[InstSimplify] Fold {u,s}{min,max} x, poison -> poison #138166
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Following from the discussion in llvm#138095 (comment), these intrinsics are poison if any of their operands are poison, and are marked as such in propagatesPoison in ValueTracking.cpp. This will help fold away leftover vectors produced by VectorCombine when scalarizing intrinsics.
|
@llvm/pr-subscribers-llvm-analysis Author: Luke Lau (lukel97) ChangesFollowing from the discussion in #138095 (comment), these intrinsics are poison if any of their operands are poison, and are marked as such in propagatesPoison in ValueTracking.cpp. This will help fold away leftover vectors produced by VectorCombine when scalarizing intrinsics. Full diff: https://github.com/llvm/llvm-project/pull/138166.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 8ffb471070d91..275ca8fa4dbc2 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -6549,6 +6549,10 @@ Value *llvm::simplifyBinaryIntrinsic(Intrinsic::ID IID, Type *ReturnType,
if (match(Op0, m_ImmConstant()))
std::swap(Op0, Op1);
+ // Propagate poison.
+ if (isa<PoisonValue>(Op1))
+ return Op1;
+
// Assume undef is the limit value.
if (Q.isUndefValue(Op1))
return ConstantInt::get(
diff --git a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
index ddd4140b3aedd..98bfe5329c290 100644
--- a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
+++ b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
@@ -75,7 +75,7 @@ define i81 @smax_undef(i81 %x) {
define i81 @smax_poison(i81 %x) {
; CHECK-LABEL: @smax_poison(
-; CHECK-NEXT: ret i81 1208925819614629174706175
+; CHECK-NEXT: ret i81 poison
;
%r = call i81 @llvm.smax.i81(i81 poison, i81 %x)
ret i81 %r
@@ -91,7 +91,7 @@ define i3 @smin_undef(i3 %x) {
define i3 @smin_poison(i3 %x) {
; CHECK-LABEL: @smin_poison(
-; CHECK-NEXT: ret i3 -4
+; CHECK-NEXT: ret i3 poison
;
%r = call i3 @llvm.smin.i3(i3 %x, i3 poison)
ret i3 %r
@@ -107,7 +107,7 @@ define <2 x i8> @umax_undef(<2 x i8> %x) {
define <2 x i8> @umax_poison(<2 x i8> %x) {
; CHECK-LABEL: @umax_poison(
-; CHECK-NEXT: ret <2 x i8> splat (i8 -1)
+; CHECK-NEXT: ret <2 x i8> poison
;
%r = call <2 x i8> @llvm.umax.v2i8(<2 x i8> poison, <2 x i8> %x)
ret <2 x i8> %r
@@ -123,7 +123,7 @@ define <2 x i8> @umin_undef(<2 x i8> %x) {
define <2 x i8> @umin_poison(<2 x i8> %x) {
; CHECK-LABEL: @umin_poison(
-; CHECK-NEXT: ret <2 x i8> zeroinitializer
+; CHECK-NEXT: ret <2 x i8> poison
;
%r = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %x, <2 x i8> poison)
ret <2 x i8> %r
|
|
@llvm/pr-subscribers-llvm-transforms Author: Luke Lau (lukel97) ChangesFollowing from the discussion in #138095 (comment), these intrinsics are poison if any of their operands are poison, and are marked as such in propagatesPoison in ValueTracking.cpp. This will help fold away leftover vectors produced by VectorCombine when scalarizing intrinsics. Full diff: https://github.com/llvm/llvm-project/pull/138166.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 8ffb471070d91..275ca8fa4dbc2 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -6549,6 +6549,10 @@ Value *llvm::simplifyBinaryIntrinsic(Intrinsic::ID IID, Type *ReturnType,
if (match(Op0, m_ImmConstant()))
std::swap(Op0, Op1);
+ // Propagate poison.
+ if (isa<PoisonValue>(Op1))
+ return Op1;
+
// Assume undef is the limit value.
if (Q.isUndefValue(Op1))
return ConstantInt::get(
diff --git a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
index ddd4140b3aedd..98bfe5329c290 100644
--- a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
+++ b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
@@ -75,7 +75,7 @@ define i81 @smax_undef(i81 %x) {
define i81 @smax_poison(i81 %x) {
; CHECK-LABEL: @smax_poison(
-; CHECK-NEXT: ret i81 1208925819614629174706175
+; CHECK-NEXT: ret i81 poison
;
%r = call i81 @llvm.smax.i81(i81 poison, i81 %x)
ret i81 %r
@@ -91,7 +91,7 @@ define i3 @smin_undef(i3 %x) {
define i3 @smin_poison(i3 %x) {
; CHECK-LABEL: @smin_poison(
-; CHECK-NEXT: ret i3 -4
+; CHECK-NEXT: ret i3 poison
;
%r = call i3 @llvm.smin.i3(i3 %x, i3 poison)
ret i3 %r
@@ -107,7 +107,7 @@ define <2 x i8> @umax_undef(<2 x i8> %x) {
define <2 x i8> @umax_poison(<2 x i8> %x) {
; CHECK-LABEL: @umax_poison(
-; CHECK-NEXT: ret <2 x i8> splat (i8 -1)
+; CHECK-NEXT: ret <2 x i8> poison
;
%r = call <2 x i8> @llvm.umax.v2i8(<2 x i8> poison, <2 x i8> %x)
ret <2 x i8> %r
@@ -123,7 +123,7 @@ define <2 x i8> @umin_undef(<2 x i8> %x) {
define <2 x i8> @umin_poison(<2 x i8> %x) {
; CHECK-LABEL: @umin_poison(
-; CHECK-NEXT: ret <2 x i8> zeroinitializer
+; CHECK-NEXT: ret <2 x i8> poison
;
%r = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %x, <2 x i8> poison)
ret <2 x i8> %r
|
dtcxzyw
reviewed
May 1, 2025
nikic
approved these changes
May 1, 2025
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
Following from the discussion in llvm#138095 (comment), these intrinsics are poison if any of their operands are poison, and are marked as such in propagatesPoison in ValueTracking.cpp. This will help fold away leftover vectors produced by VectorCombine when scalarizing intrinsics.
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
Following from the discussion in llvm#138095 (comment), these intrinsics are poison if any of their operands are poison, and are marked as such in propagatesPoison in ValueTracking.cpp. This will help fold away leftover vectors produced by VectorCombine when scalarizing intrinsics.
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
Following from the discussion in llvm#138095 (comment), these intrinsics are poison if any of their operands are poison, and are marked as such in propagatesPoison in ValueTracking.cpp. This will help fold away leftover vectors produced by VectorCombine when scalarizing intrinsics.
GeorgeARM
pushed a commit
to GeorgeARM/llvm-project
that referenced
this pull request
May 7, 2025
Following from the discussion in llvm#138095 (comment), these intrinsics are poison if any of their operands are poison, and are marked as such in propagatesPoison in ValueTracking.cpp. This will help fold away leftover vectors produced by VectorCombine when scalarizing intrinsics.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Following from the discussion in #138095 (comment), these intrinsics are poison if any of their operands are poison, and are marked as such in propagatesPoison in ValueTracking.cpp.
This will help fold away leftover vectors produced by VectorCombine when scalarizing intrinsics.