After llvm commit 0658bab870c89d81678f1f37aac0396ddd0913b3 Author: Philip Reames listmail@philipreames.com

[SCEV] Infer flags from add/gep in any block

the following benchmarks slowed down by more than 2%: - 464.h264ref slowed down by 6% from 11124 to 11783 perf samples - 464.h264ref:[.] FastFullPelBlockMotionSearch slowed down by 41% from 1504 to 2116 perf samples

Below reproducer instructions can be used to re-build both "first_bad" and "last_good" cross-toolchains used in this bisection. Naturally, the scripts will fail when triggerring benchmarking jobs if you don't have access to Linaro TCWG CI.

For your convenience, we have uploaded tarballs with pre-processed source and assembly files at: - First_bad save-temps: https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-a... - Last_good save-temps: https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-a... - Baseline save-temps: https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-a...

Configuration: - Benchmark: SPEC CPU2006 - Toolchain: Clang + Glibc + LLVM Linker - Version: all components were built from their tip of trunk - Target: aarch64-linux-gnu - Compiler flags: -O2 - Hardware: NVidia TX1 4x Cortex-A57

This benchmarking CI is work-in-progress, and we welcome feedback and suggestions at linaro-toolchain@lists.linaro.org . In our improvement plans is to add support for SPEC CPU2017 benchmarks and provide "perf report/annotate" data behind these reports.

THIS IS THE END OF INTERESTING STUFF. BELOW ARE LINKS TO BUILDS, REPRODUCTION INSTRUCTIONS, AND THE RAW COMMIT.

This commit has regressed these CI configurations: - tcwg_bmk_llvm_tx1/llvm-master-aarch64-spec2k6-O2

First_bad build: https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-a... Last_good build: https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-a... Baseline build: https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-a... Even more details: https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-a...

Reproduce builds: <cut> mkdir investigate-llvm-0658bab870c89d81678f1f37aac0396ddd0913b3 cd investigate-llvm-0658bab870c89d81678f1f37aac0396ddd0913b3

# Fetch scripts git clone https://git.linaro.org/toolchain/jenkins-scripts

# Fetch manifests and test.sh script mkdir -p artifacts/manifests curl -o artifacts/manifests/build-baseline.sh https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-a... --fail curl -o artifacts/manifests/build-parameters.sh https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-a... --fail curl -o artifacts/test.sh https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-a... --fail chmod +x artifacts/test.sh

# Reproduce the baseline build (build all pre-requisites) ./jenkins-scripts/tcwg_bmk-build.sh @@ artifacts/manifests/build-baseline.sh

# Save baseline build state (which is then restored in artifacts/test.sh) mkdir -p ./bisect rsync -a --del --delete-excluded --exclude /bisect/ --exclude /artifacts/ --exclude /llvm/ ./ ./bisect/baseline/

cd llvm

# Reproduce first_bad build git checkout --detach 0658bab870c89d81678f1f37aac0396ddd0913b3 ../artifacts/test.sh

# Reproduce last_good build git checkout --detach 2ced9a42be8aba4533225fdb8ed02fe6f50060b6 ../artifacts/test.sh

cd .. </cut>

Full commit (up to 1000 lines): <cut> commit 0658bab870c89d81678f1f37aac0396ddd0913b3 Author: Philip Reames listmail@philipreames.com Date: Wed Oct 6 10:35:01 2021 -0700

[SCEV] Infer flags from add/gep in any block

This patch removes a compile time restriction from isSCEVExprNeverPoison. We've strengthened our ability to reason about flags on scopes other than addrecs, and this bailout prevents us from using it. The comment is also suspect as well in that we're in the middle of constructing a SCEV for I. As such, we're going to visit all operands *anyways*.

Differential Revision: https://reviews.llvm.org/D111186 --- llvm/lib/Analysis/ScalarEvolution.cpp | 10 --------- .../Analysis/DependenceAnalysis/Preliminary.ll | 2 +- .../Analysis/ScalarEvolution/flags-from-poison.ll | 8 +++---- .../SLPVectorizer/X86/consecutive-access.ll | 25 +++++++++------------- 4 files changed, 15 insertions(+), 30 deletions(-)

