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nir/lower_clip: add a find_clipvertex_and_position_outputs() helper

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This will allow code sharing in a following patch that adds support
for lowering in geometry shaders. It also allows us to exit early
if there is no lowering to do which allows a small code tidy up.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Timothy Arceri 2019-06-28 10:10:28 +10:00
parent 0395b58c92
commit e38b930876
1 changed files with 35 additions and 24 deletions
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59
src/compiler/nir/nir_lower_clip.c
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@ -146,6 +146,35 @@ find_output(nir_shader *shader, unsigned drvloc)
return def;
}
static bool
find_clipvertex_and_position_outputs(nir_shader *shader,
nir_variable **clipvertex,
nir_variable **position)
{
nir_foreach_variable(var, &shader->outputs) {
switch (var->data.location) {
case VARYING_SLOT_POS:
*position = var;
break;
case VARYING_SLOT_CLIP_VERTEX:
*clipvertex = var;
break;
case VARYING_SLOT_CLIP_DIST0:
case VARYING_SLOT_CLIP_DIST1:
/* if shader is already writing CLIPDIST, then
* there should be no user-clip-planes to deal
* with.
*
* We assume nir_remove_dead_variables has removed the clipdist
* variables if they're not written.
*/
return false;
}
}
return *clipvertex || *position;
}
/*
* VS lowering
*/
@ -185,27 +214,9 @@ nir_lower_clip_vs(nir_shader *shader, unsigned ucp_enables, bool use_vars)
assert(impl->end_block->predecessors->entries == 1);
b.cursor = nir_after_cf_list(&impl->body);
/* find clipvertex/position outputs: */
nir_foreach_variable(var, &shader->outputs) {
switch (var->data.location) {
case VARYING_SLOT_POS:
position = var;
break;
case VARYING_SLOT_CLIP_VERTEX:
clipvertex = var;
break;
case VARYING_SLOT_CLIP_DIST0:
case VARYING_SLOT_CLIP_DIST1:
/* if shader is already writing CLIPDIST, then
* there should be no user-clip-planes to deal
* with.
*
* We assume nir_remove_dead_variables has removed the clipdist
* variables if they're not written.
*/
return false;
}
}
/* find clipvertex/position outputs */
if (!find_clipvertex_and_position_outputs(shader, &clipvertex, &position))
return false;
if (use_vars) {
cv = nir_load_var(&b, clipvertex ? clipvertex : position);
@ -218,10 +229,10 @@ nir_lower_clip_vs(nir_shader *shader, unsigned ucp_enables, bool use_vars)
} else {
if (clipvertex)
cv = find_output(shader, clipvertex->data.driver_location);
else if (position)
else {
assert(position);
cv = find_output(shader, position->data.driver_location);
else
return false;
}
}
/* insert CLIPDIST outputs: */