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authorAlyssa Rosenzweig <alyssa.rosenzweig@collabora.com>2020-05-21 15:49:30 -0400
committerAlyssa Rosenzweig <alyssa.rosenzweig@collabora.com>2020-05-21 15:49:47 -0400
commit1085f74239f2b81e4e17ece4b9b7a805ee8dd250 (patch)
treec15ac6ee8aed012d2c6127612b0955e9fdf5458f
parent3e4e849e6a9633702e26ee16b4a594361e42013f (diff)
panfrost: Avoid redundant shader executions with mask=0x0
Only works for a few Midgard GPUs, but hey. Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5124>
-rw-r--r--src/gallium/drivers/panfrost/pan_assemble.c8
-rw-r--r--src/gallium/drivers/panfrost/pan_cmdstream.c36
-rw-r--r--src/gallium/drivers/panfrost/pan_context.h4
-rw-r--r--src/panfrost/include/panfrost-quirks.h7
4 files changed, 54 insertions, 1 deletions
diff --git a/src/gallium/drivers/panfrost/pan_assemble.c b/src/gallium/drivers/panfrost/pan_assemble.c
index 53bf9caaafc..f804e2beb13 100644
--- a/src/gallium/drivers/panfrost/pan_assemble.c
+++ b/src/gallium/drivers/panfrost/pan_assemble.c
@@ -196,6 +196,14 @@ panfrost_shader_compile(struct panfrost_context *ctx,
state->writes_depth = true;
if (s->info.outputs_written & BITFIELD64_BIT(FRAG_RESULT_STENCIL))
state->writes_stencil = true;
+
+ /* List of reasons we need to execute frag shaders when things
+ * are masked off */
+
+ state->fs_sidefx =
+ s->info.writes_memory ||
+ s->info.fs.uses_discard ||
+ s->info.fs.uses_demote;
break;
case MESA_SHADER_COMPUTE:
/* TODO: images */
diff --git a/src/gallium/drivers/panfrost/pan_cmdstream.c b/src/gallium/drivers/panfrost/pan_cmdstream.c
index caf01663a48..59a1799bc86 100644
--- a/src/gallium/drivers/panfrost/pan_cmdstream.c
+++ b/src/gallium/drivers/panfrost/pan_cmdstream.c
@@ -620,6 +620,27 @@ panfrost_frag_meta_zsa_update(struct panfrost_context *ctx,
fragmeta->unknown2_3 |= MALI_DEPTH_FUNC(panfrost_translate_compare_func(zfunc));
}
+static bool
+panfrost_fs_required(
+ struct panfrost_shader_state *fs,
+ struct panfrost_blend_final *blend,
+ unsigned rt_count)
+{
+ /* If we generally have side effects */
+ if (fs->fs_sidefx)
+ return true;
+
+ /* If colour is written we need to execute */
+ for (unsigned i = 0; i < rt_count; ++i) {
+ if (!blend[i].no_colour)
+ return true;
+ }
+
+ /* If depth is written and not implied we need to execute.
+ * TODO: Predicate on Z/S writes being enabled */
+ return (fs->writes_depth || fs->writes_stencil);
+}
+
static void
panfrost_frag_meta_blend_update(struct panfrost_context *ctx,
struct mali_shader_meta *fragmeta,
@@ -642,6 +663,21 @@ panfrost_frag_meta_blend_update(struct panfrost_context *ctx,
blend[c] = panfrost_get_blend_for_context(ctx, c, &shader_bo,
&shader_offset);
+ /* Disable shader execution if we can */
+ if (dev->quirks & MIDGARD_SHADERLESS
+ && !panfrost_fs_required(fs, blend, rt_count)) {
+ fragmeta->shader = 0;
+ fragmeta->attribute_count = 0;
+ fragmeta->varying_count = 0;
+ fragmeta->texture_count = 0;
+ fragmeta->sampler_count = 0;
+
+ /* This feature is not known to work on Bifrost */
+ fragmeta->midgard1.work_count = 1;
+ fragmeta->midgard1.uniform_count = 0;
+ fragmeta->midgard1.uniform_buffer_count = 0;
+ }
+
/* If there is a blend shader, work registers are shared. We impose 8
* work registers as a limit for blend shaders. Should be lower XXX */
diff --git a/src/gallium/drivers/panfrost/pan_context.h b/src/gallium/drivers/panfrost/pan_context.h
index c0a6d5fa1d6..a4ea44a96b9 100644
--- a/src/gallium/drivers/panfrost/pan_context.h
+++ b/src/gallium/drivers/panfrost/pan_context.h
@@ -195,6 +195,10 @@ struct panfrost_shader_state {
unsigned stack_size;
unsigned shared_size;
+ /* Does the fragment shader have side effects? In particular, if output
+ * is masked out, is it legal to skip shader execution? */
+ bool fs_sidefx;
+
/* For Bifrost - output type for each RT */
enum bifrost_shader_type blend_types[BIFROST_MAX_RENDER_TARGET_COUNT];
diff --git a/src/panfrost/include/panfrost-quirks.h b/src/panfrost/include/panfrost-quirks.h
index e45191fe11a..1d2ca775e45 100644
--- a/src/panfrost/include/panfrost-quirks.h
+++ b/src/panfrost/include/panfrost-quirks.h
@@ -50,6 +50,11 @@
/* What it says on the tin */
#define HAS_SWIZZLES (1 << 4)
+/* Support for setting shader to NULL for masking out colour (while allowing
+ * Z/S updates to proceed) */
+
+#define MIDGARD_SHADERLESS (1 << 5)
+
/* Quirk collections common to particular uarchs */
#define MIDGARD_QUIRKS (MIDGARD_BROKEN_FP16 | HAS_SWIZZLES)
@@ -74,7 +79,7 @@ panfrost_get_quirks(unsigned gpu_id)
case 0x750:
case 0x860:
case 0x880:
- return MIDGARD_QUIRKS;
+ return MIDGARD_QUIRKS | MIDGARD_SHADERLESS;
case 0x6000: /* G71 */
return BIFROST_QUIRKS | HAS_SWIZZLES;