Successfully identified regression in *llvm* in CI configuration
tcwg_bmk_llvm_tk1/llvm-master-arm-spec2k6-Os. So far, this commit has
regressed CI configurations:
- tcwg_bmk_llvm_tk1/llvm-master-arm-spec2k6-Os
Culprit:
<cut>
commit 40b752d28d95158e52dba7cfeea92e41b7ccff9a
Author: Sanjay Patel <spa...@rotateright.com>
Date: Mon Jul 5 09:57:39 2021 -0400
[InstCombine] fold icmp slt/sgt of offset value with constant
This follows up patches for the unsigned siblings:
0c400e895306
c7b658aeb526
We are translating an offset signed compare to its
unsigned equivalent when one end of the range is
at the limit (zero or unsigned max).
(X + C2) >s C --> X <u (SMAX - C) (if C == C2 - 1)
(X + C2) <s C --> X >u (C ^ SMAX) (if C == C2)
This probably does not show up much in IR derived
from C/C++ source because that would likely have
'nsw', and we have folds for that already.
As with the previous unsigned transforms, the folds
could be generalized to handle non-constant patterns:
https://alive2.llvm.org/ce/z/Y8Xrrm
; sgt
define i1 @src(i8 %a, i8 %c) {
%c2 = add i8 %c, 1
%t = add i8 %a, %c2
%ov = icmp sgt i8 %t, %c
ret i1 %ov
}
define i1 @tgt(i8 %a, i8 %c) {
%c_off = sub i8 127, %c ; SMAX
%ov = icmp ult i8 %a, %c_off
ret i1 %ov
}
https://alive2.llvm.org/ce/z/c8uhnk
; slt
define i1 @src(i8 %a, i8 %c) {
%t = add i8 %a, %c
%ov = icmp slt i8 %t, %c
ret i1 %ov
}
define i1 @tgt(i8 %a, i8 %c) {
%c_offnot = xor i8 %c, 127 ; SMAX
%ov = icmp ugt i8 %a, %c_offnot
ret i1 %ov
}
</cut>
Results regressed to (for first_bad == 40b752d28d95158e52dba7cfeea92e41b7ccff9a)
# reset_artifacts:
-10
# build_abe binutils:
-9
# build_abe stage1 -- --set gcc_override_configure=--with-mode=thumb --set
gcc_override_configure=--disable-libsanitizer:
-8
# build_abe linux:
-7
# build_abe glibc:
-6
# build_abe stage2 -- --set gcc_override_configure=--with-mode=thumb --set
gcc_override_configure=--disable-libsanitizer:
-5
# build_llvm true:
-3
# true:
0
# benchmark -Os_mthumb --
artifacts/build-40b752d28d95158e52dba7cfeea92e41b7ccff9a/results_id:
1
# 401.bzip2,bzip2_base.default regressed by 110
# 401.bzip2,[.] BZ2_decompress regressed by 149
from (for last_good == 32dd914f7182875730eb3453f39dcc584b7219b2)
# reset_artifacts:
-10
# build_abe binutils:
-9
# build_abe stage1 -- --set gcc_override_configure=--with-mode=thumb --set
gcc_override_configure=--disable-libsanitizer:
-8
# build_abe linux:
-7
# build_abe glibc:
-6
# build_abe stage2 -- --set gcc_override_configure=--with-mode=thumb --set
gcc_override_configure=--disable-libsanitizer:
-5
# build_llvm true:
-3
# true:
0
# benchmark -Os_mthumb --
artifacts/build-32dd914f7182875730eb3453f39dcc584b7219b2/results_id:
1
Artifacts of last_good build:
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tk1-llvm-master-arm-spec2k6-Os/9/artifact/artifacts/build-32dd914f7182875730eb3453f39dcc584b7219b2/
Results ID of last_good:
tk1_32/tcwg_bmk_llvm_tk1/bisect-llvm-master-arm-spec2k6-Os/1631
Artifacts of first_bad build:
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tk1-llvm-master-arm-spec2k6-Os/9/artifact/artifacts/build-40b752d28d95158e52dba7cfeea92e41b7ccff9a/
Results ID of first_bad:
tk1_32/tcwg_bmk_llvm_tk1/bisect-llvm-master-arm-spec2k6-Os/1622
Build top page/logs:
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tk1-llvm-master-arm-spec2k6-Os/9/
Configuration details:
Reproduce builds:
<cut>
mkdir investigate-llvm-40b752d28d95158e52dba7cfeea92e41b7ccff9a
cd investigate-llvm-40b752d28d95158e52dba7cfeea92e41b7ccff9a
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_tk1-llvm-master-arm-spec2k6-Os/9/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_tk1-llvm-master-arm-spec2k6-Os/9/artifact/artifacts/manifests/build-parameters.sh
--fail
curl -o artifacts/test.sh
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tk1-llvm-master-arm-spec2k6-Os/9/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)
rsync -a --del --delete-excluded --exclude bisect/ --exclude artifacts/
--exclude llvm/ ./ ./bisect/baseline/
cd llvm
# Reproduce first_bad build
git checkout --detach 40b752d28d95158e52dba7cfeea92e41b7ccff9a
../artifacts/test.sh
# Reproduce last_good build
git checkout --detach 32dd914f7182875730eb3453f39dcc584b7219b2
../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_tk1/llvm-master-arm-spec2k6-Os
Artifacts:
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tk1-llvm-master-arm-spec2k6-Os/9/artifact/artifacts/
Build log:
https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_tk1-llvm-master-arm-spec2k6-Os/9/consoleText
Full commit (up to 1000 lines):
<cut>
commit 40b752d28d95158e52dba7cfeea92e41b7ccff9a
Author: Sanjay Patel <spa...@rotateright.com>
Date: Mon Jul 5 09:57:39 2021 -0400
[InstCombine] fold icmp slt/sgt of offset value with constant
This follows up patches for the unsigned siblings:
0c400e895306
c7b658aeb526
We are translating an offset signed compare to its
unsigned equivalent when one end of the range is
at the limit (zero or unsigned max).
