On 26/07/18 14:04, Timothy Arceri wrote:
On 23/07/18 18:02, Timothy Arceri wrote:
Since we know what side of the branch we ended up on we can just
replace the use with a constant.
All the spill changes in shader-db are from Dolphin uber shaders,
despite some small regressions the change is clearly positive.
shader-db results IVB:
total instructions in shared programs: 9999201 -> 9993483 (-0.06%)
instructions in affected programs: 163235 -> 157517 (-3.50%)
helped: 132
HURT: 2
total cycles in shared programs: 231670754 -> 219476091 (-5.26%)
cycles in affected programs: 143424120 -> 131229457 (-8.50%)
helped: 115
HURT: 24
total spills in shared programs: 4383 -> 4370 (-0.30%)
spills in affected programs: 1656 -> 1643 (-0.79%)
helped: 9
HURT: 18
total fills in shared programs: 4610 -> 4581 (-0.63%)
fills in affected programs: 374 -> 345 (-7.75%)
helped: 6
HURT: 0
---
src/compiler/nir/nir_opt_if.c | 124 ++++++++++++++++++++++++++++++++++
1 file changed, 124 insertions(+)
diff --git a/src/compiler/nir/nir_opt_if.c
b/src/compiler/nir/nir_opt_if.c
index b3d0bf1decb..b3d5046a76e 100644
--- a/src/compiler/nir/nir_opt_if.c
+++ b/src/compiler/nir/nir_opt_if.c
@@ -369,6 +369,87 @@ opt_if_loop_terminator(nir_if *nif)
return true;
}
+static void
+replace_if_condition_use_with_const(nir_src *use, unsigned nir_boolean,
+ void *mem_ctx, bool if_condition)
+{
+ /* Create const */
+ nir_load_const_instr *load = nir_load_const_instr_create(mem_ctx,
1, 32);
+ load->value.u32[0] = nir_boolean;
+
+ if (if_condition) {
+ nir_instr_insert_before_cf(&use->parent_if->cf_node,
&load->instr);
+ } else if (use->parent_instr->type == nir_instr_type_phi) {
+ nir_phi_instr *cond_phi = nir_instr_as_phi(use->parent_instr);
+
+ bool UNUSED found = false;
+ nir_foreach_phi_src(phi_src, cond_phi) {
+ if (phi_src->src.ssa == use->ssa) {
+ nir_instr_insert_before_block(phi_src->pred, &load->instr);
I've just noticed this needs to be nir_instr_insert_after_block()
otherwise we can end up inserting the const before so other phi which
trips up validation.
I've fixed this locally.
Ok we can't do that either because the last instruction in the block can
be a jump. So I've reworked this to insert the const after the last phi.
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