ARM64: avoid duplicate load of double constants

src/arm64/lithium-arm64.cc

 // Copyright 2013 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/v8.h"
 
 #include "src/arm64/lithium-arm64.h"
 #include "src/arm64/lithium-codegen-arm64.h"
 #include "src/hydrogen-osr.h"
 #include "src/lithium-allocator-inl.h"
@@ skipping 1256 matching lines @@
   if (r.IsSmiOrInteger32()) {
     ASSERT(instr->left()->representation().Equals(r));
     ASSERT(instr->right()->representation().Equals(r));
     LOperand* left = UseRegisterOrConstantAtStart(instr->left());
     LOperand* right = UseRegisterOrConstantAtStart(instr->right());
     return new(zone()) LCompareNumericAndBranch(left, right);
   } else {
     ASSERT(r.IsDouble());
     ASSERT(instr->left()->representation().IsDouble());
     ASSERT(instr->right()->representation().IsDouble());
-    // TODO(all): In fact the only case that we can handle more efficiently is
-    // when one of the operand is the constant 0. Currently the MacroAssembler
-    // will be able to cope with any constant by loading it into an internal
-    // scratch register. This means that if the constant is used more that once,
-    // it will be loaded multiple times. Unfortunatly crankshaft already
-    // duplicates constant loads, but we should modify the code below once this
-    // issue has been addressed in crankshaft.
-    LOperand* left = UseRegisterOrConstantAtStart(instr->left());
-    LOperand* right = UseRegisterOrConstantAtStart(instr->right());
+    if (instr->left()->IsConstant() && instr->right()->IsConstant()) {
+      LOperand* left = UseConstant(instr->left());
+      LOperand* right = UseConstant(instr->right());
+      return new(zone()) LCompareNumericAndBranch(left, right);
+    }
+    LOperand* left = UseRegisterAtStart(instr->left());
+    LOperand* right = UseRegisterAtStart(instr->right());
     return new(zone()) LCompareNumericAndBranch(left, right);
   }
 }
 
 
 LInstruction* LChunkBuilder::DoCompareGeneric(HCompareGeneric* instr) {
   ASSERT(instr->left()->representation().IsTagged());
   ASSERT(instr->right()->representation().IsTagged());
   LOperand* context = UseFixed(instr->context(), cp);
   LOperand* left = UseFixed(instr->left(), x1);
@@ skipping 1421 matching lines @@
     HAllocateBlockContext* instr) {
   LOperand* context = UseFixed(instr->context(), cp);
   LOperand* function = UseRegisterAtStart(instr->function());
   LAllocateBlockContext* result =
       new(zone()) LAllocateBlockContext(context, function);
   return MarkAsCall(DefineFixed(result, cp), instr);
 }
 
 
 } }  // namespace v8::internal