radv: implement out-of-order rasterization when it's safe on VI+

Disabled by default for now, it can be enabled with
RADV_PERFTEST=outoforder.

No CTS regressions on Polaris, and all Vulkan games I tested
look good as well.

Expect small performance improvements for applications where
out-of-order rasterization can be enabled by the driver.

Loosely based on RadeonSI.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>

src/amd/vulkan/radv_cmd_buffer.c

@@ -1171,10 +1171,24 @@ radv_emit_index_buffer(struct radv_cmd_buffer *cmd_buffer)
 
 void radv_set_db_count_control(struct radv_cmd_buffer *cmd_buffer)
 {
+	struct radv_pipeline *pipeline = cmd_buffer->state.pipeline;
+	uint32_t pa_sc_mode_cntl_1 =
+		pipeline ? pipeline->graphics.ms.pa_sc_mode_cntl_1 : 0;
 	uint32_t db_count_control;
 
 	if(!cmd_buffer->state.active_occlusion_queries) {
 		if (cmd_buffer->device->physical_device->rad_info.chip_class >= CIK) {
+			if (G_028A4C_OUT_OF_ORDER_PRIMITIVE_ENABLE(pa_sc_mode_cntl_1) &&
+			    pipeline->graphics.disable_out_of_order_rast_for_occlusion) {
+				/* Re-enable out-of-order rasterization if the
+				 * bound pipeline supports it and if it's has
+				 * been disabled before starting occlusion
+				 * queries.
+				 */
+				radeon_set_context_reg(cmd_buffer->cs,
+						       R_028A4C_PA_SC_MODE_CNTL_1,
+						       pa_sc_mode_cntl_1);
+			}
 			db_count_control = 0;
 		} else {
 			db_count_control = S_028004_ZPASS_INCREMENT_DISABLE(1);
@@ -1189,6 +1203,20 @@ void radv_set_db_count_control(struct radv_cmd_buffer *cmd_buffer)
 				S_028004_ZPASS_ENABLE(1) |
 				S_028004_SLICE_EVEN_ENABLE(1) |
 				S_028004_SLICE_ODD_ENABLE(1);
+
+			if (G_028A4C_OUT_OF_ORDER_PRIMITIVE_ENABLE(pa_sc_mode_cntl_1) &&
+			    pipeline->graphics.disable_out_of_order_rast_for_occlusion) {
+				/* If the bound pipeline has enabled
+				 * out-of-order rasterization, we should
+				 * disable it before starting occlusion
+				 * queries.
+				 */
+				pa_sc_mode_cntl_1 &= C_028A4C_OUT_OF_ORDER_PRIMITIVE_ENABLE;
+
+				radeon_set_context_reg(cmd_buffer->cs,
+						       R_028A4C_PA_SC_MODE_CNTL_1,
+						       pa_sc_mode_cntl_1);
+			}
 		} else {
 			db_count_control = S_028004_PERFECT_ZPASS_COUNTS(1) |
 				S_028004_SAMPLE_RATE(sample_rate);

src/amd/vulkan/radv_debug.h

@@ -50,6 +50,7 @@ enum {
 	RADV_PERFTEST_SISCHED        =   0x2,
 	RADV_PERFTEST_LOCAL_BOS      =   0x4,
 	RADV_PERFTEST_BINNING     =   0x8,
+	RADV_PERFTEST_OUT_OF_ORDER   =  0x10,
 };
 
 bool

src/amd/vulkan/radv_device.c

@@ -307,6 +307,12 @@ radv_physical_device_init(struct radv_physical_device *device,
 	device->has_scissor_bug = device->rad_info.family == CHIP_VEGA10 ||
 				  device->rad_info.family == CHIP_RAVEN;
 
+	/* Out-of-order primitive rasterization. */
+	device->has_out_of_order_rast = device->rad_info.chip_class >= VI &&
+					device->rad_info.max_se >= 2;
+	device->out_of_order_rast_allowed = device->has_out_of_order_rast &&
+					    (device->instance->perftest_flags & RADV_PERFTEST_OUT_OF_ORDER);
+
 	radv_physical_device_init_mem_types(device);
 	radv_fill_device_extension_table(device, &device->supported_extensions);
 
