The idea here is not that it gives register coalescing a little bit of a
helping hand. It doesn't actually fix the coalescing problems, but it
seems to help a good bit.
Shader-db results for vec4 programs on Haswell:
total instructions in shared programs: 1746280 -> 1683959 (-3.57%)
instructions in affected programs: 1259166 -> 1196845 (-4.95%)
helped: 11363
HURT: 148
v2 (Jason Ekstrand):
- Run nir_move_vec_src_uses_to_dest after going out of SSA
- New shader-db numbers
---
src/glsl/nir/nir_move_vec_src_uses_to_dest.c | 16 ++++++++++++----
src/mesa/drivers/dri/i965/brw_nir.c | 2 ++
2 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/src/glsl/nir/nir_move_vec_src_uses_to_dest.c
b/src/glsl/nir/nir_move_vec_src_uses_to_dest.c
index 6e248a2..4c9032d 100644
--- a/src/glsl/nir/nir_move_vec_src_uses_to_dest.c
+++ b/src/glsl/nir/nir_move_vec_src_uses_to_dest.c
@@ -79,17 +79,23 @@ move_vec_src_uses_to_dest_block(nir_block *block, void
*shader)
continue; /* The loop */
}
+ /* Can't handle non-SSA vec operations */
+ if (!vec->dest.dest.is_ssa)
+ continue;
+
/* Can't handle saturation */
if (vec->dest.saturate)
continue;
- assert(vec->dest.dest.is_ssa);
-
/* First, mark all of the sources we are going to consider for rewriting
* to the destination
*/
int srcs_remaining = 0;
for (unsigned i = 0; i < nir_op_infos[vec->op].num_inputs; i++) {
+ /* We can't rewrite a source if it's not in SSA form */
+ if (!vec->src[i].src.is_ssa)
+ continue;
+
/* We can't rewrite a source if it has modifiers */
if (vec->src[i].abs || vec->src[i].negate)
continue;
@@ -97,9 +103,11 @@ move_vec_src_uses_to_dest_block(nir_block *block, void
*shader)
srcs_remaining |= 1 << i;
}
- for (unsigned i; i = ffs(srcs_remaining) - 1, srcs_remaining;) {
- assert(vec->src[i].src.is_ssa);
+ /* We can't actually do anything with this instruction */
+ if (srcs_remaining == 0)
+ continue;
+ for (unsigned i; i = ffs(srcs_remaining) - 1, srcs_remaining;) {
int8_t swizzle[4] = { -1, -1, -1, -1 };
for (unsigned j = i; j < nir_op_infos[vec->op].num_inputs; j++) {
diff --git a/src/mesa/drivers/dri/i965/brw_nir.c
b/src/mesa/drivers/dri/i965/brw_nir.c
index f326b23..8568988 100644
--- a/src/mesa/drivers/dri/i965/brw_nir.c
+++ b/src/mesa/drivers/dri/i965/brw_nir.c
@@ -187,6 +187,8 @@ brw_create_nir(struct brw_context *brw,
nir_validate_shader(nir);
if (!is_scalar) {
+ nir_move_vec_src_uses_to_dest(nir);
+ nir_validate_shader(nir);
nir_lower_vec_to_movs(nir);
nir_validate_shader(nir);
}
--
2.5.0.400.gff86faf
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