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spirv: Accept doubles in FaceForward, Reflect and Refract

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The SPIR-V spec doesn’t specify a size requirement for these and the
equivalent functions in the GLSL spec have explicit alternatives for
doubles. Refract is a little bit more complicated due to the fact that
the final argument is always supposed to be a scalar 32- or 16- bit
float regardless of the other operands. However in practice it seems
there is a bug in glslang that makes it convert the argument to 64-bit
if you actually try to pass it a 32-bit value while the other
arguments are 64-bit. This adds an optional conversion of the final
argument in order to support any type.

These have been tested against the automatically generated tests of
glsl-4.00/execution/built-in-functions using the ARB_gl_spirv branch
which tests it with quite a large range of combinations.

The issue with glslang has been filed here:
https://github.com/KhronosGroup/glslang/issues/1279

v2: Convert the eta operand of Refract from any size in order to make
    it eventually cope with 16-bit floats.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
This commit is contained in:
Neil Roberts
2018-03-21 20:34:40 +01:00
parent 6e499572b9
commit 608d70bc02
1 changed files with 18 additions and 4 deletions
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src/compiler/spirv/vtn_glsl450.c
+18 -4
View File
@@ -629,14 +629,14 @@ handle_glsl450_alu(struct vtn_builder *b, enum GLSLstd450 entrypoint,
case GLSLstd450FaceForward:
val->ssa->def =
nir_bcsel(nb, nir_flt(nb, nir_fdot(nb, src[2], src[1]),
nir_imm_float(nb, 0.0)),
NIR_IMM_FP(nb, 0.0)),
src[0], nir_fneg(nb, src[0]));
return;
case GLSLstd450Reflect:
/* I - 2 * dot(N, I) * N */
val->ssa->def =
nir_fsub(nb, src[0], nir_fmul(nb, nir_imm_float(nb, 2.0),
nir_fsub(nb, src[0], nir_fmul(nb, NIR_IMM_FP(nb, 2.0),
nir_fmul(nb, nir_fdot(nb, src[0], src[1]),
src[1])));
return;
@@ -646,8 +646,22 @@ handle_glsl450_alu(struct vtn_builder *b, enum GLSLstd450 entrypoint,
nir_ssa_def *N = src[1];
nir_ssa_def *eta = src[2];
nir_ssa_def *n_dot_i = nir_fdot(nb, N, I);
nir_ssa_def *one = nir_imm_float(nb, 1.0);
nir_ssa_def *zero = nir_imm_float(nb, 0.0);
nir_ssa_def *one = NIR_IMM_FP(nb, 1.0);
nir_ssa_def *zero = NIR_IMM_FP(nb, 0.0);
/* According to the SPIR-V and GLSL specs, eta is always a float
* regardless of the type of the other operands. However in practice it
* seems that if you try to pass it a float then glslang will just
* promote it to a double and generate invalid SPIR-V. In order to
* support a hypothetical fixed version of glslang we’ll promote eta to
* double if the other operands are double also.
*/
if (I->bit_size != eta->bit_size) {
nir_op conversion_op =
nir_type_conversion_op(nir_type_float | eta->bit_size,
nir_type_float | I->bit_size,
nir_rounding_mode_undef);
eta = nir_build_alu(nb, conversion_op, eta, NULL, NULL, NULL);
}
/* k = 1.0 - eta * eta * (1.0 - dot(N, I) * dot(N, I)) */
nir_ssa_def *k =
nir_fsub(nb, one, nir_fmul(nb, eta, nir_fmul(nb, eta,