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, 127 insertions, 72 deletions

diff --git a/src/mesa/state_tracker/st_cb_drawpixels.c b/src/mesa/state_tracker/st_cb_drawpixels.c
index c978602457..323e7e357e 100644
--- a/src/mesa/state_tracker/st_cb_drawpixels.c
+++ b/src/mesa/state_tracker/st_cb_drawpixels.c
@@ -94,88 +94,61 @@ is_passthrough_program(const struct gl_fragment_program *prog)
 /**
  * Make fragment shader for glDraw/CopyPixels.  This shader is made
  * by combining the pixel transfer shader with the user-defined shader.
- * \return pointer to Gallium driver fragment shader
+ * \param fpIn  the current/incoming fragment program
+ * \param fpOut  returns the combined fragment program
  */
-static void *
-combined_drawpix_fragment_program(struct gl_context *ctx)
+void
+st_make_drawpix_fragment_program(struct st_context *st,
+                                 struct gl_fragment_program *fpIn,
+                                 struct gl_fragment_program **fpOut)
 {
-   struct st_context *st = st_context(ctx);
-   struct st_fragment_program *stfp;
+   struct gl_program *newProg;
 
-   if (st->pixel_xfer.program->serialNo == st->pixel_xfer.xfer_prog_sn
-       && st->fp->serialNo == st->pixel_xfer.user_prog_sn) {
-      /* the pixel tranfer program has not changed and the user-defined
-       * program has not changed, so re-use the combined program.
-       */
-      stfp = st->pixel_xfer.combined_prog;
+   if (is_passthrough_program(fpIn)) {
+      newProg = (struct gl_program *) _mesa_clone_fragment_program(st->ctx,
+                                             &st->pixel_xfer.program->Base);
    }
    else {
-      /* Concatenate the pixel transfer program with the current user-
-       * defined program.
-       */
-      if (is_passthrough_program(&st->fp->Base)) {
-         stfp = (struct st_fragment_program *)
-            _mesa_clone_fragment_program(ctx, &st->pixel_xfer.program->Base);
-      }
-      else {
 #if 0
-         printf("Base program:\n");
-         _mesa_print_program(&st->fp->Base.Base);
-         printf("DrawPix program:\n");
-         _mesa_print_program(&st->pixel_xfer.program->Base.Base);
+      /* debug */
+      printf("Base program:\n");
+      _mesa_print_program(&fpIn->Base);
+      printf("DrawPix program:\n");
+      _mesa_print_program(&st->pixel_xfer.program->Base.Base);
 #endif
-         stfp = (struct st_fragment_program *)
-            _mesa_combine_programs(ctx,
-                                   &st->pixel_xfer.program->Base.Base,
-                                   &st->fp->Base.Base);
-      }
+      newProg = _mesa_combine_programs(st->ctx,
+                                       &st->pixel_xfer.program->Base.Base,
+                                       &fpIn->Base);
+   }
 
 #if 0
-      {
-         struct gl_program *p = &stfp->Base.Base;
-         printf("Combined DrawPixels program:\n");
-         _mesa_print_program(p);
-         printf("InputsRead: 0x%x\n", p->InputsRead);
-         printf("OutputsWritten: 0x%x\n", p->OutputsWritten);
-         _mesa_print_parameter_list(p->Parameters);
-      }
+   /* debug */
+   printf("Combined DrawPixels program:\n");
+   _mesa_print_program(newProg);
+   printf("InputsRead: 0x%x\n", newProg->InputsRead);
+   printf("OutputsWritten: 0x%x\n", newProg->OutputsWritten);
+   _mesa_print_parameter_list(newProg->Parameters);
 #endif
 
-      /* translate to TGSI tokens */
-      st_translate_fragment_program(st, stfp);
-
-      /* save new program, update serial numbers */
-      st->pixel_xfer.xfer_prog_sn = st->pixel_xfer.program->serialNo;
-      st->pixel_xfer.user_prog_sn = st->fp->serialNo;
-      st->pixel_xfer.combined_prog_sn = stfp->serialNo;
-      /* can't reference new program directly, already have a reference on it */
-      st_reference_fragprog(st, &st->pixel_xfer.combined_prog, NULL);
-      st->pixel_xfer.combined_prog = stfp;
-   }
-
-   /* Ideally we'd have updated the pipe constants during the normal
-    * st/atom mechanism.  But we can't since this is specific to glDrawPixels.
-    */
-   st_upload_constants(st, stfp->Base.Base.Parameters, PIPE_SHADER_FRAGMENT);
-
-   return stfp->driver_shader;
+   *fpOut = (struct gl_fragment_program *) newProg;
 }
 
