Correctly lower memset / memcpy of undef. It should be a nop. PR6767.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100208 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 0ba65ab..39cdba7 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3094,6 +3094,8 @@
/// operand.
static SDValue getMemsetValue(SDValue Value, EVT VT, SelectionDAG &DAG,
DebugLoc dl) {
+ assert(Value.getOpcode() != ISD::UNDEF);
+
unsigned NumBits = VT.getScalarType().getSizeInBits();
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Value)) {
APInt Val = APInt(NumBits, C->getZExtValue() & 255);
@@ -3197,7 +3199,7 @@
static bool FindOptimalMemOpLowering(std::vector<EVT> &MemOps,
unsigned Limit, uint64_t Size,
unsigned DstAlign, unsigned SrcAlign,
- bool SafeToUseFP,
+ bool NonScalarIntSafe,
SelectionDAG &DAG,
const TargetLowering &TLI) {
assert((SrcAlign == 0 || SrcAlign >= DstAlign) &&
@@ -3207,7 +3209,8 @@
// the inferred alignment of the source. 'DstAlign', on the other hand, is the
// specified alignment of the memory operation. If it is zero, that means
// it's possible to change the alignment of the destination.
- EVT VT = TLI.getOptimalMemOpType(Size, DstAlign, SrcAlign, SafeToUseFP, DAG);
+ EVT VT = TLI.getOptimalMemOpType(Size, DstAlign, SrcAlign,
+ NonScalarIntSafe, DAG);
if (VT == MVT::Other) {
VT = TLI.getPointerTy();
@@ -3266,10 +3269,13 @@
unsigned Align, bool AlwaysInline,
const Value *DstSV, uint64_t DstSVOff,
const Value *SrcSV, uint64_t SrcSVOff) {
- const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+ // Turn a memcpy of undef to nop.
+ if (Src.getOpcode() == ISD::UNDEF)
+ return Chain;
// Expand memcpy to a series of load and store ops if the size operand falls
// below a certain threshold.
+ const TargetLowering &TLI = DAG.getTargetLoweringInfo();
std::vector<EVT> MemOps;
uint64_t Limit = -1ULL;
if (!AlwaysInline)
@@ -3352,10 +3358,13 @@
unsigned Align,bool AlwaysInline,
const Value *DstSV, uint64_t DstSVOff,
const Value *SrcSV, uint64_t SrcSVOff) {
- const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+ // Turn a memmove of undef to nop.
+ if (Src.getOpcode() == ISD::UNDEF)
+ return Chain;
// Expand memmove to a series of load and store ops if the size operand falls
// below a certain threshold.
+ const TargetLowering &TLI = DAG.getTargetLoweringInfo();
std::vector<EVT> MemOps;
uint64_t Limit = -1ULL;
if (!AlwaysInline)
@@ -3426,21 +3435,24 @@
SDValue Src, uint64_t Size,
unsigned Align,
const Value *DstSV, uint64_t DstSVOff) {
- const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+ // Turn a memset of undef to nop.
+ if (Src.getOpcode() == ISD::UNDEF)
+ return Chain;
// Expand memset to a series of load/store ops if the size operand
// falls below a certain threshold.
+ const TargetLowering &TLI = DAG.getTargetLoweringInfo();
std::vector<EVT> MemOps;
bool DstAlignCanChange = false;
MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Dst);
if (FI && !MFI->isFixedObjectIndex(FI->getIndex()))
DstAlignCanChange = true;
- bool IsZero = isa<ConstantSDNode>(Src) &&
- cast<ConstantSDNode>(Src)->isNullValue();
+ bool NonScalarIntSafe =
+ isa<ConstantSDNode>(Src) && cast<ConstantSDNode>(Src)->isNullValue();
if (!FindOptimalMemOpLowering(MemOps, TLI.getMaxStoresPerMemset(),
Size, (DstAlignCanChange ? 0 : Align), 0,
- IsZero, DAG, TLI))
+ NonScalarIntSafe, DAG, TLI))
return SDValue();
if (DstAlignCanChange) {
@@ -3592,9 +3604,9 @@
if (ConstantSize->isNullValue())
return Chain;
- SDValue Result =
- getMemsetStores(*this, dl, Chain, Dst, Src, ConstantSize->getZExtValue(),
- Align, DstSV, DstSVOff);
+ SDValue Result = getMemsetStores(*this, dl, Chain, Dst, Src,
+ ConstantSize->getZExtValue(),
+ Align, DstSV, DstSVOff);
if (Result.getNode())
return Result;
}