Author: Yingwei Zheng Date: 2024-02-26T13:43:35-08:00 New Revision: 3aea3d2fd3996808ab39de0cf718b292a7d52a5f
URL: https://github.com/llvm/llvm-project/commit/3aea3d2fd3996808ab39de0cf718b292a7d52a5f DIFF: https://github.com/llvm/llvm-project/commit/3aea3d2fd3996808ab39de0cf718b292a7d52a5f.diff LOG: [GVN] Drop nsw/nuw flags when replacing the result of a with.overflow intrinsic with a overflowing binary operator (#82935) Alive2: https://alive2.llvm.org/ce/z/gyL7mn Fixes https://github.com/llvm/llvm-project/issues/82884. (cherry picked from commit 892b4beeac50920e630f10905b2916295e2eb6d8) Added: llvm/test/Transforms/GVN/pr82884.ll Modified: llvm/lib/Transforms/Utils/Local.cpp Removed: ################################################################################ diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp index 459e3d98059283..a1c6bbc52fd05e 100644 --- a/llvm/lib/Transforms/Utils/Local.cpp +++ b/llvm/lib/Transforms/Utils/Local.cpp @@ -3369,11 +3369,17 @@ void llvm::patchReplacementInstruction(Instruction *I, Value *Repl) { // Patch the replacement so that it is not more restrictive than the value // being replaced. + WithOverflowInst *UnusedWO; + // When replacing the result of a llvm.*.with.overflow intrinsic with a + // overflowing binary operator, nuw/nsw flags may no longer hold. + if (isa<OverflowingBinaryOperator>(ReplInst) && + match(I, m_ExtractValue<0>(m_WithOverflowInst(UnusedWO)))) + ReplInst->dropPoisonGeneratingFlags(); // Note that if 'I' is a load being replaced by some operation, // for example, by an arithmetic operation, then andIRFlags() // would just erase all math flags from the original arithmetic // operation, which is clearly not wanted and not needed. - if (!isa<LoadInst>(I)) + else if (!isa<LoadInst>(I)) ReplInst->andIRFlags(I); // FIXME: If both the original and replacement value are part of the diff --git a/llvm/test/Transforms/GVN/pr82884.ll b/llvm/test/Transforms/GVN/pr82884.ll new file mode 100644 index 00000000000000..71abafda60d93d --- /dev/null +++ b/llvm/test/Transforms/GVN/pr82884.ll @@ -0,0 +1,21 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4 +; RUN: opt -S -passes=gvn < %s | FileCheck %s + +; Make sure nsw/nuw flags are dropped. + +define i32 @pr82884(i32 %x) { +; CHECK-LABEL: define i32 @pr82884( +; CHECK-SAME: i32 [[X:%.*]]) { +; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[X]], [[X]] +; CHECK-NEXT: call void @use(i32 [[MUL]]) +; CHECK-NEXT: [[MUL2:%.*]] = call { i32, i1 } @llvm.smul.with.overflow.i32(i32 [[X]], i32 [[X]]) +; CHECK-NEXT: ret i32 [[MUL]] +; + %mul = mul nsw nuw i32 %x, %x + call void @use(i32 %mul) + %mul2 = call { i32, i1 } @llvm.smul.with.overflow.i32(i32 %x, i32 %x) + %ret = extractvalue { i32, i1 } %mul2, 0 + ret i32 %ret +} + +declare void @use(i32) _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
