OpenGL: When possible, avoid rebinding vertex arrays between glDrawArrays

Profitable optimization in DrawArrays-heavy games like GTA.

Common/GPU/OpenGL/GLFrameData.h

@@ -39,6 +39,7 @@ struct GLQueueProfileContext {
 	bool enabled;
 	double cpuStartTime;
 	double cpuEndTime;
+	int drawArraysRebindsAvoided;
 };
 
 

Common/GPU/OpenGL/GLQueueRunner.cpp

@@ -651,7 +651,7 @@ retry_depth:
 	currentReadHandle_ = fbo->handle;
 }
 
-void GLQueueRunner::RunSteps(const std::vector<GLRStep *> &steps, bool skipGLCalls, bool keepSteps, bool useVR) {
+void GLQueueRunner::RunSteps(const std::vector<GLRStep *> &steps, bool skipGLCalls, bool keepSteps, bool useVR, GLQueueProfileContext &profile) {
 	if (skipGLCalls) {
 		if (keepSteps) {
 			return;
@@ -713,9 +713,9 @@ void GLQueueRunner::RunSteps(const std::vector<GLRStep *> &steps, bool skipGLCal
 			if (IsVREnabled()) {
 				GLRStep vrStep = step;
 				PreprocessStepVR(&vrStep);
-				PerformRenderPass(vrStep, renderCount == 1, renderCount == totalRenderCount);
+				PerformRenderPass(vrStep, renderCount == 1, renderCount == totalRenderCount, profile);
 			} else {
-				PerformRenderPass(step, renderCount == 1, renderCount == totalRenderCount);
+				PerformRenderPass(step, renderCount == 1, renderCount == totalRenderCount, profile);
 			}
 			break;
 		case GLRStepType::COPY:
@@ -778,7 +778,20 @@ void GLQueueRunner::PerformBlit(const GLRStep &step) {
 	}
 }
 
-void GLQueueRunner::PerformRenderPass(const GLRStep &step, bool first, bool last) {
+static void EnableDisableVertexArrays(uint32_t prevAttr, uint32_t newAttr) {
+	int enable = (~prevAttr) & newAttr;
+	int disable = prevAttr & (~newAttr);
+	for (int i = 0; i < 7; i++) {  // SEM_MAX
+		if (enable & (1 << i)) {
+			glEnableVertexAttribArray(i);
+		}
+		if (disable & (1 << i)) {
+			glDisableVertexAttribArray(i);
+		}
+	}
+}
+
+void GLQueueRunner::PerformRenderPass(const GLRStep &step, bool first, bool last, GLQueueProfileContext &profile) {
 	CHECK_GL_ERROR_IF_DEBUG();
 
 	PerformBindFramebufferAsRenderTarget(step);
@@ -821,6 +834,11 @@ void GLQueueRunner::PerformRenderPass(const GLRStep &step, bool first, bool last
 	bool logicEnabled = false;
 #endif
 	bool clipDistanceEnabled[8]{};
+
+	bool lastDrawIsArray = false;
+	int lastBindOffset = 0;
+	GLRInputLayout *lastDrawLayout = nullptr;
+
 	GLuint blendEqColor = (GLuint)-1;
 	GLuint blendEqAlpha = (GLuint)-1;
 
