Mesa (master): freedreno/a6xx: add early-lrz-late-z mode

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Thu Jun 4 02:49:40 UTC 2020


Module: Mesa
Branch: master
Commit: 1e3731e7119c36b759ec9492a7c9ebf90b222122
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=1e3731e7119c36b759ec9492a7c9ebf90b222122

Author: Rob Clark <robdclark at chromium.org>
Date:   Wed Jun  3 10:08:55 2020 -0700

freedreno/a6xx: add early-lrz-late-z mode

Now that we are doing a better job of managing LRZ, add support for the
EARLY_LRZ_LATE_Z mode.  Since we properly disable LRZ write in cases
where we don't know a fragment's z value during the binning pass (or
when blend is enabled in a later draw, meaning we will need the earlier
fragment's color), we can enable a mode that keeps the early-lrz test
when the frag shader has kill/discard.  This will only discard geometry
that is definitely not visible.

This is a pretty big win for games/benchmarks that have a lot of frag
shaders with kill/discard.  More than 10% gain for gfxbench trex/mh and
40% gain for mh31.

Signed-off-by: Rob Clark <robdclark at chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5298>

---

 src/gallium/drivers/freedreno/a6xx/fd6_context.h |  3 ++
 src/gallium/drivers/freedreno/a6xx/fd6_emit.c    | 45 +++++++++++++++++++++---
 src/gallium/drivers/freedreno/a6xx/fd6_program.c | 14 --------
 3 files changed, 44 insertions(+), 18 deletions(-)

diff --git a/src/gallium/drivers/freedreno/a6xx/fd6_context.h b/src/gallium/drivers/freedreno/a6xx/fd6_context.h
index bb48ecea784..6a93011aee5 100644
--- a/src/gallium/drivers/freedreno/a6xx/fd6_context.h
+++ b/src/gallium/drivers/freedreno/a6xx/fd6_context.h
@@ -42,6 +42,9 @@ struct fd6_lrz_state {
 	bool write  : 1;
 	bool test   : 1;
 	enum fd_lrz_direction direction : 2;
+
+	/* this comes from the fs program state, rather than zsa: */
+	enum a6xx_ztest_mode z_mode : 2;
 };
 
 struct fd6_context {
diff --git a/src/gallium/drivers/freedreno/a6xx/fd6_emit.c b/src/gallium/drivers/freedreno/a6xx/fd6_emit.c
index bd30d69dd37..82bf24759a4 100644
--- a/src/gallium/drivers/freedreno/a6xx/fd6_emit.c
+++ b/src/gallium/drivers/freedreno/a6xx/fd6_emit.c
@@ -585,19 +585,41 @@ build_vbo_state(struct fd6_emit *emit, const struct ir3_shader_variant *vp)
 	return ring;
 }
 
+static enum a6xx_ztest_mode
+compute_ztest_mode(struct fd6_emit *emit, bool lrz_valid)
+{
+	const struct ir3_shader_variant *fs = emit->fs;
+
+	if (fs->no_earlyz || fs->writes_pos) {
+		return A6XX_LATE_Z;
+	} else if (fs->has_kill) {
+		return lrz_valid ? A6XX_EARLY_LRZ_LATE_Z : A6XX_LATE_Z;
+	} else {
+		return A6XX_EARLY_Z;
+	}
+}
+
 /**
  * Calculate normalized LRZ state based on zsa/prog/blend state, updating
  * the zsbuf's lrz state as necessary to detect the cases where we need
  * to invalidate lrz.
  */
 static struct fd6_lrz_state
-compute_lrz_state(struct fd6_emit *emit)
+compute_lrz_state(struct fd6_emit *emit, bool binning_pass)
 {
 	struct fd_context *ctx = emit->ctx;
 	struct pipe_framebuffer_state *pfb = &ctx->batch->framebuffer;
 	const struct ir3_shader_variant *fs = emit->fs;
 	struct fd6_lrz_state lrz;
 
+	if (!pfb->zsbuf) {
+		memset(&lrz, 0, sizeof(lrz));
+		if (!binning_pass) {
+			lrz.z_mode = compute_ztest_mode(emit, false);
+		}
+		return lrz;
+	}
+
 	struct fd6_blend_stateobj *blend = fd6_blend_stateobj(ctx->blend);
 	struct fd6_zsa_stateobj *zsa = fd6_zsa_stateobj(ctx->zsa);
 	struct fd_resource *rsc = fd_resource(pfb->zsbuf->texture);
@@ -607,6 +629,8 @@ compute_lrz_state(struct fd6_emit *emit)
 	/* normalize lrz state: */
 	if (blend->reads_dest || fs->writes_pos || fs->no_earlyz || fs->has_kill) {
 		lrz.write = false;
+		if (binning_pass)
+			lrz.enable = false;
 	}
 
