Call onProgramExecutableChange in useProgram.

This cleans up the code slightly and removes a few if checks.
Also fixes a potential edge case with ProgramBinary called on a program
that is in-use.

Bug: angleproject:2763
Change-Id: Ibe0ab20ed44f593bb6c2b0612871680a7df1a15f
Reviewed-on: https://chromium-review.googlesource.com/1254041
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>

src/libANGLE/Context.cpp

@@ -5715,8 +5715,11 @@ void Context::linkProgram(GLuint program)
     //      ProgramD3D.
     if (programObject->isInUse())
     {
-        // isLinked() which forces to resolve linking, will be called.
-        mGLState.onProgramExecutableChange(programObject);
+        if (programObject->isLinked())
+        {
+            mGLState.onProgramExecutableChange(programObject);
+        }
+
         mStateCache.onProgramExecutableChange(this);
     }
 }
@@ -5927,10 +5930,10 @@ void Context::programBinary(GLuint program, GLenum binaryFormat, const void *bin
     ASSERT(programObject != nullptr);
 
     handleError(programObject->loadBinary(this, binaryFormat, binary, length));
-    mStateCache.onProgramExecutableChange(this);
     if (programObject->isInUse())
     {
-        mGLState.setObjectDirty(GL_PROGRAM);
+        mGLState.onProgramExecutableChange(programObject);
+        mStateCache.onProgramExecutableChange(this);
     }
 }
 

src/libANGLE/State.cpp

@@ -1344,11 +1344,13 @@ void State::setProgram(const Context *context, Program *newProgram)
         if (mProgram)
         {
             newProgram->addRef();
-            mDirtyObjects.set(DIRTY_OBJECT_PROGRAM_TEXTURES);
+            onProgramExecutableChange(newProgram);
         }
-        mDirtyBits.set(DIRTY_BIT_PROGRAM_EXECUTABLE);
+
+        // Note that rendering is undefined if glUseProgram(0) is called. But ANGLE will generate
+        // an error if the app tries to draw in this case.
+
         mDirtyBits.set(DIRTY_BIT_PROGRAM_BINDING);
-        mDirtyObjects.set(DIRTY_OBJECT_PROGRAM);
     }
 }
 
@@ -2879,12 +2881,11 @@ void State::onProgramExecutableChange(Program *program)
     // "If LinkProgram or ProgramBinary successfully re-links a program object
     //  that was already in use as a result of a previous call to UseProgram, then the
     //  generated executable code will be installed as part of the current rendering state."
-    if (program->isLinked() && mProgram == program)
-    {
-        mDirtyBits.set(DIRTY_BIT_PROGRAM_EXECUTABLE);
-        mDirtyObjects.set(DIRTY_OBJECT_PROGRAM_TEXTURES);
-        mDirtyObjects.set(DIRTY_OBJECT_PROGRAM);
-    }
+    ASSERT(program->isLinked());
+
+    mDirtyBits.set(DIRTY_BIT_PROGRAM_EXECUTABLE);
+    mDirtyObjects.set(DIRTY_OBJECT_PROGRAM_TEXTURES);
+    mDirtyObjects.set(DIRTY_OBJECT_PROGRAM);
 }
 
 void State::setSamplerDirty(size_t samplerIndex)