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Re: [Qemu-devel] [PATCH 1/8] target/ppc: Optimize emulation of lvsl and
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH 1/8] target/ppc: Optimize emulation of lvsl and lvsr instructions |
Date: |
Thu, 6 Jun 2019 11:46:13 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 |
On 6/6/19 5:15 AM, Stefan Brankovic wrote:
> + tcg_gen_addi_i64(result, sh, 7);
> + for (i = 7; i >= 1; i--) {
> + tcg_gen_shli_i64(tmp, sh, i * 8);
> + tcg_gen_or_i64(result, result, tmp);
> + tcg_gen_addi_i64(sh, sh, 1);
> + }
Better to replicate sh into the 8 positions and then use one add.
tcg_gen_muli_i64(sh, sh, 0x0101010101010101ull);
tcg_gen_addi_i64(hi_result, sh, 0x0001020304050607ull);
tcg_gen_addi_i64(lo_result, sh, 0x08090a0b0c0d0e0full);
and
tcg_gen_subfi_i64(hi_result, 0x1011121314151617ull, sh);
tcg_gen_subfi_i64(lo_result, 0x18191a1b1c1d1e1full, sh);
for lvsr.
r~