diff options
| -rw-r--r-- | src/compiler/nir/nir_lower_flrp.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/src/compiler/nir/nir_lower_flrp.c b/src/compiler/nir/nir_lower_flrp.c index c041fefc52b..0b32daf1dd2 100644 --- a/src/compiler/nir/nir_lower_flrp.c +++ b/src/compiler/nir/nir_lower_flrp.c @@ -272,6 +272,59 @@ sources_are_constants_with_similar_magnitudes(const nir_alu_instr *instr) return true; } +/** + * Counts of similar types of nir_op_flrp instructions + * + * If a similar instruction fits into more than one category, it will only be + * counted once. The assumption is that no other instruction will have all + * sources the same, or CSE would have removed one of the instructions. + */ +struct similar_flrp_stats { + unsigned src2; + unsigned src0_and_src2; + unsigned src1_and_src2; +}; + +/** + * Collection counts of similar FLRP instructions. + * + * This function only cares about similar instructions that have src2 in + * common. + */ +static void +get_similar_flrp_stats(nir_alu_instr *alu, struct similar_flrp_stats *st) +{ + memset(st, 0, sizeof(*st)); + + nir_foreach_use(other_use, alu->src[2].src.ssa) { + /* Is the use also a flrp? */ + nir_instr *const other_instr = other_use->parent_instr; + if (other_instr->type != nir_instr_type_alu) + continue; + + /* Eh-hem... don't match the instruction with itself. */ + if (other_instr == &alu->instr) + continue; + + nir_alu_instr *const other_alu = nir_instr_as_alu(other_instr); + if (other_alu->op != nir_op_flrp) + continue; + + /* Does the other flrp use source 2 from the first flrp as its source 2 + * as well? + */ + if (!nir_alu_srcs_equal(alu, other_alu, 2, 2)) + continue; + + if (nir_alu_srcs_equal(alu, other_alu, 0, 0)) + st->src0_and_src2++; + else if (nir_alu_srcs_equal(alu, other_alu, 1, 1)) + st->src1_and_src2++; + else + st->src2++; + } +} + static void convert_flrp_instruction(nir_builder *bld, struct u_vector *dead_flrp, @@ -404,11 +457,47 @@ convert_flrp_instruction(nir_builder *bld, replace_with_strict_ffma(bld, dead_flrp, alu); return; } + + /* + * - If FMA is supported and other flrp(x, _, t) exists: + * + * fma(y, t, fma(-x, t, x)) + * + * The hope is that the inner FMA calculation will be shared with the + * other lowered flrp. This results in two FMA instructions for the + * first flrp and one FMA instruction for each additional flrp. It + * also means that the live range for x might be complete after the + * inner ffma instead of after the last flrp. + */ + struct similar_flrp_stats st; + + get_similar_flrp_stats(alu, &st); + if (st.src0_and_src2 > 0) { + replace_with_strict_ffma(bld, dead_flrp, alu); + return; + } } else { if (always_precise) { replace_with_strict(bld, dead_flrp, alu); return; } + + /* + * - If FMA is not supported and another flrp(x, _, t) exists: + * + * x(1 - t) + yt + * + * The hope is that the x(1 - t) will be shared with the other lowered + * flrp. This results in 4 insructions for the first flrp and 2 for + * each additional flrp. + */ + struct similar_flrp_stats st; + + get_similar_flrp_stats(alu, &st); + if (st.src0_and_src2 > 0) { + replace_with_strict(bld, dead_flrp, alu); + return; + } } /* |