Disallow active attrib aliasing at shader program link time.

gpu/command_buffer/service/program_manager.cc

Index: gpu/command_buffer/service/program_manager.cc
diff --git a/gpu/command_buffer/service/program_manager.cc b/gpu/command_buffer/service/program_manager.cc
index d555be4ce1ccd6e00c9221889c95488fc98ac5b5..e8196f6c201e3ffa7b73845730f9aed81b830f28 100644
--- a/gpu/command_buffer/service/program_manager.cc
+++ b/gpu/command_buffer/service/program_manager.cc
@@ -493,7 +493,7 @@ void Program::ExecuteBindAttribLocationCalls() {
   for (LocationMap::const_iterator it = bind_attrib_location_map_.begin();
        it != bind_attrib_location_map_.end(); ++it) {
     const std::string* mapped_name = GetAttribMappedName(it->first);
-    if (mapped_name && *mapped_name != it->first)

[Ken Russell (switch to Gerrit), 2014/10/11 03:29:03]

Do you know why this test used to be there and what the effect is of taking it
out?

[Zhenyao Mo, 2014/10/11 04:30:08]

It's used to be there because we do call glBindAttribLocation in the
bindAttribLocation command, and if we don't turn on name hashing, then this
mapped_name should equal the original_name.  However, I plan to take out the
glBindAttribLocation call (see my other comment), so this will never be true in
that case.  This is never true anyway because we always do name hashing.

+    if (mapped_name)
       glBindAttribLocation(service_id_, it->second, mapped_name->c_str());
   }
 }
@@ -655,10 +655,10 @@ GLint Program::GetUniformFakeLocation(
 }
 
 GLint Program::GetAttribLocation(
-    const std::string& name) const {
+    const std::string& original_name) const {
   for (GLuint ii = 0; ii < attrib_infos_.size(); ++ii) {
     const VertexAttrib& info = attrib_infos_[ii];
-    if (info.name == name) {
+    if (info.name == original_name) {
       return info.location;
     }
   }
@@ -989,21 +989,44 @@ bool Program::DetectAttribLocationBindingConflicts() const {
   std::set<GLint> location_binding_used;
   for (LocationMap::const_iterator it = bind_attrib_location_map_.begin();
        it != bind_attrib_location_map_.end(); ++it) {
-    // Find out if an attribute is declared in this program's shaders.
-    bool active = false;
+    // Find out if an attribute is statically used in this program's shaders.
+    const sh::Attribute* attrib = NULL;
+    const std::string* mapped_name = GetAttribMappedName(it->first);
+    if (!mapped_name)
+      continue;
     for (int ii = 0; ii < kMaxAttachedShaders; ++ii) {
       if (!attached_shaders_[ii].get() || !attached_shaders_[ii]->valid())
         continue;
-      if (attached_shaders_[ii]->GetAttribInfo(it->first)) {
-        active = true;
-        break;
+      attrib = attached_shaders_[ii]->GetAttribInfo(*mapped_name);
+      if (attrib) {
+        if (attrib->staticUse)
+          break;
+        else
+          attrib = NULL;
       }
     }
-    if (active) {
-      std::pair<std::set<GLint>::iterator, bool> result =
-          location_binding_used.insert(it->second);
-      if (!result.second)
-        return true;
+    if (attrib) {
+      size_t num_of_locations = 1;
+      switch (attrib->type) {
+        case GL_FLOAT_MAT2:
+          num_of_locations = 2;
+          break;
+        case GL_FLOAT_MAT3:
+          num_of_locations = 3;
+          break;
+        case GL_FLOAT_MAT4:
+          num_of_locations = 4;
+          break;
+        default:
+          break;
+      }
+      for (size_t ii = 0; ii < num_of_locations; ++ii) {
+        GLint loc = it->second + ii;
+        std::pair<std::set<GLint>::iterator, bool> result =
+            location_binding_used.insert(loc);
+        if (!result.second)
+          return true;
+      }
     }
   }
   return false;