freedreno/ir3: allow copy-propagate out of fanout

Now that we fixed the sharp edges that this was papering over, we can
relax the restriction about eliminating a mov coming out of a fanout
(for example from result of texture fetch).

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>

diff --git a/src/freedreno/ir3/ir3_cp.c b/src/freedreno/ir3/ir3_cp.c
index a79560ec5798442637b1725cbccf0c0238cc7b3d..01386b434ee412be02896a23313c1ab0d7925f14 100644 (file)
--- a/src/freedreno/ir3/ir3_cp.c
+++ b/src/freedreno/ir3/ir3_cp.c
@@ -44,8 +44,16 @@ struct ir3_cp_ctx {
        struct ir3_shader_variant *so;
 };
 
-/* is it a type preserving mov, with ok flags? */
-static bool is_eligible_mov(struct ir3_instruction *instr, bool allow_flags)
+/* is it a type preserving mov, with ok flags?
+ *
+ * @instr: the mov to consider removing
+ * @dst_instr: the instruction consuming the mov (instr)
+ *
+ * TODO maybe drop allow_flags since this is only false when dst is
+ * NULL (ie. outputs)
+ */
+static bool is_eligible_mov(struct ir3_instruction *instr,
+               struct ir3_instruction *dst_instr, bool allow_flags)
 {
        if (is_same_type_mov(instr)) {
                struct ir3_register *dst = instr->regs[0];
@@ -70,9 +78,21 @@ static bool is_eligible_mov(struct ir3_instruction *instr, bool allow_flags)
                                        IR3_REG_SABS | IR3_REG_SNEG | IR3_REG_BNOT))
                                return false;
 
-               /* TODO: remove this hack: */
-               if (src_instr->opc == OPC_META_FO)
-                       return false;
+               /* If src is coming from fanout/split (ie. one component of a
+                * texture fetch, etc) and we have constraints on swizzle of
+                * destination, then skip it.
+                *
+                * We could possibly do a bit better, and copy-propagation if
+                * we can CP all components that are being fanned out.
+                */
+               if (src_instr->opc == OPC_META_FO) {
+                       if (!dst_instr)
+                               return false;
+                       if (dst_instr->opc == OPC_META_FI)
+                               return false;
+                       if (dst_instr->cp.left || dst_instr->cp.right)
+                               return false;
+               }
 
                return true;
        }
@@ -427,7 +447,7 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
 {
        struct ir3_instruction *src = ssa(reg);
 
-       if (is_eligible_mov(src, true)) {
+       if (is_eligible_mov(src, instr, true)) {
                /* simple case, no immed/const/relativ, only mov's w/ ssa src: */
                struct ir3_register *src_reg = src->regs[1];
                unsigned new_flags = reg->flags;
@@ -584,7 +604,7 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
 static struct ir3_instruction *
 eliminate_output_mov(struct ir3_instruction *instr)
 {
-       if (is_eligible_mov(instr, false)) {
+       if (is_eligible_mov(instr, NULL, false)) {
                struct ir3_register *reg = instr->regs[1];
                if (!(reg->flags & IR3_REG_ARRAY)) {
                        struct ir3_instruction *src_instr = ssa(reg);