From 759bab068157d93a71ef20dc28a2eaed4fec6d40 Mon Sep 17 00:00:00 2001
From: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Sun, 7 Apr 2024 14:40:21 -0500
Subject: [PATCH] [InstCombine] Add tests for folding `(icmp eq/ne (add nuw x,
 y), 0)`; NFC

---
 llvm/test/Transforms/InstCombine/icmp-add.ll | 24 ++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/llvm/test/Transforms/InstCombine/icmp-add.ll b/llvm/test/Transforms/InstCombine/icmp-add.ll
index b99ed20d7d431c..6f990890dbb2cf 100644
--- a/llvm/test/Transforms/InstCombine/icmp-add.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-add.ll
@@ -3003,4 +3003,28 @@ define i1 @icmp_dec_notnonzero(i8 %x) {
   ret i1 %c
 }
 
+define i1 @icmp_addnuw_nonzero(i8 %x, i8 %y) {
+; CHECK-LABEL: @icmp_addnuw_nonzero(
+; CHECK-NEXT:    [[I:%.*]] = sub i8 0, [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i8 [[I]], [[X:%.*]]
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %i = add nuw i8 %x, %y
+  %c = icmp eq i8 %i, 0
+  ret i1 %c
+}
+
+define i1 @icmp_addnuw_nonzero_fail_multiuse(i32 %x, i32 %y) {
+; CHECK-LABEL: @icmp_addnuw_nonzero_fail_multiuse(
+; CHECK-NEXT:    [[I:%.*]] = add nuw i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i32 [[I]], 0
+; CHECK-NEXT:    call void @use(i32 [[I]])
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %i = add nuw i32 %x, %y
+  %c = icmp eq i32 %i, 0
+  call void @use(i32 %i)
+  ret i1 %c
+}
+
 declare void @llvm.assume(i1)