[PATCH] D134134: Mark memrchr as unavailable on Windows

[Mateusz Mikuła via Phabricator via llvm-commits]

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Otherwise LLVM will optimise strrchr into memrchr on Windows resulting in linker error:

  $ cat memrchr_test.c
  #include <string.h>
  int main(int argc, char **argv) {
      return (long)strrchr("KkMm", argv[argc-1][0]);
  }
  
  $ clang memrchr_test.c -O
  memrchr_test.c:3:12: warning: cast to smaller integer type 'long' from 'char *' [-Wpointer-to-int-cast]
      return (long)strrchr("KkMm", argv[argc-1][0]);
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  1 warning generated.
  ld.lld: error: undefined symbol: memrchr
  >>> referenced by D:/msys64/tmp/memrchr_test-e7aabd.o:(main)
  clang: error: linker command failed with exit code 1 (use -v to see invocation)

Example taken from MSYS2 Discord and tested with windows-gnu target.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D134134

Files:
  llvm/lib/Analysis/TargetLibraryInfo.cpp


Index: llvm/lib/Analysis/TargetLibraryInfo.cpp
===================================================================
--- llvm/lib/Analysis/TargetLibraryInfo.cpp
+++ llvm/lib/Analysis/TargetLibraryInfo.cpp
@@ -439,6 +439,7 @@
     TLI.setUnavailable(LibFunc_htons);
     TLI.setUnavailable(LibFunc_lchown);
     TLI.setUnavailable(LibFunc_lstat);
+    TLI.setUnavailable(LibFunc_memrchr);
     TLI.setUnavailable(LibFunc_ntohl);
     TLI.setUnavailable(LibFunc_ntohs);
     TLI.setUnavailable(LibFunc_pread);


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