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

[Nikita Popov 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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nikic wrote:

I think the point of these tests is to check interaction between IPSCCP and InstCombine, so a PhaseOrdering test makes sense.

However, in the current form these tests are too hard to understand. I would suggest getting the IR again with `-fno-discard-value-names` and then running `opt -S -passes=sroa` over it to convert it into SSA form.

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