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nir/spirv/glsl450: Implement Frexp.

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This commit is contained in:
Kenneth Graunke 2016-01-19 16:46:03 -08:00
parent 68c9ca1a94
commit 549be68258
1 changed files with 41 additions and 1 deletions
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42
src/glsl/nir/spirv/vtn_glsl450.c
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@ -337,6 +337,39 @@ build_atan2(nir_builder *b, nir_ssa_def *y, nir_ssa_def *x)
return &phi->dest.ssa;
}
static nir_ssa_def *
build_frexp(nir_builder *b, nir_ssa_def *x, nir_ssa_def **exponent)
{
nir_ssa_def *abs_x = nir_fabs(b, x);
nir_ssa_def *zero = nir_imm_float(b, 0.0f);
/* Single-precision floating-point values are stored as
* 1 sign bit;
* 8 exponent bits;
* 23 mantissa bits.
*
* An exponent shift of 23 will shift the mantissa out, leaving only the
* exponent and sign bit (which itself may be zero, if the absolute value
* was taken before the bitcast and shift.
*/
nir_ssa_def *exponent_shift = nir_imm_int(b, 23);
nir_ssa_def *exponent_bias = nir_imm_int(b, -126);
nir_ssa_def *sign_mantissa_mask = nir_imm_int(b, 0x807fffffu);
/* Exponent of floating-point values in the range [0.5, 1.0). */
nir_ssa_def *exponent_value = nir_imm_int(b, 0x3f000000u);
nir_ssa_def *is_not_zero = nir_fne(b, abs_x, zero);
*exponent =
nir_iadd(b, nir_ushr(b, abs_x, exponent_shift),
nir_bcsel(b, is_not_zero, exponent_bias, zero));
return nir_ior(b, nir_iand(b, x, sign_mantissa_mask),
nir_bcsel(b, is_not_zero, exponent_value, zero));
}
static void
handle_glsl450_alu(struct vtn_builder *b, enum GLSLstd450 entrypoint,
const uint32_t *w, unsigned count)
@ -569,8 +602,15 @@ handle_glsl450_alu(struct vtn_builder *b, enum GLSLstd450 entrypoint,
val->ssa->def = build_atan2(nb, src[0], src[1]);
return;
case GLSLstd450Frexp: {
nir_ssa_def *exponent;
val->ssa->def = build_frexp(nb, src[0], &exponent);
nir_deref_var *out = vtn_value(b, w[6], vtn_value_type_deref)->deref;
nir_store_deref_var(nb, out, exponent, 0xf);
return;
}
case GLSLstd450ModfStruct:
case GLSLstd450Frexp:
case GLSLstd450FrexpStruct:
case GLSLstd450PackDouble2x32:
case GLSLstd450UnpackDouble2x32: