i965: Add an INTEL_DEBUG=reemit option.

Jason and I use this for debugging all the time.  Recompiling the driver
to enable it is kind of annoying.  It's a great thing to try along with
always_flush_batch=true and always_flush_cache=true to detect a class of
problems - namely, atoms listening to an insufficient set of dirty bits.

Reviewed-by: Matt Turner <mattst88@gmail.com>

docs/envvars.html

@@ -192,6 +192,7 @@ See the <a href="xlibdriver.html">Xlib software driver page</a> for details.
    <li>perfmon - emit messages about AMD_performance_monitor</li>
    <li>pix - emit messages about pixel operations</li>
    <li>prim - emit messages about drawing primitives</li>
+   <li>reemit - mark all state dirty on each draw call</li>
    <li>sf - emit messages about the strips &amp; fans unit (for old gens, includes the SF program)</li>
    <li>shader_time - record how much GPU time is spent in each shader</li>
    <li>spill_fs - force spilling of all registers in the scalar backend (useful to debug spilling code)</li>

src/intel/common/gen_debug.c

@@ -83,6 +83,7 @@ static const struct debug_control debug_control[] = {
    { "norbc",       DEBUG_NO_RBC },
    { "nohiz",       DEBUG_NO_HIZ },
    { "color",       DEBUG_COLOR },
+   { "reemit",      DEBUG_REEMIT },
    { NULL,    0 }
 };
 

src/intel/common/gen_debug.h

@@ -82,6 +82,7 @@ extern uint64_t INTEL_DEBUG;
 #define DEBUG_NO_RBC              (1ull << 38)
 #define DEBUG_NO_HIZ              (1ull << 39)
 #define DEBUG_COLOR               (1ull << 40)
+#define DEBUG_REEMIT              (1ull << 41)
 
 #ifdef HAVE_ANDROID_PLATFORM
 #define LOG_TAG "INTEL-MESA"

src/mesa/drivers/dri/i965/brw_state_upload.c

@@ -480,7 +480,7 @@ brw_upload_pipeline_state(struct brw_context *brw,
 
    brw_select_pipeline(brw, pipeline);
 
-   if (0) {
+   if (unlikely(INTEL_DEBUG & DEBUG_REEMIT)) {
       /* Always re-emit all state. */
       brw->NewGLState = ~0;
       ctx->NewDriverState = ~0ull;