nvc0: replace branching with predicated insns where feasible

5 files changed, 123 insertions, 46 deletions

diff --git a/src/gallium/drivers/nvc0/nvc0_pc.c b/src/gallium/drivers/nvc0/nvc0_pc.c
index a2006321021..e0cba05b976 100644
--- a/src/gallium/drivers/nvc0/nvc0_pc.c
+++ b/src/gallium/drivers/nvc0/nvc0_pc.c
@@ -55,15 +55,11 @@ nvc0_insn_can_load(struct nv_instruction *nvi, int s,
 boolean
 nvc0_insn_is_predicateable(struct nv_instruction *nvi)
 {
-   int s;
-
-   if (!nv_op_predicateable(nvi->opcode))
+   if (nvi->predicate >= 0) /* already predicated */
       return FALSE;
-   if (nvi->predicate >= 0)
+   if (!nvc0_op_info_table[nvi->opcode].predicate &&
+       !nvc0_op_info_table[nvi->opcode].pseudo)
       return FALSE;
-   for (s = 0; s < 4 && nvi->src[s]; ++s)
-      if (nvi->src[s]->value->reg.file == NV_FILE_IMM)
-         return FALSE;
    return TRUE;
 }
 
@@ -505,6 +501,9 @@ nvc0_insn_append(struct nv_basic_block *b, struct nv_instruction *i)
 
    i->bb = b;
    b->num_instructions++;
+
+   if (i->prev && i->prev->terminator)
+      nvc0_insns_permute(i->prev, i);
 }
 
 void
diff --git a/src/gallium/drivers/nvc0/nvc0_pc.h b/src/gallium/drivers/nvc0/nvc0_pc.h
index 40d728aefc7..efa073a9201 100644
--- a/src/gallium/drivers/nvc0/nvc0_pc.h
+++ b/src/gallium/drivers/nvc0/nvc0_pc.h
@@ -205,6 +205,10 @@
 #define NV_CC_C  0x11
 #define NV_CC_A  0x12
 #define NV_CC_S  0x13
+#define NV_CC_INVERSE(cc) ((cc) ^ 0x7)
+/* for 1 bit predicates: */
+#define NV_CC_P     0
+#define NV_CC_NOT_P 1
 
 #define NV_PC_MAX_INSTRUCTIONS 2048
 #define NV_PC_MAX_VALUES (NV_PC_MAX_INSTRUCTIONS * 4)
@@ -260,12 +264,6 @@ nv_op_supported_src_mods(uint opcode)
    return nvc0_op_info_table[opcode].mods;
 }
 
-static INLINE boolean
-nv_op_predicateable(uint opcode)
-{
-   return nvc0_op_info_table[opcode].predicate ? TRUE : FALSE;
-}
-
 static INLINE uint
 nv_type_order(ubyte type)
 {
@@ -488,7 +486,7 @@ nv_alloc_instruction(struct nv_pc *pc, uint opcode)
    assert(pc->num_instructions < NV_PC_MAX_INSTRUCTIONS);
 
    insn->opcode = opcode;
-   insn->cc = 0;
+   insn->cc = NV_CC_P;
    insn->indirect = -1;
    insn->predicate = -1;
 
diff --git a/src/gallium/drivers/nvc0/nvc0_pc_optimize.c b/src/gallium/drivers/nvc0/nvc0_pc_optimize.c
index 2e554dbe4e4..6cfa03d5b16 100644
--- a/src/gallium/drivers/nvc0/nvc0_pc_optimize.c
+++ b/src/gallium/drivers/nvc0/nvc0_pc_optimize.c
@@ -99,6 +99,7 @@ inst_removable(struct nv_instruction *nvi)
              nvc0_insn_refcount(nvi)));
 }
 
+/* Check if we do not actually have to emit this instruction. */
 static INLINE boolean
 inst_is_noop(struct nv_instruction *nvi)
 {
@@ -1043,7 +1044,6 @@ nv_pass_dce(struct nv_pass_dce *ctx, struct nv_basic_block *b)
    return 0;
 }
 
