mesa/vbo: move some Draw checks out of validation

These checks do not generate any errors. Move them so we can add
KHR_no_error support and still make sure we do these checks.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

src/mesa/main/api_validate.c

@@ -290,15 +290,6 @@ check_valid_to_render(struct gl_context *ctx, const char *function)
                      "%s(tess ctrl shader is missing)", function);
          return false;
       }
-
-      /* For ES2, we can draw if we have a vertex program/shader). */
-      return ctx->VertexProgram._Current != NULL;
-
-   case API_OPENGLES:
-      /* For OpenGL ES, only draw if we have vertex positions
-       */
-      if (!ctx->Array.VAO->VertexAttrib[VERT_ATTRIB_POS].Enabled)
-         return false;
       break;
 
    case API_OPENGL_CORE:
@@ -312,32 +303,10 @@ check_valid_to_render(struct gl_context *ctx, const char *function)
          _mesa_error(ctx, GL_INVALID_OPERATION, "%s(no VAO bound)", function);
          return false;
       }
+      break;
 
-      /* Section 7.3 (Program Objects) of the OpenGL 4.5 Core Profile spec
+   case API_OPENGLES:
-       * says:
-       *
-       *     "If there is no active program for the vertex or fragment shader
-       *     stages, the results of vertex and/or fragment processing will be
-       *     undefined. However, this is not an error."
-       *
-       * The fragment shader is not tested here because other state (e.g.,
-       * GL_RASTERIZER_DISCARD) affects whether or not we actually care.
-       */
-      return ctx->VertexProgram._Current != NULL;
-
    case API_OPENGL_COMPAT:
-      if (ctx->VertexProgram._Current != NULL) {
-         /* Draw regardless of whether or not we have any vertex arrays.
-          * (Ex: could draw a point using a constant vertex pos)
-          */
-         return true;
-      } else {
-         /* Draw if we have vertex positions (GL_VERTEX_ARRAY or generic
-          * array [0]).
-          */
-         return (ctx->Array.VAO->VertexAttrib[VERT_ATTRIB_POS].Enabled ||
-                 ctx->Array.VAO->VertexAttrib[VERT_ATTRIB_GENERIC0].Enabled);
-      }
       break;
 
    default:
@@ -700,14 +669,6 @@ validate_DrawElements_common(struct gl_context *ctx,
    if (!check_valid_to_render(ctx, caller))
       return false;
 
-   /* Not using a VBO for indices, so avoid NULL pointer derefs later.
-    */
-   if (!_mesa_is_bufferobj(ctx->Array.VAO->IndexBufferObj) && indices == NULL)
-      return false;
-
-   if (count == 0)
-      return false;
-
    return true;
 }
 

src/mesa/vbo/vbo_exec_array.c

@@ -179,6 +179,60 @@ check_draw_arrays_data(struct gl_context *ctx, GLint start, GLsizei count)
 }
 
 
+/**
+ * Check if we should skip the draw call even after validation was successful.
+ */
+static bool
+skip_validated_draw(struct gl_context *ctx)
+{
+   switch (ctx->API) {
+   case API_OPENGLES2:
+      /* For ES2, we can draw if we have a vertex program/shader). */
+      return ctx->VertexProgram._Current == NULL;
+
+   case API_OPENGLES:
+      /* For OpenGL ES, only draw if we have vertex positions
+       */
+      if (ctx->Array.VAO->VertexAttrib[VERT_ATTRIB_POS].Enabled)
+         return false;
+      break;
+
+   case API_OPENGL_CORE:
+      /* Section 7.3 (Program Objects) of the OpenGL 4.5 Core Profile spec
+       * says:
+       *
+       *     "If there is no active program for the vertex or fragment shader
+       *     stages, the results of vertex and/or fragment processing will be
+       *     undefined. However, this is not an error."
+       *
+       * The fragment shader is not tested here because other state (e.g.,
+       * GL_RASTERIZER_DISCARD) affects whether or not we actually care.
+       */
+      return ctx->VertexProgram._Current == NULL;
+
+   case API_OPENGL_COMPAT:
+      if (ctx->VertexProgram._Current != NULL) {
+         /* Draw regardless of whether or not we have any vertex arrays.
+          * (Ex: could draw a point using a constant vertex pos)
+          */
+         return false;
+      } else {
+         /* Draw if we have vertex positions (GL_VERTEX_ARRAY or generic
+          * array [0]).
+          */
+         return (!ctx->Array.VAO->VertexAttrib[VERT_ATTRIB_POS].Enabled &&
+                 !ctx->Array.VAO->VertexAttrib[VERT_ATTRIB_GENERIC0].Enabled);
+      }
+      break;
+
+   default:
+      unreachable("Invalid API value in check_valid_to_render()");
+   }
+
+   return false;
+}
+
+
 /**
  * Print info/data for glDrawArrays(), for debugging.
  */
@@ -410,6 +464,9 @@ vbo_draw_arrays(struct gl_context *ctx, GLenum mode, GLint start,
    struct vbo_context *vbo = vbo_context(ctx);
    struct _mesa_prim prim[2];
 
