Squashed commit of the following (st-mesa-per-context-shaders branch):

commit 4f106f44a32eaddb6cf3fea6ba5ee9787bff609a
Author: Brian Paul <brianp@vmware.com>
Date:   Mon Dec 13 14:06:08 2010 -0700

    st/mesa: reorganize vertex program translation code

    Now it looks like the fragment and geometry program code.
    Also remove the serial number fields from programs.  It was used to
    determine when new translations were needed.  Now the variant key is
    used for that.  And the st_program_string_notify() callback removes all
    variants when the program's code is changed.

commit e12d6791c5e4bff60bb2e6c04414b1b4d1325f3e
Author: Brian Paul <brianp@vmware.com>
Date:   Mon Dec 13 13:38:12 2010 -0700

    st/mesa: implement geometry shader varients

    Only needed in order to support per-context gallium shaders.

commit c5751c673644808ab069259a852f24c4c0e92b9d
Author: Brian Paul <brianp@vmware.com>
Date:   Sun Dec 12 15:28:57 2010 -0700

    st/mesa: restore glDraw/CopyPixels using new fragment program variants

    Clean up the logic for fragment programs for glDraw/CopyPixels.  We now
    generate fragment program variants for glDraw/CopyPixels as needed which
    do texture sampling, pixel scale/bias, pixelmap lookups, etc.

commit 7b0bb99bab6547f503a0176b5c0aef1482b02c97
Author: Brian Paul <brianp@vmware.com>
Date:   Fri Dec 10 17:03:23 2010 -0700

    st/mesa: checkpoint: implement fragment program variants

    The fragment programs variants are per-context, as the vertex programs.

    NOTE: glDrawPixels is totally broken at this point.

commit 2cc926183f957f8abac18d71276dd5bbd1f27be2
Author: Brian Paul <brianp@vmware.com>
Date:   Fri Dec 10 14:59:32 2010 -0700

    st/mesa: make vertex shader variants per-context

    Gallium shaders are per-context but OpenGL shaders aren't.  So we need
    to make a different variant for each context.

    During context tear-down we need to walk over all shaders/programs and
    free all variants for the context being destroyed.

1 files changed, 38 insertions, 105 deletions

diff --git a/src/mesa/state_tracker/st_atom_shader.c b/src/mesa/state_tracker/st_atom_shader.c
index 05442ef91b..f416293a7e 100644
--- a/src/mesa/state_tracker/st_atom_shader.c
+++ b/src/mesa/state_tracker/st_atom_shader.c
@@ -50,99 +50,6 @@
 #include "st_program.h"
 
 
-
-/**
- * Translate fragment program if needed.
- */
-static void
-translate_fp(struct st_context *st,
-             struct st_fragment_program *stfp)
-{
-   if (!stfp->tgsi.tokens) {
-      assert(stfp->Base.Base.NumInstructions > 0);
-
-      st_translate_fragment_program(st, stfp);
-   }
-}
-
-/*
- * Translate geometry program if needed.
- */
-static void
-translate_gp(struct st_context *st,
-             struct st_geometry_program *stgp)
-{
-   if (!stgp->tgsi.tokens) {
-      assert(stgp->Base.Base.NumInstructions > 1);
-
-      st_translate_geometry_program(st, stgp);
-   }
-}
-
-/**
- * Find a translated vertex program that corresponds to stvp and
- * has outputs matched to stfp's inputs.
- * This performs vertex and fragment translation (to TGSI) when needed.
- */
-static struct st_vp_varient *
-find_translated_vp(struct st_context *st,
-                   struct st_vertex_program *stvp )
-{
-   struct st_vp_varient *vpv;
-   struct st_vp_varient_key key;
-
-   /* Nothing in our key yet.  This will change:
-    */
-   memset(&key, 0, sizeof key);
-
-   /* When this is true, we will add an extra input to the vertex
-    * shader translation (for edgeflags), an extra output with
-    * edgeflag semantics, and extend the vertex shader to pass through
-    * the input to the output.  We'll need to use similar logic to set
-    * up the extra vertex_element input for edgeflags.
-    * _NEW_POLYGON, ST_NEW_EDGEFLAGS_DATA
-    */
-   key.passthrough_edgeflags = (st->vertdata_edgeflags && (
-                                st->ctx->Polygon.FrontMode != GL_FILL ||
-                                st->ctx->Polygon.BackMode != GL_FILL));
-
-
-   /* Do we need to throw away old translations after a change in the
-    * GL program string?
-    */
-   if (stvp->serialNo != stvp->lastSerialNo) {
-      /* These may have changed if the program string changed.
-       */
-      st_prepare_vertex_program( st, stvp );
-
-      /* We are now up-to-date:
-       */
-      stvp->lastSerialNo = stvp->serialNo;
-   }
-   
-   /* See if we've got a translated vertex program whose outputs match
-    * the fragment program's inputs.
-    */
-   for (vpv = stvp->varients; vpv; vpv = vpv->next) {
-      if (memcmp(&vpv->key, &key, sizeof key) == 0) {
-         break;
-      }
-   }
-
-   /* No?  Perform new translation here. */
-   if (!vpv) {
-      vpv = st_translate_vertex_program(st, stvp, &key);
-      if (!vpv)
-         return NULL;
-      
-      vpv->next = stvp->varients;
-      stvp->varients = vpv;
-   }
-
-   return vpv;
-}
-
-
 /**
  * Return pointer to a pass-through fragment shader.
  * This shader is used when a texture is missing/incomplete.
@@ -167,12 +74,16 @@ static void
 update_fp( struct st_context *st )
 {
    struct st_fragment_program *stfp;
+   struct st_fp_varient_key key;
 
