i965: Replace illegal compacted NOP with valid compact instructioncompact

NOP actually has no compact version, but we use it for instruction
alignment for compact kernel. Although it seems working on HW, it is
illegal and might not be valid for any future one.

This trys to get a temporary compact instruction with no effect for
alignment to replace compacted NOP. G45 spec has note that HW compact
logic could determine NENOP and drop it right away, so we can still
keep with that.

v2: rebase to master, we still need this to work with internal tool.
v3: [mattst88]
    Rename brw_get_noop_compact -> fill_compaction_padding
    Generate uncompacted NOP MOV instruction in local variable
    Replace fprintf/exit with assert

Reviewed-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

1 files changed, 30 insertions, 6 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_eu_compact.c b/src/mesa/drivers/dri/i965/brw_eu_compact.c
index 07ace6bfbcb3..3ed8e288bfab 100644
--- a/src/mesa/drivers/dri/i965/brw_eu_compact.c
+++ b/src/mesa/drivers/dri/i965/brw_eu_compact.c
@@ -1403,6 +1403,34 @@ brw_init_compaction_tables(const struct brw_device_info *devinfo)
    }
 }
 
+static void
+fill_compaction_padding(struct brw_codegen *p, brw_compact_inst *dst)
+{
+   const struct brw_device_info *devinfo = p->devinfo;
+   struct brw_reg g0 = brw_vec8_grf(0, 0);
+   brw_inst inst;
+
+   if (devinfo->is_g4x) {
+      memset(dst, 0, sizeof(*dst));
+      brw_compact_inst_set_opcode(devinfo, dst, BRW_OPCODE_NENOP);
+      brw_compact_inst_set_cmpt_control(devinfo, dst, true);
+      return;
+   }
+
+   /* As NOP has no legal compact version, try to use a legal compact
+    * instruction for compact instruction alignment.
+    */
+   memcpy(&inst, p->current, sizeof(inst));
+   brw_inst_set_opcode(devinfo, &inst, BRW_OPCODE_MOV);
+   brw_inst_set_pred_control(devinfo, &inst, BRW_PREDICATE_NONE);
+   brw_inst_set_access_mode(devinfo, &inst, BRW_ALIGN_1);
+   brw_set_dest(p, &inst, g0);
+   brw_set_src0(p, &inst, g0);
+
+   bool UNUSED ret = brw_try_compact_instruction(devinfo, dst, &inst);
+   assert(ret);
+}
+
 void
 brw_compact_instructions(struct brw_codegen *p, int start_offset,
                          int num_annotations, struct annotation *annotation)
@@ -1453,9 +1481,7 @@ brw_compact_instructions(struct brw_codegen *p, int start_offset,
          /* All uncompacted instructions need to be aligned on G45. */
          if ((offset & sizeof(brw_compact_inst)) != 0 && devinfo->is_g4x){
             brw_compact_inst *align = store + offset;
-            memset(align, 0, sizeof(*align));
-            brw_compact_inst_set_opcode(devinfo, align, BRW_OPCODE_NENOP);
-            brw_compact_inst_set_cmpt_control(devinfo, align, true);
+            fill_compaction_padding(p, align);
             offset += sizeof(brw_compact_inst);
             compacted_count--;
             compacted_counts[src_offset / sizeof(brw_inst)] = compacted_count;
@@ -1562,9 +1588,7 @@ brw_compact_instructions(struct brw_codegen *p, int start_offset,
     */
    if (p->next_insn_offset & sizeof(brw_compact_inst)) {
       brw_compact_inst *align = store + offset;
-      memset(align, 0, sizeof(*align));
-      brw_compact_inst_set_opcode(devinfo, align, BRW_OPCODE_NOP);
-      brw_compact_inst_set_cmpt_control(devinfo, align, true);
+      fill_compaction_padding(p, align);
       p->next_insn_offset += sizeof(brw_compact_inst);
    }
    p->nr_insn = p->next_insn_offset / sizeof(brw_inst);