-#if 0
 /* Register allocation inserted ELSE blocks for all IF/ENDIF without ELSE.
  * Returns TRUE if @bb initiates an IF/ELSE/ENDIF clause, or is an IF with
  * BREAK and dummy ELSE block.
@@ -1064,24 +1064,92 @@ bb_is_if_else_endif(struct nv_basic_block *bb)
    }
 }
 
-/* predicate instructions and remove branch at the end */
+/* Predicate instructions and delete any branch at the end if it is
+ * not a break from a loop.
+ */
 static void
 predicate_instructions(struct nv_pc *pc, struct nv_basic_block *b,
-                       struct nv_value *p, ubyte cc)
+                       struct nv_value *pred, uint8_t cc)
 {
+   struct nv_instruction *nvi, *prev;
+   int s;
 
+   if (!b->entry)
+      return;
+   for (nvi = b->entry; nvi; nvi = nvi->next) {
+      prev = nvi;
+      if (inst_is_noop(nvi))
+         continue;
+      for (s = 0; nvi->src[s]; ++s);
+      assert(s < 6);
+      nvi->predicate = s;
+      nvi->cc = cc;
+      nv_reference(pc, nvi, nvi->predicate, pred);
+   }
+   if (prev->opcode == NV_OP_BRA &&
+       b->out_kind[0] != CFG_EDGE_LOOP_LEAVE &&
+       b->out_kind[1] != CFG_EDGE_LOOP_LEAVE)
+      nvc0_insn_delete(prev);
 }
-#endif
 
-/* NOTE: Run this after register allocation, we can just cut out the cflow
- * instructions and hook the predicates to the conditional OPs if they are
- * not using immediates; better than inserting SELECT to join definitions.
- *
- * NOTE: Should adapt prior optimization to make this possible more often.
+static INLINE boolean
+may_predicate_insn(struct nv_instruction *nvi, struct nv_value *pred)
+{
+   if (nvi->def[0] && values_equal(nvi->def[0], pred))
+      return FALSE;
+   return nvc0_insn_is_predicateable(nvi);
+}
+
+/* Transform IF/ELSE/ENDIF constructs into predicated instructions
+ * where feasible.
  */
 static int
 nv_pass_flatten(struct nv_pass *ctx, struct nv_basic_block *b)
 {
+   struct nv_instruction *nvi;
+   struct nv_value *pred;
+   int k;
+   int n0, n1; /* instruction counts of outgoing blocks */
+
+   if (bb_is_if_else_endif(b)) {
+      assert(b->exit && b->exit->opcode == NV_OP_BRA);
+
+      assert(b->exit->predicate >= 0);
+      pred = b->exit->src[b->exit->predicate]->value;
+
+      n1 = n0 = 0;
+      for (nvi = b->out[0]->entry; nvi; nvi = nvi->next, ++n0)
+         if (!may_predicate_insn(nvi, pred))
+            break;
+      if (!nvi) {
+         /* we're after register allocation, so there always is an ELSE block */
+         for (nvi = b->out[1]->entry; nvi; nvi = nvi->next, ++n1)
+            if (!may_predicate_insn(nvi, pred))
+               break;
+      }
+
+      /* 12 is an arbitrary limit */
+      if (!nvi && n0 < 12 && n1 < 12) {
+         predicate_instructions(ctx->pc, b->out[0], pred, !b->exit->cc);
+         predicate_instructions(ctx->pc, b->out[1], pred, b->exit->cc);
+
+         nvc0_insn_delete(b->exit); /* delete the branch */
+
+         /* and a potential joinat before it */
+         if (b->exit && b->exit->opcode == NV_OP_JOINAT)
+            nvc0_insn_delete(b->exit);
+
+         /* remove join operations at the end of the conditional */
+         k = (b->out[0]->out_kind[0] == CFG_EDGE_LOOP_LEAVE) ? 1 : 0;
+         if ((nvi = b->out[0]->out[k]->entry)) {
+            nvi->join = 0;
+            if (nvi->opcode == NV_OP_JOIN)
+               nvc0_insn_delete(nvi);
+         }
+      }
+   }
+   DESCEND_ARBITRARY(k, nv_pass_flatten);
+
    return 0;
 }
 
diff --git a/src/gallium/drivers/nvc0/nvc0_pc_print.c b/src/gallium/drivers/nvc0/nvc0_pc_print.c
index 9e0bffacd60..7840078614f 100644
--- a/src/gallium/drivers/nvc0/nvc0_pc_print.c
+++ b/src/gallium/drivers/nvc0/nvc0_pc_print.c
@@ -225,7 +225,7 @@ nvc0_print_instruction(struct nv_instruction *i)
 
