[PATCH] D155168: [OSX][TargetLibraryInfo] Mark memchr as unavailable on OSX

[Pavel Kosov via Phabricator via llvm-commits]

kpdev42 created this revision.
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On Mac OSX  (tested version macOS 12.4, sdk 12.1) llvm can replace call to `strrchr()` with call to `memrchr()` when string length is known at compile time. This results in link error, because `memrchr` is not present in `libSystem`. It is needed to disable this optimization in `TargetLibraryInfo` for affected OSX versions.

This non-standard function (`memchr`) is not present on (at least) several versions of MacOS https://www.gnu.org/software/gnulib/manual/html_node/memrchr.html , so, in this patch `memchr` is marked as unavailable for all versions. If someone knows versions where it should be available - please let me know.

Github issue: https://github.com/llvm/llvm-project/issues/62254

Tests for this feature also cannot be easily added: https://reviews.llvm.org/D134134#3801747

~~~

Huawei RRI, OS Lab


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D155168

Files:
  llvm/lib/Analysis/TargetLibraryInfo.cpp


Index: llvm/lib/Analysis/TargetLibraryInfo.cpp
===================================================================
--- llvm/lib/Analysis/TargetLibraryInfo.cpp
+++ llvm/lib/Analysis/TargetLibraryInfo.cpp
@@ -203,6 +203,7 @@
     TLI.setAvailable(LibFunc_getchar_unlocked);
     TLI.setAvailable(LibFunc_putc_unlocked);
     TLI.setAvailable(LibFunc_putchar_unlocked);
+    TLI.setUnavailable(LibFunc_memchr);
 
     if (T.isMacOSXVersionLT(10, 5)) {
       TLI.setUnavailable(LibFunc_memset_pattern4);


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