@@ -1163,25 +1181,19 @@ void GLQueueRunner::PerformRenderPass(const GLRStep &step, bool first, bool last
 			if (buf != curArrayBuffer) {
 				glBindBuffer(GL_ARRAY_BUFFER, buf);
 				curArrayBuffer = buf;
+				// Invalidate any draw offset caching.
+				lastDrawLayout = nullptr;
 			}
+
 			if (attrMask != layout->semanticsMask_) {
-				int enable = layout->semanticsMask_ & ~attrMask;
-				int disable = (~layout->semanticsMask_) & attrMask;
-				for (int i = 0; i < 7; i++) {  // SEM_MAX
-					if (enable & (1 << i)) {
-						glEnableVertexAttribArray(i);
-					}
-					if (disable & (1 << i)) {
-						glDisableVertexAttribArray(i);
-					}
-				}
+				EnableDisableVertexArrays(attrMask, layout->semanticsMask_);
 				attrMask = layout->semanticsMask_;
 			}
+			if (c.draw.indexBuffer) {
 				for (size_t i = 0; i < layout->entries.size(); i++) {
 					auto &entry = layout->entries[i];
-				glVertexAttribPointer(entry.location, entry.count, entry.type, entry.normalized, entry.stride, (const void *)(c.draw.offset + entry.offset));
+					glVertexAttribPointer(entry.location, entry.count, entry.type, entry.normalized, layout->stride, (const void *)(c.draw.offset + entry.offset));
 				}
-			if (c.draw.indexBuffer) {
 				GLuint buf = c.draw.indexBuffer->buffer_;
 				_dbg_assert_(!(c.draw.indexBuffer && c.draw.indexBuffer->Mapped()));
 				if (buf != curElemArrayBuffer) {
@@ -1193,9 +1205,32 @@ void GLQueueRunner::PerformRenderPass(const GLRStep &step, bool first, bool last
 				} else {
 					glDrawElementsInstanced(c.draw.mode, c.draw.count, c.draw.indexType, c.draw.indices, c.draw.instances);
 				}
+				lastDrawIsArray = false;
 			} else {
-				glDrawArrays(c.draw.mode, c.draw.first, c.draw.count);
+				// See if we can avoid calling glVertexAttribPointer.
+				int offset = 0;
+				bool rebind = true;
+				if (lastDrawIsArray && layout == lastDrawLayout) {
+					unsigned int diff = (unsigned int)c.draw.offset - (unsigned int)lastBindOffset;
+					if (diff % layout->stride == 0) {
+						// Compatible draws.
+						offset = diff / layout->stride;
+						rebind = false;
+						profile.drawArraysRebindsAvoided++;
 					}
+				}
+				if (rebind) {
+					// Rebind.
+					for (size_t i = 0; i < layout->entries.size(); i++) {
+						auto &entry = layout->entries[i];
+						glVertexAttribPointer(entry.location, entry.count, entry.type, entry.normalized, layout->stride, (const void *)(c.draw.offset + entry.offset));
+					}
+					lastBindOffset = (int)c.draw.offset;
+				}
+				glDrawArrays(c.draw.mode, c.draw.first + offset, c.draw.count);
+				lastDrawIsArray = true;
+			}
+			lastDrawLayout = layout;
 			CHECK_GL_ERROR_IF_DEBUG();
 			break;
 		}

Common/GPU/OpenGL/GLQueueRunner.h

@@ -357,7 +357,7 @@ public:
 
 	void RunInitSteps(const std::vector<GLRInitStep> &steps, bool skipGLCalls);
 
-	void RunSteps(const std::vector<GLRStep *> &steps, bool skipGLCalls, bool keepSteps, bool useVR);
+	void RunSteps(const std::vector<GLRStep *> &steps, bool skipGLCalls, bool keepSteps, bool useVR, GLQueueProfileContext &profile);
 
 	void CreateDeviceObjects();
 	void DestroyDeviceObjects();
@@ -382,7 +382,7 @@ private:
 	void InitCreateFramebuffer(const GLRInitStep &step);
 
 	void PerformBindFramebufferAsRenderTarget(const GLRStep &pass);
-	void PerformRenderPass(const GLRStep &pass, bool first, bool last);
+	void PerformRenderPass(const GLRStep &pass, bool first, bool last, GLQueueProfileContext &profile);
 	void PerformCopy(const GLRStep &pass);
 	void PerformBlit(const GLRStep &pass);
 	void PerformReadback(const GLRStep &pass);

Common/GPU/OpenGL/GLRenderManager.cpp

@@ -193,7 +193,11 @@ std::string GLRenderManager::GetGpuProfileString() const {
 	const GLQueueProfileContext &profile = frameData_[curFrame].profile;
 
 	float cputime_ms = 1000.0f * (profile.cpuEndTime - profile.cpuStartTime);
-	return StringFromFormat("CPU time to run the list: %0.2f ms", cputime_ms);
+	return StringFromFormat(
+		"CPU time to run the list: %0.2f ms\n"
+		"Avoided DrawArrays rebinds: %d",
+		cputime_ms,
+		profile.drawArraysRebindsAvoided);
 }
 
 void GLRenderManager::BindFramebufferAsRenderTarget(GLRFramebuffer *fb, GLRRenderPassAction color, GLRRenderPassAction depth, GLRRenderPassAction stencil, uint32_t clearColor, float clearDepth, uint8_t clearStencil, const char *tag) {
@@ -429,17 +433,18 @@ bool GLRenderManager::Run(GLRRenderThreadTask &task) {
 
