diff options
Diffstat (limited to 'src/compiler')
| -rw-r--r-- | src/compiler/nir/nir_lower_flrp.c | 57 |
1 files changed, 56 insertions, 1 deletions
diff --git a/src/compiler/nir/nir_lower_flrp.c b/src/compiler/nir/nir_lower_flrp.c index 0b32daf1dd2..5094a714504 100644 --- a/src/compiler/nir/nir_lower_flrp.c +++ b/src/compiler/nir/nir_lower_flrp.c @@ -70,6 +70,39 @@ replace_with_strict_ffma(struct nir_builder *bld, struct u_vector *dead_flrp, } /** + * Replace flrp(a, b, c) with ffma(a, (1 - c), bc) + */ +static void +replace_with_single_ffma(struct nir_builder *bld, struct u_vector *dead_flrp, + struct nir_alu_instr *alu) +{ + nir_ssa_def *const a = nir_ssa_for_alu_src(bld, alu, 0); + nir_ssa_def *const b = nir_ssa_for_alu_src(bld, alu, 1); + nir_ssa_def *const c = nir_ssa_for_alu_src(bld, alu, 2); + + nir_ssa_def *const neg_c = nir_fneg(bld, c); + nir_instr_as_alu(neg_c->parent_instr)->exact = alu->exact; + + nir_ssa_def *const one_minus_c = + nir_fadd(bld, nir_imm_float(bld, 1.0f), neg_c); + nir_instr_as_alu(one_minus_c->parent_instr)->exact = alu->exact; + + nir_ssa_def *const b_times_c = nir_fmul(bld, b, c); + nir_instr_as_alu(b_times_c->parent_instr)->exact = alu->exact; + + nir_ssa_def *const final_ffma = nir_ffma(bld, a, one_minus_c, b_times_c); + nir_instr_as_alu(final_ffma->parent_instr)->exact = alu->exact; + + nir_ssa_def_rewrite_uses(&alu->dest.dest.ssa, nir_src_for_ssa(final_ffma)); + + /* DO NOT REMOVE the original flrp yet. Many of the lowering choices are + * based on other uses of the sources. Removing the flrp may cause the + * last flrp in a sequence to make a different, incorrect choice. + */ + append_flrp_to_dead_list(dead_flrp, alu); +} + +/** * Replace flrp(a, b, c) with a(1-c) + bc. */ static void @@ -476,6 +509,20 @@ convert_flrp_instruction(nir_builder *bld, replace_with_strict_ffma(bld, dead_flrp, alu); return; } + + /* + * - If FMA is supported and another flrp(_, y, t) exists: + * + * fma(x, (1 - t), yt) + * + * The hope is that the (1 - t) and the yt will be shared with the + * other lowered flrp. This results in 3 insructions for the first + * flrp and 1 for each additional flrp. + */ + if (st.src1_and_src2 > 0) { + replace_with_single_ffma(bld, dead_flrp, alu); + return; + } } else { if (always_precise) { replace_with_strict(bld, dead_flrp, alu); @@ -490,11 +537,19 @@ convert_flrp_instruction(nir_builder *bld, * 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. + * + * - If FMA is not supported and another flrp(_, y, t) exists: + * + * x(1 - t) + yt + * + * The hope is that the (1 - t) and the yt 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) { + if (st.src0_and_src2 > 0 || st.src1_and_src2 > 0) { replace_with_strict(bld, dead_flrp, alu); return; } |