[AArch64] FEAT_LRCPC3 load/store optimisations
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Authored by tmatheson on Jan 10 2023, 2:01 PM.

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Reviewers

lenary
pratlucas
stuij

Summary

Extend the load/store optimizer to identify cases where the offset variants of
+rcpc3 instructions can be used.

The non-indexed LDIAPP/STILP are output by instruction selection and are
optimised to their +/- 8/16 byte variants by the load/store optimiser.

Diff Detail

Repository: rG LLVM Github Monorepo

Unit TestsFailed
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	Time	Test
	130 ms	x64 debian > LLVM.CodeGen/AArch64::aarch64-rcpc3-ldst.ll Script: -- : 'RUN: at line 3'; /var/lib/buildkite-agent/builds/llvm-project/build/bin/llc /var/lib/buildkite-agent/builds/llvm-project/llvm/test/CodeGen/AArch64/aarch64-rcpc3-ldst.ll -o - -mtriple=aarch64-none-linux-gnu -O1 -mattr=+v8.1a,+rcpc,+rcpc-immo,+rcpc3 -global-isel -global-isel-abort=1 \| /var/lib/buildkite-agent/builds/llvm-project/build/bin/FileCheck /var/lib/buildkite-agent/builds/llvm-project/llvm/test/CodeGen/AArch64/aarch64-rcpc3-ldst.ll --check-prefixes=GISEL-NO-LSE2
	60,070 ms	x64 debian > MLIR.Examples/standalone::test.toy Script: -- : 'RUN: at line 1'; /usr/bin/cmake /var/lib/buildkite-agent/builds/llvm-project/mlir/examples/standalone -G "Ninja" -DCMAKE_CXX_COMPILER=/usr/bin/clang++ -DCMAKE_C_COMPILER=/usr/bin/clang -DLLVM_ENABLE_LIBCXX=OFF -DMLIR_DIR=/var/lib/buildkite-agent/builds/llvm-project/build/lib/cmake/mlir -DLLVM_USE_LINKER=lld -DPython3_EXECUTABLE="/usr/bin/python3.9"
	60,040 ms	x64 debian > libFuzzer.libFuzzer::minimize_crash.test Script: -- : 'RUN: at line 1'; /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/NullDerefTest.cpp -o /var/lib/buildkite-agent/builds/llvm-project/build/projects/compiler-rt/test/fuzzer/X86_64DefaultLinuxConfig/Output/minimize_crash.test.tmp-NullDerefTest
	60,070 ms	x64 debian > libFuzzer.libFuzzer::value-profile-load.test Script: -- : 'RUN: at line 2'; /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/LoadTest.cpp -fsanitize-coverage=trace-gep -o /var/lib/buildkite-agent/builds/llvm-project/build/projects/compiler-rt/test/fuzzer/X86_64DefaultLinuxConfig/Output/value-profile-load.test.tmp-LoadTest

Event Timeline

tmatheson created this revision.Jan 10 2023, 2:01 PM

Herald added a project: Restricted Project. · View Herald TranscriptJan 10 2023, 2:01 PM

Herald added subscribers: hiraditya, kristof.beyls. · View Herald Transcript

tmatheson requested review of this revision.Jan 10 2023, 2:01 PM

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Harbormaster completed remote builds in B206930: Diff 487986.Jan 10 2023, 8:14 PM

Review Notes:

Post/pre-indexing looks good.
There's no merging.
We talked about codegen for the neon instructions in RCPC3. Maybe that should be a different patch when you do implement it?

llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
2535–2537	Can you rewrite this with `llvm::any`?
2540–2542	I think this fixme is unnecessary, or is development-only.
2552–2556	Please split this into three different `if`s with comments to make these conditions readable/explanable.
llvm/test/CodeGen/AArch64/aarch64-rcpc3-ldst.ll
10–15	Can you check this TODO?
24–46	The codegen is not different here and is not showing merging. LDIAPP has constraints on when you can merge, which depend on the order of the two accesses, which will need testing.
380–389	TODO?
395–396	TODO?