[llvm] [InferAttrs] Refine attributes for a few libc routines (PR #131117)

[Antonio Frighetto via llvm-commits]

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@@ -816,7 +816,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setDoesNotThrow(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 3);
-    // FIXME: readonly #1?
+    Changed |= setOnlyReadsMemory(F, 0);
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antoniofrighetto wrote:

Right, thanks! Think it should be as well for fgets first arg.

https://github.com/llvm/llvm-project/pull/131117