[llvm] IR: Use poison in dropDroppableUse (PR #134576)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-llvm-ir

Author: Matt Arsenault (arsenm)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/134576.diff


4 Files Affected:

- (modified) llvm/lib/IR/Value.cpp (+1-1) 
- (modified) llvm/test/Transforms/Mem2Reg/ignore-droppable.ll (+9-9) 
- (modified) llvm/test/Transforms/SROA/assume.ll (+1-1) 
- (modified) llvm/test/Transforms/SROA/ignore-droppable.ll (+9-9) 


``````````diff
diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index 2c41101ef56ff..bb8d69288b923 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -221,7 +221,7 @@ void Value::dropDroppableUse(Use &U) {
     if (OpNo == 0)
       U.set(ConstantInt::getTrue(Assume->getContext()));
     else {
-      U.set(UndefValue::get(U.get()->getType()));
+      U.set(PoisonValue::get(U.get()->getType()));
       CallInst::BundleOpInfo &BOI = Assume->getBundleOpInfoForOperand(OpNo);
       BOI.Tag = Assume->getContext().pImpl->getOrInsertBundleTag("ignore");
     }
diff --git a/llvm/test/Transforms/Mem2Reg/ignore-droppable.ll b/llvm/test/Transforms/Mem2Reg/ignore-droppable.ll
index b63c09f03ffdf..e9f40b56400f4 100644
--- a/llvm/test/Transforms/Mem2Reg/ignore-droppable.ll
+++ b/llvm/test/Transforms/Mem2Reg/ignore-droppable.ll
@@ -7,8 +7,8 @@ declare void @llvm.lifetime.end.p0(i64 %size, ptr nocapture %ptr)
 
 define void @positive_assume_uses(ptr %arg) {
 ; CHECK-LABEL: @positive_assume_uses(
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "nonnull"(ptr [[ARG:%.*]]), "ignore"(ptr undef, i64 2) ]
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef, i64 8), "nonnull"(ptr [[ARG]]) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "nonnull"(ptr [[ARG:%.*]]), "ignore"(ptr poison, i64 2) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison, i64 8), "nonnull"(ptr [[ARG]]) ]
 ; CHECK-NEXT:    ret void
 ;
   %A = alloca i32
@@ -35,8 +35,8 @@ define void @negative_assume_condition_use() {
 
 define void @positive_multiple_assume_uses() {
 ; CHECK-LABEL: @positive_multiple_assume_uses(
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef, i64 8), "ignore"(ptr undef, i64 16) ]
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef), "ignore"(ptr undef, i64 2) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison, i64 8), "ignore"(ptr poison, i64 16) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison), "ignore"(ptr poison, i64 2) ]
 ; CHECK-NEXT:    ret void
 ;
   %A = alloca {i8, i16}
@@ -48,8 +48,8 @@ define void @positive_multiple_assume_uses() {
 
 define void @positive_gep_assume_uses() {
 ; CHECK-LABEL: @positive_gep_assume_uses(
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef, i64 8), "ignore"(ptr undef, i64 16) ]
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef), "ignore"(ptr undef, i64 2) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison, i64 8), "ignore"(ptr poison, i64 16) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison), "ignore"(ptr poison, i64 2) ]
 ; CHECK-NEXT:    ret void
 ;
   %A = alloca {i8, i16}
@@ -64,9 +64,9 @@ define void @positive_gep_assume_uses() {
 
 define void @positive_mixed_assume_uses() {
 ; CHECK-LABEL: @positive_mixed_assume_uses(
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef), "ignore"(ptr undef, i64 8), "ignore"(ptr undef, i64 16) ]
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef), "ignore"(ptr undef, i64 2), "ignore"(ptr undef) ]
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef), "ignore"(ptr undef, i64 2), "ignore"(ptr undef) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison), "ignore"(ptr poison, i64 8), "ignore"(ptr poison, i64 16) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison), "ignore"(ptr poison, i64 2), "ignore"(ptr poison) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison), "ignore"(ptr poison, i64 2), "ignore"(ptr poison) ]
