The output field of an asm goto statement is not supported by all
compilers. If it is not supported, fallback to the non-optimized code.
Signed-off-by: Charlie Jenkins <[email protected]>
Fixes: a04c192eabfb ("riscv: Add checksum library")
---
The OutputOperands field for asm goto statements is only supported
starting from GCC 11. Split the asm goto to remove the use of this
feature.
---
Changes in v2:
- Use CC_HAS_ASM_GOTO_TIED_OUTPUT
- Link to v1: https://lore.kernel.org/r/20240118-csum_remove_output_operands_asm_goto-v1-1-47c672bb9d4b@rivosinc.com
---
arch/riscv/lib/csum.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/riscv/lib/csum.c b/arch/riscv/lib/csum.c
index 06ce8e7250d9..af3df5274ccb 100644
--- a/arch/riscv/lib/csum.c
+++ b/arch/riscv/lib/csum.c
@@ -156,6 +156,7 @@ do_csum_with_alignment(const unsigned char *buff, int len)
end = (const unsigned long *)(buff + len);
csum = do_csum_common(ptr, end, data);
+#ifdef CC_HAS_ASM_GOTO_TIED_OUTPUT
/*
* Zbb support saves 6 instructions, so not worth checking without
* alternatives if supported
@@ -214,6 +215,7 @@ do_csum_with_alignment(const unsigned char *buff, int len)
return csum >> 16;
}
no_zbb:
+#endif /* CC_HAS_ASM_GOTO_TIED_OUTPUT */
#ifndef CONFIG_32BIT
csum += ror64(csum, 32);
csum >>= 32;
---
base-commit: 080c4324fa5e81ff3780206a138223abfb57a68e
change-id: 20240118-csum_remove_output_operands_asm_goto-49922c141ce7
--
- Charlie
On Thu, Jan 18, 2024 at 02:36:45PM -0800, Charlie Jenkins wrote:
> The output field of an asm goto statement is not supported by all
> compilers. If it is not supported, fallback to the non-optimized code.
>
> Signed-off-by: Charlie Jenkins <[email protected]>
> Fixes: a04c192eabfb ("riscv: Add checksum library")
> ---
> The OutputOperands field for asm goto statements is only supported
> starting from GCC 11. Split the asm goto to remove the use of this
> feature.
> ---
> Changes in v2:
> - Use CC_HAS_ASM_GOTO_TIED_OUTPUT
> - Link to v1: https://lore.kernel.org/r/20240118-csum_remove_output_operands_asm_goto-v1-1-47c672bb9d4b@rivosinc.com
> ---
> arch/riscv/lib/csum.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/riscv/lib/csum.c b/arch/riscv/lib/csum.c
> index 06ce8e7250d9..af3df5274ccb 100644
> --- a/arch/riscv/lib/csum.c
> +++ b/arch/riscv/lib/csum.c
> @@ -156,6 +156,7 @@ do_csum_with_alignment(const unsigned char *buff, int len)
> end = (const unsigned long *)(buff + len);
> csum = do_csum_common(ptr, end, data);
>
> +#ifdef CC_HAS_ASM_GOTO_TIED_OUTPUT
Can't we just add another IS_ENABLED() to the if rather than this #ifdef?
> /*
> * Zbb support saves 6 instructions, so not worth checking without
> * alternatives if supported
> @@ -214,6 +215,7 @@ do_csum_with_alignment(const unsigned char *buff, int len)
> return csum >> 16;
> }
> no_zbb:
> +#endif /* CC_HAS_ASM_GOTO_TIED_OUTPUT */
> #ifndef CONFIG_32BIT
> csum += ror64(csum, 32);
> csum >>= 32;
BTW, I wonder how/if the check for CC_HAS_ASM_GOTO_TIED_OUTPUT in
init/Kconfig is working as expected. I see $CC, as opposed to $(CC),
being used there. I believe $CC is just the expansion of $C with a
'C' appended.
