[llvm-branch-commits] [llvm] PR for llvm/llvm-project#78621 (PR #80260)
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Tue Feb 6 16:05:42 PST 2024
https://github.com/llvmbot updated https://github.com/llvm/llvm-project/pull/80260
>From 42512617acf38425909676a190ed1b0ce9335616 Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Wed, 24 Jan 2024 11:56:02 +0000
Subject: [PATCH 1/2] [ConstraintElim] Add tests for #78621.
Tests with umin where the result may be poison for
https://github.com/llvm/llvm-project/issues/78621.
(cherry picked from commit c83180c1248615cf6ea8842eb4e0cebebba4ab57)
---
.../umin-result-may-be-poison.ll | 60 +++++++++++++++++++
1 file changed, 60 insertions(+)
create mode 100644 llvm/test/Transforms/ConstraintElimination/umin-result-may-be-poison.ll
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 00000000000000..35ac72e54d1894
--- /dev/null
+++ b/llvm/test/Transforms/ConstraintElimination/umin-result-may-be-poison.ll
@@ -0,0 +1,60 @@
+; 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: [[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 false
+;
+ %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: [[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 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 @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()
>From 56c50a4e0b50fb59ae1f1b322b31a5546522a928 Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Wed, 24 Jan 2024 14:25:54 +0000
Subject: [PATCH 2/2] [ConstraintElim] Make sure min/max intrinsic results are
not poison.
The result of umin may be poison and in that case the added constraints
are not be valid in contexts where poison doesn't cause UB. Only queue
facts for min/max intrinsics if the result is guaranteed to not be
poison.
This could be improved in the future, by only adding the fact when
solving conditions using the result value.
Fixes https://github.com/llvm/llvm-project/issues/78621.
(cherry picked from commit 3d91d9613e294b242d853039209b40a0cb7853f2)
---
llvm/lib/Transforms/Scalar/ConstraintElimination.cpp | 7 ++++++-
llvm/test/Transforms/ConstraintElimination/minmax.ll | 4 +++-
.../ConstraintElimination/umin-result-may-be-poison.ll | 6 ++++--
3 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
index 8f09569d0d9cc9..7b672e89b67aae 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<CallInst>(&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 a31cf6845ad67d..82b932f14c4ffa 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
index 35ac72e54d1894..6d1d95ec4fdba7 100644
--- a/llvm/test/Transforms/ConstraintElimination/umin-result-may-be-poison.ll
+++ b/llvm/test/Transforms/ConstraintElimination/umin-result-may-be-poison.ll
@@ -6,10 +6,11 @@
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 false
+; CHECK-NEXT: ret i1 [[ICMP]]
;
%icmp = icmp slt i32 %arg, 0
%shl = shl nuw nsw i32 %arg, 3
@@ -38,12 +39,13 @@ define i1 @umin_poison_is_UB_via_call(i32 %arg) {
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 false
+; CHECK-NEXT: ret i1 [[ICMP]]
;
%icmp = icmp slt i32 %arg, 0
%shl = shl nuw nsw i32 %arg, 3
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