<div dir="ltr"><div>I cannot generate a reproducer, for some reason -gen-reproducer gets stuck as well, but I'm able to reproduce the issue by running:</div><div><br></div><div>/src/clang-llvm/llvm-build/fuchsia/./bin/clang++ -DXRAY_HAS_EXCEPTIONS=1 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/src/clang-llvm/llvm-project/compiler-rt/lib/xray/.. -I/src/clang-llvm/llvm-project/compiler-rt/lib/xray/../../include -fPIC -fvisibility-inlines-hidden -ffunction-sections -fdata-sections -std=c++14 -g -DNDEBUG -fno-builtin -fno-exceptions -fomit-frame-pointer -funwind-tables -fno-stack-protector -fvisibility=hidden -O3 -gline-tables-only -fno-rtti -MD -MT compiler-rt/lib/xray/CMakeFiles/RTXray.x86_64.dir/xray_x86_64.cpp.o -MF compiler-rt/lib/xray/CMakeFiles/RTXray.x86_64.dir/xray_x86_64.cpp.o.d -o compiler-rt/lib/xray/CMakeFiles/RTXray.x86_64.dir/xray_x86_64.cpp.o -c /src/clang-llvm/llvm-project/compiler-rt/lib/xray/xray_x86_64.cpp<br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Apr 7, 2021 at 12:25 AM Roman Lebedev <<a href="mailto:lebedev.ri@gmail.com">lebedev.ri@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Reproducer please?<br>
<br>
On Wed, Apr 7, 2021 at 8:46 AM Petr Hosek via llvm-commits<br>
<<a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a>> wrote:<br>
><br>
><br>
> Author: Petr Hosek<br>
> Date: 2021-04-06T22:30:28-07:00<br>
> New Revision: a547b4e26b311e417cd51100e379693f51a3f448<br>
><br>
> URL: <a href="https://github.com/llvm/llvm-project/commit/a547b4e26b311e417cd51100e379693f51a3f448" rel="noreferrer" target="_blank">https://github.com/llvm/llvm-project/commit/a547b4e26b311e417cd51100e379693f51a3f448</a><br>
> DIFF: <a href="https://github.com/llvm/llvm-project/commit/a547b4e26b311e417cd51100e379693f51a3f448.diff" rel="noreferrer" target="_blank">https://github.com/llvm/llvm-project/commit/a547b4e26b311e417cd51100e379693f51a3f448.diff</a><br>
><br>
> LOG: Revert "[InstCombine] Fold `((X - Y) - Z)` to `X - (Y + Z)` (PR49858)"<br>
><br>
> This reverts commit 31d219d2997fed1b7dc97e0adf170d5aaf65883e which<br>
> causes an infinite loop when compiling the XRay runtime.<br>
><br>
> Added:<br>
><br>
><br>
> Modified:<br>
> llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp<br>
> llvm/test/Transforms/InstCombine/abs-1.ll<br>
> llvm/test/Transforms/InstCombine/sub-from-sub.ll<br>
><br>
> Removed:<br>
><br>
><br>
><br>
> ################################################################################<br>
> diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp<br>
> index 4ced5994ffa6..bacb8689892a 100644<br>
> --- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp<br>
> +++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp<br>
> @@ -1801,12 +1801,6 @@ Instruction *InstCombinerImpl::visitSub(BinaryOperator &I) {<br>
> return BinaryOperator::CreateSub(XZ, YW);<br>
> }<br>
><br>
> - // ((X - Y) - Op1) --> X - (Y + Op1)<br>