@@ -391,6 +397,7 @@ static const struct debug_control radv_perftest_options[] = {
 	{"sisched", RADV_PERFTEST_SISCHED},
 	{"localbos", RADV_PERFTEST_LOCAL_BOS},
 	{"binning", RADV_PERFTEST_BINNING},
+	{"outoforderrast", RADV_PERFTEST_OUT_OF_ORDER},
 	{NULL, 0}
 };
 

src/amd/vulkan/radv_extensions.py

@@ -95,7 +95,7 @@ EXTENSIONS = [
     Extension('VK_EXT_shader_viewport_index_layer',       1, True),
     Extension('VK_AMD_draw_indirect_count',               1, True),
     Extension('VK_AMD_gcn_shader',                        1, True),
-    Extension('VK_AMD_rasterization_order',               1, 'device->rad_info.chip_class >= VI && device->rad_info.max_se >= 2'),
+    Extension('VK_AMD_rasterization_order',               1, 'device->has_out_of_order_rast'),
     Extension('VK_AMD_shader_info',                       1, True),
     Extension('VK_AMD_shader_trinary_minmax',             1, True),
 ]

src/amd/vulkan/radv_pipeline.c

@@ -63,10 +63,25 @@ struct radv_blend_state {
 	uint32_t cb_shader_mask;
 	uint32_t db_alpha_to_mask;
 
+	uint32_t commutative_4bit;
+
 	bool single_cb_enable;
 	bool mrt0_is_dual_src;
 };
 
+struct radv_dsa_order_invariance {
+	/* Whether the final result in Z/S buffers is guaranteed to be
+	 * invariant under changes to the order in which fragments arrive.
+	 */
+	bool zs;
+
+	/* Whether the set of fragments that pass the combined Z/S test is
+	 * guaranteed to be invariant under changes to the order in which
+	 * fragments arrive.
+	 */
+	bool pass_set;
+};
+
 struct radv_tessellation_state {
 	uint32_t ls_hs_config;
 	unsigned num_patches;
@@ -530,6 +545,40 @@ radv_pipeline_compute_get_int_clamp(const VkGraphicsPipelineCreateInfo *pCreateI
 	}
 }
 
+static void
+radv_blend_check_commutativity(struct radv_blend_state *blend,
+			       VkBlendOp op, VkBlendFactor src,
+			       VkBlendFactor dst, unsigned chanmask)
+{
+	/* Src factor is allowed when it does not depend on Dst. */
+	static const uint32_t src_allowed =
+		(1u << VK_BLEND_FACTOR_ONE) |
+		(1u << VK_BLEND_FACTOR_SRC_COLOR) |
+		(1u << VK_BLEND_FACTOR_SRC_ALPHA) |
+		(1u << VK_BLEND_FACTOR_SRC_ALPHA_SATURATE) |
+		(1u << VK_BLEND_FACTOR_CONSTANT_COLOR) |
+		(1u << VK_BLEND_FACTOR_CONSTANT_ALPHA) |
+		(1u << VK_BLEND_FACTOR_SRC1_COLOR) |
+		(1u << VK_BLEND_FACTOR_SRC1_ALPHA) |
+		(1u << VK_BLEND_FACTOR_ZERO) |
+		(1u << VK_BLEND_FACTOR_ONE_MINUS_SRC_COLOR) |
+		(1u << VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA) |
+		(1u << VK_BLEND_FACTOR_ONE_MINUS_CONSTANT_COLOR) |
+		(1u << VK_BLEND_FACTOR_ONE_MINUS_CONSTANT_ALPHA) |
+		(1u << VK_BLEND_FACTOR_ONE_MINUS_SRC1_COLOR) |
+		(1u << VK_BLEND_FACTOR_ONE_MINUS_SRC1_ALPHA);
+
+	if (dst == VK_BLEND_FACTOR_ONE &&
+	    (src_allowed && (1u << src))) {
+		/* Addition is commutative, but floating point addition isn't
+		 * associative: subtle changes can be introduced via different
+		 * rounding. Be conservative, only enable for min and max.
+		 */
+		if (op == VK_BLEND_OP_MAX || op == VK_BLEND_OP_MIN)
+			blend->commutative_4bit |= chanmask;
+	}
+}
+
 static struct radv_blend_state
 radv_pipeline_init_blend_state(struct radv_pipeline *pipeline,
 			       const VkGraphicsPipelineCreateInfo *pCreateInfo,
@@ -600,6 +649,11 @@ radv_pipeline_init_blend_state(struct radv_pipeline *pipeline,
 			dstA = VK_BLEND_FACTOR_ONE;
 		}
 
