[all-commits] [llvm/llvm-project] ef58ae: [RISCV] Fix mcount name

[Nathan Chancellor via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ef58ae86ba778ed7d01cd3f6bd6d08f943abab44
      https://github.com/llvm/llvm-project/commit/ef58ae86ba778ed7d01cd3f6bd6d08f943abab44
  Author: Nathan Chancellor <nathan at kernel.org>
  Date:   2021-03-24 (Wed, 24 Mar 2021)

  Changed paths:
    M clang/lib/Basic/Targets/OSTargets.h
    M clang/lib/Basic/Targets/RISCV.h
    M clang/test/CodeGen/mcount.c

  Log Message:
  -----------
  [RISCV] Fix mcount name

GCC's name for this symbol is _mcount, which the Linux kernel expects in
a few different place:

  $ echo 'int main(void) { return 0; }' | riscv32-linux-gcc -c -pg -o tmp.o -x c -

  $ llvm-objdump -dr tmp.o | grep mcount
                          0000000c:  R_RISCV_CALL _mcount

  $ echo 'int main(void) { return 0; }' | riscv64-linux-gcc -c -pg -o tmp.o -x c -

  $ llvm-objdump -dr tmp.o | grep mcount
                  000000000000000c:  R_RISCV_CALL _mcount

  $ echo 'int main(void) { return 0; }' | clang -c -pg -o tmp.o --target=riscv32-linux-gnu -x c -

  $ llvm-objdump -dr tmp.o | grep mcount
                          0000000a:  R_RISCV_CALL_PLT     mcount

  $ echo 'int main(void) { return 0; }' | clang -c -pg -o tmp.o --target=riscv64-linux-gnu -x c -

  $ llvm-objdump -dr tmp.o | grep mcount
                  000000000000000a:  R_RISCV_CALL_PLT     mcount

Set MCountName to "_mcount" in RISCVTargetInfo then prevent it from
getting overridden in certain OSTargetInfo constructors.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D98881

Signed-off-by: Nathan Chancellor <nathan at kernel.org>