On 3/2/21 4:50 PM, Ilya Leoshkevich via Gcc-patches wrote:
> Hello,
>
> I would like to ping the following patch:
>
> Add input_modes parameter to TARGET_MD_ASM_ADJUST hook
> https://gcc.gnu.org/pipermail/gcc-patches/2021-January/562898.html
>
> It is needed for the following regression fix:
>
> IBM Z: Fix usage of "f" constraint with long doubles
> https://gcc.gnu.org/pipermail/gcc-patches/2021-January/564380.html
>
>
> Jakub, who would be the right person to review this change? I've
> decided to ask you, since `git shortlog -ns gcc/cfgexpand.c` shows that
> you deal with this code a lot.
>
> Best regards,
> Ilya
>
>
>
>
> If TARGET_MD_ASM_ADJUST changes a mode of an input operand (which
> should be ok as long as the hook itself as well as after_md_seq make up
> for it), input_mode will contain stale information.
>
> It might be tempting to fix this by removing input_mode altogether and
> just using GET_MODE (), but this will not work correctly with constants.
> So add input_modes parameter and document that it should be updated
> whenever inputs parameter is updated.
>
> gcc/ChangeLog:
>
> 2021-01-05 Ilya Leoshkevich <i...@linux.ibm.com>
>
> * cfgexpand.c (expand_asm_loc): Pass new parameter.
> (expand_asm_stmt): Likewise.
> * config/arm/aarch-common-protos.h (arm_md_asm_adjust): Add new
> parameter.
> * config/arm/aarch-common.c (arm_md_asm_adjust): Likewise.
> * config/arm/arm.c (thumb1_md_asm_adjust): Likewise.
> * config/cris/cris.c (cris_md_asm_adjust): Likewise.
> * config/i386/i386.c (ix86_md_asm_adjust): Likewise.
> * config/mn10300/mn10300.c (mn10300_md_asm_adjust): Likewise.
> * config/nds32/nds32.c (nds32_md_asm_adjust): Likewise.
> * config/pdp11/pdp11.c (pdp11_md_asm_adjust): Likewise.
> * config/rs6000/rs6000.c (rs6000_md_asm_adjust): Likewise.
> * config/vax/vax.c (vax_md_asm_adjust): Likewise.
> * config/visium/visium.c (visium_md_asm_adjust): Likewise.
> * target.def (md_asm_adjust): Likewise.
Ugh. A couple questions
Are there any cases where you're going to want to change modes for
arguments that were constants? I'm a bit surprised that we don't have
a mode for constants for the cases that we care about. Presumably we
can get a (modeless) CONST_INT here and we're not restricted to
CONST_DOUBLE and friends (which have modes).
Is input_modes read after the call to md_asm_adjust? I'm trying to
figure out why we'd need to update it.
Not acking or naking at this point, I just want to make sure I
understand what's going on.
jeff
