Mesa (main): nir,zink: Make lower_discard_if a common pass
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Fri Feb 4 19:57:49 UTC 2022
Module: Mesa
Branch: main
Commit: aaf00a1b4d9f21283d5e706647fd2d4f51a48331
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=aaf00a1b4d9f21283d5e706647fd2d4f51a48331
Author: Alyssa Rosenzweig <alyssa at rosenzweig.io>
Date: Tue Dec 14 15:59:45 2021 -0500
nir,zink: Make lower_discard_if a common pass
This pass (lowering discard_if to control flow and unconditional
discard) was originally written for Zink, but is useful for hardware
that lacks conditional discard instructions like AGX. In theory AGX
could implement a conditional discard with CSEL, but the vendor
compiler uses a lowering like this one. Since I like not writing code,
I'd like to use the pass that's already in tree.
v2: Don't preserve dominance (Jason). Assert we don't see demotes or
terminates (Jason). Add Mike's ack.
Signed-off-by: Alyssa Rosenzweig <alyssa at rosenzweig.io>
Acked-by: Mike Blumenkrantz <michael.blumenkrantz at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14217>
---
src/compiler/nir/meson.build | 1 +
src/compiler/nir/nir.h | 2 +
src/compiler/nir/nir_lower_discard_if.c | 103 +++++++++++++++++++++++++++++++
src/gallium/drivers/zink/zink_compiler.c | 75 +---------------------
4 files changed, 107 insertions(+), 74 deletions(-)
diff --git a/src/compiler/nir/meson.build b/src/compiler/nir/meson.build
index 40f148ba96a..5323e682637 100644
--- a/src/compiler/nir/meson.build
+++ b/src/compiler/nir/meson.build
@@ -143,6 +143,7 @@ files_libnir = files(
'nir_lower_clip_halfz.c',
'nir_lower_convert_alu_types.c',
'nir_lower_variable_initializers.c',
+ 'nir_lower_discard_if.c',
'nir_lower_discard_or_demote.c',
'nir_lower_double_ops.c',
'nir_lower_drawpixels.c',
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 91660a2f836..dc675939215 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -5137,6 +5137,8 @@ typedef enum {
bool nir_lower_interpolation(nir_shader *shader,
nir_lower_interpolation_options options);
+bool nir_lower_discard_if(nir_shader *shader);
+
bool nir_lower_discard_or_demote(nir_shader *shader,
bool force_correct_quad_ops_after_discard);
diff --git a/src/compiler/nir/nir_lower_discard_if.c b/src/compiler/nir/nir_lower_discard_if.c
new file mode 100644
index 00000000000..ac34ad45ae2
--- /dev/null
+++ b/src/compiler/nir/nir_lower_discard_if.c
@@ -0,0 +1,103 @@
+/*
+ * 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_, UNUSED void *cb_data)
+{
+ if (instr_->type != nir_instr_type_intrinsic)
+ return false;
+
+ nir_intrinsic_instr *instr = nir_instr_as_intrinsic(instr_);
+
+ if (instr->intrinsic == nir_intrinsic_discard_if) {
+ b->cursor = nir_before_instr(&instr->instr);
+
+ nir_if *if_stmt = nir_push_if(b, nir_ssa_for_src(b, instr->src[0], 1));
+ nir_discard(b);
+ nir_pop_if(b, if_stmt);
+ nir_instr_remove(&instr->instr);
+ return true;
+ } else if (instr->intrinsic == nir_intrinsic_terminate_if ||
+ instr->intrinsic == nir_intrinsic_demote_if) {
+ unreachable("todo: handle terminates and demotes for Vulkan");
+ }
+
+ /* a shader like this (shaders at 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)
+{
+ return nir_shader_instructions_pass(shader,
+ lower_discard_if_instr,
+ nir_metadata_none,
+ NULL);
+}
diff --git a/src/gallium/drivers/zink/zink_compiler.c b/src/gallium/drivers/zink/zink_compiler.c
index d677bfc79e6..6fb257697dd 100644
--- a/src/gallium/drivers/zink/zink_compiler.c
+++ b/src/gallium/drivers/zink/zink_compiler.c
@@ -75,79 +75,6 @@ reads_work_dim(nir_shader *shader)
return BITSET_TEST(shader->info.system_values_read, SYSTEM_VALUE_WORK_DIM);
}
-static bool
-lower_discard_if_instr(nir_builder *b, nir_instr *instr_, UNUSED void *cb_data)
-{
- if (instr_->type != nir_instr_type_intrinsic)
- return false;
-
- nir_intrinsic_instr *instr = nir_instr_as_intrinsic(instr_);
-
- if (instr->intrinsic == nir_intrinsic_discard_if) {
- b->cursor = nir_before_instr(&instr->instr);
-
- nir_if *if_stmt = nir_push_if(b, nir_ssa_for_src(b, instr->src[0], 1));
- nir_discard(b);
- nir_pop_if(b, if_stmt);
- nir_instr_remove(&instr->instr);
- return true;
- }
- /* a shader like this (shaders at 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 post-vtn optimizing will dce the instructions following the discard
- */
-
- return false;
-}
-
-static bool
-lower_discard_if(nir_shader *shader)
-{
- return nir_shader_instructions_pass(shader,
- lower_discard_if_instr,
- nir_metadata_dominance,
- NULL);
-}
-
static bool
lower_work_dim_instr(nir_builder *b, nir_instr *in, void *data)
{
@@ -1858,7 +1785,7 @@ zink_shader_create(struct zink_screen *screen, struct nir_shader *nir,
optimize_nir(nir);
NIR_PASS_V(nir, nir_remove_dead_variables, nir_var_function_temp, NULL);
- NIR_PASS_V(nir, lower_discard_if);
+ NIR_PASS_V(nir, nir_lower_discard_if);
NIR_PASS_V(nir, nir_lower_fragcolor,
nir->info.fs.color_is_dual_source ? 1 : 8);
NIR_PASS_V(nir, lower_64bit_vertex_attribs);
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