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aco: implement some exclusive scans with inclusive scans

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exclusive scan lowering uses full wave shift, for iadd/ixor it's faster
to do inclusive scans and subtract/xor the thread's source.

Foz-DB Navi21:
Totals from 21 (0.02% of 132657) affected shaders:
Instrs: 10925 -> 10727 (-1.81%)
CodeSize: 58064 -> 56488 (-2.71%)
Latency: 178471 -> 177928 (-0.30%)
InvThroughput: 24374 -> 24145 (-0.94%)

Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24555>
This commit is contained in:
Georg Lehmann 2023-08-08 13:35:18 +02:00 • committed by Marge Bot
parent f90f68aa1c
commit 2ae94b3894
1 changed files with 47 additions and 0 deletions
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47
src/amd/compiler/aco_instruction_selection.cpp
View file

@ -7916,6 +7916,42 @@ emit_reduction_instr(isel_context* ctx, aco_opcode aco_op, ReduceOp op, unsigned
return dst.getTemp();
}
Temp
inclusive_scan_to_exclusive(isel_context* ctx, ReduceOp op, Temp scan, Temp src)
{
Builder bld(ctx->program, ctx->block);
switch (op) {
case iadd8:
case iadd16:
case iadd32: return bld.vsub32(bld.def(scan.regClass()), scan, src);
case ixor64:
case iadd64: {
Temp src00 = bld.tmp(v1);
Temp src01 = bld.tmp(v1);
bld.pseudo(aco_opcode::p_split_vector, Definition(src00), Definition(src01), scan);
Temp src10 = bld.tmp(v1);
Temp src11 = bld.tmp(v1);
bld.pseudo(aco_opcode::p_split_vector, Definition(src10), Definition(src11), src);
Temp lower = bld.tmp(v1);
Temp upper = bld.tmp(v1);
if (op == iadd64) {
Temp borrow = bld.vsub32(Definition(lower), src00, src10, true).def(1).getTemp();
bld.vsub32(Definition(upper), src01, src11, false, borrow);
} else {
bld.vop2(aco_opcode::v_xor_b32, Definition(lower), src00, src10);
bld.vop2(aco_opcode::v_xor_b32, Definition(upper), src01, src11);
}
return bld.pseudo(aco_opcode::p_create_vector, bld.def(v2), lower, upper);
}
case ixor8:
case ixor16:
case ixor32: return bld.vop2(aco_opcode::v_xor_b32, bld.def(scan.regClass()), scan, src);
default: unreachable("Unsupported op");
}
}
void
emit_interp_center(isel_context* ctx, Temp dst, Temp bary, Temp pos1, Temp pos2)
{
@ -8453,8 +8489,19 @@ visit_intrinsic(isel_context* ctx, nir_intrinsic_instr* instr)
default: unreachable("unknown reduce intrinsic");
}
/* Avoid whole wave shift. */
const bool use_inclusive_for_exclusive = aco_op == aco_opcode::p_exclusive_scan &&
(op == nir_op_iadd || op == nir_op_ixor) &&
dst.type() == RegType::vgpr;
if (use_inclusive_for_exclusive)
aco_op = aco_opcode::p_inclusive_scan;
Temp tmp_dst = emit_reduction_instr(ctx, aco_op, reduce_op, cluster_size,
bld.def(dst.regClass()), src);
if (use_inclusive_for_exclusive)
tmp_dst = inclusive_scan_to_exclusive(ctx, reduce_op, tmp_dst, src);
emit_wqm(bld, tmp_dst, dst, create_helpers);
}
break;