+		radv_blend_check_commutativity(&blend, eqRGB, srcRGB, dstRGB,
+					       0x7 << (4 * i));
+		radv_blend_check_commutativity(&blend, eqA, srcA, dstA,
+					       0x8 << (4 * i));
+
 		/* Blending optimizations for RB+.
 		 * These transformations don't change the behavior.
 		 *
@@ -750,13 +804,182 @@ static uint8_t radv_pipeline_get_ps_iter_samples(const VkPipelineMultisampleStat
 	return ps_iter_samples;
 }
 
+static bool
+radv_is_depth_write_enabled(const VkPipelineDepthStencilStateCreateInfo *pCreateInfo)
+{
+	return pCreateInfo->depthTestEnable &&
+	       pCreateInfo->depthWriteEnable &&
+	       pCreateInfo->depthCompareOp != VK_COMPARE_OP_NEVER;
+}
+
+static bool
+radv_writes_stencil(const VkStencilOpState *state)
+{
+	return state->writeMask &&
+	       (state->failOp != VK_STENCIL_OP_KEEP ||
+		state->passOp != VK_STENCIL_OP_KEEP ||
+		state->depthFailOp != VK_STENCIL_OP_KEEP);
+}
+
+static bool
+radv_is_stencil_write_enabled(const VkPipelineDepthStencilStateCreateInfo *pCreateInfo)
+{
+	return pCreateInfo->stencilTestEnable &&
+	       (radv_writes_stencil(&pCreateInfo->front) ||
+		radv_writes_stencil(&pCreateInfo->back));
+}
+
+static bool
+radv_is_ds_write_enabled(const VkPipelineDepthStencilStateCreateInfo *pCreateInfo)
+{
+	return radv_is_depth_write_enabled(pCreateInfo) ||
+	       radv_is_stencil_write_enabled(pCreateInfo);
+}
+
+static bool
+radv_order_invariant_stencil_op(VkStencilOp op)
+{
+	/* REPLACE is normally order invariant, except when the stencil
+	 * reference value is written by the fragment shader. Tracking this
+	 * interaction does not seem worth the effort, so be conservative.
+	 */
+	return op != VK_STENCIL_OP_INCREMENT_AND_CLAMP &&
+	       op != VK_STENCIL_OP_DECREMENT_AND_CLAMP &&
+	       op != VK_STENCIL_OP_REPLACE;
+}
+
+static bool
+radv_order_invariant_stencil_state(const VkStencilOpState *state)
+{
+	/* Compute whether, assuming Z writes are disabled, this stencil state
+	 * is order invariant in the sense that the set of passing fragments as
+	 * well as the final stencil buffer result does not depend on the order
+	 * of fragments.
+	 */
+	return !state->writeMask ||
+	       /* The following assumes that Z writes are disabled. */
+	       (state->compareOp == VK_COMPARE_OP_ALWAYS &&
+		radv_order_invariant_stencil_op(state->passOp) &&
+		radv_order_invariant_stencil_op(state->depthFailOp)) ||
+	       (state->compareOp == VK_COMPARE_OP_NEVER &&
+		radv_order_invariant_stencil_op(state->failOp));
+}
+
+static bool
+radv_pipeline_out_of_order_rast(struct radv_pipeline *pipeline,
+				struct radv_blend_state *blend,
+				const VkGraphicsPipelineCreateInfo *pCreateInfo)
+{
+	RADV_FROM_HANDLE(radv_render_pass, pass, pCreateInfo->renderPass);
+	struct radv_subpass *subpass = pass->subpasses + pCreateInfo->subpass;
+	unsigned colormask = blend->cb_target_enabled_4bit;
+
+	if (!pipeline->device->physical_device->out_of_order_rast_allowed)
+		return false;
+
+	/* Be conservative if a logic operation is enabled with color buffers. */
+	if (colormask && pCreateInfo->pColorBlendState->logicOpEnable)
+		return false;
+
+	/* Default depth/stencil invariance when no attachment is bound. */
+	struct radv_dsa_order_invariance dsa_order_invariant = {
+		.zs = true, .pass_set = true
+	};
+
+	if (pCreateInfo->pDepthStencilState &&
