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intel/brw: Algebraic optimizations for CSEL 

No shader-db or fossil-db changes on any Intel platform. In this MR, the
only benefit of these changes is to convert some "-a > 0" CSEL
comparisons to "a < 0" for improved readability.

v2: Add integer CSEL support

v3: Use fs_inst::resize_sources and brw_type_is_sint. Both suggested by
Ken.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29095>
This commit is contained in:
Ian Romanick 2024-04-05 10:16:40 -07:00 committed by Marge Bot
parent 033405cd4b
commit 864268ff0d
1 changed files with 81 additions and 0 deletions
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81
src/intel/compiler/brw_fs_opt_algebraic.cpp
View File

@ -290,6 +290,87 @@ brw_fs_opt_algebraic(fs_visitor &s)
}
}
break;
case BRW_OPCODE_CSEL:
if (brw_type_is_float(inst->dst.type)) {
/* This transformation can both clean up spurious modifiers
* (making assembly dumps easier to read) and convert GE with -abs
* to LE with abs. See abs handling below.
*/
if (inst->src[2].negate) {
inst->conditional_mod = brw_swap_cmod(inst->conditional_mod);
inst->src[2].negate = false;
progress = true;
}
if (inst->src[2].abs) {
switch (inst->conditional_mod) {
case BRW_CONDITIONAL_Z:
case BRW_CONDITIONAL_NZ:
inst->src[2].abs = false;
progress = true;
break;
case BRW_CONDITIONAL_LE:
/* Converting to Z can help constant propagation into src0
* and src1.
*/
inst->conditional_mod = BRW_CONDITIONAL_Z;
inst->src[2].abs = false;
progress = true;
break;
default:
/* GE or L conditions with absolute value could be used to
* implement isnan(x) in CSEL. Transforming G with absolute
* value to NZ is **not** NaN safe.
*/
break;
}
}
} else if (brw_type_is_sint(inst->src[2].type)) {
/* Integer transformations are more challenging than floating
* point transformations due to INT_MIN == -(INT_MIN) ==
* abs(INT_MIN).
*/
if (inst->src[2].negate && inst->src[2].abs) {
switch (inst->conditional_mod) {
case BRW_CONDITIONAL_GE:
inst->src[2].negate = false;
inst->src[2].abs = false;
inst->conditional_mod = BRW_CONDITIONAL_Z;
progress = true;
break;
case BRW_CONDITIONAL_L:
inst->src[2].negate = false;
inst->src[2].abs = false;
inst->conditional_mod = BRW_CONDITIONAL_NZ;
progress = true;
break;
case BRW_CONDITIONAL_G:
/* This is a contradtion. -abs(x) cannot be > 0. */
inst->opcode = BRW_OPCODE_MOV;
inst->src[0] = inst->src[1];
inst->resize_sources(1);
progress = true;
break;
case BRW_CONDITIONAL_LE:
/* This is a tautology. -abs(x) must be <= 0. */
inst->opcode = BRW_OPCODE_MOV;
inst->resize_sources(1);
progress = true;
break;
case BRW_CONDITIONAL_Z:
case BRW_CONDITIONAL_NZ:
inst->src[2].negate = false;
inst->src[2].abs = false;
progress = true;
break;
default:
unreachable("Impossible icsel condition.");
}
}
}
break;
case BRW_OPCODE_MAD:
if (inst->src[0].type != BRW_TYPE_F ||
inst->src[1].type != BRW_TYPE_F ||