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/*
* Copyright 2018 Collabora Ltd.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* on the rights to use, copy, modify, merge, publish, distribute, sub
* license, and/or sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
* THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
* USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "nir.h"
#include "compiler/nir/nir_builder.h"
static bool
lower_discard_if_instr(nir_builder *b, nir_instr *instr_, void *cb_data)
{
nir_lower_discard_if_options options = *(nir_lower_discard_if_options *)cb_data;
if (instr_->type != nir_instr_type_intrinsic)
return false;
nir_intrinsic_instr *instr = nir_instr_as_intrinsic(instr_);
switch (instr->intrinsic) {
case nir_intrinsic_discard_if:
if (!(options & nir_lower_discard_if_to_cf))
return false;
break;
case nir_intrinsic_demote_if:
if (!(options & nir_lower_demote_if_to_cf))
return false;
break;
case nir_intrinsic_terminate_if:
if (!(options & nir_lower_terminate_if_to_cf))
return false;
break;
default:
return false;
}
b->cursor = nir_before_instr(&instr->instr);
nir_if *if_stmt = nir_push_if(b, nir_ssa_for_src(b, instr->src[0], 1));
switch (instr->intrinsic) {
case nir_intrinsic_discard_if:
nir_discard(b);
break;
case nir_intrinsic_demote_if:
nir_demote(b);
break;
case nir_intrinsic_terminate_if:
nir_terminate(b);
break;
default:
unreachable("bad intrinsic");
}
nir_pop_if(b, if_stmt);
nir_instr_remove(&instr->instr);
return true;
/* a shader like this (shaders@glsl-fs-discard-04):
uniform int j, k;
void main()
{
for (int i = 0; i < j; i++) {
if (i > k)
continue;
discard;
}
gl_FragColor = vec4(0.0, 1.0, 0.0, 0.0);
}
will generate nir like:
loop {
//snip
if ssa_11 {
block block_5:
/ preds: block_4 /
vec1 32 ssa_17 = iadd ssa_50, ssa_31
/ succs: block_7 /
} else {
block block_6:
/ preds: block_4 /
intrinsic discard () () <-- not last instruction
vec1 32 ssa_23 = iadd ssa_50, ssa_31 <-- dead code loop itr increment
/ succs: block_7 /
}
//snip
}
which means that we can't assert like this:
assert(instr->intrinsic != nir_intrinsic_discard ||
nir_block_last_instr(instr->instr.block) == &instr->instr);
and it's unnecessary anyway since later optimizations will dce the
instructions following the discard
*/
return false;
}
bool
nir_lower_discard_if(nir_shader *shader, nir_lower_discard_if_options options)
{
return nir_shader_instructions_pass(shader,
lower_discard_if_instr,
nir_metadata_none,
&options);
}
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