 	if (frameData.profile.enabled) {
 		frameData.profile.cpuStartTime = time_now_d();
+		frameData.profile.drawArraysRebindsAvoided = 0;
 	}
 
 	if (IsVREnabled()) {
 		int passes = GetVRPassesCount();
 		for (int i = 0; i < passes; i++) {
 			PreVRFrameRender(i);
-			queueRunner_.RunSteps(task.steps, skipGLCalls_, i < passes - 1, true);
+			queueRunner_.RunSteps(task.steps, skipGLCalls_, i < passes - 1, true, frameData.profile);
 			PostVRFrameRender();
 		}
 	} else {
-		queueRunner_.RunSteps(task.steps, skipGLCalls_, false, false);
+		queueRunner_.RunSteps(task.steps, skipGLCalls_, false, false, frameData.profile);
 	}
 
 	if (frameData.profile.enabled) {

Common/GPU/OpenGL/GLRenderManager.h

@@ -359,10 +359,10 @@ public:
 		int count;
 		GLenum type;
 		GLboolean normalized;
-		int stride;
 		intptr_t offset;
 	};
 	std::vector<Entry> entries;
+	unsigned int stride;
 	int semanticsMask_ = 0;
 };
 
@@ -487,10 +487,11 @@ public:
 		return step.create_program.program;
 	}
 
-	GLRInputLayout *CreateInputLayout(const std::vector<GLRInputLayout::Entry> &entries) {
+	GLRInputLayout *CreateInputLayout(const std::vector<GLRInputLayout::Entry> &entries, int stride) {
 		GLRInitStep step{ GLRInitStepType::CREATE_INPUT_LAYOUT };
 		step.create_input_layout.inputLayout = new GLRInputLayout();
 		step.create_input_layout.inputLayout->entries = entries;
+		step.create_input_layout.inputLayout->stride = stride;
 		for (auto &iter : step.create_input_layout.inputLayout->entries) {
 			step.create_input_layout.inputLayout->semanticsMask_ |= 1 << iter.location;
 		}

Common/GPU/OpenGL/thin3d_gl.cpp

@@ -1393,13 +1393,13 @@ OpenGLInputLayout::~OpenGLInputLayout() {
 void OpenGLInputLayout::Compile(const InputLayoutDesc &desc) {
 	// TODO: This is only accurate if there's only one stream. But whatever, for now we
 	// never use multiple streams anyway.
-	stride = desc.bindings.empty() ? 0 : (GLsizei)desc.bindings[0].stride;
+	_dbg_assert_(desc.bindings.size() == 1);
+	stride = (GLsizei)desc.bindings[0].stride;
 
 	std::vector<GLRInputLayout::Entry> entries;
 	for (auto &attr : desc.attributes) {
 		GLRInputLayout::Entry entry;
 		entry.location = attr.location;
-		entry.stride = (GLsizei)desc.bindings[attr.binding].stride;
 		entry.offset = attr.offset;
 		switch (attr.format) {
 		case DataFormat::R32G32_FLOAT:
@@ -1431,7 +1431,7 @@ void OpenGLInputLayout::Compile(const InputLayoutDesc &desc) {
 		entries.push_back(entry);
 	}
 	if (!entries.empty()) {
-		inputLayout_ = render_->CreateInputLayout(entries);
+		inputLayout_ = render_->CreateInputLayout(entries, stride);
 	} else {
 		inputLayout_ = nullptr;
 	}

