Skip to content

[AArch64] - Improve costing for Identity shuffles for SVE targets. #165375

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 4 commits into
base: main
Choose a base branch
from
+90 −8
Open

[AArch64] - Improve costing for Identity shuffles for SVE targets. #165375

Show file tree
Hide file tree
Changes from 2 commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
70bf624
[AArch64] - Improve costing for Identity shuffles for SVE targets.
Oct 28, 2025
eca25d4
Merge branch 'main' into identity-shuffle-costs
pawan-nirpal-031 Oct 28, 2025
d2f6cc3
Update identity-shuffle-sve.ll
pawan-nirpal-031 Nov 3, 2025
cae9a19
fix tests
Nov 6, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 9 additions & 0 deletions llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5906,6 +5906,15 @@ AArch64TTIImpl::getShuffleCost(TTI::ShuffleKind Kind, VectorType *DstTy,
VTy->getPrimitiveSizeInBits() / AArch64::SVEBitsPerBlock;
unsigned SegmentElts = VTy->getNumElements() / Segments;

// Check for identity masks when SVE is available, which we can treat as
// free.
if (LT.second.isFixedLengthVector() && ST->isSVEorStreamingSVEAvailable() &&
(Kind == TTI::SK_PermuteTwoSrc || Kind == TTI::SK_PermuteSingleSrc) &&
all_of(enumerate(Mask), [](const auto &M) {
return M.value() < 0 || M.value() == (int)M.index();
}))
return 0;

// dupq zd.t, zn.t[idx]
if ((ST->hasSVE2p1() || ST->hasSME2p1()) &&
ST->isSVEorStreamingSVEAvailable() &&
Expand Down
Loading