InstructionSelector::SupportedMachineOperatorFlags() {
-  return MachineOperatorBuilder::kFloat64Floor |
-         MachineOperatorBuilder::kFloat64Ceil |
+  return MachineOperatorBuilder::kFloat64RoundDown |
          MachineOperatorBuilder::kFloat64RoundTruncate |
          MachineOperatorBuilder::kFloat64RoundTiesAway |
          MachineOperatorBuilder::kWord32ShiftIsSafe |