i965: Factor out logic to build a send message instruction with indirect descriptor.

This is going to be useful because the Gen7+ uniform and varying pull
constant, texturing, typed and untyped surface read, write, and atomic
generation code on the vec4 and fs back-end all require the same logic
to handle conditionally indirect surface indices.  In pseudocode:

|   if (surface.file == BRW_IMMEDIATE_VALUE) {
|      inst = brw_SEND(p, dst, payload);
|      set_descriptor_control_bits(inst, surface, ...);
|   } else {
|      inst = brw_OR(p, addr, surface, 0);
|      set_descriptor_control_bits(inst, ...);
|      inst = brw_SEND(p, dst, payload);
|      set_indirect_send_descriptor(inst, addr);
|   }

This patch abstracts out this frequently recurring pattern so we can
now write:

| inst = brw_send_indirect_message(p, sfid, dst, payload, surface)
| set_descriptor_control_bits(inst, ...);

without worrying about handling the immediate and indirect surface
index cases explicitly.

v2: Rebase.  Improve documentatation and commit message. (Topi)
    Preserve UW destination type cargo-cult. (Topi, Ken, Matt)

Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>

1 files changed, 16 insertions, 5 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_eu.h b/src/mesa/drivers/dri/i965/brw_eu.h
index d9ad5bd..a87787e 100644
--- a/src/mesa/drivers/dri/i965/brw_eu.h
+++ b/src/mesa/drivers/dri/i965/brw_eu.h
@@ -205,11 +205,6 @@ void brw_set_sampler_message(struct brw_compile *p,
                              unsigned simd_mode,
                              unsigned return_format);
 
-void brw_set_indirect_send_descriptor(struct brw_compile *p,
-                                      brw_inst *insn,
-                                      unsigned sfid,
-                                      struct brw_reg descriptor);
-
 void brw_set_dp_read_message(struct brw_compile *p,
 			     brw_inst *insn,
 			     unsigned binding_table_index,
@@ -242,6 +237,22 @@ void brw_urb_WRITE(struct brw_compile *p,
 		   unsigned offset,
 		   unsigned swizzle);
 
+/**
+ * Send message to shared unit \p sfid with a possibly indirect descriptor \p
+ * desc.  If \p desc is not an immediate it will be transparently loaded to an
+ * address register using an OR instruction.  The returned instruction can be
+ * passed as argument to the usual brw_set_*_message() functions in order to
+ * specify any additional descriptor bits -- If \p desc is an immediate this
+ * will be the SEND instruction itself, otherwise it will be the OR
+ * instruction.
+ */
+struct brw_inst *
+brw_send_indirect_message(struct brw_compile *p,
+                          unsigned sfid,
+                          struct brw_reg dst,
+                          struct brw_reg payload,
+                          struct brw_reg desc);
+
 void brw_ff_sync(struct brw_compile *p,
 		   struct brw_reg dest,
 		   unsigned msg_reg_nr,