[SimplifyCFG] Bail out on vector GEPs in passingValueIsAlwaysUndefined
#142526
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@llvm/pr-subscribers-llvm-transforms Author: Yingwei Zheng (dtcxzyw) ChangesCloses #142522. Full diff: https://github.com/llvm/llvm-project/pull/142526.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index b7299e01b0c5f..898ff3d1f8f12 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -8109,6 +8109,7 @@ bool SimplifyCFGOpt::simplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) {
/// Check if passing a value to an instruction will cause undefined behavior.
static bool passingValueIsAlwaysUndefined(Value *V, Instruction *I, bool PtrValueMayBeModified) {
+ assert(V->getType() == I->getType() && "Mismatched types");
Constant *C = dyn_cast<Constant>(V);
if (!C)
return false;
@@ -8177,6 +8178,10 @@ static bool passingValueIsAlwaysUndefined(Value *V, Instruction *I, bool PtrValu
NullPointerIsDefined(GEP->getFunction(),
GEP->getPointerAddressSpace())))
PtrValueMayBeModified = true;
+ // The type of GEP may differ from the type of base pointer.
+ if (V->getType() != GEP->getType())
+ V = ConstantVector::getSplat(
+ cast<VectorType>(GEP->getType())->getElementCount(), C);
return passingValueIsAlwaysUndefined(V, GEP, PtrValueMayBeModified);
}
diff --git a/llvm/test/Transforms/SimplifyCFG/UnreachableEliminate.ll b/llvm/test/Transforms/SimplifyCFG/UnreachableEliminate.ll
index 2da5d18b63f49..5b439a23c3585 100644
--- a/llvm/test/Transforms/SimplifyCFG/UnreachableEliminate.ll
+++ b/llvm/test/Transforms/SimplifyCFG/UnreachableEliminate.ll
@@ -244,6 +244,7 @@ declare ptr @fn_nonnull_arg(ptr nonnull %p)
declare ptr @fn_noundef_arg(ptr noundef %p)
declare ptr @fn_ptr_arg(ptr)
declare ptr @fn_ptr_arg_nounwind_willreturn(ptr) nounwind willreturn
+declare void @fn_arg_vec(<2 x ptr>)
define void @test9(i1 %X, ptr %Y) {
; CHECK-LABEL: @test9(
@@ -917,6 +918,25 @@ bb5: ; preds = %bb3, %bb
ret i32 %i7
}
+define void @test9_gep_splat(i1 %X, ptr %Y) {
+; CHECK-LABEL: @test9_gep_splat(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[SPEC_SELECT:%.*]] = select i1 [[X:%.*]], ptr null, ptr [[Y:%.*]]
+; CHECK-NEXT: [[GEP:%.*]] = getelementptr i8, ptr [[SPEC_SELECT]], <2 x i64> zeroinitializer
+; CHECK-NEXT: call void @fn_arg_vec(<2 x ptr> [[GEP]])
+; CHECK-NEXT: ret void
+;
+entry:
+ br i1 %X, label %if, label %else
+if:
+ br label %else
+else:
+ %phi = phi ptr [ %Y, %entry ], [ null, %if ]
+ %gep = getelementptr i8, ptr %phi, <2 x i64> zeroinitializer
+ call void @fn_arg_vec(<2 x ptr> %gep)
+ ret void
+}
+
declare void @side.effect()
declare i8 @get.i8()
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nikic
reviewed
Jun 3, 2025
dtcxzyw
changed the title
passingValueIsAlwaysUndefinedpassingValueIsAlwaysUndefined
nikic
approved these changes
Jun 3, 2025
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/88/builds/12412 Here is the relevant piece of the build log for the reference |
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/24/builds/9128 Here is the relevant piece of the build log for the reference |
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Closes #142522.