    assert(st->ctx->FragmentProgram._Current);
    stfp = st_fragment_program(st->ctx->FragmentProgram._Current);
    assert(stfp->Base.Base.Target == GL_FRAGMENT_PROGRAM_ARB);
 
-   translate_fp(st, stfp);
+   memset(&key, 0, sizeof(key));
+   key.st = st;
+
+   st->fp_varient = st_get_fp_varient(st, stfp, &key);
 
    st_reference_fragprog(st, &st->fp, stfp);
 
@@ -182,7 +93,8 @@ update_fp( struct st_context *st )
       cso_set_fragment_shader_handle(st->cso_context, fs);
    }
    else {
-      cso_set_fragment_shader_handle(st->cso_context, stfp->driver_shader);
+      cso_set_fragment_shader_handle(st->cso_context,
+                                     st->fp_varient->driver_shader);
    }
 }
 
@@ -206,6 +118,7 @@ static void
 update_vp( struct st_context *st )
 {
    struct st_vertex_program *stvp;
+   struct st_vp_varient_key key;
 
    /* find active shader and params -- Should be covered by
     * ST_NEW_VERTEX_PROGRAM
@@ -214,7 +127,21 @@ update_vp( struct st_context *st )
    stvp = st_vertex_program(st->ctx->VertexProgram._Current);
    assert(stvp->Base.Base.Target == GL_VERTEX_PROGRAM_ARB);
 
-   st->vp_varient = find_translated_vp(st, stvp);
+   memset(&key, 0, sizeof key);
+   key.st = st;  /* variants are per-context */
+
+   /* When this is true, we will add an extra input to the vertex
+    * shader translation (for edgeflags), an extra output with
+    * edgeflag semantics, and extend the vertex shader to pass through
+    * the input to the output.  We'll need to use similar logic to set
+    * up the extra vertex_element input for edgeflags.
+    * _NEW_POLYGON, ST_NEW_EDGEFLAGS_DATA
+    */
+   key.passthrough_edgeflags = (st->vertdata_edgeflags && (
+                                st->ctx->Polygon.FrontMode != GL_FILL ||
+                                st->ctx->Polygon.BackMode != GL_FILL));
+
+   st->vp_varient = st_get_vp_varient(st, stvp, &key);
 
    st_reference_vertprog(st, &st->vp, stvp);
 
@@ -231,14 +158,16 @@ const struct st_tracked_state st_update_vp = {
       _NEW_POLYGON,					/* mesa */
       ST_NEW_VERTEX_PROGRAM | ST_NEW_EDGEFLAGS_DATA	/* st */
    },
-   update_vp					/* update */
+   update_vp						/* update */
 };
 
+
+
 static void
 update_gp( struct st_context *st )
 {
-
    struct st_geometry_program *stgp;
+   struct st_gp_varient_key key;
 
    if (!st->ctx->GeometryProgram._Current) {
       cso_set_geometry_shader_handle(st->cso_context, NULL);
@@ -248,18 +177,22 @@ update_gp( struct st_context *st )
    stgp = st_geometry_program(st->ctx->GeometryProgram._Current);
    assert(stgp->Base.Base.Target == MESA_GEOMETRY_PROGRAM);
 
-   translate_gp(st, stgp);
+   memset(&key, 0, sizeof(key));
+   key.st = st;
+
+   st->gp_varient = st_get_gp_varient(st, stgp, &key);
 
    st_reference_geomprog(st, &st->gp, stgp);
 
-   cso_set_geometry_shader_handle(st->cso_context, stgp->driver_shader);
+   cso_set_geometry_shader_handle(st->cso_context,
+                                  st->gp_varient->driver_shader);
 }
 
 const struct st_tracked_state st_update_gp = {
-   "st_update_gp",					/* name */
-   {							/* dirty */
-      0,						/* mesa */
-      ST_NEW_GEOMETRY_PROGRAM                           /* st */
+   "st_update_gp",			/* name */
+   {					/* dirty */
+      0,				/* mesa */
+      ST_NEW_GEOMETRY_PROGRAM           /* st */
    },
-   update_gp  					/* update */
+   update_gp  				/* update */
 };