[llvm] r328119 - [InstCombine] add folds for xor-of-icmp signbit tests (PR36682)
Reid Kleckner via llvm-commits
llvm-commits at lists.llvm.org
Wed Mar 21 13:41:03 PDT 2018
This changes causes assertions when compiling safe_numerics_unittest.cpp in
Chromium with MSan:
https://ci.chromium.org/buildbot/chromium.clang/ToTLinuxMSan/1945
I have reverted this change in r328145. I will send you pre-processed
source offline that reproduces the problem.
On Wed, Mar 21, 2018 at 10:20 AM Sanjay Patel via llvm-commits <
llvm-commits at lists.llvm.org> wrote:
> Author: spatel
> Date: Wed Mar 21 10:17:13 2018
> New Revision: 328119
>
> URL: http://llvm.org/viewvc/llvm-project?rev=328119&view=rev
> Log:
> [InstCombine] add folds for xor-of-icmp signbit tests (PR36682)
>
> This is part of solving:
> https://bugs.llvm.org/show_bug.cgi?id=36682
>
> There's also a leftover improvement from the long-ago-closed:
> https://bugs.llvm.org/show_bug.cgi?id=5438
>
> https://rise4fun.com/Alive/dC1
>
>
> Modified:
> llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
> llvm/trunk/test/Transforms/InstCombine/compare-signs.ll
> llvm/trunk/test/Transforms/InstCombine/xor-icmps.ll
>
> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=328119&r1=328118&r2=328119&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
> (original)
> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Wed Mar
> 21 10:17:13 2018
> @@ -2363,6 +2363,36 @@ Value *InstCombiner::foldXorOfICmps(ICmp
> }
> }
>
> + // TODO: This can be generalized to compares of non-signbits using
> + // decomposeBitTestICmp(). It could be enhanced more by using
> (something like)
> + // foldLogOpOfMaskedICmps().
> + ICmpInst::Predicate PredL = LHS->getPredicate();
> + ICmpInst::Predicate PredR = RHS->getPredicate();
> + Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1);
> + Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1);
> + if ((LHS->hasOneUse() || RHS->hasOneUse()) && PredL == PredR) {
> + // (X > -1) ^ (Y > -1) --> (X ^ Y) < 0
> + // (X < 0) ^ (Y < 0) --> (X ^ Y) < 0
> + if ((match(LHS1, m_AllOnes()) && match(RHS1, m_AllOnes()) &&
> + PredL == CmpInst::ICMP_SGT) ||
> + (match(LHS1, m_Zero()) && match(RHS1, m_Zero()) &&
> + PredL == CmpInst::ICMP_SLT)) {
> + Value *Zero = ConstantInt::getNullValue(LHS0->getType());
> + return Builder.CreateICmpSLT(Builder.CreateXor(LHS0, RHS0), Zero);
> + }
> + }
> + if ((LHS->hasOneUse() || RHS->hasOneUse())) {
> + // (X > -1) ^ (Y < 0) --> (X ^ Y) > -1
> + // (X < 0) ^ (Y > -1) --> (X ^ Y) > -1
> + if ((match(LHS1, m_AllOnes()) && match(RHS1, m_Zero()) &&
> + PredL == CmpInst::ICMP_SGT && PredR == CmpInst::ICMP_SLT) ||
> + (match(LHS1, m_Zero()) && match(RHS1, m_AllOnes()) &&
> + PredL == CmpInst::ICMP_SLT && PredR == CmpInst::ICMP_SGT)) {
> + Value *MinusOne = ConstantInt::getAllOnesValue(LHS0->getType());
> + return Builder.CreateICmpSGT(Builder.CreateXor(LHS0, RHS0),
> MinusOne);
> + }
> + }
> +
> // Instead of trying to imitate the folds for and/or, decompose this
> 'xor'
> // into those logic ops. That is, try to turn this into an and-of-icmps
> // because we have many folds for that pattern.
>
> Modified: llvm/trunk/test/Transforms/InstCombine/compare-signs.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/compare-signs.ll?rev=328119&r1=328118&r2=328119&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/InstCombine/compare-signs.ll (original)
> +++ llvm/trunk/test/Transforms/InstCombine/compare-signs.ll Wed Mar 21
> 10:17:13 2018
> @@ -1,15 +1,14 @@
> ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
> ; RUN: opt -instcombine -S < %s | FileCheck %s
> +
> ; PR5438
>
> -; TODO: This should also optimize down.
