Successfully identified regression in *llvm* in CI configuration
tcwg_bmk_llvm_tx1/llvm-master-aarch64-spec2k6-O2. So far, this commit has
regressed CI configurations:
- tcwg_bmk_llvm_tx1/llvm-master-aarch64-spec2k6-O2
Culprit:
<cut>
commit a0a9c9e188f5b97ff8b74287d1536f57ec5dda54
Author: Sanjay Patel <spa...@rotateright.com>
Date: Wed Aug 11 12:41:47 2021 -0400
[InstCombine] avoid breaking up min/max (cmp+sel) idioms
This is a quick fix for a motivating case that looks like this:
https://godbolt.org/z/GeMqzMc38
As noted, we might be able to restore the min/max patterns
with select folds, or we just wait for this to become easier
with canonicalization to min/max intrinsics.
</cut>
Results regressed to (for first_bad == a0a9c9e188f5b97ff8b74287d1536f57ec5dda54)
# reset_artifacts:
-10
# build_abe binutils:
-9
# build_abe stage1 -- --set gcc_override_configure=--disable-libsanitizer:
-8
# build_abe linux:
-7
# build_abe glibc:
-6
# build_abe stage2 -- --set gcc_override_configure=--disable-libsanitizer:
-5
# build_llvm true:
-3
# true:
0
# benchmark -- -O2
artifacts/build-a0a9c9e188f5b97ff8b74287d1536f57ec5dda54/results_id:
1
# 464.h264ref,h264ref_base.default regressed by 106
# 464.h264ref,[.] FastFullPelBlockMotionSearch regressed by 146
from (for last_good == 5bf4ab0e79e1a8552019918a662bdf7af8b3825a)
# reset_artifacts:
-10
# build_abe binutils:
-9
# build_abe stage1 -- --set gcc_override_configure=--disable-libsanitizer:
-8
# build_abe linux:
-7
# build_abe glibc:
-6
# build_abe stage2 -- --set gcc_override_configure=--disable-libsanitizer:
-5
# build_llvm true:
-3
# true:
0
# benchmark -- -O2
artifacts/build-5bf4ab0e79e1a8552019918a662bdf7af8b3825a/results_id:
1
Artifacts of last_good build:
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-aarch64-spec2k6-O2/15/artifact/artifacts/build-5bf4ab0e79e1a8552019918a662bdf7af8b3825a/
Results ID of last_good:
tx1_64/tcwg_bmk_llvm_tx1/bisect-llvm-master-aarch64-spec2k6-O2/3875
Artifacts of first_bad build:
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-aarch64-spec2k6-O2/15/artifact/artifacts/build-a0a9c9e188f5b97ff8b74287d1536f57ec5dda54/
Results ID of first_bad:
tx1_64/tcwg_bmk_llvm_tx1/bisect-llvm-master-aarch64-spec2k6-O2/3877
Build top page/logs:
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-aarch64-spec2k6-O2/15/
Configuration details:
Reproduce builds:
<cut>
mkdir investigate-llvm-a0a9c9e188f5b97ff8b74287d1536f57ec5dda54
cd investigate-llvm-a0a9c9e188f5b97ff8b74287d1536f57ec5dda54
git clone https://git.linaro.org/toolchain/jenkins-scripts
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-aarch64-spec2k6-O2/15/artifact/artifacts/manifests/build-baseline.sh
--fail
curl -o artifacts/manifests/build-parameters.sh
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-aarch64-spec2k6-O2/15/artifact/artifacts/manifests/build-parameters.sh
--fail
curl -o artifacts/test.sh
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-aarch64-spec2k6-O2/15/artifact/artifacts/test.sh
--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 a0a9c9e188f5b97ff8b74287d1536f57ec5dda54
../artifacts/test.sh
# Reproduce last_good build
git checkout --detach 5bf4ab0e79e1a8552019918a662bdf7af8b3825a
../artifacts/test.sh
cd ..
