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spirv: Generate shorter code for SpvOpFUnord comparisons 

No shader-db or fossil-db changes on any Intel platform.

v2: Keep the flt <-> fge switcharoo local to the SpvOpFUnordLessThan,
etc. handling.  Add a comment explaining why the suboptimal
SpvOpFUnordEqual implementation is used here.  Suggested by Caio.

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12320>
This commit is contained in:
Ian Romanick 2021-03-11 09:46:07 -08:00 committed by Marge Bot
parent 1ce48ce91d
commit 0cf25f559f
1 changed files with 32 additions and 6 deletions
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38
src/compiler/spirv/vtn_alu.c
View File

@ -600,7 +600,29 @@ vtn_handle_alu(struct vtn_builder *b, SpvOp opcode,
break;
}
case SpvOpFUnordEqual:
case SpvOpFUnordEqual: {
const bool save_exact = b->nb.exact;
b->nb.exact = true;
/* This could also be implemented as !(a < b || b < a). If one or both
* of the source are numbers, later optimization passes can easily
* eliminate the isnan() checks. This may trim the sequence down to a
* single (a == b) operation. Otherwise, the optimizer can transform
* whatever is left to !(a < b || b < a). Since some applications will
* open-code this sequence, these optimizations are needed anyway.
*/
dest->def =
nir_ior(&b->nb,
nir_feq(&b->nb, src[0], src[1]),
nir_ior(&b->nb,
nir_fneu(&b->nb, src[0], src[0]),
nir_fneu(&b->nb, src[1], src[1])));
b->nb.exact = save_exact;
break;
}
case SpvOpFUnordLessThan:
case SpvOpFUnordGreaterThan:
case SpvOpFUnordLessThanEqual:
@ -623,12 +645,16 @@ vtn_handle_alu(struct vtn_builder *b, SpvOp opcode,
b->nb.exact = true;
/* Use the property FUnordLessThan(a, b) ≡ !FOrdGreaterThanEqual(a, b). */
switch (op) {
case nir_op_fge: op = nir_op_flt; break;
case nir_op_flt: op = nir_op_fge; break;
default: unreachable("Impossible opcode.");
}
dest->def =
nir_ior(&b->nb,
nir_build_alu(&b->nb, op, src[0], src[1], NULL, NULL),
nir_ior(&b->nb,
nir_fneu(&b->nb, src[0], src[0]),
nir_fneu(&b->nb, src[1], src[1])));
nir_inot(&b->nb,
nir_build_alu(&b->nb, op, src[0], src[1], NULL, NULL));
b->nb.exact = save_exact;
break;