GL: Unbind buffers after mapping them.

Qualcomm drivers generate errors if a bound array buffer is
mapped during a draw call even if it is not used by the draw.

Bug: chromium:1345777
Change-Id: I0639caf5d74c8cbdc7245324fdcb136bd3d51b86
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3871333
Reviewed-by: Peng Huang <penghuang@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>

src/libANGLE/renderer/gl/BufferGL.cpp

@@ -152,19 +152,26 @@ angle::Result BufferGL::map(const gl::Context *context, GLenum access, void **ma
     {
         *mapPtr = mShadowCopy.data();
     }
-    else if (functions->mapBuffer)
-    {
-        stateManager->bindBuffer(DestBufferOperationTarget, mBufferID);
-        *mapPtr = ANGLE_GL_TRY(
-            context, functions->mapBuffer(gl::ToGLenum(DestBufferOperationTarget), access));
-    }
     else
     {
-        ASSERT(functions->mapBufferRange && access == GL_WRITE_ONLY_OES);
         stateManager->bindBuffer(DestBufferOperationTarget, mBufferID);
-        *mapPtr =
-            ANGLE_GL_TRY(context, functions->mapBufferRange(gl::ToGLenum(DestBufferOperationTarget),
-                                                            0, mBufferSize, GL_MAP_WRITE_BIT));
+        if (functions->mapBuffer)
+        {
+            *mapPtr = ANGLE_GL_TRY(
+                context, functions->mapBuffer(gl::ToGLenum(DestBufferOperationTarget), access));
+        }
+        else
+        {
+            ASSERT(functions->mapBufferRange && access == GL_WRITE_ONLY_OES);
+            *mapPtr = ANGLE_GL_TRY(
+                context, functions->mapBufferRange(gl::ToGLenum(DestBufferOperationTarget), 0,
+                                                   mBufferSize, GL_MAP_WRITE_BIT));
+        }
+
+        // Unbind the mapped buffer from the array buffer binding. Some drivers generate errors if
+        // any mapped buffer is bound to array buffer bindings.
+        // crbug.com/1345777
+        stateManager->bindBuffer(DestBufferOperationTarget, 0);
     }
 
     mIsMapped  = true;
@@ -197,6 +204,11 @@ angle::Result BufferGL::mapRange(const gl::Context *context,
         *mapPtr =
             ANGLE_GL_TRY(context, functions->mapBufferRange(gl::ToGLenum(DestBufferOperationTarget),
                                                             offset, length, access));
+
+        // Unbind the mapped buffer from the array buffer binding. Some drivers generate errors if
+        // any mapped buffer is bound to array buffer bindings.
+        // crbug.com/1345777
+        stateManager->bindBuffer(DestBufferOperationTarget, 0);
     }
 
     mIsMapped  = true;

src/tests/gl_tests/BufferDataTest.cpp

@@ -979,6 +979,40 @@ TEST_P(BufferDataTest, BufferSizeValidation32Bit)
     EXPECT_GL_ERROR(GL_INVALID_VALUE);
 }
 
+// Some drivers generate errors when array buffer bindings are left mapped during draw calls.
+// crbug.com/1345777
+TEST_P(BufferDataTestES3, GLDriverErrorWhenMappingArrayBuffersDuringDraw)
+{
+    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::Red());
+    ASSERT_NE(program, 0u);
+
+    glUseProgram(program);
+
+    auto quadVertices = GetQuadVertices();
+
+    GLBuffer vb;
+    glBindBuffer(GL_ARRAY_BUFFER, vb.get());
+    glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * quadVertices.size(), quadVertices.data(),
+                 GL_STATIC_DRAW);
+
+    GLint positionLocation = glGetAttribLocation(program, essl3_shaders::PositionAttrib());
+    ASSERT_NE(-1, positionLocation);
+    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
+    glEnableVertexAttribArray(positionLocation);
+
+    glDrawArrays(GL_TRIANGLES, 0, 6);
+    EXPECT_GL_NO_ERROR();
+
+    GLBuffer pb;
+    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pb);
+    glBufferData(GL_PIXEL_UNPACK_BUFFER, 1024, nullptr, GL_STREAM_DRAW);
+    glMapBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, 1024, GL_MAP_WRITE_BIT);
+    EXPECT_GL_NO_ERROR();
+
+    glDrawArrays(GL_TRIANGLES, 0, 6);
+    EXPECT_GL_NO_ERROR();
+}
+
 // Tests a null crash bug caused by copying from null back-end buffer pointer
 // when calling bufferData again after drawing without calling bufferData in D3D11.
 TEST_P(BufferDataTestES3, DrawWithNotCallingBufferData)