RISC-V: Drop invalid test from CONFIG_AS_HAS_OPTION_ARCH

Commit e4bb020f3dbb ("riscv: detect assembler support for .option arch")
added two tests, one for a valid value to '.option arch' that should
succeed and one for an invalid value that is expected to fail to make
sure that support for '.option arch' is properly detected because Clang
does not error when '.option arch' is not supported:

  $ clang --target=riscv64-linux-gnu -Werror -x assembler -c -o /dev/null <(echo '.option arch, +m')
  /dev/fd/63:1:9: warning: unknown option, expected 'push', 'pop', 'rvc', 'norvc', 'relax' or 'norelax'
  .option arch, +m
          ^
  $ echo $?
  0

Unfortunately, the invalid test started being accepted by Clang after
the linked llvm-project change, which causes CONFIG_AS_HAS_OPTION_ARCH
and configurations that depend on it to be silently disabled, even
though those versions do support '.option arch'.

The invalid test can be avoided altogether by using
'-Wa,--fatal-warnings', which will turn all assembler warnings into
errors, like '-Werror' does for the compiler:

  $ clang --target=riscv64-linux-gnu -Werror -Wa,--fatal-warnings -x assembler -c -o /dev/null <(echo '.option arch, +m')
  /dev/fd/63:1:9: error: unknown option, expected 'push', 'pop', 'rvc', 'norvc', 'relax' or 'norelax'
  .option arch, +m
          ^
  $ echo $?
  1

The as-instr macros have been updated to make use of this flag, so
remove the invalid test, which allows CONFIG_AS_HAS_OPTION_ARCH to work
for all compiler versions.

Cc: [email protected]
Fixes: e4bb020f3dbb ("riscv: detect assembler support for .option arch")
Link: https://github.com/llvm/llvm-project/commit/3ac9fe69f70a2b3541266daedbaaa7dc9c007a2a
Reported-by: Eric Biggers <[email protected]>
Closes: https://lore.kernel.org/r/[email protected]/
Signed-off-by: Nathan Chancellor <[email protected]>
Tested-by: Eric Biggers <[email protected]>
Tested-by: Andy Chiu <[email protected]>
Reviewed-by: Andy Chiu <[email protected]>
Tested-by: Conor Dooley <[email protected]>
Reviewed-by: Conor Dooley <[email protected]>
Acked-by: Masahiro Yamada <[email protected]>
Link: https://lore.kernel.org/r/20240125-fix-riscv-option-arch-llvm-18-v1-2-390ac9cc3cd0@kernel.org
Signed-off-by: Palmer Dabbelt <[email protected]>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index bffbd869a0682842883591788da784648acf1626..e3142ce531a097b8cf0e39251ba88ae143d6594c 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -315,7 +315,6 @@ config AS_HAS_OPTION_ARCH
        # https://reviews.llvm.org/D123515
        def_bool y
        depends on $(as-instr, .option arch$(comma) +m)
-       depends on !$(as-instr, .option arch$(comma) -i)
 
 source "arch/riscv/Kconfig.socs"
 source "arch/riscv/Kconfig.errata"