[PATCH v2 1/2] ARM: drop WASM to work around LLVM issue
ndesaulniers at google.com
Mon Mar 18 11:09:10 PDT 2019
On Sun, Mar 17, 2019 at 4:05 PM Stefan Agner <stefan at agner.ch> wrote:
> Currently LLVM's integrated assembler does not recognize .w form
> of the pld instructions (LLVM Bug 40972 ):
> ./arch/arm/include/asm/processor.h:133:5: error: invalid instruction
> "pldw.w\t%a0 \n"
> <inline asm>:2:1: note: instantiated into assembly here
> pldw.w [r0]
> 1 error generated.
> The W macro for generating wide instructions when targeting Thumb-2
> is not strictly required for the preload data instructions (pld, pldw)
> since they are only available as wide instructions. The GNU assembler
> works with or without the .w appended when compiling an Thumb-2 kernel.
> Drop the macro to work around LLVM Bug 40972 issue.
>  https://bugs.llvm.org/show_bug.cgi?id=40972
> Signed-off-by: Stefan Agner <stefan at agner.ch>
Thanks for the bug report and patch.
Reviewed-by: Nick Desaulniers <ndesaulniers at google.com>
Just curious, there are only 3 other expansion sites of this macro.
Are any of those problematic? Looks like nop.w, sev.w and b.w?
> Changes in v2:
> - Reword commit message to reflect the fact that this is a work around
> for LLVM.
> arch/arm/include/asm/processor.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
> index 57fe73ea0f72..5d06f75ffad4 100644
> --- a/arch/arm/include/asm/processor.h
> +++ b/arch/arm/include/asm/processor.h
> @@ -135,8 +135,8 @@ static inline void prefetchw(const void *ptr)
> __asm__ __volatile__(
> ".arch_extension mp\n"
> - WASM(pldw) "\t%a0",
> - WASM(pld) "\t%a0"
> + "pldw\t%a0",
> + "pld\t%a0"
> :: "p" (ptr));
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