Do some peephole optimizations to remove pointless VMOVs from Neon to integer
registers that arise from argument shuffling with the soft float ABI. These
instructions are particularly slow on Cortex A8. This fixes one half of
<rdar://problem/8674845>.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128759 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 5502ca4..d11c956 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -5561,6 +5561,37 @@
SDValue InDouble = N->getOperand(0);
if (InDouble.getOpcode() == ARMISD::VMOVDRR)
return DCI.CombineTo(N, InDouble.getOperand(0), InDouble.getOperand(1));
+
+ // vmovrrd(load f64) -> (load i32), (load i32)
+ SDNode *InNode = InDouble.getNode();
+ if (ISD::isNormalLoad(InNode) && InNode->hasOneUse() &&
+ InNode->getValueType(0) == MVT::f64 &&
+ InNode->getOperand(1).getOpcode() == ISD::FrameIndex &&
+ !cast<LoadSDNode>(InNode)->isVolatile()) {
+ // TODO: Should this be done for non-FrameIndex operands?
+ LoadSDNode *LD = cast<LoadSDNode>(InNode);
+
+ SelectionDAG &DAG = DCI.DAG;
+ DebugLoc DL = LD->getDebugLoc();
+ SDValue BasePtr = LD->getBasePtr();
+ SDValue NewLD1 = DAG.getLoad(MVT::i32, DL, LD->getChain(), BasePtr,
+ LD->getPointerInfo(), LD->isVolatile(),
+ LD->isNonTemporal(), LD->getAlignment());
+
+ SDValue OffsetPtr = DAG.getNode(ISD::ADD, DL, MVT::i32, BasePtr,
+ DAG.getConstant(4, MVT::i32));
+ SDValue NewLD2 = DAG.getLoad(MVT::i32, DL, NewLD1.getValue(1), OffsetPtr,
+ LD->getPointerInfo(), LD->isVolatile(),
+ LD->isNonTemporal(),
+ std::min(4U, LD->getAlignment() / 2));
+
+ DAG.ReplaceAllUsesOfValueWith(SDValue(LD, 1), NewLD2.getValue(1));
+ SDValue Result = DCI.CombineTo(N, NewLD1, NewLD2);
+ DCI.RemoveFromWorklist(LD);
+ DAG.DeleteNode(LD);
+ return Result;
+ }
+
return SDValue();
}