[PATCH] D148975: -fdebug-prefix-map=: make the last win when multiple prefixes match

[Fangrui Song via Phabricator via cfe-commits]

MaskRay created this revision.
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For
`clang -c -g -fdebug-prefix-map=a/b=y -fdebug-prefix-map=a=x a/b/c.c`,
we apply the longest prefix substitution, but
GCC has always been picking the last applicable option (`a=x`, see
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109591).

I feel that GCC's behavior is reasonable given the convention that the last
value wins for the same option.

Before D49466 <https://reviews.llvm.org/D49466>, Clang appeared to apply the shortest prefix substitution,
which likely made the least sense.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D148975

Files:
  clang/include/clang/Basic/CodeGenOptions.h
  clang/lib/CodeGen/CGDebugInfo.cpp
  clang/lib/CodeGen/CGDebugInfo.h
  clang/lib/Frontend/CompilerInvocation.cpp
  clang/test/CodeGen/debug-prefix-map.c
  clang/tools/driver/cc1as_main.cpp
  llvm/include/llvm/MC/MCContext.h
  llvm/lib/MC/MCContext.cpp
  llvm/test/MC/ELF/debug-prefix-map.s

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