</cut>
History of pending regressions and results:
https://git.linaro.org/toolchain/ci/base-artifacts.git/log/?h=linaro-local/ci/tcwg_bmk_llvm_tx1/llvm-master-aarch64-spec2k6-O2
Artifacts:
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-aarch64-spec2k6-O2/15/artifact/artifacts/
Build log:
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tx1-llvm-master-aarch64-spec2k6-O2/15/consoleText
Full commit (up to 1000 lines):
<cut>
commit a0a9c9e188f5b97ff8b74287d1536f57ec5dda54
Author: Sanjay Patel <spa...@rotateright.com>
Date: Wed Aug 11 12:41:47 2021 -0400
[InstCombine] avoid breaking up min/max (cmp+sel) idioms
This is a quick fix for a motivating case that looks like this:
https://godbolt.org/z/GeMqzMc38
As noted, we might be able to restore the min/max patterns
with select folds, or we just wait for this to become easier
with canonicalization to min/max intrinsics.
---
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp | 12 +++++++++---
llvm/test/Transforms/InstCombine/icmp-add.ll | 13 ++++++-------
2 files changed, 15 insertions(+), 10 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 2e20bca300d3..71037616585c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -5755,9 +5755,6 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I)
{
if (Instruction *Res = foldICmpWithDominatingICmp(I))
return Res;
- if (Instruction *Res = foldICmpBinOp(I, Q))
- return Res;
-
if (Instruction *Res = foldICmpUsingKnownBits(I))
return Res;
@@ -5803,6 +5800,15 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst
&I) {
}
}
+ // The folds in here may rely on wrapping flags and special constants, so
+ // they can break up min/max idioms in some cases but not seemingly similar
+ // patterns.
+ // FIXME: It may be possible to enhance select folding to make this
+ // unnecessary. It may also be moot if we canonicalize to min/max
+ // intrinsics.
+ if (Instruction *Res = foldICmpBinOp(I, Q))
+ return Res;
+
if (Instruction *Res = foldICmpInstWithConstant(I))
return Res;
diff --git a/llvm/test/Transforms/InstCombine/icmp-add.ll
b/llvm/test/Transforms/InstCombine/icmp-add.ll
index 187e0ad1a31b..1750b5685c50 100644
--- a/llvm/test/Transforms/InstCombine/icmp-add.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-add.ll
@@ -972,7 +972,6 @@ define i1 @slt_offset_nsw(i8 %a, i8 %c) {
ret i1 %ov
}
-; FIXME:
; In the following 4 tests, we could push the inc/dec
; through the min/max, but we should not break up the
; min/max idiom by using different icmp and select
@@ -980,9 +979,9 @@ define i1 @slt_offset_nsw(i8 %a, i8 %c) {
define i32 @increment_max(i32 %x) {
; CHECK-LABEL: @increment_max(
-; CHECK-NEXT: [[A:%.*]] = add nsw i32 [[X:%.*]], 1
-; CHECK-NEXT: [[C_INV:%.*]] = icmp slt i32 [[X]], 0
-; CHECK-NEXT: [[S:%.*]] = select i1 [[C_INV]], i32 0, i32 [[A]]
+; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i32 [[X:%.*]], -1
+; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 [[X]], i32 -1
+; CHECK-NEXT: [[S:%.*]] = add nsw i32 [[TMP2]], 1
; CHECK-NEXT: ret i32 [[S]]
;
%a = add nsw i32 %x, 1
@@ -1019,9 +1018,9 @@ define i32 @increment_min(i32 %x) {
define i32 @decrement_min(i32 %x) {
; CHECK-LABEL: @decrement_min(
-; CHECK-NEXT: [[A:%.*]] = add nsw i32 [[X:%.*]], -1
-; CHECK-NEXT: [[C_INV:%.*]] = icmp sgt i32 [[X]], 0
-; CHECK-NEXT: [[S:%.*]] = select i1 [[C_INV]], i32 0, i32 [[A]]
+; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 [[X:%.*]], 1
+; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 [[X]], i32 1
+; CHECK-NEXT: [[S:%.*]] = add nsw i32 [[TMP2]], -1
; CHECK-NEXT: ret i32 [[S]]
;
%a = add nsw i32 %x, -1
</cut>
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