[clang] [CIR] Implement cir.cmp3way Operation (PR #186294)

[Erich Keane via cfe-commits]

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@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
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erichkeane wrote:

We've been doing a pattern of tests where we test this in 3 different sets of runlines to make sure the test is consistent, please do it that way (almost every file in this directory has something like it).

https://github.com/llvm/llvm-project/pull/186294