 
 /**
- * Create fragment shader that does a TEX() instruction to get a Z and/or
+ * Create fragment program that does a TEX() instruction to get a Z and/or
  * stencil value value, then writes to FRAG_RESULT_DEPTH/FRAG_RESULT_STENCIL.
  * Used for glDrawPixels(GL_DEPTH_COMPONENT / GL_STENCIL_INDEX).
  * Pass fragment color through as-is.
- * \return pointer to the Gallium driver fragment shader
+ * \return pointer to the gl_fragment program
  */
-static void *
-make_fragment_shader_z_stencil(struct st_context *st, GLboolean write_depth,
-                               GLboolean write_stencil)
+struct gl_fragment_program *
+st_make_drawpix_z_stencil_program(struct st_context *st,
+                                  GLboolean write_depth,
+                                  GLboolean write_stencil)
 {
    struct gl_context *ctx = st->ctx;
    struct gl_program *p;
-   struct st_fragment_program *stp;
+   struct gl_fragment_program *fp;
    GLuint ic = 0;
    const GLuint shaderIndex = write_depth * 2 + write_stencil;
 
@@ -183,7 +156,7 @@ make_fragment_shader_z_stencil(struct st_context *st, GLboolean write_depth,
 
    if (st->drawpix.shaders[shaderIndex]) {
       /* already have the proper shader */
-      return st->drawpix.shaders[shaderIndex]->driver_shader;
+      return st->drawpix.shaders[shaderIndex];
    }
 
    /*
@@ -245,18 +218,15 @@ make_fragment_shader_z_stencil(struct st_context *st, GLboolean write_depth,
    if (write_stencil)
       p->SamplersUsed |= 1 << 1;
 
-   stp = st_fragment_program((struct gl_fragment_program *) p);
+   fp = (struct gl_fragment_program *) p;
 
    /* save the new shader */
-   st->drawpix.shaders[shaderIndex] = stp;
+   st->drawpix.shaders[shaderIndex] = fp;
 
-   st_translate_fragment_program(st, stp);
-
-   return stp->driver_shader;
+   return fp;
 }
 
 
-
 /**
  * Create a simple vertex shader that just passes through the
  * vertex position and texcoord (and optionally, color).
@@ -873,6 +843,61 @@ draw_stencil_pixels(struct gl_context *ctx, GLint x, GLint y,
 
 
 /**
+ * Get fragment program variant for a glDrawPixels or glCopyPixels
+ * command for RGBA data.
+ */
+static struct st_fp_varient *
+get_color_fp_varient(struct st_context *st)
+{
+   struct gl_context *ctx = st->ctx;
+   struct st_fp_varient_key key;
+   struct st_fp_varient *fpv;
+
+   memset(&key, 0, sizeof(key));
+
+   key.st = st;
+   key.drawpixels = 1;
+   key.scaleAndBias = (ctx->Pixel.RedBias != 0.0 ||
+                       ctx->Pixel.RedScale != 1.0 ||
+                       ctx->Pixel.GreenBias != 0.0 ||
+                       ctx->Pixel.GreenScale != 1.0 ||
+                       ctx->Pixel.BlueBias != 0.0 ||
+                       ctx->Pixel.BlueScale != 1.0 ||
+                       ctx->Pixel.AlphaBias != 0.0 ||
+                       ctx->Pixel.AlphaScale != 1.0);
+   key.pixelMaps = ctx->Pixel.MapColorFlag;
+
+   fpv = st_get_fp_varient(st, st->fp, &key);
+
+   return fpv;
+}
+
+
+/**
+ * Get fragment program variant for a glDrawPixels or glCopyPixels
+ * command for depth/stencil data.
+ */
+static struct st_fp_varient *
+get_depth_stencil_fp_varient(struct st_context *st, GLboolean write_depth,
+                             GLboolean write_stencil)
+{
+   struct st_fp_varient_key key;
+   struct st_fp_varient *fpv;
+
+   memset(&key, 0, sizeof(key));
+
+   key.st = st;
+   key.drawpixels = 1;
+   key.drawpixels_z = write_depth;
+   key.drawpixels_stencil = write_stencil;
+
+   fpv = st_get_fp_varient(st, st->fp, &key);
+
+   return fpv;
+}
+
+
+/**
  * Called via ctx->Driver.DrawPixels()
  */
 static void
@@ -889,6 +914,7 @@ st_DrawPixels(struct gl_context *ctx, GLint x, GLint y,
    struct pipe_sampler_view *sv[2];
    int num_sampler_view = 1;
    enum pipe_format stencil_format = PIPE_FORMAT_NONE;
+   struct st_fp_varient *fpv;
 
    if (format == GL_DEPTH_STENCIL)
       write_stencil = write_depth = GL_TRUE;
@@ -921,14 +947,25 @@ st_DrawPixels(struct gl_context *ctx, GLint x, GLint y,
 
    st_validate_state(st);
 
