[llvm] [Scalarizer] Make `uadd_with_overflow` scalarizable (PR #126815)

[Deric Cheung via llvm-commits]

https://github.com/Icohedron created https://github.com/llvm/llvm-project/pull/126815

Addresses issue #126809

- Made `uadd_with_overflow` trivially scalarizable in `isTriviallyScalarizable` from `VectorUtils.cpp`
- Updated the test `Scalarizer/uadd_overflow.ll` to check that `uadd_with_overflow` gets scalarized

>From 1ee9014449adece2d817cd5f03d570ea3fe0af41 Mon Sep 17 00:00:00 2001
From: Icohedron <cheung.deric at gmail.com>
Date: Tue, 11 Feb 2025 22:45:26 +0000
Subject: [PATCH] Make uadd_with_overflow scalarizable

---
 llvm/lib/Analysis/VectorUtils.cpp                |  1 +
 llvm/test/Transforms/Scalarizer/uadd_overflow.ll | 16 ++++++++++++----
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Analysis/VectorUtils.cpp b/llvm/lib/Analysis/VectorUtils.cpp
index ad80e458ab57d..97b29cfc3c737 100644
--- a/llvm/lib/Analysis/VectorUtils.cpp
+++ b/llvm/lib/Analysis/VectorUtils.cpp
@@ -125,6 +125,7 @@ bool llvm::isTriviallyScalarizable(Intrinsic::ID ID,
   // https://github.com/llvm/llvm-project/issues/112408
   switch (ID) {
   case Intrinsic::frexp:
+  case Intrinsic::uadd_with_overflow:
     return true;
   }
   return false;
diff --git a/llvm/test/Transforms/Scalarizer/uadd_overflow.ll b/llvm/test/Transforms/Scalarizer/uadd_overflow.ll
index 39094451523a5..f266e5f08b3f6 100644
--- a/llvm/test/Transforms/Scalarizer/uadd_overflow.ll
+++ b/llvm/test/Transforms/Scalarizer/uadd_overflow.ll
@@ -1,13 +1,21 @@
 ; 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:    [[B_I0:%.*]] = extractelement <3 x i32> [[B]], i64 0
+; CHECK-NEXT:    [[R_I0:%.*]] = call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 [[B_I0]], i32 [[B_I0]])
+; CHECK-NEXT:    [[B_I1:%.*]] = extractelement <3 x i32> [[B]], i64 1
+; CHECK-NEXT:    [[R_I1:%.*]] = call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 [[B_I1]], i32 [[B_I1]])
+; CHECK-NEXT:    [[B_I2:%.*]] = extractelement <3 x i32> [[B]], i64 2
+; CHECK-NEXT:    [[R_I2:%.*]] = call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 [[B_I2]], i32 [[B_I2]])
+; CHECK-NEXT:    [[EL_ELEM0:%.*]] = extractvalue { i32, i1 } [[R_I0]], 0
+; CHECK-NEXT:    [[EL_ELEM01:%.*]] = extractvalue { i32, i1 } [[R_I1]], 0
+; CHECK-NEXT:    [[EL_ELEM02:%.*]] = extractvalue { i32, i1 } [[R_I2]], 0
+; CHECK-NEXT:    [[EL_UPTO0:%.*]] = insertelement <3 x i32> poison, i32 [[EL_ELEM0]], i64 0
+; CHECK-NEXT:    [[EL_UPTO1:%.*]] = insertelement <3 x i32> [[EL_UPTO0]], i32 [[EL_ELEM01]], i64 1
+; CHECK-NEXT:    [[EL:%.*]] = insertelement <3 x i32> [[EL_UPTO1]], i32 [[EL_ELEM02]], i64 2
 ; 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)