> define i32 @test1(i32 %a, i32 %b) nounwind readnone {
> ; CHECK-LABEL: @test1(
> -; CHECK-NEXT: [[T0:%.*]] = icmp sgt i32 [[A:%.*]], -1
> -; CHECK-NEXT: [[T1:%.*]] = icmp slt i32 [[B:%.*]], 0
> -; CHECK-NEXT: [[T2:%.*]] = xor i1 [[T1]], [[T0]]
> -; CHECK-NEXT: [[T3:%.*]] = zext i1 [[T2]] to i32
> -; CHECK-NEXT: ret i32 [[T3]]
> +; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[B:%.*]], [[A:%.*]]
> +; CHECK-NEXT: [[DOTLOBIT:%.*]] = lshr i32 [[TMP1]], 31
> +; CHECK-NEXT: [[DOTLOBIT_NOT:%.*]] = xor i32 [[DOTLOBIT]], 1
> +; CHECK-NEXT: ret i32 [[DOTLOBIT_NOT]]
> ;
> %t0 = icmp sgt i32 %a, -1
> %t1 = icmp slt i32 %b, 0
> @@ -36,7 +35,7 @@ define i32 @test2(i32 %a, i32 %b) nounwi
>
> define i32 @test3(i32 %a, i32 %b) nounwind readnone {
> ; CHECK-LABEL: @test3(
> -; CHECK-NEXT: [[T2_UNSHIFTED:%.*]] = xor i32 %a, %b
> +; CHECK-NEXT: [[T2_UNSHIFTED:%.*]] = xor i32 [[A:%.*]], [[B:%.*]]
> ; CHECK-NEXT: [[T2_UNSHIFTED_LOBIT:%.*]] = lshr i32 [[T2_UNSHIFTED]],
> 31
> ; CHECK-NEXT: [[T2_UNSHIFTED_LOBIT_NOT:%.*]] = xor i32
> [[T2_UNSHIFTED_LOBIT]], 1
> ; CHECK-NEXT: ret i32 [[T2_UNSHIFTED_LOBIT_NOT]]
> @@ -68,7 +67,7 @@ define <2 x i32> @test3vec(<2 x i32> %a,
> ; is one, not zero.
> define i32 @test3i(i32 %a, i32 %b) nounwind readnone {
> ; CHECK-LABEL: @test3i(
> -; CHECK-NEXT: [[T01:%.*]] = xor i32 %a, %b
> +; CHECK-NEXT: [[T01:%.*]] = xor i32 [[A:%.*]], [[B:%.*]]
> ; CHECK-NEXT: [[TMP1:%.*]] = lshr i32 [[T01]], 31
> ; CHECK-NEXT: [[T4:%.*]] = xor i32 [[TMP1]], 1
> ; CHECK-NEXT: ret i32 [[T4]]
> @@ -84,7 +83,7 @@ define i32 @test3i(i32 %a, i32 %b) nounw
>
> define i1 @test4a(i32 %a) {
> ; CHECK-LABEL: @test4a(
> -; CHECK-NEXT: [[C:%.*]] = icmp slt i32 %a, 1
> +; CHECK-NEXT: [[C:%.*]] = icmp slt i32 [[A:%.*]], 1
> ; CHECK-NEXT: ret i1 [[C]]
> ;
> %l = ashr i32 %a, 31
> @@ -97,7 +96,7 @@ define i1 @test4a(i32 %a) {
>
> define <2 x i1> @test4a_vec(<2 x i32> %a) {
> ; CHECK-LABEL: @test4a_vec(
> -; CHECK-NEXT: [[C:%.*]] = icmp slt <2 x i32> %a, <i32 1, i32 1>
> +; CHECK-NEXT: [[C:%.*]] = icmp slt <2 x i32> [[A:%.*]], <i32 1, i32 1>
> ; CHECK-NEXT: ret <2 x i1> [[C]]
> ;
> %l = ashr <2 x i32> %a, <i32 31, i32 31>
> @@ -110,7 +109,7 @@ define <2 x i1> @test4a_vec(<2 x i32> %a
>
> define i1 @test4b(i64 %a) {
> ; CHECK-LABEL: @test4b(
> -; CHECK-NEXT: [[C:%.*]] = icmp slt i64 %a, 1
> +; CHECK-NEXT: [[C:%.*]] = icmp slt i64 [[A:%.*]], 1
> ; CHECK-NEXT: ret i1 [[C]]
> ;
> %l = ashr i64 %a, 63
> @@ -123,7 +122,7 @@ define i1 @test4b(i64 %a) {
>
> define i1 @test4c(i64 %a) {
> ; CHECK-LABEL: @test4c(
> -; CHECK-NEXT: [[C:%.*]] = icmp slt i64 %a, 1
> +; CHECK-NEXT: [[C:%.*]] = icmp slt i64 [[A:%.*]], 1
> ; CHECK-NEXT: ret i1 [[C]]
> ;
> %l = ashr i64 %a, 63
> @@ -137,7 +136,7 @@ define i1 @test4c(i64 %a) {
>
> define <2 x i1> @test4c_vec(<2 x i64> %a) {
> ; CHECK-LABEL: @test4c_vec(
> -; CHECK-NEXT: [[C:%.*]] = icmp slt <2 x i64> %a, <i64 1, i64 1>
