https://github.com/tru updated https://github.com/llvm/llvm-project/pull/116097
>From c9b952e0e0b8f90c8d2b99f07263c43bced043f5 Mon Sep 17 00:00:00 2001 From: Yingwei Zheng <dtcxzyw2...@gmail.com> Date: Fri, 8 Nov 2024 16:20:04 +0800 Subject: [PATCH] [InstCombine] Drop nsw in negation of select (#112893) Closes https://github.com/llvm/llvm-project/issues/112666 and https://github.com/llvm/llvm-project/issues/114181. (cherry picked from commit ff07df6620c32571c7e13ff96ec7976c63ed0ab8) --- .../InstCombine/InstCombineNegator.cpp | 11 +++++ .../InstCombine/sub-of-negatible.ll | 42 +++++++++++++++++++ 2 files changed, 53 insertions(+) diff --git a/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp b/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp index e4895b59f4b4a9..cb052da79bb3c6 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp @@ -334,6 +334,17 @@ std::array<Value *, 2> Negator::getSortedOperandsOfBinOp(Instruction *I) { NewSelect->swapValues(); // Don't swap prof metadata, we didn't change the branch behavior. NewSelect->setName(I->getName() + ".neg"); + // Poison-generating flags should be dropped + Value *TV = NewSelect->getTrueValue(); + Value *FV = NewSelect->getFalseValue(); + if (match(TV, m_Neg(m_Specific(FV)))) + cast<Instruction>(TV)->dropPoisonGeneratingFlags(); + else if (match(FV, m_Neg(m_Specific(TV)))) + cast<Instruction>(FV)->dropPoisonGeneratingFlags(); + else { + cast<Instruction>(TV)->dropPoisonGeneratingFlags(); + cast<Instruction>(FV)->dropPoisonGeneratingFlags(); + } Builder.Insert(NewSelect); return NewSelect; } diff --git a/llvm/test/Transforms/InstCombine/sub-of-negatible.ll b/llvm/test/Transforms/InstCombine/sub-of-negatible.ll index b2e14ceaca1b08..f9549881aa3131 100644 --- a/llvm/test/Transforms/InstCombine/sub-of-negatible.ll +++ b/llvm/test/Transforms/InstCombine/sub-of-negatible.ll @@ -1374,6 +1374,48 @@ define i8 @negate_select_of_op_vs_negated_op(i8 %x, i8 %y, i1 %c) { %t2 = sub i8 %y, %t1 ret i8 %t2 } + +define i8 @negate_select_of_op_vs_negated_op_nsw(i8 %x, i8 %y, i1 %c) { +; CHECK-LABEL: @negate_select_of_op_vs_negated_op_nsw( +; CHECK-NEXT: [[T0:%.*]] = sub i8 0, [[X:%.*]] +; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[C:%.*]], i8 [[X]], i8 [[T0]] +; CHECK-NEXT: [[T2:%.*]] = add i8 [[TMP1]], [[Y:%.*]] +; CHECK-NEXT: ret i8 [[T2]] +; + %t0 = sub nsw i8 0, %x + %t1 = select i1 %c, i8 %t0, i8 %x + %t2 = sub i8 %y, %t1 + ret i8 %t2 +} + +define i8 @negate_select_of_op_vs_negated_op_nsw_commuted(i8 %x, i8 %y, i1 %c) { +; CHECK-LABEL: @negate_select_of_op_vs_negated_op_nsw_commuted( +; CHECK-NEXT: [[T0:%.*]] = sub i8 0, [[X:%.*]] +; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[C:%.*]], i8 [[T0]], i8 [[X]] +; CHECK-NEXT: [[T2:%.*]] = add i8 [[TMP1]], [[Y:%.*]] +; CHECK-NEXT: ret i8 [[T2]] +; + %t0 = sub nsw i8 0, %x + %t1 = select i1 %c, i8 %x, i8 %t0 + %t2 = sub i8 %y, %t1 + ret i8 %t2 +} + +define i8 @negate_select_of_op_vs_negated_op_nsw_xyyx(i8 %x, i8 %y, i8 %z, i1 %c) { +; CHECK-LABEL: @negate_select_of_op_vs_negated_op_nsw_xyyx( +; CHECK-NEXT: [[SUB1:%.*]] = sub i8 [[X:%.*]], [[Y:%.*]] +; CHECK-NEXT: [[SUB2:%.*]] = sub i8 [[Y]], [[X]] +; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[C:%.*]], i8 [[SUB2]], i8 [[SUB1]] +; CHECK-NEXT: [[T2:%.*]] = add i8 [[TMP1]], [[Z:%.*]] +; CHECK-NEXT: ret i8 [[T2]] +; + %sub1 = sub nsw i8 %x, %y + %sub2 = sub nsw i8 %y, %x + %t1 = select i1 %c, i8 %sub1, i8 %sub2 + %t2 = sub i8 %z, %t1 + ret i8 %t2 +} + define i8 @dont_negate_ordinary_select(i8 %x, i8 %y, i8 %z, i1 %c) { ; CHECK-LABEL: @dont_negate_ordinary_select( ; CHECK-NEXT: [[T0:%.*]] = select i1 [[C:%.*]], i8 [[X:%.*]], i8 [[Y:%.*]] _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
