mesa/main: Add trace dispatch plumbing for MESA_VERBOSE=api

Reintroduce VERBOSE_API as a bit that will cause a parallel trace
dispatch table to be installed at context create. The table itself is
populated in a follow-up commit. This commit only wires the TLS-publish
indirection via _mesa_set_dispatch(..).

With Trace NULL (the common case), the helper is equivalent to a plain
_mesa_glapi_set_dispatch — no behaviour change yet.

Signed-off-by: Christian Gmeiner <cgmeiner@igalia.com>
Assisted-by: Claude

src/mesa/main/context.c

@@ -77,6 +77,7 @@
 
 
 #include "util/glheader.h"
+#include "util/u_thread.h"
 
 #include "accum.h"
 #include "arrayobj.h"
@@ -860,7 +861,7 @@ _mesa_alloc_dispatch_tables(gl_api api, struct gl_dispatch *d, bool glthread)
          return false;
    }
 
-   d->Current = d->Exec = d->OutsideBeginEnd;
+   d->RealPublished = d->Current = d->Exec = d->OutsideBeginEnd;
    return true;
 }
 
@@ -874,6 +875,22 @@ _mesa_free_dispatch_tables(struct gl_dispatch *d)
    free(d->ContextLost);
 }
 
+void
+_mesa_set_dispatch(struct gl_context *ctx, struct _glapi_table *t)
+{
+   /* On the glthread worker, the user-thread wrapper already logged the
+    * call; bypass Trace and don't touch RealPublished (main-thread state).
+    */
+   if (ctx->GLThread.enabled &&
+       u_thread_is_self(ctx->GLThread.queue.threads[0])) {
+      _mesa_glapi_set_dispatch(t);
+      return;
+   }
+
+   ctx->Dispatch.RealPublished = t;
+   _mesa_glapi_set_dispatch(ctx->Dispatch.Trace ? ctx->Dispatch.Trace : t);
+}
+
 bool
 _mesa_initialize_dispatch_tables(struct gl_context *ctx)
 {
@@ -1475,7 +1492,7 @@ _mesa_make_current( struct gl_context *newCtx,
    else {
       _mesa_glapi_set_context((void *) newCtx);
       assert(_mesa_get_current_context() == newCtx);
-      _mesa_glapi_set_dispatch(newCtx->GLApi);
+      _mesa_set_dispatch(newCtx, newCtx->GLApi);
 
       if (drawBuffer && readBuffer) {
          assert(_mesa_is_winsys_fbo(drawBuffer));

src/mesa/main/context.h

@@ -91,6 +91,9 @@ _mesa_alloc_dispatch_tables(gl_api api, struct gl_dispatch *d, bool glthread);
 extern bool
 _mesa_initialize_dispatch_tables(struct gl_context *ctx);
 
+extern void
+_mesa_set_dispatch(struct gl_context *ctx, struct _glapi_table *t);
+
 extern struct _glapi_table *
 _mesa_new_nop_table(bool glthread);
 

src/mesa/main/debug.c

@@ -103,6 +103,7 @@ set_verbose_flags(const char *str)
    static const struct option opts[] = {
       { "state",     VERBOSE_STATE },
       { "list",      VERBOSE_DISPLAY_LIST },
+      { "api",       VERBOSE_API },
    };
    GLuint i;
 

src/mesa/main/dlist.c

@@ -13204,7 +13204,7 @@ _mesa_NewList(GLuint name, GLenum mode)
    vbo_save_NewList(ctx, name, mode);
 
    ctx->Dispatch.Current = ctx->Dispatch.Save;
-   _mesa_glapi_set_dispatch(ctx->Dispatch.Current);
+   _mesa_set_dispatch(ctx, ctx->Dispatch.Current);
    if (!ctx->GLThread.enabled) {
       ctx->GLApi = ctx->Dispatch.Current;
    }
@@ -13423,7 +13423,7 @@ _mesa_EndList(void)
    ctx->CompileFlag = GL_FALSE;
 
    ctx->Dispatch.Current = ctx->Dispatch.Exec;
-   _mesa_glapi_set_dispatch(ctx->Dispatch.Current);
+   _mesa_set_dispatch(ctx, ctx->Dispatch.Current);
    if (!ctx->GLThread.enabled) {
       ctx->GLApi = ctx->Dispatch.Current;
    }

src/mesa/main/glthread.c

@@ -303,7 +303,7 @@ void _mesa_glthread_enable(struct gl_context *ctx)
 
    /* Update the dispatch only if the dispatch is current. */
    if (GET_DISPATCH() == ctx->Dispatch.Current) {
-       _mesa_glapi_set_dispatch(ctx->GLApi);
+       _mesa_set_dispatch(ctx, ctx->GLApi);
    }
 }
 
@@ -323,7 +323,7 @@ void _mesa_glthread_disable(struct gl_context *ctx)
 
    /* Update the dispatch only if the dispatch is current. */
    if (GET_DISPATCH() == ctx->MarshalExec) {
-       _mesa_glapi_set_dispatch(ctx->GLApi);
+       _mesa_set_dispatch(ctx, ctx->GLApi);
    }
 
    /* Unbind VBOs in all VAOs that glthread bound for non-VBO vertex uploads

src/mesa/main/mtypes.h

@@ -3247,6 +3247,9 @@ struct gl_dispatch
     * - ContextLost
     */
    struct _glapi_table *Current;
+
+   struct _glapi_table *Trace;
+   struct _glapi_table *RealPublished;
 };
 
 /**
@@ -3672,6 +3675,7 @@ enum _verbose
 {
    VERBOSE_STATE        = 0x0001,
    VERBOSE_DISPLAY_LIST = 0x0002,
+   VERBOSE_API          = 0x0004,
 };
 
 

src/mesa/main/robustness.c

@@ -104,7 +104,7 @@ _mesa_set_context_lost_dispatch(struct gl_context *ctx)
    }
 
    ctx->Dispatch.Current = ctx->Dispatch.ContextLost;
-   _mesa_glapi_set_dispatch(ctx->Dispatch.Current);
+   _mesa_set_dispatch(ctx, ctx->Dispatch.Current);
 }
 
 /**

src/mesa/vbo/vbo_exec_api.c

@@ -862,7 +862,7 @@ _mesa_Begin(GLenum mode)
          ctx->Dispatch.Current = ctx->Dispatch.Exec;
    } else if (ctx->GLApi == ctx->Dispatch.OutsideBeginEnd) {
       ctx->GLApi = ctx->Dispatch.Current = ctx->Dispatch.Exec;
-      _mesa_glapi_set_dispatch(ctx->GLApi);
+      _mesa_set_dispatch(ctx, ctx->GLApi);
    } else {
       assert(ctx->GLApi == ctx->Dispatch.Save);
    }
@@ -925,7 +925,7 @@ _mesa_End(void)
    } else if (ctx->GLApi == ctx->Dispatch.BeginEnd ||
               ctx->GLApi == ctx->Dispatch.HWSelectModeBeginEnd) {
       ctx->GLApi = ctx->Dispatch.Current = ctx->Dispatch.Exec;
-      _mesa_glapi_set_dispatch(ctx->GLApi);
+      _mesa_set_dispatch(ctx, ctx->GLApi);
    }
 
    if (exec->vtx.prim_count > 0) {