diff options
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_nir_opt_peephole_ffma.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_nir_opt_peephole_ffma.c b/src/mesa/drivers/dri/i965/brw_nir_opt_peephole_ffma.c index a8448e73a3f..5603129bde7 100644 --- a/src/mesa/drivers/dri/i965/brw_nir_opt_peephole_ffma.c +++ b/src/mesa/drivers/dri/i965/brw_nir_opt_peephole_ffma.c @@ -133,6 +133,28 @@ get_mul_for_src(nir_alu_src *src, int num_components, return alu; } +/** + * Given a list of (at least two) nir_alu_src's, tells if any of them is a + * constant value and is used only once. + */ +static bool +any_alu_src_is_a_constant(nir_alu_src srcs[]) +{ + for (unsigned i = 0; i < 2; i++) { + if (srcs[i].src.ssa->parent_instr->type == nir_instr_type_load_const) { + nir_load_const_instr *load_const = + nir_instr_as_load_const (srcs[i].src.ssa->parent_instr); + + if (list_is_singular(&load_const->def.uses) && + list_empty(&load_const->def.if_uses)) { + return true; + } + } + } + + return false; +} + static bool brw_nir_opt_peephole_ffma_block(nir_block *block, void *void_state) { @@ -183,6 +205,15 @@ brw_nir_opt_peephole_ffma_block(nir_block *block, void *void_state) mul_src[0] = mul->src[0].src.ssa; mul_src[1] = mul->src[1].src.ssa; + /* If any of the operands of the fmul and any of the fadd is a constant, + * we bypass because it will be more efficient as the constants will be + * propagated as operands, potentially saving two load_const instructions. + */ + if (any_alu_src_is_a_constant(mul->src) && + any_alu_src_is_a_constant(add->src)) { + continue; + } + if (abs) { for (unsigned i = 0; i < 2; i++) { nir_alu_instr *abs = nir_alu_instr_create(state->mem_ctx, |