Re: RISC-V: Use extension instructions instead of bitwise "and"

[Jeff Law <jeffreyalaw@gmail.com>]

On 5/23/23 13:46, Jivan Hakobyan via Gcc-patches wrote:
> In the case where the target supports extension instructions,
> it is preferable to use that instead of doing the same in other ways.
> For the following case
> 
> void foo (unsigned long a, unsigned long* ptr) {
>      ptr[0] = a & 0xffffffffUL;
>      ptr[1] &= 0xffffffffUL;
> }
> 
> GCC generates
> foo:
>          li      a5,-1
>          srli    a5,a5,32
>          and     a0,a0,a5
>          sd      a0,0(a1)
>          ld      a4,8(a1)
>          and     a5,a4,a5
>          sd      a5,8(a1)
>          ret
> 
> but it will be profitable to generate this one
> 
> foo:
>    zext.w a0,a0
>    sd a0,0(a1)
>    lwu a5,8(a1)
>    sd a5,8(a1)
>    ret
> 
> This patch fixes mentioned issue.
> It supports HI -> DI, HI->SI and SI -> DI extensions.
> 
> gcc/ChangeLog:
>          * config/riscv/riscv.md (and<mode>3): New expander.
>          (*and<mode>3) New pattern.
>          * config/riscv/predicates.md (arith_operand_or_mode_mask): New
>          predicate.
> 
> gcc/testsuite/ChangeLog:
>          * gcc.target/riscv/and-extend-1.c: New test
>          * gcc.target/riscv/and-extend-2.c: New test
Thanks.  I made some minor whitespace fixes and pushed this to the trunk.

Jeff