VPWidenCanonicalIVRecipe does not create PHI instructions, so it does
not need to be placed in the phi section of a VPBasicBlock.
Discussed D113223.
Details
Details
Diff Detail
Diff Detail
- Repository
- rG LLVM Github Monorepo
Event Timeline
| llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | ||
|---|---|---|
| 8445–8451 | How about ironing this a bit, while we're here, e.g.: // Introduce the early-exit compare IV <= BTC to form header block mask.
// This is used instead of IV < TC because TC may wrap, unlike BTC.
// Start by constructing the desired canonical IV in the header block as its first non-phi instructions.
assert(CM.foldTailByMasking() && "must fold the tail");
VPBasicBlock *HeaderVPBB = Plan->getEntry()->getEntryBasicBlock();
auto NewInsertionPoint = HeaderVPBB->getFirstNonPhi();
VPValue *IV = nullptr;
if (Legal->getPrimaryInduction())
IV = Plan->getOrAddVPValue(Legal->getPrimaryInduction());
else {
auto *IVRecipe = new VPWidenCanonicalIVRecipe();
HeaderVPBB->insert(IVRecipe, NewInsertionPoint);
IV = IVRecipe;
}
assert(Builder.getInsertBlock() == HeaderVPBB && "..."); // if desired?
VPBuilder::InsertPointGuard Guard(Builder);
Builder.setInsertPoint(HeaderVPBB, NewInsertionPoint); | |
| llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | ||
|---|---|---|
| 8445–8451 | This now means that the compare recipe always gets created in the header VPBB whereas before it may be created in a different VPBB (but still reachable from the header through single branches). This causes some slight changes in the order the IR is generated, but overall seems like a nice simplification. I updated the patch. | |
Comment Actions
This looks good to me, thanks!
| llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | ||
|---|---|---|
| 8445–8451 | Well, the documentation claims that the desired canonical IV is constructed "in the header block" The distinct VPBB's seem to be equivalent, necessarily? Such as the entry of a replicating region and its single predecessor that appear in vplan-sink-scalars-and-merge.ll, which should be fused during code-gen. | |
How about ironing this a bit, while we're here, e.g.:
// Introduce the early-exit compare IV <= BTC to form header block mask. // This is used instead of IV < TC because TC may wrap, unlike BTC. // Start by constructing the desired canonical IV in the header block as its first non-phi instructions. assert(CM.foldTailByMasking() && "must fold the tail"); VPBasicBlock *HeaderVPBB = Plan->getEntry()->getEntryBasicBlock(); auto NewInsertionPoint = HeaderVPBB->getFirstNonPhi(); VPValue *IV = nullptr; if (Legal->getPrimaryInduction()) IV = Plan->getOrAddVPValue(Legal->getPrimaryInduction()); else { auto *IVRecipe = new VPWidenCanonicalIVRecipe(); HeaderVPBB->insert(IVRecipe, NewInsertionPoint); IV = IVRecipe; } assert(Builder.getInsertBlock() == HeaderVPBB && "..."); // if desired? VPBuilder::InsertPointGuard Guard(Builder); Builder.setInsertPoint(HeaderVPBB, NewInsertionPoint);