[Mesa-dev] [PATCH 3/3] mesa: don't check mapped buffers in every draw call if drivers allow it

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

Before: DrawElements (16 VBOs) w/ no state change: 4.34 million/s
After:  DrawElements (16 VBOs) w/ no state change: 8.80 million/s

This inefficiency was uncovered by Timothy Arceri's no_error work.
---
 src/mesa/main/api_validate.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/mesa/main/api_validate.c b/src/mesa/main/api_validate.c
index cbb2361..b804e05 100644
--- a/src/mesa/main/api_validate.c
+++ b/src/mesa/main/api_validate.c
@@ -236,21 +236,34 @@ _mesa_valid_to_render(struct gl_context *ctx, const char *where)
 /**
  * Check if OK to draw arrays/elements.
  */
 static bool
 check_valid_to_render(struct gl_context *ctx, const char *function)
 {
    if (!_mesa_valid_to_render(ctx, function)) {
       return false;
    }
 
-   if (!_mesa_all_buffers_are_unmapped(ctx->Array.VAO)) {
+   /* Section 6.3.2 from the GL 4.5:
+    * "Any GL command which attempts to read from, write to, or change
+    *  the state of a buffer object may generate an INVALID_OPERATION error if
+    *  all or part of the buffer object is mapped ... However, only commands
+    *  which explicitly describe this error are required to do so. If an error
+    *  is not generated, such commands will have undefined results and may
+    *  result in GL interruption or termination."
+    *
+    * Only some buffer API functions require INVALID_OPERATION with mapped
+    * buffers. No other functions list such an error, thus it's not required
+    * to report INVALID_OPERATION for draw calls with mapped buffers.
+    */
+   if (!ctx->Const.AllowMappedBuffersDuringExecution &&
+       !_mesa_all_buffers_are_unmapped(ctx->Array.VAO)) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "%s(vertex buffers are mapped)", function);
       return false;
    }
 
    /* Section 11.2 (Tessellation) of the ES 3.2 spec says:
     *
     * "An INVALID_OPERATION error is generated by any command that
     *  transfers vertices to the GL if the current program state has
     *  one but not both of a tessellation control shader and tessellation
-- 
2.7.4