[Scalarizer] Fix to only scalarize if intrinsic was marked as isTriviallyScalarizable

[farzonl]

fixes #113624

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Farzon Lotfi (farzonl)

Changes

fixes #113624

---

Full diff: https://github.com/llvm/llvm-project/pull/113625.diff

2 Files Affected:

• (modified) llvm/lib/Transforms/Scalar/Scalarizer.cpp (+10)
• (added) llvm/test/Transforms/Scalarizer/uadd_overflow.ll (+16)

diff --git a/llvm/lib/Transforms/Scalar/Scalarizer.cpp b/llvm/lib/Transforms/Scalar/Scalarizer.cpp
index 772f4c6c35ddec..94e10b707102af 100644
--- a/llvm/lib/Transforms/Scalar/Scalarizer.cpp
+++ b/llvm/lib/Transforms/Scalar/Scalarizer.cpp
@@ -1084,6 +1084,16 @@ bool ScalarizerVisitor::visitExtractValueInst(ExtractValueInst &EVI) {
   ValueVector Res;
   if (!isStructOfMatchingFixedVectors(OpTy))
     return false;
+  if (CallInst *CI = dyn_cast<CallInst>(Op)) {
+    Function *F = CI->getCalledFunction();
+    if (!F)
+      return false;
+    Intrinsic::ID ID = F->getIntrinsicID();
+    if (ID == Intrinsic::not_intrinsic || !isTriviallyScalarizable(ID))
+      return false;
+    // Note: Only proceed if Operand is a`CallInst` and it is defined in `isTriviallyScalarizable`.
+  } else
+    return false;
   Type *VecType = cast<FixedVectorType>(OpTy->getContainedType(0));
   std::optional<VectorSplit> VS = getVectorSplit(VecType);
   if (!VS)
diff --git a/llvm/test/Transforms/Scalarizer/uadd_overflow.ll b/llvm/test/Transforms/Scalarizer/uadd_overflow.ll
new file mode 100644
index 00000000000000..39094451523a5e
--- /dev/null
+++ b/llvm/test/Transforms/Scalarizer/uadd_overflow.ll
@@ -0,0 +1,16 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt %s -passes='function(scalarizer)' -S | FileCheck %s
+
+; Test to make sure that struct return intrinsics that are not `isTriviallyScalarizable` do not get scalarized.
+
+define <3 x i32> @test_(<3 x i32> %a, <3 x i32> %b) {
+; CHECK-LABEL: define <3 x i32> @test_(
+; CHECK-SAME: <3 x i32> [[A:%.*]], <3 x i32> [[B:%.*]]) {
+; CHECK-NEXT:    [[R:%.*]] = call { <3 x i32>, <3 x i1> } @llvm.uadd.with.overflow.v3i32(<3 x i32> [[B]], <3 x i32> [[B]])
+; CHECK-NEXT:    [[EL:%.*]] = extractvalue { <3 x i32>, <3 x i1> } [[R]], 0
+; CHECK-NEXT:    ret <3 x i32> [[EL]]
+;
+  %r = call { <3 x i32>, <3 x i1> } @llvm.uadd.with.overflow.v3i32(<3 x i32> %b, <3 x i32> %b)
+  %el = extractvalue { <3 x i32>, <3 x i1> } %r, 0
+  ret <3 x i32> %el
+}

[mariusz-sikora-at-amd]

Thanks for the fix !

[jayfoad]

Will you ever see non-intrinsic calls here? If so, please add a test case for that.

Also nit: the "else" clause should have braces if the "if" clause has braces.

[jayfoad]

Can you just handle IntrinsicInst here, instead of manually checking for a known callee and looking up the id?

[farzonl]

Still need to lookup the id, but yes this could be IntrinsicInst.