AcoSail/llvm-project
8
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

[LFTR] Use evaluateAtIteration in genLoopLimit [nfc]

Browse Source 
Note that the comments being removed appear to be very out of sync with the actual code in question.

Differential Revision: https://reviews.llvm.org/D146468
This commit is contained in:
Philip Reames 2023-03-21 19:08:34 -07:00 committed by Philip Reames
parent a124b4c7f9
commit 206dc54534
1 changed files with 6 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
View File

@ -914,28 +914,14 @@ static Value *genLoopLimit(PHINode *IndVar, BasicBlock *ExitingBB,
assert(AR->getStepRecurrence(*SE)->isOne() && "only handles unit stride");
// IVInit may be a pointer while ExitCount is an integer when FindLoopCounter
// finds a valid pointer IV. Sign extend ExitCount in order to materialize a
// GEP. Avoid running SCEVExpander on a new pointer value, instead reusing
// the existing GEPs whenever possible.
// finds a valid pointer IV.
if (IndVar->getType()->isPointerTy()) {
// IVOffset will be the new GEP offset that is interpreted by GEP as a
// signed value. ExitCount on the other hand represents the loop trip count,
// which is an unsigned value. FindLoopCounter only allows induction
// variables that have a positive unit stride of one. This means we don't
// have to handle the case of negative offsets (yet) and just need to zero
// extend ExitCount.
Type *OfsTy = SE->getEffectiveSCEVType(IVInit->getType());
const SCEV *IVOffset = SE->getTruncateOrZeroExtend(ExitCount, OfsTy);
if (UsePostInc)
IVOffset = SE->getAddExpr(IVOffset, SE->getOne(OfsTy));
// Expand the code for the iteration count.
assert(SE->isLoopInvariant(IVOffset, L) &&
const SCEVAddRecExpr *ARBase = UsePostInc ? AR->getPostIncExpr(*SE) : AR;
const SCEV *IVLimit = ARBase->evaluateAtIteration(ExitCount, *SE);
assert(SE->isLoopInvariant(IVLimit, L) &&
"Computed iteration count is not loop invariant!");
const SCEV *IVLimit = SE->getAddExpr(IVInit, IVOffset);
BranchInst *BI = cast<BranchInst>(ExitingBB->getTerminator());
return Rewriter.expandCodeFor(IVLimit, IndVar->getType(), BI);
return Rewriter.expandCodeFor(IVLimit, IndVar->getType(),
ExitingBB->getTerminator());
} else {
// In any other case, convert both IVInit and ExitCount to integers before
// comparing. This may result in SCEV expansion of pointers, but in practice