freedreno/ir3: handle the progress case

In some cases, in particular when you have things that can be src
modifiers ((abs)/(neg)), once eliminating one mov, there is a
possibility to remove another.  Handle this by re-visiting an
instruction after eliminating a copy on one of it's srcs.

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 16dd8583f3982a7609823329e9862c524baff778..fa25c9ca8a1248e3fd4e4ef8f64ed5bc8a1ada3a 100644 (file)
--- a/src/freedreno/ir3/ir3_cp.c
+++ b/src/freedreno/ir3/ir3_cp.c
@@ -431,7 +431,7 @@ try_swap_mad_two_srcs(struct ir3_instruction *instr, unsigned new_flags)
  * src (which needs to also fixup the address src reference by the
  * instruction).
  */
-static void
+static bool
 reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
                struct ir3_register *reg, unsigned n)
 {
@@ -457,8 +457,9 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
 
                        unuse(src);
                        reg->instr->use_count++;
-               }
 
+                       return true;
+               }
        } else if (is_same_type_mov(src) &&
                        /* cannot collapse const/immed/etc into meta instrs: */
                        !is_meta(instr)) {
@@ -477,7 +478,7 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
                                debug_assert(new_flags & IR3_REG_IMMED);
 
                                instr->regs[n + 1] = lower_immed(ctx, src_reg, new_flags, f_opcode);
-                               return;
+                               return true;
                        }
 
                        /* special case for "normal" mad instructions, we can
@@ -488,10 +489,9 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
                         * src[0] is !CONST and src[1] is CONST:
                         */
                        if ((n == 1) && try_swap_mad_two_srcs(instr, new_flags)) {
-                               /* we swapped, so now we are dealing with 1st src: */
-                               n = 0;
+                               return true;
                        } else {
-                               return;
+                               return false;
                        }
                }
 
@@ -509,7 +509,7 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
                         */
                        if ((src_reg->flags & IR3_REG_RELATIV) &&
                                        conflicts(instr->address, reg->instr->address))
-                               return;
+                               return false;
 
                        /* This seems to be a hw bug, or something where the timings
                         * just somehow don't work out.  This restriction may only
@@ -518,7 +518,7 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
                        if ((opc_cat(instr->opc) == 3) && (n == 2) &&
                                        (src_reg->flags & IR3_REG_RELATIV) &&
                                        (src_reg->array.offset == 0))
-                               return;
+                               return false;
 
                        src_reg = ir3_reg_clone(instr->block->shader, src_reg);
                        src_reg->flags = new_flags;
@@ -527,7 +527,7 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
                        if (src_reg->flags & IR3_REG_RELATIV)
                                ir3_instr_set_address(instr, reg->instr->address);
 
-                       return;
+                       return true;
                }
 
                if ((src_reg->flags & IR3_REG_RELATIV) &&
@@ -537,7 +537,7 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
                        instr->regs[n+1] = src_reg;
                        ir3_instr_set_address(instr, reg->instr->address);
 
-                       return;
+                       return true;
                }
 
                /* NOTE: seems we can only do immed integers, so don't
@@ -574,16 +574,21 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
                                src_reg->flags = new_flags;
                                src_reg->iim_val = iim_val;
                                instr->regs[n+1] = src_reg;
+
+                               return true;
                        } else if (valid_flags(instr, n, (new_flags & ~IR3_REG_IMMED) | IR3_REG_CONST)) {
                                bool f_opcode = (ir3_cat2_float(instr->opc) ||
                                                ir3_cat3_float(instr->opc)) ? true : false;
 
                                /* See if lowering an immediate to const would help. */
                                instr->regs[n+1] = lower_immed(ctx, src_reg, new_flags, f_opcode);
+
+                               return true;
                        }
-                       return;
                }
        }
+
+       return false;
 }
 
 /* Handle special case of eliminating output mov, and similar cases where
@@ -621,26 +626,30 @@ instr_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr)
                return;
 
        /* walk down the graph from each src: */
-       foreach_src_n(reg, n, instr) {
-               struct ir3_instruction *src = ssa(reg);
+       bool progress;
+       do {
+               progress = false;
+               foreach_src_n(reg, n, instr) {
+                       struct ir3_instruction *src = ssa(reg);
 
-               if (!src)
-                       continue;
+                       if (!src)
+                               continue;
 
-               instr_cp(ctx, src);
+                       instr_cp(ctx, src);
 
-               /* TODO non-indirect access we could figure out which register
-                * we actually want and allow cp..
-                */
-               if (reg->flags & IR3_REG_ARRAY)
-                       continue;
+                       /* TODO non-indirect access we could figure out which register
+                        * we actually want and allow cp..
+                        */
+                       if (reg->flags & IR3_REG_ARRAY)
+                               continue;
 
-               /* Don't CP absneg into meta instructions, that won't end well: */
-               if (is_meta(instr) && (src->opc != OPC_MOV))
-                       continue;
+                       /* Don't CP absneg into meta instructions, that won't end well: */
+                       if (is_meta(instr) && (src->opc != OPC_MOV))
+                               continue;
 
-               reg_cp(ctx, instr, reg, n);
-       }
+                       progress |= reg_cp(ctx, instr, reg, n);
+               }
+       } while (progress);
 
        if (instr->regs[0]->flags & IR3_REG_ARRAY) {
                struct ir3_instruction *src = ssa(instr->regs[0]);