Emit VMLA for multiply-add on ARM

src/ia32/lithium-ia32.cc

Index: src/ia32/lithium-ia32.cc
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index ba9c97eba215922c87fc43ba459d75527452c364..8755c32bdaff5f1f142409ca5808254ce7d41da8 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -1349,6 +1349,20 @@ LInstruction* LChunkBuilder::DoMul(HMul* 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());