Re: [PATCH] RISC-V: improve codegen for large constants with same 32-bit lo and hi parts [2]

[Jeff Law via Gcc-patches]

On 5/18/23 14:57, Vineet Gupta wrote:
[part #2 of PR/109279]

SPEC2017 deepsjeng uses large constants which currently generates less than
ideal code. This fix improves codegen for large constants which have
same low and hi parts: e.g.

        long long f(void) { return 0x0101010101010101ull; }

Before
         li      a5,0x1010000
         addi    a5,a5,0x101
         mv      a0,a5
         slli    a5,a5,32
         add     a0,a5,a0
         ret

With patch
        li      a5,0x1010000
        addi    a5,a5,0x101
        slli    a0,a5,32
        add     a0,a0,a5
        ret

This is testsuite clean.

gcc/ChangeLog:

        * config/riscv/riscv.cc (riscv_split_integer): if loval is equal
          to hival, ASHIFT the corresponding regs.
LGTM.  Please install.  Thanks for taking care of this!  The updated 
sequence looks good.

Jeff