[turbofan] Negate with shifted input for ARM64

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 7a5b84275acd05008f13de95121235ee1b8f8f15..4abbc1e370fc662663b423a0eacd76bdb57c5d84 100644
--- a/src/compiler/arm64/instruction-selector-arm64.cc
+++ b/src/compiler/arm64/instruction-selector-arm64.cc
@@ -37,6 +37,15 @@ class Arm64OperandGenerator final : public OperandGenerator {
     return UseRegister(node);
   }
 
+  // Use the zero register if the node has the immediate value zero, otherwise
+  // assign a register.
+  InstructionOperand UseRegisterOrImmediateZero(Node* node) {
+    if (IsIntegerConstant(node) && (GetIntegerConstantValue(node) == 0)) {
+      return UseImmediate(node);
+    }
+    return UseRegister(node);
+  }
+
   // Use the provided node if it has the required value, or create a
   // TempImmediate otherwise.
   InstructionOperand UseImmediateOrTemp(Node* node, int32_t value) {
@@ -247,18 +256,18 @@ void VisitBinop(InstructionSelector* selector, Node* node,
   } else if (TryMatchAnyShift(selector, node, right_node, &opcode,
                               !is_add_sub)) {
     Matcher m_shift(right_node);
-    inputs[input_count++] = g.UseRegister(left_node);
+    inputs[input_count++] = g.UseRegisterOrImmediateZero(left_node);
     inputs[input_count++] = g.UseRegister(m_shift.left().node());
     inputs[input_count++] = g.UseImmediate(m_shift.right().node());
   } else if (can_commute && TryMatchAnyShift(selector, node, left_node, &opcode,
                                              !is_add_sub)) {
     if (is_cmp) cont->Commute();
     Matcher m_shift(left_node);
-    inputs[input_count++] = g.UseRegister(right_node);
+    inputs[input_count++] = g.UseRegisterOrImmediateZero(right_node);
     inputs[input_count++] = g.UseRegister(m_shift.left().node());
     inputs[input_count++] = g.UseImmediate(m_shift.right().node());
   } else {
-    inputs[input_count++] = g.UseRegister(left_node);
+    inputs[input_count++] = g.UseRegisterOrImmediateZero(left_node);
     inputs[input_count++] = g.UseRegister(right_node);
   }
 
@@ -997,12 +1006,7 @@ void InstructionSelector::VisitInt32Sub(Node* node) {
     }
   }
 
-  if (m.left().Is(0)) {
-    Emit(kArm64Neg32, g.DefineAsRegister(node),
-         g.UseRegister(m.right().node()));
-  } else {
-    VisitAddSub<Int32BinopMatcher>(this, node, kArm64Sub32, kArm64Add32);
-  }
+  VisitAddSub<Int32BinopMatcher>(this, node, kArm64Sub32, kArm64Add32);
 }
 
 
@@ -1023,11 +1027,7 @@ void InstructionSelector::VisitInt64Sub(Node* node) {
     }
   }
 
-  if (m.left().Is(0)) {
-    Emit(kArm64Neg, g.DefineAsRegister(node), g.UseRegister(m.right().node()));
-  } else {
-    VisitAddSub<Int64BinopMatcher>(this, node, kArm64Sub, kArm64Add);
-  }
+  VisitAddSub<Int64BinopMatcher>(this, node, kArm64Sub, kArm64Add);
 }