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

[Yingwei Zheng via cfe-commits]

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@@ -0,0 +1,126 @@
+; RUN: opt < %s --O3 -S | FileCheck %s
+
+define signext i16 @vecreduce_smax_v2i16(i32 noundef %0, ptr noundef %1) #0 {
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dtcxzyw wrote:

Could you please reduce the test case and move it into `InstCombine`?

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