[llvm] [SCEV] Rewrite more SCEVAddExpr when applying guards. (PR #159942)

[Florian Hahn via llvm-commits]

================
@@ -61,9 +61,9 @@ define void @test_memset_size_can_use_info_from_guards(i32 %x, ptr %dst) {
 ; CHECK:       [[LOOP1_BACKEDGE]]:
 ; CHECK-NEXT:    br label %[[LOOP1]]
 ; CHECK:       [[LOOP2_PREHEADER]]:
-; CHECK-NEXT:    [[TMP0:%.*]] = zext i32 [[SUB]] to i64
-; CHECK-NEXT:    [[TMP1:%.*]] = lshr i64 [[TMP0]], 1
-; CHECK-NEXT:    [[UMAX:%.*]] = call i64 @llvm.umax.i64(i64 [[TMP1]], i64 1)
+; CHECK-NEXT:    [[TMP0:%.*]] = add nsw i32 [[SHR]], -1
+; CHECK-NEXT:    [[TMP1:%.*]] = zext i32 [[TMP0]] to i64
+; CHECK-NEXT:    [[UMAX:%.*]] = add nuw nsw i64 [[TMP1]], 1
----------------
fhahn wrote:

This is missing a fold end-to-end from https://github.com/dtcxzyw/llvm-opt-benchmark/pull/2845/files/ed058c0c689f0dadf267033c74e0960c3593baff#r2367574398

https://alive2.llvm.org/ce/z/BuHtNm

https://github.com/llvm/llvm-project/pull/159942