Emit VMLA for multiply-add on ARM

src/ia32/lithium-ia32.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 1331 matching lines @@
     return DefineSameAsFirst(mul);
   } else if (instr->representation().IsDouble()) {
     return DoArithmeticD(Token::MUL, instr);
   } else {
     ASSERT(instr->representation().IsTagged());
     return DoArithmeticT(Token::MUL, instr);
   }
 }
 
 
+LInstruction* LChunkBuilder::DoMultiplyAddD(HMultiplyAddD* instr) {
+  ASSERT(instr->representation().IsDouble());
+  ASSERT(instr->a()->representation().IsDouble());
+  ASSERT(instr->b()->representation().IsDouble());
+  ASSERT(instr->c()->representation().IsDouble());
+
+  LOperand* a = UseRegisterAtStart(instr->a());
+  LOperand* b = UseRegisterAtStart(instr->b());
+  LOperand* c = UseRegisterAtStart(instr->c());

[Vyacheslav Egorov (Google), 2012/11/12 17:12:53]

c is not used at start at all in the instruction pattern so this constraint is
incorrect.

AtStart means: no destructive operations are performed over registers until the
use.

I think it happens to work in expression like a * a + a only because SameAsFirst
accidentally creates artificial interference.

+  LMultiplyAddD* result = new(zone()) LMultiplyAddD(a, b, c);
+  return DefineSameAsFirst(result);
+}
+
+
 LInstruction* LChunkBuilder::DoSub(HSub* instr) {
   if (instr->representation().IsInteger32()) {
     ASSERT(instr->left()->representation().IsInteger32());
     ASSERT(instr->right()->representation().IsInteger32());
     LOperand* left = UseRegisterAtStart(instr->left());
     LOperand* right = UseOrConstantAtStart(instr->right());
     LSubI* sub = new(zone()) LSubI(left, right);
     LInstruction* result = DefineSameAsFirst(sub);
     if (instr->CheckFlag(HValue::kCanOverflow)) {
       result = AssignEnvironment(result);
@@ skipping 1028 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32