GPU/GLES/DrawEngineGLES.cpp

@@ -103,12 +103,12 @@ void DrawEngineGLES::InitDeviceObjects() {
 
 	int vertexSize = sizeof(TransformedVertex);
 	std::vector<GLRInputLayout::Entry> entries;
-	entries.push_back({ ATTR_POSITION, 4, GL_FLOAT, GL_FALSE, vertexSize, offsetof(TransformedVertex, x) });
-	entries.push_back({ ATTR_TEXCOORD, 3, GL_FLOAT, GL_FALSE, vertexSize, offsetof(TransformedVertex, u) });
-	entries.push_back({ ATTR_COLOR0, 4, GL_UNSIGNED_BYTE, GL_TRUE, vertexSize, offsetof(TransformedVertex, color0) });
-	entries.push_back({ ATTR_COLOR1, 3, GL_UNSIGNED_BYTE, GL_TRUE, vertexSize, offsetof(TransformedVertex, color1) });
-	entries.push_back({ ATTR_NORMAL, 1, GL_FLOAT, GL_FALSE, vertexSize, offsetof(TransformedVertex, fog) });
-	softwareInputLayout_ = render_->CreateInputLayout(entries);
+	entries.push_back({ ATTR_POSITION, 4, GL_FLOAT, GL_FALSE, offsetof(TransformedVertex, x) });
+	entries.push_back({ ATTR_TEXCOORD, 3, GL_FLOAT, GL_FALSE, offsetof(TransformedVertex, u) });
+	entries.push_back({ ATTR_COLOR0, 4, GL_UNSIGNED_BYTE, GL_TRUE, offsetof(TransformedVertex, color0) });
+	entries.push_back({ ATTR_COLOR1, 3, GL_UNSIGNED_BYTE, GL_TRUE, offsetof(TransformedVertex, color1) });
+	entries.push_back({ ATTR_NORMAL, 1, GL_FLOAT, GL_FALSE, offsetof(TransformedVertex, fog) });
+	softwareInputLayout_ = render_->CreateInputLayout(entries, vertexSize);
 
 	draw_->SetInvalidationCallback(std::bind(&DrawEngineGLES::Invalidate, this, std::placeholders::_1));
 }
@@ -189,7 +189,7 @@ static const GlTypeInfo GLComp[] = {
 	{GL_UNSIGNED_SHORT, 4, GL_TRUE},// 	DEC_U16_4,
 };
 
-static inline void VertexAttribSetup(int attrib, int fmt, int stride, int offset, std::vector<GLRInputLayout::Entry> &entries) {
+static inline void VertexAttribSetup(int attrib, int fmt, int offset, std::vector<GLRInputLayout::Entry> &entries) {
 	if (fmt) {
 		const GlTypeInfo &type = GLComp[fmt];
 		GLRInputLayout::Entry entry;
@@ -197,7 +197,6 @@ static inline void VertexAttribSetup(int attrib, int fmt, int stride, int offset
 		entry.location = attrib;
 		entry.normalized = type.normalized;
 		entry.type = type.type;
-		entry.stride = stride;
 		entry.count = type.count;
 		entries.push_back(entry);
 	}
@@ -212,15 +211,15 @@ GLRInputLayout *DrawEngineGLES::SetupDecFmtForDraw(LinkedShader *program, const
 	}
 
 	std::vector<GLRInputLayout::Entry> entries;
-	VertexAttribSetup(ATTR_W1, decFmt.w0fmt, decFmt.stride, decFmt.w0off, entries);
-	VertexAttribSetup(ATTR_W2, decFmt.w1fmt, decFmt.stride, decFmt.w1off, entries);
-	VertexAttribSetup(ATTR_TEXCOORD, decFmt.uvfmt, decFmt.stride, decFmt.uvoff, entries);
-	VertexAttribSetup(ATTR_COLOR0, decFmt.c0fmt, decFmt.stride, decFmt.c0off, entries);
-	VertexAttribSetup(ATTR_COLOR1, decFmt.c1fmt, decFmt.stride, decFmt.c1off, entries);
-	VertexAttribSetup(ATTR_NORMAL, decFmt.nrmfmt, decFmt.stride, decFmt.nrmoff, entries);
-	VertexAttribSetup(ATTR_POSITION, decFmt.posfmt, decFmt.stride, decFmt.posoff, entries);
+	VertexAttribSetup(ATTR_W1, decFmt.w0fmt, decFmt.w0off, entries);
+	VertexAttribSetup(ATTR_W2, decFmt.w1fmt, decFmt.w1off, entries);
+	VertexAttribSetup(ATTR_TEXCOORD, decFmt.uvfmt, decFmt.uvoff, entries);
+	VertexAttribSetup(ATTR_COLOR0, decFmt.c0fmt, decFmt.c0off, entries);
+	VertexAttribSetup(ATTR_COLOR1, decFmt.c1fmt, decFmt.c1off, entries);
+	VertexAttribSetup(ATTR_NORMAL, decFmt.nrmfmt, decFmt.nrmoff, entries);
+	VertexAttribSetup(ATTR_POSITION, decFmt.posfmt, decFmt.posoff, entries);
 
-	inputLayout = render_->CreateInputLayout(entries);
+	inputLayout = render_->CreateInputLayout(entries, decFmt.stride);
 	inputLayoutMap_.Insert(key, inputLayout);
 	return inputLayout;
 }