GL: give up and disable DSA for everything buffer-related on Intel/Windows.

Sad.

doc/changelog.dox

@@ -52,6 +52,14 @@ See also:
 -   Recognizing @gl_extension{AMD,shader_explicit_vertex_parameter} desktop
     and @gl_extension{NV,fragment_shader_barycentric} desktop / ES extensions.
     These add only shading language features.
+-   A @cpp "intel-windows-crazy-broken-buffer-dsa" @ce workaround for Intel
+    Windows drivers, disabling @gl_extension{ARB,direct_state_access} code
+    paths in everything releated to buffers. There are several issues occuring
+    only in heavier apps, impossible to track down and reproduce in a
+    controlled environment. This replaces the previous
+    @cpp "intel-windows-buggy-dsa-bufferdata-for-index-buffers" @ce workaround
+    that attempted to fix this by doing an explicit buffer binding in some
+    cases. See @ref opengl-workarounds for more information.
 
 @subsubsection changelog-latest-new-math Math library
 

src/Magnum/GL/Buffer.cpp

@@ -458,18 +458,6 @@ void Buffer::dataImplementationDefault(GLsizeiptr size, const GLvoid* data, Buff
 void Buffer::dataImplementationDSA(const GLsizeiptr size, const GLvoid* const data, const BufferUsage usage) {
     glNamedBufferData(_id, size, data, GLenum(usage));
 }
-
-#ifdef CORRADE_TARGET_WINDOWS
-void Buffer::dataImplementationDSAIntelWindows(const GLsizeiptr size, const GLvoid* const data, const BufferUsage usage) {
-    glNamedBufferData(_id, size, data, GLenum(usage));
-    /* See the "intel-windows-buggy-dsa-bufferdata-for-index-buffers"
-       workaround for more information */
-    if(_targetHint == TargetHint::ElementArray) {
-        bindInternal(TargetHint::ElementArray, nullptr);
-        bindInternal(TargetHint::ElementArray, this);
-    }
-}
-#endif
 #endif
 
 void Buffer::subDataImplementationDefault(GLintptr offset, GLsizeiptr size, const GLvoid* data) {

src/Magnum/GL/Buffer.h

@@ -1216,7 +1216,6 @@ class MAGNUM_GL_EXPORT Buffer: public AbstractObject {
 
         void MAGNUM_GL_LOCAL dataImplementationDefault(GLsizeiptr size, const GLvoid* data, BufferUsage usage);
         #ifndef MAGNUM_TARGET_GLES
-        void MAGNUM_GL_LOCAL dataImplementationDSAIntelWindows(GLsizeiptr size, const GLvoid* data, BufferUsage usage);
         void MAGNUM_GL_LOCAL dataImplementationDSA(GLsizeiptr size, const GLvoid* data, BufferUsage usage);
         #endif
 

src/Magnum/GL/Implementation/BufferState.cpp

@@ -88,25 +88,21 @@ BufferState::BufferState(Context& context, std::vector<std::string>& extensions)
     , uniformOffsetAlignment{0}, maxUniformBindings{0}
     #endif
 {
-    /* Create implementation */
+    /* DSA, except Intel Windows, because I have no patience for that anymore */
     #ifndef MAGNUM_TARGET_GLES
-    if(context.isExtensionSupported<Extensions::ARB::direct_state_access>()) {
-        extensions.emplace_back(Extensions::ARB::direct_state_access::string());
-        createImplementation = &Buffer::createImplementationDSA;
-
-    } else
-    #endif
-    {
-        createImplementation = &Buffer::createImplementationDefault;
-    }
-
-    #ifndef MAGNUM_TARGET_GLES
-    if(context.isExtensionSupported<Extensions::ARB::direct_state_access>()) {
+    if(context.isExtensionSupported<Extensions::ARB::direct_state_access>()
+        #ifdef CORRADE_TARGET_WINDOWS
+        && (!(context.detectedDriver() & Context::DetectedDriver::IntelWindows) ||
+        context.isDriverWorkaroundDisabled("intel-windows-crazy-broken-buffer-dsa"))
+        #endif
+    ) {
         extensions.emplace_back(Extensions::ARB::direct_state_access::string());
 
