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pan/bi: Lower frcp to Newton-Raphson

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For G71 but should work on any Bifrost, probably overlaps some CL stuff.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Acked-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8894>
This commit is contained in:
Alyssa Rosenzweig 2021-01-15 15:38:35 -05:00 • committed by Marge Bot
parent 94fed29680
commit c5e5d11599
1 changed files with 15 additions and 0 deletions
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15
src/panfrost/bifrost/bifrost_compile.c
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@ -974,6 +974,21 @@ bi_fmul_f32(bi_builder *b, bi_index s0, bi_index s1)
return bi_fma_f32(b, s0, s1, bi_imm_f32(-0.0f), BI_ROUND_NONE);
}
/* Approximate with FRCP_APPROX.f32 and apply a single iteration of
* Newton-Raphson to improve precision */
static void
bi_lower_frcp_32(bi_builder *b, bi_index dst, bi_index s0)
{
bi_index x1 = bi_frcp_approx_f32(b, s0);
bi_index m = bi_frexpm_f32(b, s0, false, false);
bi_index e = bi_frexpe_f32(b, bi_neg(s0), false, false);
bi_index t1 = bi_fma_rscale_f32(b, m, bi_neg(x1), bi_imm_f32(1.0),
bi_zero(), BI_ROUND_NONE, BI_SPECIAL_N);
bi_fma_rscale_f32_to(b, dst, t1, x1, x1, e,
BI_ROUND_NONE, BI_SPECIAL_NONE);
}
static void
bi_emit_alu(bi_builder *b, nir_alu_instr *instr)
{