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Avoid GL undefined behavior in ubershaders

This commit is contained in:
Pedro J. Estébanez 2022-07-02 13:19:12 +02:00
parent a9920ae54f
commit 65a83785fd
6 changed files with 59 additions and 6 deletions
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2
drivers/gles3/rasterizer_scene_gles3.cpp
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@ -5297,7 +5297,7 @@ void RasterizerSceneGLES3::initialize() {
glFrontFace(GL_CW);
if (storage->config.async_compilation_enabled) {
state.scene_shader.init_async_compilation();
state.scene_shader.init_async_compilation(storage->resources.depth_tex);
}
}

11
drivers/gles3/rasterizer_storage_gles3.cpp
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@ -8241,6 +8241,14 @@ void RasterizerStorageGLES3::initialize() {
glGenerateMipmap(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, 0);
glGenTextures(1, &resources.depth_tex);
unsigned char depthtexdata[8 * 8 * 2] = {};
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, resources.depth_tex);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT16, 8, 8, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_SHORT, depthtexdata);
glBindTexture(GL_TEXTURE_2D, 0);
glGenTextures(1, &resources.white_tex_3d);
glActiveTexture(GL_TEXTURE0);
@ -8331,7 +8339,7 @@ void RasterizerStorageGLES3::initialize() {
shaders.cubemap_filter.set_conditional(CubemapFilterShaderGLES3::LOW_QUALITY, !ggx_hq);
shaders.particles.init();
if (config.async_compilation_enabled) {
shaders.particles.init_async_compilation();
shaders.particles.init_async_compilation(resources.depth_tex);
}
#ifdef GLES_OVER_GL
@ -8389,6 +8397,7 @@ void RasterizerStorageGLES3::finalize() {
glDeleteTextures(1, &resources.white_tex);
glDeleteTextures(1, &resources.black_tex);
glDeleteTextures(1, &resources.normal_tex);
glDeleteTextures(1, &resources.depth_tex);
}
void RasterizerStorageGLES3::update_dirty_resources() {

1
drivers/gles3/rasterizer_storage_gles3.h
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@ -142,6 +142,7 @@ public:
GLuint black_tex;
GLuint normal_tex;
GLuint aniso_tex;
GLuint depth_tex;
GLuint white_tex_3d;
GLuint white_tex_array;

28
drivers/gles3/shader_gles3.cpp
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@ -195,6 +195,27 @@ bool ShaderGLES3::_bind_ubershader() {
CRASH_COND(new_conditional_version.version >= 0x80000000);
#endif
glUniform1i(conditionals_uniform, new_conditional_version.version);
// This is done to avoid running into the GL UB message id 131222. Long explanation:
// If an ubershader has shadow samplers, they are generally not used if the current material has shadowing disabled,
// but that also implies the rasterizer won't do any preparation to the relevant shadow samplers (which won't really exist,
// so that's the correct way in a conditioned shader).
// However, in the case of the ubershader those shadow samplers are unconditionally declared, although potentially unused and
// thus "uninitialized". Sampling in that situation (compare disabled, no depth texture bound) is undefined behavior for GL.
// And that's a problem for us because, even if dynamic branching will serve to avoid using the unprepared sampler when shadowing
// is not enabled, the GPU may still run the other branch. And it's not just that the results from the sampling are undefined
// (that wouldn't be a problem and we could just ignore the warning); the problem is that sampling in that state is fully UB.
for (int i = 0; i < shadow_texunit_count; i++) {
int unit = shadow_texunits[i];
if (unit >= 0) {
glActiveTexture(GL_TEXTURE0 + unit);
} else {
glActiveTexture(GL_TEXTURE0 + max_image_units + unit);
}
glBindTexture(GL_TEXTURE_2D, depth_tex);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_COMPARE_REF_TO_TEXTURE);
}
return bound;
}
@ -1107,7 +1128,7 @@ GLint ShaderGLES3::get_uniform_location(const String &p_name) const {
return glGetUniformLocation(version->ids.main, p_name.ascii().get_data());
}
void ShaderGLES3::setup(const char **p_conditional_defines, int p_conditional_count, const char **p_uniform_names, int p_uniform_count, const AttributePair *p_attribute_pairs, int p_attribute_count, const TexUnitPair *p_texunit_pairs, int p_texunit_pair_count, const UBOPair *p_ubo_pairs, int p_ubo_pair_count, const Feedback *p_feedback, int p_feedback_count, const char *p_vertex_code, const char *p_fragment_code, int p_vertex_code_start, int p_fragment_code_start) {
void ShaderGLES3::setup(const char **p_conditional_defines, int p_conditional_count, const char **p_uniform_names, int p_uniform_count, const AttributePair *p_attribute_pairs, int p_attribute_count, const TexUnitPair *p_texunit_pairs, int p_texunit_pair_count, const int *p_shadow_texunits, int p_shadow_texunit_count, const UBOPair *p_ubo_pairs, int p_ubo_pair_count, const Feedback *p_feedback, int p_feedback_count, const char *p_vertex_code, const char *p_fragment_code, int p_vertex_code_start, int p_fragment_code_start) {
ERR_FAIL_COND(version);
conditional_version.key = 0;
new_conditional_version.key = 0;
@ -1119,6 +1140,8 @@ void ShaderGLES3::setup(const char **p_conditional_defines, int p_conditional_co
fragment_code = p_fragment_code;
texunit_pairs = p_texunit_pairs;
texunit_pair_count = p_texunit_pair_count;
shadow_texunits = p_shadow_texunits;
shadow_texunit_count = p_shadow_texunit_count;
vertex_code_start = p_vertex_code_start;
fragment_code_start = p_fragment_code_start;
attribute_pairs = p_attribute_pairs;
@ -1209,7 +1232,8 @@ void ShaderGLES3::setup(const char **p_conditional_defines, int p_conditional_co
glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS, &max_image_units);
}
void ShaderGLES3::init_async_compilation() {
void ShaderGLES3::init_async_compilation(GLuint p_depth_tex) {
depth_tex = p_depth_tex;
if (is_async_compilation_supported() && get_ubershader_flags_uniform() != -1) {
// Warm up the ubershader for the case of no custom code
new_conditional_version.code_version = 0;