> - if (match(Op0, m_OneUse(m_Sub(m_Value(X), m_Value(Y))))) {<br>
> - Value *Add = Builder.CreateAdd(Y, Op1);<br>
> - return BinaryOperator::CreateSub(X, Add);<br>
> - }<br>
> -<br>
> auto m_AddRdx = [](Value *&Vec) {<br>
> return m_OneUse(m_Intrinsic<Intrinsic::vector_reduce_add>(m_Value(Vec)));<br>
> };<br>
><br>
> diff --git a/llvm/test/Transforms/InstCombine/abs-1.ll b/llvm/test/Transforms/InstCombine/abs-1.ll<br>
> index ea77dfb5fef4..7452798ead77 100644<br>
> --- a/llvm/test/Transforms/InstCombine/abs-1.ll<br>
> +++ b/llvm/test/Transforms/InstCombine/abs-1.ll<br>
> @@ -305,9 +305,9 @@ define i32 @nabs_canonical_8(i32 %a) {<br>
> define i32 @nabs_canonical_9(i32 %a, i32 %b) {<br>
> ; CHECK-LABEL: @nabs_canonical_9(<br>
> ; CHECK-NEXT: [[T1:%.*]] = sub i32 [[A:%.*]], [[B:%.*]]<br>
> +; CHECK-NEXT: [[T2:%.*]] = sub i32 [[B]], [[A]]<br>
> ; CHECK-NEXT: [[TMP1:%.*]] = call i32 @llvm.abs.i32(i32 [[T1]], i1 false)<br>
> -; CHECK-NEXT: [[TMP2:%.*]] = add i32 [[TMP1]], [[A]]<br>
> -; CHECK-NEXT: [[ADD:%.*]] = sub i32 [[B]], [[TMP2]]<br>
> +; CHECK-NEXT: [[ADD:%.*]] = sub i32 [[T2]], [[TMP1]]<br>
> ; CHECK-NEXT: ret i32 [[ADD]]<br>
> ;<br>
> %t1 = sub i32 %a, %b<br>
><br>
> diff --git a/llvm/test/Transforms/InstCombine/sub-from-sub.ll b/llvm/test/Transforms/InstCombine/sub-from-sub.ll<br>
> index aaa8b1db32de..202dbd1072a4 100644<br>
> --- a/llvm/test/Transforms/InstCombine/sub-from-sub.ll<br>
> +++ b/llvm/test/Transforms/InstCombine/sub-from-sub.ll<br>
> @@ -8,8 +8,8 @@ declare void @use8(i8)<br>
> ; Basic test<br>
> define i8 @t0(i8 %x, i8 %y, i8 %z) {<br>
> ; CHECK-LABEL: @t0(<br>
> -; CHECK-NEXT: [[TMP1:%.*]] = add i8 [[Y:%.*]], [[Z:%.*]]<br>
> -; CHECK-NEXT: [[R:%.*]] = sub i8 [[X:%.*]], [[TMP1]]<br>
> +; CHECK-NEXT: [[I0:%.*]] = sub i8 [[X:%.*]], [[Y:%.*]]<br>
> +; CHECK-NEXT: [[R:%.*]] = sub i8 [[I0]], [[Z:%.*]]<br>
> ; CHECK-NEXT: ret i8 [[R]]<br>
> ;<br>
> %i0 = sub i8 %x, %y<br>
> @@ -20,8 +20,8 @@ define i8 @t0(i8 %x, i8 %y, i8 %z) {<br>
> ; No flags are propagated<br>
> define i8 @t1_flags(i8 %x, i8 %y, i8 %z) {<br>
> ; CHECK-LABEL: @t1_flags(<br>
> -; CHECK-NEXT: [[TMP1:%.*]] = add i8 [[Y:%.*]], [[Z:%.*]]<br>
> -; CHECK-NEXT: [[R:%.*]] = sub i8 [[X:%.*]], [[TMP1]]<br>
> +; CHECK-NEXT: [[O0:%.*]] = sub nuw nsw i8 [[X:%.*]], [[Y:%.*]]<br>
> +; CHECK-NEXT: [[R:%.*]] = sub nuw nsw i8 [[O0]], [[Z:%.*]]<br>
> ; CHECK-NEXT: ret i8 [[R]]<br>
> ;<br>
> %o0 = sub nuw nsw i8 %x, %y<br>
> @@ -47,8 +47,8 @@ define i8 @n2(i8 %x, i8 %y, i8 %z) {<br>
><br>
> define i8 @t3_c0(i8 %y, i8 %z) {<br>
> ; CHECK-LABEL: @t3_c0(<br>
> -; CHECK-NEXT: [[TMP1:%.*]] = add i8 [[Y:%.*]], [[Z:%.*]]<br>
> -; CHECK-NEXT: [[R:%.*]] = sub i8 42, [[TMP1]]<br>
> +; CHECK-NEXT: [[I0:%.*]] = sub i8 42, [[Y:%.*]]<br>
> +; CHECK-NEXT: [[R:%.*]] = sub i8 [[I0]], [[Z:%.*]]<br>
> ; CHECK-NEXT: ret i8 [[R]]<br>
> ;<br>
> %i0 = sub i8 42, %y<br>
><br>
><br>
><br>
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</blockquote></div></div>