Emit VMLS for multiply-subtract on ARM.

src/arm/lithium-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1344 matching lines @@
       left = UseRegisterAtStart(instr->LeastConstantOperand());
     }
     LMulI* mul = new(zone()) LMulI(left, right, temp);
     if (instr->CheckFlag(HValue::kCanOverflow) ||
         instr->CheckFlag(HValue::kBailoutOnMinusZero)) {
       AssignEnvironment(mul);
     }
     return DefineAsRegister(mul);
 
   } else if (instr->representation().IsDouble()) {
-    if (instr->UseCount() == 1 && instr->uses().value()->IsAdd()) {
-      HAdd* add = HAdd::cast(instr->uses().value());
-      if (instr == add->left()) {
-        // This mul is the lhs of an add. The add and mul will be folded
-        // into a multiply-add.
+    if (instr->UseCount() == 1 && (instr->uses().value()->IsAdd() ||
+                                   instr->uses().value()->IsSub())) {
+      HBinaryOperation* use = HBinaryOperation::cast(instr->uses().value());
+
+      if (use->IsAdd() && instr == use->left()) {
+        // This mul is the lhs of an add. The add and mul will be folded into a
+        // multiply-add in DoAdd.
         return NULL;
       }
-      if (instr == add->right() && !add->left()->IsMul()) {
+      if (instr == use->right() && use->IsAdd() && !use->left()->IsMul()) {
         // This mul is the rhs of an add, where the lhs is not another mul.
-        // The add and mul will be folded into a multiply-add.
+        // The add and mul will be folded into a multiply-add in DoAdd.
+        return NULL;
+      }
+      if (instr == use->right() && use->IsSub()) {
+        // This mul is the rhs of a sub. The sub and mul will be folded into a
+        // multiply-sub in DoSub.
         return NULL;
       }
     }
 
     return DoArithmeticD(Token::MUL, instr);
   } else {
     return DoArithmeticT(Token::MUL, instr);
   }
 }
 
@@ skipping 10 matching lines @@
 
     LOperand* left = UseRegisterAtStart(instr->left());
     LOperand* right = UseOrConstantAtStart(instr->right());
     LSubI* sub = new(zone()) LSubI(left, right);
     LInstruction* result = DefineAsRegister(sub);
     if (instr->CheckFlag(HValue::kCanOverflow)) {
       result = AssignEnvironment(result);
     }
     return result;
   } else if (instr->representation().IsDouble()) {
+    if (instr->right()->IsMul())
+      return DoMultiplySub(instr->left(), HMul::cast(instr->right()));
+
     return DoArithmeticD(Token::SUB, instr);
   } else {
     return DoArithmeticT(Token::SUB, instr);
   }
 }
 
 
 LInstruction* LChunkBuilder::DoRSub(HSub* instr) {
   ASSERT(instr->representation().IsInteger32());
   ASSERT(instr->left()->representation().IsInteger32());
@@ skipping 13 matching lines @@
 
 
 LInstruction* LChunkBuilder::DoMultiplyAdd(HMul* mul, HValue* addend) {
   LOperand* multiplier_op = UseRegisterAtStart(mul->left());
   LOperand* multiplicand_op = UseRegisterAtStart(mul->right());
   LOperand* addend_op = UseRegisterAtStart(addend);
   return DefineSameAsFirst(new(zone()) LMultiplyAddD(addend_op, multiplier_op,
                                                      multiplicand_op));
 }
 
+
+LInstruction* LChunkBuilder::DoMultiplySub(HValue* minuend, HMul* mul) {
+  LOperand* minuend_op = UseRegisterAtStart(minuend);
+  LOperand* multiplier_op = UseRegisterAtStart(mul->left());
+  LOperand* multiplicand_op = UseRegisterAtStart(mul->right());
+
+  return DefineSameAsFirst(new(zone()) LMultiplySubD(minuend_op,
+                                                     multiplier_op,
+                                                     multiplicand_op));
+}
+
+
 LInstruction* LChunkBuilder::DoAdd(HAdd* instr) {
   if (instr->representation().IsInteger32()) {
     ASSERT(instr->left()->representation().IsInteger32());
     ASSERT(instr->right()->representation().IsInteger32());
     LOperand* left = UseRegisterAtStart(instr->LeastConstantOperand());
     LOperand* right = UseOrConstantAtStart(instr->MostConstantOperand());
     LAddI* add = new(zone()) LAddI(left, right);
     LInstruction* result = DefineAsRegister(add);
     if (instr->CheckFlag(HValue::kCanOverflow)) {
       result = AssignEnvironment(result);
@@ skipping 1007 matching lines @@
 
 
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseRegister(instr->index());
   return DefineAsRegister(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal