[llvm] [clang] [Instcombine] use zext's nneg flag for icmp folding (PR #70845)

[Léonard Oest O'Leary via cfe-commits]

================
@@ -0,0 +1,175 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 3
+; See PR-70845 for more details
+; RUN: opt < %s -S -passes=instcombine | FileCheck %s
+
+
+define signext i32 @sext_sext(i16 %x, i16 %y) {
----------------
leo-ard wrote:

The technique of commenting and seeing which tests crashed worked really well. Thanks for the trick

https://github.com/llvm/llvm-project/pull/70845