i965: Correct scratch space allocation.

One, it was allocating increments of 1kb, but per thread scratch space
is a power of two.  Two, the new FS wasn't getting total_scratch set
at all, so everyone thought they had 1kb and writes beyond 1kb would
go stomping on a neighbor thread.

With this plus the previous register spilling for the new FS,
glsl-fs-convolution-1 passes.

1 files changed, 13 insertions, 8 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_wm.c b/src/mesa/drivers/dri/i965/brw_wm.c
index f2ce756564..7f3ba5f058 100644
--- a/src/mesa/drivers/dri/i965/brw_wm.c
+++ b/src/mesa/drivers/dri/i965/brw_wm.c
@@ -114,14 +114,6 @@ brw_wm_non_glsl_emit(struct brw_context *brw, struct brw_wm_compile *c)
    /* how many general-purpose registers are used */
    c->prog_data.total_grf = c->max_wm_grf;
 
-   /* Scratch space is used for register spilling */
-   if (c->last_scratch) {
-      c->prog_data.total_scratch = c->last_scratch + 0x40;
-   }
-   else {
-      c->prog_data.total_scratch = 0;
-   }
-
    /* Emit GEN4 code.
     */
    brw_wm_emit(c);
@@ -193,6 +185,19 @@ static void do_wm_prog( struct brw_context *brw,
       }
    }
 
+   /* Scratch space is used for register spilling */
+   if (c->last_scratch) {
+      /* Per-thread scratch space is power-of-two sized. */
+      for (c->prog_data.total_scratch = 1024;
+	   c->prog_data.total_scratch <= c->last_scratch;
+	   c->prog_data.total_scratch *= 2) {
+	 /* empty */
+      }
+   }
+   else {
+      c->prog_data.total_scratch = 0;
+   }
+
    if (INTEL_DEBUG & DEBUG_WM)
       fprintf(stderr, "\n");