Thanks,
drew
>
> ---
> base-commit: 080c4324fa5e81ff3780206a138223abfb57a68e
> change-id: 20240118-csum_remove_output_operands_asm_goto-49922c141ce7
> --
> - Charlie
>
>
> _______________________________________________
> linux-riscv mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-riscv
On Fri, Jan 19, 2024 at 10:41:14AM +0100, Andrew Jones wrote:
> On Thu, Jan 18, 2024 at 02:36:45PM -0800, Charlie Jenkins wrote:
> > The output field of an asm goto statement is not supported by all
> > compilers. If it is not supported, fallback to the non-optimized code.
> >
> > Signed-off-by: Charlie Jenkins <[email protected]>
> > Fixes: a04c192eabfb ("riscv: Add checksum library")
> > ---
> > The OutputOperands field for asm goto statements is only supported
> > starting from GCC 11. Split the asm goto to remove the use of this
> > feature.
> > ---
> > Changes in v2:
> > - Use CC_HAS_ASM_GOTO_TIED_OUTPUT
> > - Link to v1: https://lore.kernel.org/r/20240118-csum_remove_output_operands_asm_goto-v1-1-47c672bb9d4b@rivosinc.com
> > ---
> > arch/riscv/lib/csum.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/arch/riscv/lib/csum.c b/arch/riscv/lib/csum.c
> > index 06ce8e7250d9..af3df5274ccb 100644
> > --- a/arch/riscv/lib/csum.c
> > +++ b/arch/riscv/lib/csum.c
> > @@ -156,6 +156,7 @@ do_csum_with_alignment(const unsigned char *buff, int len)
> > end = (const unsigned long *)(buff + len);
> > csum = do_csum_common(ptr, end, data);
> >
> > +#ifdef CC_HAS_ASM_GOTO_TIED_OUTPUT
>
> Can't we just add another IS_ENABLED() to the if rather than this #ifdef?
Unfortunately no. GCC throws syntax before it determines if a branch
will never be taken, so even though the code is not emitted it will
still fail with IS_ENABLED.
>
> > /*
> > * Zbb support saves 6 instructions, so not worth checking without
> > * alternatives if supported
> > @@ -214,6 +215,7 @@ do_csum_with_alignment(const unsigned char *buff, int len)
> > return csum >> 16;
> > }
> > no_zbb:
> > +#endif /* CC_HAS_ASM_GOTO_TIED_OUTPUT */
> > #ifndef CONFIG_32BIT
> > csum += ror64(csum, 32);
> > csum >>= 32;
>
> BTW, I wonder how/if the check for CC_HAS_ASM_GOTO_TIED_OUTPUT in
> init/Kconfig is working as expected. I see $CC, as opposed to $(CC),
> being used there. I believe $CC is just the expansion of $C with a
> 'C' appended.
Huh that is strange. It does work but I am not sure how.
- Charlie
>
> Thanks,
> drew
>
> >
> > ---
> > base-commit: 080c4324fa5e81ff3780206a138223abfb57a68e
> > change-id: 20240118-csum_remove_output_operands_asm_goto-49922c141ce7
> > --
> > - Charlie
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > [email protected]
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
Hello:
This patch was applied to riscv/linux.git (fixes)
by Palmer Dabbelt <[email protected]>:
On Thu, 18 Jan 2024 14:36:45 -0800 you wrote:
> The output field of an asm goto statement is not supported by all
> compilers. If it is not supported, fallback to the non-optimized code.
>
> Signed-off-by: Charlie Jenkins <[email protected]>
> Fixes: a04c192eabfb ("riscv: Add checksum library")
> ---
> The OutputOperands field for asm goto statements is only supported
> starting from GCC 11. Split the asm goto to remove the use of this
> feature.
>
> [...]
Here is the summary with links:
- [v2] riscv: lib: Check if output in asm goto supported
https://git.kernel.org/riscv/c/4525462dd0db
You are awesome, thank you!
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