From 8f8aeaef77da16958024d9ddeba75102484758aa Mon Sep 17 00:00:00 2001
From: "Unknown W. Brackets" <checkins@unknownbrackets.org>
Date: Sun, 15 Mar 2015 13:15:16 -0700
Subject: [PATCH] Improve depal shader failure cases.

Primarily, this handles lost (e.g. Android sleep) better, in that it
recreates the vertex shader.  Previously, this would simply cause all
future depal operations to fail, and to constantly retry compiling and
linking the failed program.
---
 GPU/GLES/DepalettizeShader.cpp | 57 +++++++++++++++++++++++++---------
 GPU/GLES/DepalettizeShader.h   |  2 ++
 2 files changed, 44 insertions(+), 15 deletions(-)

diff --git a/GPU/GLES/DepalettizeShader.cpp b/GPU/GLES/DepalettizeShader.cpp
index e3de9532f4..e4747500eb 100644
--- a/GPU/GLES/DepalettizeShader.cpp
+++ b/GPU/GLES/DepalettizeShader.cpp
@@ -94,18 +94,34 @@ DepalShaderCache::DepalShaderCache() {
 	// Pre-build the vertex program
 	useGL3_ = gl_extensions.GLES3 || gl_extensions.VersionGEThan(3, 3);
 
+	vertexShaderFailed_ = false;
+	vertexShader_ = 0;
+}
+
+DepalShaderCache::~DepalShaderCache() {
+	Clear();
+	if (vertexShader_) {
+		glDeleteShader(vertexShader_);
+	}
+}
+
+bool DepalShaderCache::CreateVertexShader() {
+	if (vertexShaderFailed_) {
+		return false;
+	}
+
 	vertexShader_ = glCreateShader(GL_VERTEX_SHADER);
 	glShaderSource(vertexShader_, 1, useGL3_ ? &depalVShader300 : &depalVShader100, 0);
 	glCompileShader(vertexShader_);
 
 	if (!CheckShaderCompileSuccess(vertexShader_, useGL3_ ? depalVShader300 : depalVShader100)) {
-		// ...
+		glDeleteShader(vertexShader_);
+		vertexShader_ = 0;
+		// Don't try to recompile.
+		vertexShaderFailed_ = true;
 	}
-}
 
-DepalShaderCache::~DepalShaderCache() {
-	Clear();
-	glDeleteShader(vertexShader_);
+	return !vertexShaderFailed_;
 }
 
 u32 DepalShaderCache::GenerateShaderID(GEBufferFormat pixelFormat) {
@@ -152,7 +168,9 @@ GLuint DepalShaderCache::GetClutTexture(const u32 clutID, u32 *rawClut) {
 void DepalShaderCache::Clear() {
 	for (auto shader = cache_.begin(); shader != cache_.end(); ++shader) {
 		glDeleteShader(shader->second->fragShader);
-		glDeleteProgram(shader->second->program);
+		if (shader->second->program) {
+			glDeleteProgram(shader->second->program);
+		}
 		delete shader->second;
 	}
 	cache_.clear();
@@ -183,6 +201,13 @@ GLuint DepalShaderCache::GetDepalettizeShader(GEBufferFormat pixelFormat) {
 		return shader->second->program;
 	}
 
+	if (vertexShader_ == 0) {
+		if (!CreateVertexShader()) {
+			// The vertex shader failed, no need to bother trying the fragment.
+			return 0;
+		}
+	}
+
 	char *buffer = new char[2048];
 
 	GenerateDepalShader(buffer, pixelFormat, useGL3_ ? GLSL_300 : GLSL_140);
@@ -211,6 +236,11 @@ GLuint DepalShaderCache::GetDepalettizeShader(GEBufferFormat pixelFormat) {
 	glUniform1i(u_tex, 0);
 	glUniform1i(u_pal, 3);
 
+	DepalShader *depal = new DepalShader();
+	depal->program = program;
+	depal->fragShader = fragShader;
+	cache_[id] = depal;
+
 	GLint linkStatus = GL_FALSE;
 	glGetProgramiv(program, GL_LINK_STATUS, &linkStatus);
 	if (linkStatus != GL_TRUE) {
@@ -227,17 +257,14 @@ GLuint DepalShaderCache::GetDepalettizeShader(GEBufferFormat pixelFormat) {
 			delete[] errorbuf;	// we're dead!
 		}
 
-		delete[] buffer;
-		return 0;
+		// Since it failed, let's mark it in the cache so we don't keep retrying.
+		// That will only make it slower.
+		depal->program = 0;
+
+		// We will delete the shader later in Clear().
+		glDeleteProgram(program);
 	}
 
-	DepalShader *depal = new DepalShader();
-	depal->program = program;
-	depal->fragShader = fragShader;
-
-	cache_[id] = depal;
-
 	delete[] buffer;
-
 	return depal->program;
 }
diff --git a/GPU/GLES/DepalettizeShader.h b/GPU/GLES/DepalettizeShader.h
index 34cbc01447..a85ed65c06 100644
--- a/GPU/GLES/DepalettizeShader.h
+++ b/GPU/GLES/DepalettizeShader.h
@@ -47,8 +47,10 @@ public:
 
 private:
 	u32 GenerateShaderID(GEBufferFormat pixelFormat);
+	bool CreateVertexShader();
 
 	bool useGL3_;
+	bool vertexShaderFailed_;
 	GLuint vertexShader_;
 	std::map<u32, DepalShader *> cache_;
 	std::map<u32, DepalTexture *> texCache_;