freedreno/ir3: don't fetch unused tex components

Detect when a component of an (for example) texture fetch is unused and
propagate the updated wrmask back to the parent instruction.

Signed-off-by: Rob Clark <robdclark@gmail.com>

diff --git a/src/freedreno/ir3/ir3_depth.c b/src/freedreno/ir3/ir3_depth.c
index 73bf5e19926d3e7ee28e5d804a01afe7d76cf8d8..77f9af6173f14a9db4921c3143b1e659e462446f 100644 (file)
--- a/src/freedreno/ir3/ir3_depth.c
+++ b/src/freedreno/ir3/ir3_depth.c
@@ -174,6 +174,33 @@ remove_unused_by_block(struct ir3_block *block)
                if (instr->opc == OPC_END)
                        continue;
                if (instr->flags & IR3_INSTR_UNUSED) {
+                       if (instr->opc == OPC_META_FO) {
+                               struct ir3_instruction *src = ssa(instr->regs[1]);
+                               if (src->regs[0]->wrmask > 1) {
+                                       unsigned newn, lastn;
+
+                                       lastn = util_last_bit(src->regs[0]->wrmask);
+                                       src->regs[0]->wrmask &= ~(1 << instr->fo.off);
+                                       newn = util_last_bit(src->regs[0]->wrmask);
+
+                                       /* prune no-longer needed right-neighbors.  We could
+                                        * probably do the same for left-neighbors (ie. tex
+                                        * fetch that only need .yw components), but that
+                                        * makes RA a bit more confusing than it already is
+                                        */
+                                       if (newn < lastn) {
+                                               struct ir3_instruction *n = ir3_neighbor_first(instr);
+                                               for (unsigned i = 1; i < newn; i++) {
+                                                       n = n->cp.right;
+                                               }
+                                               // XXX I don't think n should be null here!
+                                               if (n) {
+                                                       debug_assert(n->cp.right->flags & IR3_INSTR_UNUSED);
+                                                       n->cp.right = NULL;
+                                               }
+                                       }
+                               }
+                       }
                        list_delinit(&instr->node);
                        progress = true;
                }

diff --git a/src/freedreno/ir3/ir3_ra.c b/src/freedreno/ir3/ir3_ra.c
index ad09c4018d3eaab25a685f0c83406b25aaa27d9d..b202c1413786e6d12c2236f2bc1d2404d2f97611 100644 (file)
--- a/src/freedreno/ir3/ir3_ra.c
+++ b/src/freedreno/ir3/ir3_ra.c
@@ -509,6 +509,8 @@ get_definer(struct ir3_ra_ctx *ctx, struct ir3_instruction *instr,
                d = dd;
        }
 
+       debug_assert(d->opc != OPC_META_FO);
+
        id->defn = d;
        id->sz = *sz;
        id->off = *off;