Make sure no loads resulting from load->switch DAGCombine are marked invariant

Currently when DAGCombine converts loads feeding a switch into a switch of
addresses feeding a load the new load inherits the isInvariant flag of the left
side. This is incorrect since invariant loads can be reordered in cases where it
is illegal to reoarder normal loads.

This patch adds an isInvariant parameter to getExtLoad() and updates all call
sites to pass in the data if they have it or false if they don't. It also
changes the DAGCombine to use that data to make the right decision when
creating the new load.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214449 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Louis Gerbarg
2014-07-31 21:45:05 +00:00
parent f7be7f15c1
commit 7d54c5b0f2
19 changed files with 82 additions and 64 deletions

View File

@@ -463,14 +463,15 @@ LowerLOAD(SDValue Op, SelectionDAG &DAG) const {
if (LD->getAlignment() == 2) {
SDValue Low = DAG.getExtLoad(ISD::ZEXTLOAD, DL, MVT::i32, Chain,
BasePtr, LD->getPointerInfo(), MVT::i16,
LD->isVolatile(), LD->isNonTemporal(), 2);
LD->isVolatile(), LD->isNonTemporal(),
LD->isInvariant(), 2);
SDValue HighAddr = DAG.getNode(ISD::ADD, DL, MVT::i32, BasePtr,
DAG.getConstant(2, MVT::i32));
SDValue High = DAG.getExtLoad(ISD::EXTLOAD, DL, MVT::i32, Chain,
HighAddr,
LD->getPointerInfo().getWithOffset(2),
MVT::i16, LD->isVolatile(),
LD->isNonTemporal(), 2);
LD->isNonTemporal(), LD->isInvariant(), 2);
SDValue HighShifted = DAG.getNode(ISD::SHL, DL, MVT::i32, High,
DAG.getConstant(16, MVT::i32));
SDValue Result = DAG.getNode(ISD::OR, DL, MVT::i32, Low, HighShifted);
@@ -981,13 +982,13 @@ LowerATOMIC_LOAD(SDValue Op, SelectionDAG &DAG) const {
return DAG.getExtLoad(ISD::EXTLOAD, SDLoc(Op), MVT::i32, N->getChain(),
N->getBasePtr(), N->getPointerInfo(), MVT::i16,
N->isVolatile(), N->isNonTemporal(),
N->getAlignment(), N->getAAInfo());
N->isInvariant(), N->getAlignment(), N->getAAInfo());
}
if (N->getMemoryVT() == MVT::i8)
return DAG.getExtLoad(ISD::EXTLOAD, SDLoc(Op), MVT::i32, N->getChain(),
N->getBasePtr(), N->getPointerInfo(), MVT::i8,
N->isVolatile(), N->isNonTemporal(),
N->getAlignment(), N->getAAInfo());
N->isInvariant(), N->getAlignment(), N->getAAInfo());
return SDValue();
}