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index 6683b1a5205c..4fb2266b6e89 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -6645,16 +6645,6 @@ bool ScalarEvolution::isGuaranteedToTransferExecutionTo(const Instruction *A,

bool ScalarEvolution::isSCEVExprNeverPoison(const Instruction *I) { - // Here we check that I is in the header of the innermost loop containing I, - // since we only deal with instructions in the loop header. The actual loop we - // need to check later will come from an add recurrence, but getting that - // requires computing the SCEV of the operands, which can be expensive. This - // check we can do cheaply to rule out some cases early. - Loop *InnermostContainingLoop = LI.getLoopFor(I->getParent()); - if (InnermostContainingLoop == nullptr || - InnermostContainingLoop->getHeader() != I->getParent()) - return false; - // Only proceed if we can prove that I does not yield poison. if (!programUndefinedIfPoison(I)) return false; diff --git a/llvm/test/Analysis/DependenceAnalysis/Preliminary.ll b/llvm/test/Analysis/DependenceAnalysis/Preliminary.ll index 0899f67d6914..91827f3231ba 100644 --- a/llvm/test/Analysis/DependenceAnalysis/Preliminary.ll +++ b/llvm/test/Analysis/DependenceAnalysis/Preliminary.ll @@ -623,7 +623,7 @@ entry:

; CHECK-LABEL: p9 ; CHECK: da analyze - none! -; CHECK: da analyze - flow [|<]! +; CHECK: da analyze - none! ; CHECK: da analyze - confused! ; CHECK: da analyze - none! ; CHECK: da analyze - confused! diff --git a/llvm/test/Analysis/ScalarEvolution/flags-from-poison.ll b/llvm/test/Analysis/ScalarEvolution/flags-from-poison.ll index f0bda26edb38..0423854bbc3b 100644 --- a/llvm/test/Analysis/ScalarEvolution/flags-from-poison.ll +++ b/llvm/test/Analysis/ScalarEvolution/flags-from-poison.ll @@ -1628,9 +1628,9 @@ define noundef i32 @add-basic(i32 %a, i32 %b) { ; CHECK-LABEL: 'add-basic' ; CHECK-NEXT: Classifying expressions for: @add-basic ; CHECK-NEXT: %res = add nuw nsw i32 %a, %b -; CHECK-NEXT: --> (%a + %b) U: full-set S: full-set +; CHECK-NEXT: --> (%a + %b)<nuw><nsw> U: full-set S: full-set ; CHECK-NEXT: %res2 = udiv i32 255, %res -; CHECK-NEXT: --> (255 /u (%a + %b)) U: [0,256) S: [0,256) +; CHECK-NEXT: --> (255 /u (%a + %b)<nuw><nsw>) U: [0,256) S: [0,256) ; CHECK-NEXT: Determining loop execution counts for: @add-basic ; %res = add nuw nsw i32 %a, %b @@ -1656,9 +1656,9 @@ define noundef i32 @mul-basic(i32 %a, i32 %b) { ; CHECK-LABEL: 'mul-basic' ; CHECK-NEXT: Classifying expressions for: @mul-basic ; CHECK-NEXT: %res = mul nuw nsw i32 %a, %b -; CHECK-NEXT: --> (%a * %b) U: full-set S: full-set +; CHECK-NEXT: --> (%a * %b)<nuw><nsw> U: full-set S: full-set ; CHECK-NEXT: %res2 = udiv i32 255, %res -; CHECK-NEXT: --> (255 /u (%a * %b)) U: [0,256) S: [0,256) +; CHECK-NEXT: --> (255 /u (%a * %b)<nuw><nsw>) U: [0,256) S: [0,256) ; CHECK-NEXT: Determining loop execution counts for: @mul-basic ; %res = mul nuw nsw i32 %a, %b diff --git a/llvm/test/Transforms/SLPVectorizer/X86/consecutive-access.ll b/llvm/test/Transforms/SLPVectorizer/X86/consecutive-access.ll index e4000b52c4a9..8f57fe6866bd 100644 --- a/llvm/test/Transforms/SLPVectorizer/X86/consecutive-access.ll +++ b/llvm/test/Transforms/SLPVectorizer/X86/consecutive-access.ll @@ -8,10 +8,6 @@ target triple = "x86_64-apple-macosx10.9.0" @C = common global [2000 x float] zeroinitializer, align 16 @D = common global [2000 x float] zeroinitializer, align 16