+   if (skip_validated_draw(ctx))
+      return;
+
    vbo_bind_arrays(ctx);
 
    /* OpenGL 4.5 says that primitive restart is ignored with non-indexed
@@ -739,6 +796,25 @@ dump_element_buffer(struct gl_context *ctx, GLenum type)
 #endif
 
 
+static bool
+skip_draw_elements(struct gl_context *ctx, GLsizei count,
+                   const GLvoid *indices)
+{
+   if (count == 0)
+      return true;
+
+   /* Not using a VBO for indices, so avoid NULL pointer derefs later.
+    */
+   if (!_mesa_is_bufferobj(ctx->Array.VAO->IndexBufferObj) && indices == NULL)
+      return true;
+
+   if (skip_validated_draw(ctx))
+      return true;
+
+   return false;
+}
+
+
 /**
  * Inner support for both _mesa_DrawElements and _mesa_DrawRangeElements.
  * Do the rendering for a glDrawElements or glDrawRangeElements call after
@@ -757,6 +833,9 @@ vbo_validated_drawrangeelements(struct gl_context *ctx, GLenum mode,
    struct _mesa_index_buffer ib;
    struct _mesa_prim prim[1];
 
+   if (skip_draw_elements(ctx, count, indices))
+      return;
+
    vbo_bind_arrays(ctx);
 
    ib.count = count;
@@ -1230,6 +1309,9 @@ vbo_exec_MultiDrawElements(GLenum mode,
                                          primcount))
       return;
 
+   if (skip_validated_draw(ctx))
+      return;
+
    vbo_validated_multidrawelements(ctx, mode, count, type, indices, primcount,
                                    NULL);
 }
@@ -1248,6 +1330,9 @@ vbo_exec_MultiDrawElementsBaseVertex(GLenum mode,
                                          primcount))
       return;
 
+   if (skip_validated_draw(ctx))
+      return;
+
    vbo_validated_multidrawelements(ctx, mode, count, type, indices, primcount,
                                    basevertex);
 }
@@ -1275,6 +1360,9 @@ vbo_draw_transform_feedback(struct gl_context *ctx, GLenum mode,
       return;
    }
 
+   if (skip_validated_draw(ctx))
+      return;
+
    vbo_bind_arrays(ctx);
 
    /* init most fields to zero */
@@ -1482,6 +1570,9 @@ vbo_exec_DrawArraysIndirect(GLenum mode, const GLvoid *indirect)
    if (!_mesa_validate_DrawArraysIndirect(ctx, mode, indirect))
       return;
 
+   if (skip_validated_draw(ctx))
+      return;
+
    vbo_validated_drawarraysindirect(ctx, mode, indirect);
 }
 
@@ -1499,6 +1590,9 @@ vbo_exec_DrawElementsIndirect(GLenum mode, GLenum type, const GLvoid *indirect)
    if (!_mesa_validate_DrawElementsIndirect(ctx, mode, type, indirect))
       return;
 
+   if (skip_validated_draw(ctx))
+      return;
+
    vbo_validated_drawelementsindirect(ctx, mode, type, indirect);
 }
 
@@ -1521,6 +1615,9 @@ vbo_exec_MultiDrawArraysIndirect(GLenum mode, const GLvoid *indirect,
                                                primcount, stride))
       return;
 
+   if (skip_validated_draw(ctx))
+      return;
+
    vbo_validated_multidrawarraysindirect(ctx, mode, indirect,
                                          primcount, stride);
 }
@@ -1546,6 +1643,9 @@ vbo_exec_MultiDrawElementsIndirect(GLenum mode, GLenum type,
                                                  primcount, stride))
       return;
 
+   if (skip_validated_draw(ctx))
+      return;
+
    vbo_validated_multidrawelementsindirect(ctx, mode, type, indirect,
                                            primcount, stride);
 }
@@ -1634,6 +1734,9 @@ vbo_exec_MultiDrawArraysIndirectCount(GLenum mode, GLintptr indirect,
                                                     maxdrawcount, stride))
       return;
 
+   if (skip_validated_draw(ctx))
+      return;
+
    vbo_validated_multidrawarraysindirectcount(ctx, mode, indirect, drawcount,
                                               maxdrawcount, stride);
 }
@@ -1662,6 +1765,9 @@ vbo_exec_MultiDrawElementsIndirectCount(GLenum mode, GLenum type,
                                                       maxdrawcount, stride))
       return;
 
+   if (skip_validated_draw(ctx))
+      return;
+
    vbo_validated_multidrawelementsindirectcount(ctx, mode, type, indirect,
                                                 drawcount, maxdrawcount,
                                                 stride);