 	/* if we change depthfunc direction, bail out on using LRZ.  The
@@ -631,6 +655,10 @@ compute_lrz_state(struct fd6_emit *emit)
 		lrz.test = false;
 	}
 
+	if (!binning_pass) {
+		lrz.z_mode = compute_ztest_mode(emit, rsc->lrz_valid);
+	}
+
 	/* Once we start writing to the real depth buffer, we lock in the
 	 * direction for LRZ.. if we have to skip a LRZ write for any
 	 * reason, it is still safe to have LRZ until there is a direction
@@ -653,7 +681,8 @@ build_lrz(struct fd6_emit *emit, bool binning_pass)
 {
 	struct fd_context *ctx = emit->ctx;
 	struct fd6_context *fd6_ctx = fd6_context(ctx);
-	struct fd6_lrz_state lrz = compute_lrz_state(emit);
+	struct fd6_lrz_state lrz =
+			compute_lrz_state(emit, binning_pass);
 
 	/* If the LRZ state has not changed, we can skip the emit: */
 	if (!ctx->last.dirty &&
@@ -663,7 +692,7 @@ build_lrz(struct fd6_emit *emit, bool binning_pass)
 	fd6_ctx->last.lrz[binning_pass] = lrz;
 
 	struct fd_ringbuffer *ring = fd_submit_new_ringbuffer(ctx->batch->submit,
-			4*4, FD_RINGBUFFER_STREAMING);
+			8*4, FD_RINGBUFFER_STREAMING);
 
 	OUT_REG(ring, A6XX_GRAS_LRZ_CNTL(
 			.enable        = lrz.enable,
@@ -675,6 +704,14 @@ build_lrz(struct fd6_emit *emit, bool binning_pass)
 			.enable = lrz.enable,
 		));
 
+	OUT_REG(ring, A6XX_RB_DEPTH_PLANE_CNTL(
+			.z_mode = lrz.z_mode,
+		));
+
+	OUT_REG(ring, A6XX_GRAS_SU_DEPTH_PLANE_CNTL(
+			.z_mode = lrz.z_mode,
+		));
+
 	return ring;
 }
 
@@ -789,7 +826,7 @@ fd6_emit_state(struct fd_ringbuffer *ring, struct fd6_emit *emit)
 			fd6_emit_add_group(emit, zsa->stateobj, FD6_GROUP_ZSA, ENABLE_ALL);
 	}
 
-	if ((dirty & (FD_DIRTY_ZSA | FD_DIRTY_BLEND | FD_DIRTY_PROG)) && pfb->zsbuf) {
+	if (dirty & (FD_DIRTY_ZSA | FD_DIRTY_BLEND | FD_DIRTY_PROG)) {
 		struct fd_ringbuffer *state;
 
 		state = build_lrz(emit, false);
diff --git a/src/gallium/drivers/freedreno/a6xx/fd6_program.c b/src/gallium/drivers/freedreno/a6xx/fd6_program.c
index dad117688af..4c0e14c2b88 100644
--- a/src/gallium/drivers/freedreno/a6xx/fd6_program.c
+++ b/src/gallium/drivers/freedreno/a6xx/fd6_program.c
@@ -835,20 +835,6 @@ setup_stateobj(struct fd_ringbuffer *ring, struct fd_screen *screen,
 	OUT_RING(ring,
 			 COND(primid_passthru, A6XX_VFD_CONTROL_6_PRIMID_PASSTHRU));   /* VFD_CONTROL_6 */
 
-	enum a6xx_ztest_mode zmode;
-
-	if (fs->no_earlyz || fs->has_kill || fs->writes_pos) {
-		zmode = A6XX_LATE_Z;
-	} else {
-		zmode = A6XX_EARLY_Z;
-	}
-
-	OUT_PKT4(ring, REG_A6XX_RB_DEPTH_PLANE_CNTL, 1);
-	OUT_RING(ring, A6XX_RB_DEPTH_PLANE_CNTL_Z_MODE(zmode));
-
-	OUT_PKT4(ring, REG_A6XX_GRAS_SU_DEPTH_PLANE_CNTL, 1);
-	OUT_RING(ring, A6XX_GRAS_SU_DEPTH_PLANE_CNTL_Z_MODE(zmode));
-
 	if (!binning_pass)
 		fd6_emit_immediates(screen, fs, ring);
 }



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