+   /*
+    * Get vertex/fragment shaders
+    */
    if (write_depth || write_stencil) {
-      driver_fp = make_fragment_shader_z_stencil(st, write_depth, write_stencil);
+      fpv = get_depth_stencil_fp_varient(st, write_depth, write_stencil);
+
+      driver_fp = fpv->driver_shader;
+
       driver_vp = make_passthrough_vertex_shader(st, GL_TRUE);
+
       color = ctx->Current.RasterColor;
    }
    else {
-      driver_fp = combined_drawpix_fragment_program(ctx);
+      fpv = get_color_fp_varient(st);
+
+      driver_fp = fpv->driver_shader;
+
       driver_vp = make_passthrough_vertex_shader(st, GL_FALSE);
+
       color = NULL;
       if (st->pixel_xfer.pixelmap_enabled) {
 	  sv[1] = st->pixel_xfer.pixelmap_sampler_view;
@@ -936,6 +973,9 @@ st_DrawPixels(struct gl_context *ctx, GLint x, GLint y,
       }
    }
 
+   /* update fragment program constants */
+   st_upload_constants(st, fpv->parameters, PIPE_SHADER_FRAGMENT);
+
    /* draw with textured quad */
    {
       struct pipe_resource *pt
@@ -1116,6 +1156,7 @@ st_CopyPixels(struct gl_context *ctx, GLint srcx, GLint srcy,
    GLint readX, readY, readW, readH;
    GLuint sample_count;
    struct gl_pixelstore_attrib pack = ctx->DefaultPacking;
+   struct st_fp_varient *fpv;
 
    st_validate_state(st);
 
@@ -1125,11 +1166,18 @@ st_CopyPixels(struct gl_context *ctx, GLint srcx, GLint srcy,
       return;
    }
 
+   /*
+    * Get vertex/fragment shaders
+    */
    if (type == GL_COLOR) {
       rbRead = st_get_color_read_renderbuffer(ctx);
       color = NULL;
-      driver_fp = combined_drawpix_fragment_program(ctx);
+
+      fpv = get_color_fp_varient(st);
+      driver_fp = fpv->driver_shader;
+
       driver_vp = make_passthrough_vertex_shader(st, GL_FALSE);
+
       if (st->pixel_xfer.pixelmap_enabled) {
 	  sv[1] = st->pixel_xfer.pixelmap_sampler_view;
 	  num_sampler_view++;
@@ -1139,10 +1187,17 @@ st_CopyPixels(struct gl_context *ctx, GLint srcx, GLint srcy,
       assert(type == GL_DEPTH);
       rbRead = st_renderbuffer(ctx->ReadBuffer->_DepthBuffer);
       color = ctx->Current.Attrib[VERT_ATTRIB_COLOR0];
-      driver_fp = make_fragment_shader_z_stencil(st, GL_TRUE, GL_FALSE);
+
+      fpv = get_depth_stencil_fp_varient(st, GL_TRUE, GL_FALSE);
+      driver_fp = fpv->driver_shader;
+
       driver_vp = make_passthrough_vertex_shader(st, GL_TRUE);
    }
 
+   /* update fragment program constants */
+   st_upload_constants(st, fpv->parameters, PIPE_SHADER_FRAGMENT);
+
+
    if (rbRead->Base.Wrapped)
       rbRead = st_renderbuffer(rbRead->Base.Wrapped);
 
@@ -1294,7 +1349,7 @@ st_destroy_drawpix(struct st_context *st)
 
    for (i = 0; i < Elements(st->drawpix.shaders); i++) {
       if (st->drawpix.shaders[i])
-         st_reference_fragprog(st, &st->drawpix.shaders[i], NULL);
+         _mesa_reference_fragprog(st->ctx, &st->drawpix.shaders[i], NULL);
    }
 
    st_reference_fragprog(st, &st->pixel_xfer.combined_prog, NULL);