+	    subpass->depth_stencil_attachment.attachment != VK_ATTACHMENT_UNUSED) {
+		const VkPipelineDepthStencilStateCreateInfo *vkds =
+			pCreateInfo->pDepthStencilState;
+		struct radv_render_pass_attachment *attachment =
+			pass->attachments + subpass->depth_stencil_attachment.attachment;
+		bool has_stencil = vk_format_is_stencil(attachment->format);
+		struct radv_dsa_order_invariance order_invariance[2];
+		struct radv_shader_variant *ps =
+			pipeline->shaders[MESA_SHADER_FRAGMENT];
+
+		/* Compute depth/stencil order invariance in order to know if
+		 * it's safe to enable out-of-order.
+		 */
+		bool zfunc_is_ordered =
+			vkds->depthCompareOp == VK_COMPARE_OP_NEVER ||
+			vkds->depthCompareOp == VK_COMPARE_OP_LESS ||
+			vkds->depthCompareOp == VK_COMPARE_OP_LESS_OR_EQUAL ||
+			vkds->depthCompareOp == VK_COMPARE_OP_GREATER ||
+			vkds->depthCompareOp == VK_COMPARE_OP_GREATER_OR_EQUAL;
+
+		bool nozwrite_and_order_invariant_stencil =
+			!radv_is_ds_write_enabled(vkds) ||
+			(!radv_is_depth_write_enabled(vkds) &&
+			 radv_order_invariant_stencil_state(&vkds->front) &&
+			 radv_order_invariant_stencil_state(&vkds->back));
+
+		order_invariance[1].zs =
+			nozwrite_and_order_invariant_stencil ||
+			(!radv_is_stencil_write_enabled(vkds) &&
+			 zfunc_is_ordered);
+		order_invariance[0].zs =
+			!radv_is_depth_write_enabled(vkds) || zfunc_is_ordered;
+
+		order_invariance[1].pass_set =
+			nozwrite_and_order_invariant_stencil ||
+			(!radv_is_stencil_write_enabled(vkds) &&
+			 (vkds->depthCompareOp == VK_COMPARE_OP_ALWAYS ||
+			  vkds->depthCompareOp == VK_COMPARE_OP_NEVER));
+		order_invariance[0].pass_set =
+			!radv_is_depth_write_enabled(vkds) ||
+			(vkds->depthCompareOp == VK_COMPARE_OP_ALWAYS ||
+			 vkds->depthCompareOp == VK_COMPARE_OP_NEVER);
+
+		dsa_order_invariant = order_invariance[has_stencil];
+		if (!dsa_order_invariant.zs)
+			return false;
+
+		/* The set of PS invocations is always order invariant,
+		 * except when early Z/S tests are requested.
+		 */
+		if (ps &&
+		    ps->info.info.ps.writes_memory &&
+		    ps->info.fs.early_fragment_test &&
+		    !dsa_order_invariant.pass_set)
+			return false;
+
+		/* Determine if out-of-order rasterization should be disabled
+		 * when occlusion queries are used.
+		 */
+		pipeline->graphics.disable_out_of_order_rast_for_occlusion =
+			!dsa_order_invariant.pass_set;
+	}
+
+	/* No color buffers are enabled for writing. */
+	if (!colormask)
+		return true;
+
+	unsigned blendmask = colormask & blend->blend_enable_4bit;
+
+	if (blendmask) {
+		/* Only commutative blending. */
+		if (blendmask & ~blend->commutative_4bit)
+			return false;
+
+		if (!dsa_order_invariant.pass_set)
+			return false;
+	}
+
+	if (colormask & ~blendmask)
+		return false;
+
+	return true;
+}
+
 static void
 radv_pipeline_init_multisample_state(struct radv_pipeline *pipeline,
+				     struct radv_blend_state *blend,
 				     const VkGraphicsPipelineCreateInfo *pCreateInfo)
 {
 	const VkPipelineMultisampleStateCreateInfo *vkms = pCreateInfo->pMultisampleState;
 	struct radv_multisample_state *ms = &pipeline->graphics.ms;
 	unsigned num_tile_pipes = pipeline->device->physical_device->rad_info.num_tile_pipes;
+	bool out_of_order_rast = false;
 	int ps_iter_samples = 1;
 	uint32_t mask = 0xffff;
 
