diff --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp index 8f09569d0d9cc..7b672e89b67aa 100644 --- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp +++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp @@ -1061,11 +1061,16 @@ void State::addInfoFor(BasicBlock &BB) { FactOrCheck::getCheck(DT.getNode(&BB), cast(&I))); break; // Enqueue the intrinsics to add extra info. - case Intrinsic::abs: case Intrinsic::umin: case Intrinsic::umax: case Intrinsic::smin: case Intrinsic::smax: + // TODO: Check if it is possible to instead only added the min/max facts + // when simplifying uses of the min/max intrinsics. + if (!isGuaranteedNotToBePoison(&I)) + break; + [[fallthrough]]; + case Intrinsic::abs: WorkList.push_back(FactOrCheck::getInstFact(DT.getNode(&BB), &I)); break; } diff --git a/llvm/test/Transforms/ConstraintElimination/minmax.ll b/llvm/test/Transforms/ConstraintElimination/minmax.ll index a31cf6845ad67..82b932f14c4ff 100644 --- a/llvm/test/Transforms/ConstraintElimination/minmax.ll +++ b/llvm/test/Transforms/ConstraintElimination/minmax.ll @@ -306,7 +306,9 @@ define i1 @smin_branchless(i32 %x, i32 %y) { ; CHECK-SAME: (i32 [[X:%.*]], i32 [[Y:%.*]]) { ; CHECK-NEXT: entry: ; CHECK-NEXT: [[MIN:%.*]] = call i32 @llvm.smin.i32(i32 [[X]], i32 [[Y]]) -; CHECK-NEXT: [[RET:%.*]] = xor i1 true, false +; CHECK-NEXT: [[CMP1:%.*]] = icmp sle i32 [[MIN]], [[X]] +; CHECK-NEXT: [[CMP2:%.*]] = icmp sgt i32 [[MIN]], [[X]] +; CHECK-NEXT: [[RET:%.*]] = xor i1 [[CMP1]], [[CMP2]] ; CHECK-NEXT: ret i1 [[RET]] ; entry: diff --git a/llvm/test/Transforms/ConstraintElimination/umin-result-may-be-poison.ll b/llvm/test/Transforms/ConstraintElimination/umin-result-may-be-poison.ll new file mode 100644 index 0000000000000..6d1d95ec4fdba --- /dev/null +++ b/llvm/test/Transforms/ConstraintElimination/umin-result-may-be-poison.ll @@ -0,0 +1,62 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4 +; RUN: opt -p constraint-elimination -S %s | FileCheck %s + +; Tests for https://github.com/llvm/llvm-project/issues/78621. + +define i1 @umin_not_used(i32 %arg) { +; CHECK-LABEL: define i1 @umin_not_used( +; CHECK-SAME: i32 [[ARG:%.*]]) { +; CHECK-NEXT: [[ICMP:%.*]] = icmp slt i32 [[ARG]], 0 +; CHECK-NEXT: [[SHL:%.*]] = shl nuw nsw i32 [[ARG]], 3 +; CHECK-NEXT: [[TMP1:%.*]] = call i32 @llvm.umin.i32(i32 [[SHL]], i32 80) +; CHECK-NEXT: [[CMP2:%.*]] = shl nuw nsw i32 [[ARG]], 3 +; CHECK-NEXT: ret i1 [[ICMP]] +; + %icmp = icmp slt i32 %arg, 0 + %shl = shl nuw nsw i32 %arg, 3 + call i32 @llvm.umin.i32(i32 %shl, i32 80) + %cmp2 = shl nuw nsw i32 %arg, 3 + ret i1 %icmp +} + +define i1 @umin_poison_is_UB_via_call(i32 %arg) { +; CHECK-LABEL: define i1 @umin_poison_is_UB_via_call( +; CHECK-SAME: i32 [[ARG:%.*]]) { +; CHECK-NEXT: [[SHL:%.*]] = shl nuw nsw i32 [[ARG]], 3 +; CHECK-NEXT: [[MIN:%.*]] = call i32 @llvm.umin.i32(i32 [[SHL]], i32 80) +; CHECK-NEXT: call void @noundef(i32 noundef [[MIN]]) +; CHECK-NEXT: [[CMP2:%.*]] = shl nuw nsw i32 [[ARG]], 3 +; CHECK-NEXT: ret i1 false +; + %icmp = icmp slt i32 %arg, 0 + %shl = shl nuw nsw i32 %arg, 3 + %min = call i32 @llvm.umin.i32(i32 %shl, i32 80) + call void @noundef(i32 noundef %min) + %cmp2 = shl nuw nsw i32 %arg, 3 + ret i1 %icmp +} + +define i1 @umin_poison_call_before_UB(i32 %arg) { +; CHECK-LABEL: define i1 @umin_poison_call_before_UB( +; CHECK-SAME: i32 [[ARG:%.*]]) { +; CHECK-NEXT: [[ICMP:%.*]] = icmp slt i32 [[ARG]], 0 +; CHECK-NEXT: [[SHL:%.*]] = shl nuw nsw i32 [[ARG]], 3 +; CHECK-NEXT: [[MIN:%.*]] = call i32 @llvm.umin.i32(i32 [[SHL]], i32 80) +; CHECK-NEXT: call void @fn() +; CHECK-NEXT: call void @noundef(i32 noundef [[MIN]]) +; CHECK-NEXT: [[CMP2:%.*]] = shl nuw nsw i32 [[ARG]], 3 +; CHECK-NEXT: ret i1 [[ICMP]] +; + %icmp = icmp slt i32 %arg, 0 + %shl = shl nuw nsw i32 %arg, 3 + %min = call i32 @llvm.umin.i32(i32 %shl, i32 80) + call void @fn() + call void @noundef(i32 noundef %min) + %cmp2 = shl nuw nsw i32 %arg, 3 + ret i1 %icmp +} + +declare i32 @llvm.umin.i32(i32, i32) #0 + +declare void @noundef(i32 noundef) +declare void @fn()