(X + C2) >s C --> X <u (SMAX - C) (if C == C2 - 1)
(X + C2) <s C --> X >u (C ^ SMAX) (if C == C2)
This probably does not show up much in IR derived
from C/C++ source because that would likely have
'nsw', and we have folds for that already.
As with the previous unsigned transforms, the folds
could be generalized to handle non-constant patterns:
https://alive2.llvm.org/ce/z/Y8Xrrm
; sgt
define i1 @src(i8 %a, i8 %c) {
%c2 = add i8 %c, 1
%t = add i8 %a, %c2
%ov = icmp sgt i8 %t, %c
ret i1 %ov
}
define i1 @tgt(i8 %a, i8 %c) {
%c_off = sub i8 127, %c ; SMAX
%ov = icmp ult i8 %a, %c_off
ret i1 %ov
}
https://alive2.llvm.org/ce/z/c8uhnk
; slt
define i1 @src(i8 %a, i8 %c) {
%t = add i8 %a, %c
%ov = icmp slt i8 %t, %c
ret i1 %ov
}
define i1 @tgt(i8 %a, i8 %c) {
%c_offnot = xor i8 %c, 127 ; SMAX
%ov = icmp ugt i8 %a, %c_offnot
ret i1 %ov
}
---
.../Transforms/InstCombine/InstCombineCompares.cpp | 21 ++++++++++++++-------
llvm/test/Transforms/InstCombine/icmp-add.ll | 20 ++++++++++----------
2 files changed, 24 insertions(+), 17 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 6bd479def210..6e66c61f5e46 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2636,20 +2636,27 @@ Instruction
*InstCombinerImpl::foldICmpAddConstant(ICmpInst &Cmp,
// Fold icmp pred (add X, C2), C.
Value *X = Add->getOperand(0);
Type *Ty = Add->getType();
- CmpInst::Predicate Pred = Cmp.getPredicate();
+ const CmpInst::Predicate Pred = Cmp.getPredicate();
+ const APInt SMax = APInt::getSignedMaxValue(Ty->getScalarSizeInBits());
+ const APInt SMin = APInt::getSignedMinValue(Ty->getScalarSizeInBits());
- // Fold an unsigned compare with offset to signed compare:
+ // Fold compare with offset to opposite sign compare if it eliminates offset:
// (X + C2) >u C --> X <s -C2 (if C == C2 + SMAX)
- // TODO: Find the signed predicate siblings.
- if (Pred == CmpInst::ICMP_UGT &&
- C == *C2 + APInt::getSignedMaxValue(Ty->getScalarSizeInBits()))
+ if (Pred == CmpInst::ICMP_UGT && C == *C2 + SMax)
return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantInt::get(Ty, -(*C2)));
// (X + C2) <u C --> X >s ~C2 (if C == C2 + SMIN)
- if (Pred == CmpInst::ICMP_ULT &&
- C == *C2 + APInt::getSignedMinValue(Ty->getScalarSizeInBits()))
+ if (Pred == CmpInst::ICMP_ULT && C == *C2 + SMin)
return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantInt::get(Ty, ~(*C2)));
+ // (X + C2) >s C --> X <u (SMAX - C) (if C == C2 - 1)
+ if (Pred == CmpInst::ICMP_SGT && C == *C2 - 1)
+ return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantInt::get(Ty, SMax - C));
+
+ // (X + C2) <s C --> X >u (C ^ SMAX) (if C == C2)
+ if (Pred == CmpInst::ICMP_SLT && C == *C2)
+ return new ICmpInst(ICmpInst::ICMP_UGT, X, ConstantInt::get(Ty, C ^ SMax));
+
// If the add does not wrap, we can always adjust the compare by subtracting
// the constants. Equality comparisons are handled elsewhere. SGE/SLE/UGE/ULE
// are canonicalized to SGT/SLT/UGT/ULT.