@@ -808,8 +1031,21 @@ radv_pipeline_init_multisample_state(struct radv_pipeline *pipeline,
 	const struct VkPipelineRasterizationStateRasterizationOrderAMD *raster_order =
 		vk_find_struct_const(pCreateInfo->pRasterizationState->pNext, PIPELINE_RASTERIZATION_STATE_RASTERIZATION_ORDER_AMD);
 	if (raster_order && raster_order->rasterizationOrder == VK_RASTERIZATION_ORDER_RELAXED_AMD) {
+		/* Out-of-order rasterization is explicitly enabled by the
+		 * application.
+		 */
+		out_of_order_rast = true;
+	} else {
+		/* Determine if the driver can enable out-of-order
+		 * rasterization internally.
+		 */
+		out_of_order_rast =
+			radv_pipeline_out_of_order_rast(pipeline, blend, pCreateInfo);
+	}
+
+	if (out_of_order_rast) {
 		ms->pa_sc_mode_cntl_1 |= S_028A4C_OUT_OF_ORDER_PRIMITIVE_ENABLE(1) |
-					S_028A4C_OUT_OF_ORDER_WATER_MARK(0x7);
+					 S_028A4C_OUT_OF_ORDER_WATER_MARK(0x7);
 	}
 
 	if (vkms && vkms->pSampleMask) {
@@ -3094,7 +3330,7 @@ radv_pipeline_init(struct radv_pipeline *pipeline,
 	                    pStages);
 
 	pipeline->graphics.spi_baryc_cntl = S_0286E0_FRONT_FACE_ALL_BITS(1);
-	radv_pipeline_init_multisample_state(pipeline, pCreateInfo);
+	radv_pipeline_init_multisample_state(pipeline, &blend, pCreateInfo);
 	uint32_t gs_out;
 	uint32_t prim = si_translate_prim(pCreateInfo->pInputAssemblyState->topology);
 

src/amd/vulkan/radv_private.h

@@ -291,6 +291,9 @@ struct radv_physical_device {
 	bool cpdma_prefetch_writes_memory;
 	bool has_scissor_bug;
 
+	bool has_out_of_order_rast;
+	bool out_of_order_rast_allowed;
+
 	/* This is the drivers on-disk cache used as a fallback as opposed to
 	 * the pipeline cache defined by apps.
 	 */
@@ -1232,6 +1235,7 @@ struct radv_pipeline {
 			struct radv_prim_vertex_count prim_vertex_count;
  			bool can_use_guardband;
 			uint32_t needed_dynamic_state;
+			bool disable_out_of_order_rast_for_occlusion;
 		} graphics;
 	};