maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[SDAG] clean up scalarizing load transform 

I have not found a way to expose a difference for this patch in a test
because it only triggers for a one-use load, but this is the code that
was adapted into D118376 and caused miscompiles. The new code pattern
is the same as what we do in narrowExtractedVectorLoad() (reduces load
width for a subvector extract).

This removes seemingly unnecessary manual worklist management and fixes
the chain updating via "SelectionDAG::makeEquivalentMemoryOrdering()".

Differential Revision: https://reviews.llvm.org/D119549
This commit is contained in:
Sanjay Patel 2022-02-12 10:34:51 -05:00
parent 1f43367377
commit 96b7e0b5a0
1 changed files with 6 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -19195,14 +19195,9 @@ SDValue DAGCombiner::scalarizeExtractedVectorLoad(SDNode *EVE, EVT InVecVT,
SDValue NewPtr = TLI.getVectorElementPointer(DAG, OriginalLoad->getBasePtr(), SDValue NewPtr = TLI.getVectorElementPointer(DAG, OriginalLoad->getBasePtr(),
InVecVT, EltNo); InVecVT, EltNo);
// The replacement we need to do here is a little tricky: we need to // We are replacing a vector load with a scalar load. The new load must have
// replace an extractelement of a load with a load. // identical memory op ordering to the original.
// Use ReplaceAllUsesOfValuesWith to do the replacement.
// Note that this replacement assumes that the extractvalue is the only
// use of the load; that's okay because we don't want to perform this
// transformation in other cases anyway.
SDValue Load; SDValue Load;
SDValue Chain;
if (ResultVT.bitsGT(VecEltVT)) { if (ResultVT.bitsGT(VecEltVT)) {
// If the result type of vextract is wider than the load, then issue an // If the result type of vextract is wider than the load, then issue an
// extending load instead. // extending load instead.
@ -19213,28 +19208,20 @@ SDValue DAGCombiner::scalarizeExtractedVectorLoad(SDNode *EVE, EVT InVecVT,
NewPtr, MPI, VecEltVT, Alignment, NewPtr, MPI, VecEltVT, Alignment,
OriginalLoad->getMemOperand()->getFlags(), OriginalLoad->getMemOperand()->getFlags(),
OriginalLoad->getAAInfo()); OriginalLoad->getAAInfo());
Chain = Load.getValue(1); DAG.makeEquivalentMemoryOrdering(OriginalLoad, Load);
} else { } else {
// The result type is narrower or the same width as the vector element
Load = DAG.getLoad(VecEltVT, DL, OriginalLoad->getChain(), NewPtr, MPI, Load = DAG.getLoad(VecEltVT, DL, OriginalLoad->getChain(), NewPtr, MPI,
Alignment, OriginalLoad->getMemOperand()->getFlags(), Alignment, OriginalLoad->getMemOperand()->getFlags(),
OriginalLoad->getAAInfo()); OriginalLoad->getAAInfo());
Chain = Load.getValue(1); DAG.makeEquivalentMemoryOrdering(OriginalLoad, Load);
if (ResultVT.bitsLT(VecEltVT)) if (ResultVT.bitsLT(VecEltVT))
Load = DAG.getNode(ISD::TRUNCATE, DL, ResultVT, Load); Load = DAG.getNode(ISD::TRUNCATE, DL, ResultVT, Load);
else else
Load = DAG.getBitcast(ResultVT, Load); Load = DAG.getBitcast(ResultVT, Load);
} }
WorklistRemover DeadNodes(*this);
SDValue From[] = {SDValue(EVE, 0), SDValue(OriginalLoad, 1)};
SDValue To[] = {Load, Chain};
DAG.ReplaceAllUsesOfValuesWith(From, To, 2);
// Make sure to revisit this node to clean it up; it will usually be dead.
AddToWorklist(EVE);
// Since we're explicitly calling ReplaceAllUses, add the new node to the
// worklist explicitly as well.
AddToWorklistWithUsers(Load.getNode());
++OpsNarrowed; ++OpsNarrowed;
return SDValue(EVE, 0); return Load;
} }
/// Transform a vector binary operation into a scalar binary operation by moving /// Transform a vector binary operation into a scalar binary operation by moving