+        createImplementation = &Buffer::createImplementationDSA;
         copyImplementation = &Buffer::copyImplementationDSA;
         getParameterImplementation = &Buffer::getParameterImplementationDSA;
         getSubDataImplementation = &Buffer::getSubDataImplementationDSA;
+        dataImplementation = &Buffer::dataImplementationDSA;
         subDataImplementation = &Buffer::subDataImplementationDSA;
         mapImplementation = &Buffer::mapImplementationDSA;
         mapRangeImplementation = &Buffer::mapRangeImplementationDSA;
@@ -115,6 +111,7 @@ BufferState::BufferState(Context& context, std::vector<std::string>& extensions)
     } else
     #endif
     {
+        createImplementation = &Buffer::createImplementationDefault;
         #ifndef MAGNUM_TARGET_GLES2
         copyImplementation = &Buffer::copyImplementationDefault;
         #endif
@@ -122,6 +119,7 @@ BufferState::BufferState(Context& context, std::vector<std::string>& extensions)
         #ifndef MAGNUM_TARGET_GLES
         getSubDataImplementation = &Buffer::getSubDataImplementationDefault;
         #endif
+        dataImplementation = &Buffer::dataImplementationDefault;
         subDataImplementation = &Buffer::subDataImplementationDefault;
         #ifndef MAGNUM_TARGET_WEBGL
         mapImplementation = &Buffer::mapImplementationDefault;
@@ -179,24 +177,6 @@ BufferState::BufferState(Context& context, std::vector<std::string>& extensions)
         setTargetHintImplementation = &Buffer::setTargetHintImplementationDefault;
     }
 
-    #ifndef MAGNUM_TARGET_GLES
-    if(context.isExtensionSupported<Extensions::ARB::direct_state_access>()) {
-        #ifdef CORRADE_TARGET_WINDOWS
-        if((context.detectedDriver() & Context::DetectedDriver::IntelWindows) &&
-           !context.isDriverWorkaroundDisabled("intel-windows-buggy-dsa-bufferdata-for-index-buffers"))
-        {
-            dataImplementation = &Buffer::dataImplementationDSAIntelWindows;
-        } else
-        #endif
-        {
-            dataImplementation = &Buffer::dataImplementationDSA;
-        }
-    } else
-    #endif
-    {
-        dataImplementation = &Buffer::dataImplementationDefault;
-    }
-
     #ifdef MAGNUM_TARGET_GLES
     static_cast<void>(context);
     static_cast<void>(extensions);

src/Magnum/GL/Implementation/driverSpecific.cpp

@@ -231,11 +231,12 @@ namespace {
 /* Intel drivers on Windows have some synchronization / memory alignment bug in
    the DSA glNamedBufferData() when the same buffer is set as an index buffer
    to a mesh right after or repeatedly. Calling glBindBuffer() right before or
-   after the data upload fixes the issue. Note that this workaround is done
-   only for buffers with TargetHint::ElementArray, as the issue was not
-   observed elsewhere. Reproducible with the 2019.01 ImGui example,
-   unfortunately I was not able to create a standalone minimal repro case. */
-"intel-windows-buggy-dsa-bufferdata-for-index-buffers",
+   after the data upload fixes the issue. The above is reproducible with the
+   2019.01 ImGui example, however there are numerous reports of things going
+   *bad* in heavier ImGui-based apps and none of my tests are able to reproduce
+   anything. Since I lost patience already, I'm disabling the DSA code paths
+   for everything related to buffers. */
+"intel-windows-crazy-broken-buffer-dsa",
 
 /* ARB_direct_state_access implementation on Intel Windows drivers has broken
    *everything* related to cube map textures (but not cube map arrays) -- data