On Wed, Dec 19, 2018 at 5:51 AM Iago Toral Quiroga <ito...@igalia.com>
wrote:
> v2:
> - use nir_fadd_imm and nir_fmul_imm helpers (Jason)
> ---
> src/compiler/spirv/vtn_glsl450.c | 44 +++++++++++++++++++-------------
> 1 file changed, 26 insertions(+), 18 deletions(-)
>
> diff --git a/src/compiler/spirv/vtn_glsl450.c
> b/src/compiler/spirv/vtn_glsl450.c
> index ec91d9308c5..c8400d6c80f 100644
> --- a/src/compiler/spirv/vtn_glsl450.c
> +++ b/src/compiler/spirv/vtn_glsl450.c
> @@ -654,17 +654,17 @@ handle_glsl450_alu(struct vtn_builder *b, enum
> GLSLstd450 entrypoint,
> case GLSLstd450Sinh:
> /* 0.5 * (e^x - e^(-x)) */
> val->ssa->def =
> - nir_fmul(nb, nir_imm_float(nb, 0.5f),
> - nir_fsub(nb, build_exp(nb, src[0]),
> - build_exp(nb, nir_fneg(nb, src[0]))));
> + nir_fmul_imm(nb, nir_fsub(nb, build_exp(nb, src[0]),
> + build_exp(nb, nir_fneg(nb,
> src[0]))),
> + 0.5f);
> return;
>
> case GLSLstd450Cosh:
> /* 0.5 * (e^x + e^(-x)) */
> val->ssa->def =
> - nir_fmul(nb, nir_imm_float(nb, 0.5f),
> - nir_fadd(nb, build_exp(nb, src[0]),
> - build_exp(nb, nir_fneg(nb, src[0]))));
> + nir_fmul_imm(nb, nir_fadd(nb, build_exp(nb, src[0]),
> + build_exp(nb, nir_fneg(nb,
> src[0]))),
> + 0.5f);
> return;
>
> case GLSLstd450Tanh: {
> @@ -675,30 +675,38 @@ handle_glsl450_alu(struct vtn_builder *b, enum
> GLSLstd450 entrypoint,
> * We clamp x to (-inf, +10] to avoid precision problems. When x >
> 10,
> * e^2x is so much larger than 1.0 that 1.0 gets flushed to zero in
> the
> * computation e^2x +/- 1 so it can be ignored.
> + *
> + * For 16-bit precision we clamp x to (-inf, +4.2] since the maximum
> + * representable number is only 65,504 and e^(2*6) exceeds that.
> Also,
> + * if x > 4.2, tanh(x) will return 1.0 in fp16.
> */
> - nir_ssa_def *x = nir_fmin(nb, src[0], nir_imm_float(nb, 10));
> - nir_ssa_def *exp2x = build_exp(nb, nir_fmul(nb, x,
> nir_imm_float(nb, 2)));
> - val->ssa->def = nir_fdiv(nb, nir_fsub(nb, exp2x, nir_imm_float(nb,
> 1)),
> - nir_fadd(nb, exp2x, nir_imm_float(nb,
> 1)));
> + const uint32_t bit_size = src[0]->bit_size;
> + const double clamped_x = bit_size > 16 ? 10.0 : 4.2;
> + nir_ssa_def *x = nir_fmin(nb, src[0],
> + nir_imm_floatN_t(nb, clamped_x,
> bit_size));
> + nir_ssa_def *exp2x = build_exp(nb, nir_fmul_imm(nb, x, 2.0));
> + val->ssa->def = nir_fdiv(nb, nir_fadd_imm(nb, exp2x, -1.0),
> + nir_fadd_imm(nb, exp2x, 1.0));
> return;
> }
>
> case GLSLstd450Asinh:
> val->ssa->def = nir_fmul(nb, nir_fsign(nb, src[0]),
> build_log(nb, nir_fadd(nb, nir_fabs(nb, src[0]),
> - nir_fsqrt(nb, nir_fadd(nb, nir_fmul(nb, src[0],
> src[0]),
> - nir_imm_float(nb,
> 1.0f))))));
> + nir_fsqrt(nb, nir_fadd_imm(nb, nir_fmul(nb,
> src[0], src[0]),
> + 1.0f)))));
> return;
> case GLSLstd450Acosh:
> val->ssa->def = build_log(nb, nir_fadd(nb, src[0],
> - nir_fsqrt(nb, nir_fsub(nb, nir_fmul(nb, src[0], src[0]),
> - nir_imm_float(nb, 1.0f)))));
> + nir_fsqrt(nb, nir_fadd_imm(nb, nir_fmul(nb, src[0], src[0]),
> + -1.0f))));
> return;
> case GLSLstd450Atanh: {
> - nir_ssa_def *one = nir_imm_float(nb, 1.0);
> - val->ssa->def = nir_fmul(nb, nir_imm_float(nb, 0.5f),
> - build_log(nb, nir_fdiv(nb, nir_fadd(nb, one, src[0]),
> - nir_fsub(nb, one, src[0]))));
> + nir_ssa_def *one = nir_imm_floatN_t(nb, 1.0, src[0]->bit_size);
> + val->ssa->def =
> + nir_fmul_imm(nb, build_log(nb, nir_fdiv(nb, nir_fadd_imm(nb,
> src[0], 1.0f),
>
Since you had to declare one for the line below, you could just use it
here. Doesn't really matter though.
> + nir_fsub(nb, one, src[0]))),
> + 0.5f);
> return;
> }
>
> --
> 2.17.1
>
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