[llvm] [clang] [FuncAttrs] Deduce `noundef` attributes for return values (PR #76553)

[Nikita Popov via cfe-commits]

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@@ -27,7 +27,7 @@
 #endif
 
 // function return types
-// CHECK-LABEL: define dso_local <8 x half> @test_ret_v8f16(
+// CHECK-LABEL: define dso_local noundef <8 x half> @test_ret_v8f16(
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nikic wrote:

Ah, it seems to indeed be a "weird C rule":
https://github.com/llvm/llvm-project/blob/3c92011b600bdf70424e2547594dd461fe411a41/clang/lib/CodeGen/CGCall.cpp#L1816-L1819

https://github.com/llvm/llvm-project/pull/76553