7
drivers/gles3/shader_gles3.h
View File

@ -96,6 +96,7 @@ private:
//@TODO Optimize to a fixed set of shader pools and use a LRU
int uniform_count;
int texunit_pair_count;
int shadow_texunit_count;
int conditional_count;
int ubo_count;
int feedback_count;
@ -245,6 +246,7 @@ private:
const char **uniform_names;
const AttributePair *attribute_pairs;
const TexUnitPair *texunit_pairs;
const int *shadow_texunits;
const UBOPair *ubo_pairs;
const Feedback *feedbacks;
const char *vertex_code;
@ -278,6 +280,7 @@ private:
static ShaderGLES3 *active;
int max_image_units;
GLuint depth_tex = 0;
_FORCE_INLINE_ void _set_uniform_variant(GLint p_uniform, const Variant &p_value) {
if (p_uniform < 0) {
@ -375,7 +378,7 @@ protected:
_FORCE_INLINE_ int _get_uniform(int p_which) const;
_FORCE_INLINE_ void _set_conditional(int p_which, bool p_value);
void setup(const char **p_conditional_defines, int p_conditional_count, const char **p_uniform_names, int p_uniform_count, const AttributePair *p_attribute_pairs, int p_attribute_count, const TexUnitPair *p_texunit_pairs, int p_texunit_pair_count, const UBOPair *p_ubo_pairs, int p_ubo_pair_count, const Feedback *p_feedback, int p_feedback_count, const char *p_vertex_code, const char *p_fragment_code, int p_vertex_code_start, int p_fragment_code_start);
void setup(const char **p_conditional_defines, int p_conditional_count, const char **p_uniform_names, int p_uniform_count, const AttributePair *p_attribute_pairs, int p_attribute_count, const TexUnitPair *p_texunit_pairs, int p_texunit_pair_count, const int *p_shadow_texunits, int p_shadow_texunit_count, const UBOPair *p_ubo_pairs, int p_ubo_pair_count, const Feedback *p_feedback, int p_feedback_count, const char *p_vertex_code, const char *p_fragment_code, int p_vertex_code_start, int p_fragment_code_start);
ShaderGLES3();
@ -404,7 +407,7 @@ public:
_FORCE_INLINE_ bool is_version_valid() const { return version && version->compile_status == Version::COMPILE_STATUS_OK; }
virtual void init() = 0;
void init_async_compilation();
void init_async_compilation(GLuint p_depth_tex);
bool is_async_compilation_supported();
void finish();

16
gles_builders.py
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@ -19,6 +19,7 @@ class LegacyGLHeaderStruct:
self.enums = {}
self.texunits = []
self.texunit_names = []
self.shadow_texunits = []
self.ubos = []
self.ubo_names = []
@ -106,6 +107,8 @@ def include_file_in_legacygl_header(filename, header_data, depth):
if not x in header_data.texunit_names:
header_data.texunits += [(x, texunit)]
if line.find("sampler2DShadow") != -1:
header_data.shadow_texunits += [texunit]
header_data.texunit_names += [x]
elif line.find("uniform") != -1 and line.lower().find("ubo:") != -1:
@ -483,6 +486,15 @@ def build_legacygl_header(filename, include, class_suffix, output_attribs, gles2
else:
fd.write("\t\tstatic TexUnitPair *_texunit_pairs=NULL;\n")
if not gles2:
if header_data.shadow_texunits:
fd.write("\t\tstatic int _shadow_texunits[]={")
for x in header_data.shadow_texunits:
fd.write(str(x) + ',')
fd.write("};\n\n")
else:
fd.write("\t\tstatic int *_shadow_texunits=NULL;\n")
if not gles2 and header_data.ubos:
fd.write("\t\tstatic UBOPair _ubo_pairs[]={\n")
for x in header_data.ubos:
@ -537,6 +549,8 @@ def build_legacygl_header(filename, include, class_suffix, output_attribs, gles2
+ str(len(header_data.attributes))
+ ", _texunit_pairs,"
+ str(len(header_data.texunits))
+ ", _shadow_texunits,"
+ str(len(header_data.shadow_texunits))
+ ",_ubo_pairs,"
+ str(len(header_data.ubos))
+ ",_feedbacks,"
@ -566,6 +580,8 @@ def build_legacygl_header(filename, include, class_suffix, output_attribs, gles2
+ str(len(header_data.uniforms))
+ ",_texunit_pairs,"
+ str(len(header_data.texunits))
+ ",_shadow_texunits,"
+ str(len(header_data.shadow_texunits))
+ ",_enums,"
+ str(len(header_data.enums))
+ ",_enum_values,"