[SVE][CodeGen] Add support for scalable vectors in AArch64TargetLowering::ReconstructShuffle
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Authored by david-arm on Feb 10 2022, 4:14 AM.

Details

Reviewers

sdesmalen
peterwaller-arm
CarolineConcatto
dmgreen
efriedma

Summary

At the moment if AArch64TargetLowering::ReconstructShuffle encounters
a scalable vector it just bails out of the optimisation entirely.
However, there are cases when we can make the transformation succeed
and produce far better code than if we just immediately bail out.

You can see the codegen improvement in the following tests:

CodeGen/AArch64/sve-fixed-length-reshuffle.ll

I have tried to highlight in sve-fixed-length-reshuffle.ll those tests
that exercise the AArch64TargetLowering::ReconstructShuffle code path
when the transformation succeeds or fails.

Diff Detail

Unit TestsFailed
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	Time	Test
	60,070 ms	x64 debian > Clang.CodeGen/RISCV/rvv-intrinsics::vloxseg.c Script: -- : 'RUN: at line 3'; /var/lib/buildkite-agent/builds/llvm-project/build/bin/clang -cc1 -internal-isystem /var/lib/buildkite-agent/builds/llvm-project/build/lib/clang/15.0.0/include -nostdsysteminc -triple riscv64 -target-feature +f -target-feature +d -target-feature +zfh -target-feature +v -disable-O0-optnone -emit-llvm /var/lib/buildkite-agent/builds/llvm-project/clang/test/CodeGen/RISCV/rvv-intrinsics/vloxseg.c -o - \| /var/lib/buildkite-agent/builds/llvm-project/build/bin/opt -S -mem2reg \| /var/lib/buildkite-agent/builds/llvm-project/build/bin/FileCheck --check-prefix=CHECK-RV64 /var/lib/buildkite-agent/builds/llvm-project/clang/test/CodeGen/RISCV/rvv-intrinsics/vloxseg.c
	60,080 ms	x64 debian > Clang.CodeGen/RISCV/rvv-intrinsics::vluxseg.c Script: -- : 'RUN: at line 3'; /var/lib/buildkite-agent/builds/llvm-project/build/bin/clang -cc1 -internal-isystem /var/lib/buildkite-agent/builds/llvm-project/build/lib/clang/15.0.0/include -nostdsysteminc -triple riscv64 -target-feature +f -target-feature +d -target-feature +zfh -target-feature +v -disable-O0-optnone -emit-llvm /var/lib/buildkite-agent/builds/llvm-project/clang/test/CodeGen/RISCV/rvv-intrinsics/vluxseg.c -o - \| /var/lib/buildkite-agent/builds/llvm-project/build/bin/opt -S -mem2reg \| /var/lib/buildkite-agent/builds/llvm-project/build/bin/FileCheck --check-prefix=CHECK-RV64 /var/lib/buildkite-agent/builds/llvm-project/clang/test/CodeGen/RISCV/rvv-intrinsics/vluxseg.c
	60,040 ms	x64 debian > Clang.CodeGen/RISCV/rvv-intrinsics-overloaded::vloxseg.c Script: -- : 'RUN: at line 3'; /var/lib/buildkite-agent/builds/llvm-project/build/bin/clang -cc1 -internal-isystem /var/lib/buildkite-agent/builds/llvm-project/build/lib/clang/15.0.0/include -nostdsysteminc -triple riscv64 -target-feature +f -target-feature +d -target-feature +v -disable-O0-optnone -emit-llvm /var/lib/buildkite-agent/builds/llvm-project/clang/test/CodeGen/RISCV/rvv-intrinsics-overloaded/vloxseg.c -o - \| /var/lib/buildkite-agent/builds/llvm-project/build/bin/opt -S -mem2reg \| /var/lib/buildkite-agent/builds/llvm-project/build/bin/FileCheck --check-prefix=CHECK-RV64 /var/lib/buildkite-agent/builds/llvm-project/clang/test/CodeGen/RISCV/rvv-intrinsics-overloaded/vloxseg.c
	60,080 ms	x64 debian > Clang.CodeGen/RISCV/rvv-intrinsics-overloaded::vluxseg.c Script: -- : 'RUN: at line 3'; /var/lib/buildkite-agent/builds/llvm-project/build/bin/clang -cc1 -internal-isystem /var/lib/buildkite-agent/builds/llvm-project/build/lib/clang/15.0.0/include -nostdsysteminc -triple riscv64 -target-feature +f -target-feature +d -target-feature +v -disable-O0-optnone -emit-llvm /var/lib/buildkite-agent/builds/llvm-project/clang/test/CodeGen/RISCV/rvv-intrinsics-overloaded/vluxseg.c -o - \| /var/lib/buildkite-agent/builds/llvm-project/build/bin/opt -S -mem2reg \| /var/lib/buildkite-agent/builds/llvm-project/build/bin/FileCheck --check-prefix=CHECK-RV64 /var/lib/buildkite-agent/builds/llvm-project/clang/test/CodeGen/RISCV/rvv-intrinsics-overloaded/vluxseg.c
	60,050 ms	x64 debian > libFuzzer.libFuzzer::large.test Script: -- : 'RUN: at line 3'; /var/lib/buildkite-agent/builds/llvm-project/build/./bin/clang --driver-mode=g++ -O2 -gline-tables-only -fsanitize=address,fuzzer -I/var/lib/buildkite-agent/builds/llvm-project/compiler-rt/lib/fuzzer -m64 /var/lib/buildkite-agent/builds/llvm-project/compiler-rt/test/fuzzer/LargeTest.cpp -o /var/lib/buildkite-agent/builds/llvm-project/build/projects/compiler-rt/test/fuzzer/X86_64DefaultLinuxConfig/Output/large.test.tmp-LargeTest

Event Timeline

david-arm created this revision.Feb 10 2022, 4:14 AM

Herald added a reviewer: efriedma. · View Herald TranscriptFeb 10 2022, 4:14 AM

Herald added subscribers: ctetreau, psnobl, hiraditya and 2 others. · View Herald Transcript

david-arm requested review of this revision.Feb 10 2022, 4:14 AM

Herald added a project: Restricted Project. · View Herald TranscriptFeb 10 2022, 4:14 AM

Herald added subscribers: llvm-commits, alextsao1999. · View Herald Transcript

david-arm added a parent revision: D116602: [SVE][CodeGen] Bail out for scalable vectors in AArch64TargetLowering::ReconstructShuffle.Feb 10 2022, 4:14 AM

paulwalker-arm added a subscriber: paulwalker-arm.Feb 10 2022, 4:28 AM

paulwalker-arm added inline comments.

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
9048	When protecting code can you check the positive rather than the negative. So `if (SrcVTSize.isFixed() && ...)`. Looking at TypeSize suggests there's no such function, but I think that's an omission.