diff --git a/llvm/test/Transforms/InstCombine/icmp-add.ll
b/llvm/test/Transforms/InstCombine/icmp-add.ll
index 1f00dc6e2992..aa69325d716c 100644
--- a/llvm/test/Transforms/InstCombine/icmp-add.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-add.ll
@@ -842,8 +842,7 @@ define i1 @ult_wrong_offset(i8 %a) {
define i1 @sgt_offset(i8 %a) {
; CHECK-LABEL: @sgt_offset(
-; CHECK-NEXT: [[T:%.*]] = add i8 [[A:%.*]], -6
-; CHECK-NEXT: [[OV:%.*]] = icmp sgt i8 [[T]], -7
+; CHECK-NEXT: [[OV:%.*]] = icmp ult i8 [[A:%.*]], -122
; CHECK-NEXT: ret i1 [[OV]]
;
%t = add i8 %a, -6
@@ -855,7 +854,7 @@ define i1 @sgt_offset_use(i32 %a) {
; CHECK-LABEL: @sgt_offset_use(
; CHECK-NEXT: [[T:%.*]] = add i32 [[A:%.*]], 42
; CHECK-NEXT: call void @use(i32 [[T]])
-; CHECK-NEXT: [[OV:%.*]] = icmp sgt i32 [[T]], 41
+; CHECK-NEXT: [[OV:%.*]] = icmp ult i32 [[A]], 2147483606
; CHECK-NEXT: ret i1 [[OV]]
;
%t = add i32 %a, 42
@@ -866,8 +865,7 @@ define i1 @sgt_offset_use(i32 %a) {
define <2 x i1> @sgt_offset_splat(<2 x i5> %a) {
; CHECK-LABEL: @sgt_offset_splat(
-; CHECK-NEXT: [[T:%.*]] = add <2 x i5> [[A:%.*]], <i5 9, i5 9>
-; CHECK-NEXT: [[OV:%.*]] = icmp sgt <2 x i5> [[T]], <i5 8, i5 8>
+; CHECK-NEXT: [[OV:%.*]] = icmp ult <2 x i5> [[A:%.*]], <i5 7, i5 7>
; CHECK-NEXT: ret <2 x i1> [[OV]]
;
%t = add <2 x i5> %a, <i5 9, i5 9>
@@ -875,6 +873,8 @@ define <2 x i1> @sgt_offset_splat(<2 x i5> %a) {
ret <2 x i1> %ov
}
+; negative test - constants must differ by 1
+
define i1 @sgt_wrong_offset(i8 %a) {
; CHECK-LABEL: @sgt_wrong_offset(
; CHECK-NEXT: [[T:%.*]] = add i8 [[A:%.*]], -7
@@ -888,8 +888,7 @@ define i1 @sgt_wrong_offset(i8 %a) {
define i1 @slt_offset(i8 %a) {
; CHECK-LABEL: @slt_offset(
-; CHECK-NEXT: [[T:%.*]] = add i8 [[A:%.*]], -6
-; CHECK-NEXT: [[OV:%.*]] = icmp slt i8 [[T]], -6
+; CHECK-NEXT: [[OV:%.*]] = icmp ugt i8 [[A:%.*]], -123
; CHECK-NEXT: ret i1 [[OV]]
;
%t = add i8 %a, -6
@@ -901,7 +900,7 @@ define i1 @slt_offset_use(i32 %a) {
; CHECK-LABEL: @slt_offset_use(
; CHECK-NEXT: [[T:%.*]] = add i32 [[A:%.*]], 42
; CHECK-NEXT: call void @use(i32 [[T]])
-; CHECK-NEXT: [[OV:%.*]] = icmp slt i32 [[T]], 42
+; CHECK-NEXT: [[OV:%.*]] = icmp ugt i32 [[A]], 2147483605
; CHECK-NEXT: ret i1 [[OV]]
;
%t = add i32 %a, 42
@@ -912,8 +911,7 @@ define i1 @slt_offset_use(i32 %a) {
define <2 x i1> @slt_offset_splat(<2 x i5> %a) {
; CHECK-LABEL: @slt_offset_splat(
-; CHECK-NEXT: [[T:%.*]] = add <2 x i5> [[A:%.*]], <i5 9, i5 9>
-; CHECK-NEXT: [[OV:%.*]] = icmp slt <2 x i5> [[T]], <i5 9, i5 9>
+; CHECK-NEXT: [[OV:%.*]] = icmp ugt <2 x i5> [[A:%.*]], <i5 6, i5 6>
; CHECK-NEXT: ret <2 x i1> [[OV]]
;
%t = add <2 x i5> %a, <i5 9, i5 9>
@@ -921,6 +919,8 @@ define <2 x i1> @slt_offset_splat(<2 x i5> %a) {
ret <2 x i1> %ov
}
+; negative test - constants must be equal
+
define i1 @slt_wrong_offset(i8 %a) {
; CHECK-LABEL: @slt_wrong_offset(
; CHECK-NEXT: [[T:%.*]] = add i8 [[A:%.*]], -6
</cut>
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