Index: llvm/lib/Analysis/InstructionSimplify.cpp =================================================================== --- llvm/lib/Analysis/InstructionSimplify.cpp +++ llvm/lib/Analysis/InstructionSimplify.cpp @@ -3796,10 +3796,7 @@ // TODO: This is an unusual limitation because better analysis results in // worse simplification. InstCombine can do this fold more generally // by dropping the flags. Remove this fold to save compile-time? - if (isa(B)) - if (Q.IIQ.hasNoSignedWrap(B) || Q.IIQ.hasNoUnsignedWrap(B)) - return nullptr; - if (isa(B) && Q.IIQ.isExact(B)) + if (canCreatePoison(cast(I))) return nullptr; if (MaxRecurse) { Index: llvm/test/Transforms/InstSimplify/select.ll =================================================================== --- llvm/test/Transforms/InstSimplify/select.ll +++ llvm/test/Transforms/InstSimplify/select.ll @@ -941,3 +941,19 @@ %spec.select = and i1 %spec.select39, %spec.select40 ret i1 %spec.select } + +define i32 @pr47322_more_poisonous_replacement(i32 %arg) { +; CHECK-LABEL: @pr47322_more_poisonous_replacement( +; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[ARG:%.*]], 0 +; CHECK-NEXT: [[TRAILING:%.*]] = call i32 @llvm.cttz.i32(i32 [[ARG]], i1 immarg true) +; CHECK-NEXT: [[SHIFTED:%.*]] = lshr i32 [[ARG]], [[TRAILING]] +; CHECK-NEXT: [[R1_SROA_0_1:%.*]] = select i1 [[CMP]], i32 0, i32 [[SHIFTED]] +; CHECK-NEXT: ret i32 [[R1_SROA_0_1]] +; + %cmp = icmp eq i32 %arg, 0 + %trailing = call i32 @llvm.cttz.i32(i32 %arg, i1 immarg true) + %shifted = lshr i32 %arg, %trailing + %r1.sroa.0.1 = select i1 %cmp, i32 0, i32 %shifted + ret i32 %r1.sroa.0.1 +} +declare i32 @llvm.cttz.i32(i32, i1 immarg)