[llvm] [ConstantFolding] Fix type mismatch in ConstantFolding for vector types. (PR #181695)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-analysis

Author: Marcos Maronas (maarquitos14)

<details>
<summary>Changes</summary>

Use `getScalarType()` to extract the element type before calculating `OpSize`. This ensures the `APInt` size matches what `ConstantInt::get` expects, and the function properly handles vector types by broadcasting the scalar constant.

---
Full diff: https://github.com/llvm/llvm-project/pull/181695.diff


2 Files Affected:

- (modified) llvm/lib/Analysis/ConstantFolding.cpp (+1-1) 
- (added) llvm/test/Transforms/EarlyCSE/AMDGPU/vector-type-constant-folding.ll (+21) 


``````````diff
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index b0ac14ba8b393..e0ed4b3d6a19b 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -827,7 +827,7 @@ Constant *SymbolicallyEvaluateBinop(unsigned Opc, Constant *Op0, Constant *Op1,
 
     if (IsConstantOffsetFromGlobal(Op0, GV1, Offs1, DL))
       if (IsConstantOffsetFromGlobal(Op1, GV2, Offs2, DL) && GV1 == GV2) {
-        unsigned OpSize = DL.getTypeSizeInBits(Op0->getType());
+        unsigned OpSize = DL.getTypeSizeInBits(Op0->getType()->getScalarType());
 
         // (&GV+C1) - (&GV+C2) -> C1-C2, pointer arithmetic cannot overflow.
         // PtrToInt may change the bitwidth so we have convert to the right size
diff --git a/llvm/test/Transforms/EarlyCSE/AMDGPU/vector-type-constant-folding.ll b/llvm/test/Transforms/EarlyCSE/AMDGPU/vector-type-constant-folding.ll
new file mode 100644
index 0000000000000..9871716aa9f60
--- /dev/null
+++ b/llvm/test/Transforms/EarlyCSE/AMDGPU/vector-type-constant-folding.ll
@@ -0,0 +1,21 @@
+; RUN: opt < %s -mtriple=amdgcn -passes='default<O2>' -S | FileCheck %s
+;
+; Test type mismatch in ConstantFolding for vector types.
+
+define internal void @f() {
+  ret void
+}
+
+define void @test() {
+; CHECK-LABEL: define void @test(
+; CHECK-NEXT:    store <4 x i16> zeroinitializer, ptr @f
+; CHECK-NEXT:    ret void
+  %p = alloca ptr, addrspace(5)
+  %v1 = load <4 x i16>, ptr addrspace(5) %p
+  %v2 = load <4 x i16>, ptr addrspace(5) %p
+  store ptr @f, ptr addrspace(5) %p
+  %sub = sub <4 x i16> %v1, %v2
+  %fp = load ptr, ptr addrspace(5) %p
+  store <4 x i16> %sub, ptr %fp
+  ret void
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/181695