[all-commits] [llvm/llvm-project] a07b13: [Driver][gcov] Derive .gcno .gcda file names from ...

[Fangrui Song via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a07b135ce0c0111bd83450b5dc29ef0381cdbc39
      https://github.com/llvm/llvm-project/commit/a07b135ce0c0111bd83450b5dc29ef0381cdbc39
  Author: Fangrui Song <i at maskray.me>
  Date:   2023-05-17 (Wed, 17 May 2023)

  Changed paths:
    M clang/lib/Driver/ToolChains/Clang.cpp
    M clang/test/Driver/coverage.c
    M clang/test/Driver/working-directory.c

  Log Message:
  -----------
  [Driver][gcov] Derive .gcno .gcda file names from -o and -dumpdir

Resolve a FIXME.
When -ftest-profile, -fprofile-arcs, or --coverage is specified and the
driver performs both compilation and linking phases, derive the .gcno &
.gcda file names from -o and -dumpdir.

`clang --coverage d/a.c d/b.c -o e/x && e/x` will now emit
`e/x-[ab].gc{no,da}` like GCC.

For -fprofile-dir=, we make the deliberate decision to not mangle the
input filename if relative.

The following script demonstrates the .gcno and .gcda filenames.

```
PATH=/tmp/Rel/bin:$PATH                # adapt according to your build directory
mkdir -p d e f
echo 'int main() {}' > d/a.c
echo > d/b.c

a() { rm $@ || exit 1; }

clang --coverage d/a.c d/b.c && ./a.out
a a-[ab].gc{no,da}
clang --coverage d/a.c d/b.c -o e/x && e/x
a e/x-[ab].gc{no,da}
clang --coverage d/a.c d/b.c -o e/x -dumpdir f/ && e/x
a f/[ab].gc{no,da}
clang --coverage -fprofile-dir=f d/a.c d/b.c -o e/x && e/x
a e/x-[ab].gcno f/e/x-[ab].gcda

clang -c --coverage d/a.c d/b.c && clang --coverage a.o b.o && ./a.out
a [ab].gc{no,da}
clang -c --coverage -fprofile-dir=f d/a.c d/b.c && clang --coverage a.o b.o && ./a.out
a [ab].gcno f/[ab].gcda

clang -c --coverage d/a.c -o e/xa.o && clang --coverage e/xa.o && ./a.out
a e/xa.gc{no,da}
clang -c --coverage d/a.c -o e/xa.o -dumpdir f/g && clang --coverage e/xa.o && ./a.out
a f/ga.gc{no,da}
```

The gcov code accidentally claims -c and -S, so -fsyntax-only -c/-S and
-E -c/-S don't lead to a -Wunused-command-line-argument warning. Keep
the unintended code for now.