 ; CHECK-NEXT:    ret void
 ;
   %A = alloca i8
diff --git a/llvm/test/Transforms/SROA/assume.ll b/llvm/test/Transforms/SROA/assume.ll
index 50bddc833a9ad..80522eecf5e8a 100644
--- a/llvm/test/Transforms/SROA/assume.ll
+++ b/llvm/test/Transforms/SROA/assume.ll
@@ -14,7 +14,7 @@ target triple = "x86_64-unknown-linux-gnu"
 define void @_ZN2bg2baIiEC2ES_(i64 %v) {
 ; CHECK-LABEL: @_ZN2bg2baIiEC2ES_(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison) ]
 ; CHECK-NEXT:    ret void
 ;
 entry:
diff --git a/llvm/test/Transforms/SROA/ignore-droppable.ll b/llvm/test/Transforms/SROA/ignore-droppable.ll
index 2d090a5f01fe2..0b9a036b243b4 100644
--- a/llvm/test/Transforms/SROA/ignore-droppable.ll
+++ b/llvm/test/Transforms/SROA/ignore-droppable.ll
@@ -8,8 +8,8 @@ declare void @llvm.lifetime.end.p0(i64 %size, ptr nocapture %ptr)
 
 define void @positive_assume_uses(ptr %arg) {
 ; CHECK-LABEL: @positive_assume_uses(
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "nonnull"(ptr [[ARG:%.*]]), "ignore"(ptr undef, i64 2) ]
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef, i64 8), "nonnull"(ptr [[ARG]]) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "nonnull"(ptr [[ARG:%.*]]), "ignore"(ptr poison, i64 2) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison, i64 8), "nonnull"(ptr [[ARG]]) ]
 ; CHECK-NEXT:    ret void
 ;
   %A = alloca i32
@@ -36,8 +36,8 @@ define void @negative_assume_condition_use() {
 
 define void @positive_multiple_assume_uses() {
 ; CHECK-LABEL: @positive_multiple_assume_uses(
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef, i64 8), "ignore"(ptr undef, i64 16) ]
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef), "ignore"(ptr undef, i64 2) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison, i64 8), "ignore"(ptr poison, i64 16) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison), "ignore"(ptr poison, i64 2) ]
 ; CHECK-NEXT:    ret void
 ;
   %A = alloca {i8, i16}
@@ -49,8 +49,8 @@ define void @positive_multiple_assume_uses() {
 
 define void @positive_gep_assume_uses() {
 ; CHECK-LABEL: @positive_gep_assume_uses(
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef, i64 8), "ignore"(ptr undef, i64 16) ]
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef), "ignore"(ptr undef, i64 2) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison, i64 8), "ignore"(ptr poison, i64 16) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison), "ignore"(ptr poison, i64 2) ]
 ; CHECK-NEXT:    ret void
 ;
   %A = alloca {i8, i16}
@@ -65,9 +65,9 @@ define void @positive_gep_assume_uses() {
 
 define void @positive_mixed_assume_uses() {
 ; CHECK-LABEL: @positive_mixed_assume_uses(
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef), "ignore"(ptr undef, i64 8), "ignore"(ptr undef, i64 16) ]
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef), "ignore"(ptr undef, i64 2), "ignore"(ptr undef) ]
-; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr undef), "ignore"(ptr undef, i64 2), "ignore"(ptr undef) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison), "ignore"(ptr poison, i64 8), "ignore"(ptr poison, i64 16) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison), "ignore"(ptr poison, i64 2), "ignore"(ptr poison) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "ignore"(ptr poison), "ignore"(ptr poison, i64 2), "ignore"(ptr poison) ]
 ; CHECK-NEXT:    ret void
 ;
   %A = alloca i8

``````````

</details>


https://github.com/llvm/llvm-project/pull/134576