[Mesa-dev] [PATCH] i965: Move program_id to intel_screen instead of brw_context.

[Kenneth Graunke]

According to bug #54524, I regressed oglconform's multicontext test
when I reenabled the fragment shader precompile.

However, these test cases only passed by miraculous coincedence.  We
assign each fragment program a unique ID (brw_fragment_program::id which
becomes brw_wm_prog_key::program_string_id) which we obtain by storing a
per-context counter.

The test case uses GLX context sharing to access the same fragment
program from two different contexts.  This means that we share a program
cache.  Before the precompile, if both contexts happened to use the same
shaders in the same order, we'd obtain the same program_string_ids (by
virtue of doing the same computation twice).  However, the more likely
scenario is that they completely disagree on program_string_id.

This meant that we'd have two completely different fragment shaders in
the cache with the same ID, tricking us to think they were the same
(aside from NOS), so we'd render using the wrong program.

This patch implements a simple fix suggested by Eric: it moves the
global counter out of brw_context and into intel_screen, which is shared
across all contexts.  A mutex protects it from concurrent access.

This is also the first direct usage of pthreads in the i965 driver.

Fixes 10 subcases of oglconform's multicontext test.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=54524
Cc: Eric Anholt <eric at anholt.net>
---
 src/mesa/drivers/dri/i965/brw_context.h    |  3 ---
 src/mesa/drivers/dri/i965/brw_program.c    | 19 +++++++++++++++----
 src/mesa/drivers/dri/intel/intel_context.c |  3 ++-
 src/mesa/drivers/dri/intel/intel_screen.h  |  5 +++++
 4 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
index c7fc586..f3a3efe 100644
--- a/src/mesa/drivers/dri/i965/brw_context.h
+++ b/src/mesa/drivers/dri/i965/brw_context.h
@@ -1053,9 +1053,6 @@ struct brw_context
       int index;
       bool begin_emitted;
    } query;
-   /* Used to give every program string a unique id
-    */
-   GLuint program_id;
 
    int num_atoms;
    const struct brw_tracked_state **atoms;
diff --git a/src/mesa/drivers/dri/i965/brw_program.c b/src/mesa/drivers/dri/i965/brw_program.c
index 5bfdcca..75eb6bc 100644
--- a/src/mesa/drivers/dri/i965/brw_program.c
+++ b/src/mesa/drivers/dri/i965/brw_program.c
@@ -29,6 +29,7 @@
   *   Keith Whitwell <keith at tungstengraphics.com>
   */
   
+#include <pthread.h>
 #include "main/imports.h"
 #include "main/enums.h"
 #include "main/shaderobj.h"
@@ -41,6 +42,16 @@
 #include "brw_context.h"
 #include "brw_wm.h"
 
+static unsigned
+get_new_program_id(struct intel_screen *screen)
+{
+   static pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER;
+   pthread_mutex_lock(&m);
+   unsigned id = screen->program_id++;
+   pthread_mutex_unlock(&m);
+   return id;
+}
+
 static void brwBindProgram( struct gl_context *ctx,
 			    GLenum target, 
 			    struct gl_program *prog )
@@ -67,7 +78,7 @@ static struct gl_program *brwNewProgram( struct gl_context *ctx,
    case GL_VERTEX_PROGRAM_ARB: {
       struct brw_vertex_program *prog = CALLOC_STRUCT(brw_vertex_program);
       if (prog) {
-	 prog->id = brw->program_id++;
+	 prog->id = get_new_program_id(brw->intel.intelScreen);
 
 	 return _mesa_init_vertex_program( ctx, &prog->program,
 					     target, id );
@@ -79,7 +90,7 @@ static struct gl_program *brwNewProgram( struct gl_context *ctx,
    case GL_FRAGMENT_PROGRAM_ARB: {
       struct brw_fragment_program *prog = CALLOC_STRUCT(brw_fragment_program);
       if (prog) {
-	 prog->id = brw->program_id++;
+	 prog->id = get_new_program_id(brw->intel.intelScreen);
 
 	 return _mesa_init_fragment_program( ctx, &prog->program,
 					     target, id );
@@ -123,7 +134,7 @@ brwProgramStringNotify(struct gl_context *ctx,
 
       if (newFP == curFP)
 	 brw->state.dirty.brw |= BRW_NEW_FRAGMENT_PROGRAM;
-      newFP->id = brw->program_id++;      
+      newFP->id = get_new_program_id(brw->intel.intelScreen);
    }
    else if (target == GL_VERTEX_PROGRAM_ARB) {
       struct gl_vertex_program *vprog = (struct gl_vertex_program *) prog;
@@ -136,7 +147,7 @@ brwProgramStringNotify(struct gl_context *ctx,
       if (newVP->program.IsPositionInvariant) {
 	 _mesa_insert_mvp_code(ctx, &newVP->program);
       }
-      newVP->id = brw->program_id++;      
+      newVP->id = get_new_program_id(brw->intel.intelScreen);
 
       /* Also tell tnl about it:
        */
diff --git a/src/mesa/drivers/dri/intel/intel_context.c b/src/mesa/drivers/dri/intel/intel_context.c
index f3f9983..8b0a4f6 100644
--- a/src/mesa/drivers/dri/intel/intel_context.c
+++ b/src/mesa/drivers/dri/intel/intel_context.c
@@ -609,6 +609,8 @@ intelInitContext(struct intel_context *intel,
       mesaVis = &visual;
    }
 
+   intel->intelScreen = intelScreen;
+
    if (!_mesa_initialize_context(&intel->ctx, api, mesaVis, shareCtx,
                                  functions)) {
       printf("%s: failed to init mesa context\n", __FUNCTION__);
@@ -616,7 +618,6 @@ intelInitContext(struct intel_context *intel,
    }
 
    driContextPriv->driverPrivate = intel;
-   intel->intelScreen = intelScreen;
    intel->driContext = driContextPriv;
    intel->driFd = sPriv->fd;
 
diff --git a/src/mesa/drivers/dri/intel/intel_screen.h b/src/mesa/drivers/dri/intel/intel_screen.h
index f5a374d..8a4a0a2 100644
--- a/src/mesa/drivers/dri/intel/intel_screen.h
+++ b/src/mesa/drivers/dri/intel/intel_screen.h
@@ -65,6 +65,11 @@ struct intel_screen
    struct _mesa_HashTable *named_regions;
 
    /**
+    * A unique ID for shader programs.
+    */
+   unsigned program_id;
+
+   /**
    * Configuration cache with default values for all contexts
    */
    driOptionCache optionCache;
-- 
1.8.1