AlexIndustrial/mesa
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

intel/fs: Use De Morgan's laws to avoid logical-not of a logic result on Gen8+

Browse Source 
Instead of emitting ~(a & b), emit (~a | ~b) since logical-not of
operands is free on Gen8+.

v2: Fix swizzles.  Fix types for cmod propagation.

v3: Simplify logic for inverting source of inot(ixor(a, b)).  Suggested
by Ken.

Skylake and Broadwell had similar results. (Skylake shown)
Skylake
total instructions in shared programs: 15185593 -> 15185583 (<.01%)
instructions in affected programs: 5673 -> 5663 (-0.18%)
helped: 12
HURT: 1
helped stats (abs) min: 1 max: 2 x̄: 1.17 x̃: 1
helped stats (rel) min: 0.30% max: 5.88% x̄: 1.50% x̃: 0.70%
HURT stats (abs)   min: 4 max: 4 x̄: 4.00 x̃: 4
HURT stats (rel)   min: 0.12% max: 0.12% x̄: 0.12% x̃: 0.12%
95% mean confidence interval for instructions value: -1.66 0.13
95% mean confidence interval for instructions %-change: -2.60% -0.15%
Inconclusive result (value mean confidence interval includes 0).

total cycles in shared programs: 370977726 -> 370964249 (<.01%)
cycles in affected programs: 869987 -> 856510 (-1.55%)
helped: 15
HURT: 2
helped stats (abs) min: 2 max: 6640 x̄: 902.20 x̃: 16
helped stats (rel) min: <.01% max: 4.92% x̄: 1.71% x̃: 1.53%
HURT stats (abs)   min: 14 max: 42 x̄: 28.00 x̃: 28
HURT stats (rel)   min: 1.08% max: 3.18% x̄: 2.13% x̃: 2.13%
95% mean confidence interval for cycles value: -1654.87 69.34
95% mean confidence interval for cycles %-change: -2.29% -0.23%
Inconclusive result (value mean confidence interval includes 0).

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Ian Romanick
2017-02-09 15:21:47 +00:00
parent 8eb36c9129
commit cb3e21cd19
1 changed files with 59 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/intel/compiler/brw_fs_nir.cpp
+59
View File
@@ -1155,6 +1155,65 @@ fs_visitor::nir_emit_alu(const fs_builder &bld, nir_alu_instr *instr)
case nir_op_inot:
if (devinfo->gen >= 8) {
nir_alu_instr *const inot_src_instr =
nir_src_as_alu_instr(&instr->src[0].src);
if (inot_src_instr != NULL &&
(inot_src_instr->op == nir_op_ior ||
inot_src_instr->op == nir_op_ixor ||
inot_src_instr->op == nir_op_iand) &&
!inot_src_instr->src[0].abs &&
!inot_src_instr->src[0].negate &&
!inot_src_instr->src[1].abs &&
!inot_src_instr->src[1].negate) {
/* The sources of the source logical instruction are now the
* sources of the instruction that will be generated.
*/
prepare_alu_destination_and_sources(bld, inot_src_instr, op, false);
resolve_inot_sources(bld, inot_src_instr, op);
/* Smash all of the sources and destination to be signed. This
* doesn't matter for the operation of the instruction, but cmod
* propagation fails on unsigned sources with negation (due to
* fs_inst::can_do_cmod returning false).
*/
result.type =
brw_type_for_nir_type(devinfo,
(nir_alu_type)(nir_type_int |
nir_dest_bit_size(instr->dest.dest)));
op[0].type =
brw_type_for_nir_type(devinfo,
(nir_alu_type)(nir_type_int |
nir_src_bit_size(inot_src_instr->src[0].src)));
op[1].type =
brw_type_for_nir_type(devinfo,
(nir_alu_type)(nir_type_int |
nir_src_bit_size(inot_src_instr->src[1].src)));
/* For XOR, only invert one of the sources. Arbitrarily choose
* the first source.
*/
op[0].negate = !op[0].negate;
if (inot_src_instr->op != nir_op_ixor)
op[1].negate = !op[1].negate;
switch (inot_src_instr->op) {
case nir_op_ior:
bld.AND(result, op[0], op[1]);
return;
case nir_op_iand:
bld.OR(result, op[0], op[1]);
return;
case nir_op_ixor:
bld.XOR(result, op[0], op[1]);
return;
default:
unreachable("impossible opcode");
}
}
op[0] = resolve_source_modifiers(op[0]);
}
bld.NOT(result, op[0]);