[llvm] [SPIR-V] Add pre-headers to loops. (PR #75844)

[Nathan Gauër via llvm-commits]

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@@ -0,0 +1,67 @@
+; RUN: llc -mtriple=spirv-unknown-unknown -O0 %s -o - | FileCheck %s
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Keenuts wrote:

Fixed the test to generate "valid" SPIR-V (function returned an int instead of void, etc), but I cannot add this line just yet. There are branches, and no OpSelectionMerge/OpLoopMerge yet, so this is not a valid SPIR-V module.

https://github.com/llvm/llvm-project/pull/75844