> +; CHECK-NEXT: [[C:%.*]] = icmp slt <2 x i64> [[A:%.*]], <i64 1, i64 1>
> ; CHECK-NEXT: ret <2 x i1> [[C]]
> ;
> %l = ashr <2 x i64> %a, <i64 63, i64 63>
>
> Modified: llvm/trunk/test/Transforms/InstCombine/xor-icmps.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/xor-icmps.ll?rev=328119&r1=328118&r2=328119&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/InstCombine/xor-icmps.ll (original)
> +++ llvm/trunk/test/Transforms/InstCombine/xor-icmps.ll Wed Mar 21
> 10:17:13 2018
> @@ -42,10 +42,9 @@ define i1 @eq_ne_zero(i4 %x, i4 %y) {
>
> define i1 @slt_zero(i4 %x, i4 %y) {
> ; CHECK-LABEL: @slt_zero(
> -; CHECK-NEXT: [[I0:%.*]] = icmp slt i4 [[X:%.*]], 0
> -; CHECK-NEXT: [[I1:%.*]] = icmp slt i4 [[Y:%.*]], 0
> -; CHECK-NEXT: [[R:%.*]] = xor i1 [[I0]], [[I1]]
> -; CHECK-NEXT: ret i1 [[R]]
> +; CHECK-NEXT: [[TMP1:%.*]] = xor i4 [[X:%.*]], [[Y:%.*]]
> +; CHECK-NEXT: [[TMP2:%.*]] = icmp slt i4 [[TMP1]], 0
> +; CHECK-NEXT: ret i1 [[TMP2]]
> ;
> %i0 = icmp slt i4 %x, 0
> %i1 = icmp slt i4 %y, 0
> @@ -68,10 +67,9 @@ define i1 @sgt_zero(i4 %x, i4 %y) {
>
> define i1 @sgt_minus1(i4 %x, i4 %y) {
> ; CHECK-LABEL: @sgt_minus1(
> -; CHECK-NEXT: [[I0:%.*]] = icmp sgt i4 [[X:%.*]], -1
> -; CHECK-NEXT: [[I1:%.*]] = icmp sgt i4 [[Y:%.*]], -1
> -; CHECK-NEXT: [[R:%.*]] = xor i1 [[I0]], [[I1]]
> -; CHECK-NEXT: ret i1 [[R]]
> +; CHECK-NEXT: [[TMP1:%.*]] = xor i4 [[X:%.*]], [[Y:%.*]]
> +; CHECK-NEXT: [[TMP2:%.*]] = icmp slt i4 [[TMP1]], 0
> +; CHECK-NEXT: ret i1 [[TMP2]]
> ;
> %i0 = icmp sgt i4 %x, -1
> %i1 = icmp sgt i4 %y, -1
> @@ -81,10 +79,9 @@ define i1 @sgt_minus1(i4 %x, i4 %y) {
>
> define i1 @slt_zero_sgt_minus1(i4 %x, i4 %y) {
> ; CHECK-LABEL: @slt_zero_sgt_minus1(
> -; CHECK-NEXT: [[I0:%.*]] = icmp slt i4 [[X:%.*]], 0
> -; CHECK-NEXT: [[I1:%.*]] = icmp sgt i4 [[Y:%.*]], -1
> -; CHECK-NEXT: [[R:%.*]] = xor i1 [[I0]], [[I1]]
> -; CHECK-NEXT: ret i1 [[R]]
> +; CHECK-NEXT: [[TMP1:%.*]] = xor i4 [[X:%.*]], [[Y:%.*]]
> +; CHECK-NEXT: [[TMP2:%.*]] = icmp sgt i4 [[TMP1]], -1
> +; CHECK-NEXT: ret i1 [[TMP2]]
> ;
> %i0 = icmp slt i4 %x, 0
> %i1 = icmp sgt i4 %y, -1
> @@ -94,10 +91,9 @@ define i1 @slt_zero_sgt_minus1(i4 %x, i4
>
> define <2 x i1> @sgt_minus1_slt_zero_sgt(<2 x i4> %x, <2 x i4> %y) {
> ; CHECK-LABEL: @sgt_minus1_slt_zero_sgt(
> -; CHECK-NEXT: [[I1:%.*]] = icmp sgt <2 x i4> [[X:%.*]], <i4 -1, i4 -1>
> -; CHECK-NEXT: [[I0:%.*]] = icmp slt <2 x i4> [[Y:%.*]], zeroinitializer
> -; CHECK-NEXT: [[R:%.*]] = xor <2 x i1> [[I0]], [[I1]]
> -; CHECK-NEXT: ret <2 x i1> [[R]]
> +; CHECK-NEXT: [[TMP1:%.*]] = xor <2 x i4> [[Y:%.*]], [[X:%.*]]
> +; CHECK-NEXT: [[TMP2:%.*]] = icmp sgt <2 x i4> [[TMP1]], <i4 -1, i4 -1>
> +; CHECK-NEXT: ret <2 x i1> [[TMP2]]
> ;
> %i1 = icmp sgt <2 x i4> %x, <i4 -1, i4 -1>
> %i0 = icmp slt <2 x i4> %y, zeroinitializer
>
>
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