-; Currently SCEV isn't smart enough to figure out that accesses -; A[3*i], A[3*i+1] and A[3*i+2] are consecutive, but in future -; that would hopefully be fixed. For now, check that this isn't -; vectorized. ; Function Attrs: nounwind ssp uwtable define void @foo_3double(i32 %u) #0 { ; CHECK-LABEL: @foo_3double( @@ -21,26 +17,25 @@ define void @foo_3double(i32 %u) #0 { ; CHECK-NEXT: [[MUL:%.*]] = mul nsw i32 [[U]], 3 ; CHECK-NEXT: [[IDXPROM:%.*]] = sext i32 [[MUL]] to i64 ; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds [2000 x double], [2000 x double]* @A, i32 0, i64 [[IDXPROM]] -; CHECK-NEXT: [[TMP0:%.*]] = load double, double* [[ARRAYIDX]], align 8 ; CHECK-NEXT: [[ARRAYIDX4:%.*]] = getelementptr inbounds [2000 x double], [2000 x double]* @B, i32 0, i64 [[IDXPROM]] -; CHECK-NEXT: [[TMP1:%.*]] = load double, double* [[ARRAYIDX4]], align 8 -; CHECK-NEXT: [[ADD5:%.*]] = fadd double [[TMP0]], [[TMP1]] -; CHECK-NEXT: store double [[ADD5]], double* [[ARRAYIDX]], align 8 ; CHECK-NEXT: [[ADD11:%.*]] = add nsw i32 [[MUL]], 1 ; CHECK-NEXT: [[IDXPROM12:%.*]] = sext i32 [[ADD11]] to i64 ; CHECK-NEXT: [[ARRAYIDX13:%.*]] = getelementptr inbounds [2000 x double], [2000 x double]* @A, i32 0, i64 [[IDXPROM12]] -; CHECK-NEXT: [[TMP2:%.*]] = load double, double* [[ARRAYIDX13]], align 8 +; CHECK-NEXT: [[TMP0:%.*]] = bitcast double* [[ARRAYIDX]] to <2 x double>* +; CHECK-NEXT: [[TMP1:%.*]] = load <2 x double>, <2 x double>* [[TMP0]], align 8 ; CHECK-NEXT: [[ARRAYIDX17:%.*]] = getelementptr inbounds [2000 x double], [2000 x double]* @B, i32 0, i64 [[IDXPROM12]] -; CHECK-NEXT: [[TMP3:%.*]] = load double, double* [[ARRAYIDX17]], align 8 -; CHECK-NEXT: [[ADD18:%.*]] = fadd double [[TMP2]], [[TMP3]] -; CHECK-NEXT: store double [[ADD18]], double* [[ARRAYIDX13]], align 8 +; CHECK-NEXT: [[TMP2:%.*]] = bitcast double* [[ARRAYIDX4]] to <2 x double>* +; CHECK-NEXT: [[TMP3:%.*]] = load <2 x double>, <2 x double>* [[TMP2]], align 8 +; CHECK-NEXT: [[TMP4:%.*]] = fadd <2 x double> [[TMP1]], [[TMP3]] +; CHECK-NEXT: [[TMP5:%.*]] = bitcast double* [[ARRAYIDX]] to <2 x double>* +; CHECK-NEXT: store <2 x double> [[TMP4]], <2 x double>* [[TMP5]], align 8 ; CHECK-NEXT: [[ADD24:%.*]] = add nsw i32 [[MUL]], 2 ; CHECK-NEXT: [[IDXPROM25:%.*]] = sext i32 [[ADD24]] to i64 ; CHECK-NEXT: [[ARRAYIDX26:%.*]] = getelementptr inbounds [2000 x double], [2000 x double]* @A, i32 0, i64 [[IDXPROM25]] -; CHECK-NEXT: [[TMP4:%.*]] = load double, double* [[ARRAYIDX26]], align 8 +; CHECK-NEXT: [[TMP6:%.*]] = load double, double* [[ARRAYIDX26]], align 8 ; CHECK-NEXT: [[ARRAYIDX30:%.*]] = getelementptr inbounds [2000 x double], [2000 x double]* @B, i32 0, i64 [[IDXPROM25]] -; CHECK-NEXT: [[TMP5:%.*]] = load double, double* [[ARRAYIDX30]], align 8 -; CHECK-NEXT: [[ADD31:%.*]] = fadd double [[TMP4]], [[TMP5]] +; CHECK-NEXT: [[TMP7:%.*]] = load double, double* [[ARRAYIDX30]], align 8 +; CHECK-NEXT: [[ADD31:%.*]] = fadd double [[TMP6]], [[TMP7]] ; CHECK-NEXT: store double [[ADD31]], double* [[ARRAYIDX26]], align 8 ; CHECK-NEXT: ret void ; </cut>