    PRINT("%s", gree);
    if (NV_BASEOP(i->opcode) == NV_OP_SET)
-      PRINT("set %s", nv_cond_name(i->set_cond));
+      PRINT("%s %s", nvc0_opcode_name(i->opcode), nv_cond_name(i->set_cond));
    else
    if (i->saturate)
       PRINT("sat %s", nvc0_opcode_name(i->opcode));
@@ -278,7 +278,7 @@ struct nv_op_info nvc0_op_info_table[NV_OP_COUNT + 1] =
    { NV_OP_MERGE,  "merge",  NV_TYPE_ANY, 0, /* fcvpoi */ 0, 0, 1, 0, 1, 0, 0 },
    { NV_OP_PHI,    "phi",    NV_TYPE_ANY, 0, /* fcvpoi */ 0, 0, 0, 0, 1, 0, 0 },
    { NV_OP_SELECT, "select", NV_TYPE_ANY, 0, /* fcvpoi */ 0, 0, 0, 0, 1, 0, 0 },
-   { NV_OP_NOP,    "nop",    NV_TYPE_ANY, 0, /* fcvpoi */ 0, 0, 0, 0, 0, 0, 0 },
+   { NV_OP_NOP,    "nop",    NV_TYPE_ANY, 0, /* fcvpoi */ 0, 0, 0, 1, 0, 0, 0 },
 
    { NV_OP_LD,  "ld",  NV_TYPE_ANY, 0, 0, 0, 0, 1, 0, 0, 0 },
    { NV_OP_ST,  "st",  NV_TYPE_ANY, 0, 0, 0, 0, 1, 0, 0, 0 },
@@ -343,18 +343,18 @@ struct nv_op_info nvc0_op_info_table[NV_OP_COUNT + 1] =
    { NV_OP_MIN, "max", NV_TYPE_U32, 0, 0, 1, 0, 1, 0, 0, 0 },
    { NV_OP_MAX, "min", NV_TYPE_S32, 0, 0, 1, 0, 1, 0, 0, 0 },
    { NV_OP_MIN, "min", NV_TYPE_U32, 0, 0, 1, 0, 1, 0, 0, 0 },
-   { NV_OP_SET, "set", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 1, 0, 0, 2 },
-   { NV_OP_SET, "set", NV_TYPE_S32, 0, 0, 0, 0, 1, 0, 0, 0 },
-   { NV_OP_SET, "set", NV_TYPE_U32, 0, 0, 0, 0, 1, 0, 0, 0 },
+   { NV_OP_SET, "set", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 1, 0, 2, 2 },
+   { NV_OP_SET, "set", NV_TYPE_S32, 0, 0, 0, 0, 1, 0, 2, 2 },
+   { NV_OP_SET, "set", NV_TYPE_U32, 0, 0, 0, 0, 1, 0, 2, 2 },
    { NV_OP_SHR, "sar", NV_TYPE_S32, 0, 0, 0, 0, 1, 0, 1, 0 },
-   { NV_OP_RCP, "rcp", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 0, 0, 0, 0 },
-   { NV_OP_RSQ, "rsqrt", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 0, 0, 0, 0 },
-   { NV_OP_LG2, "lg2", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 0, 0, 0, 0 },
-   { NV_OP_SIN, "sin", NV_TYPE_F32, 0, 0, 0, 0, 0, 0, 0, 0 },
-   { NV_OP_COS, "cos", NV_TYPE_F32, 0, 0, 0, 0, 0, 0, 0, 0 },
-   { NV_OP_EX2, "ex2", NV_TYPE_F32, 0, 0, 0, 0, 0, 0, 0, 0 },
-   { NV_OP_PRESIN, "presin", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 0, 0, 0, 0 },
-   { NV_OP_PREEX2, "preex2", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 0, 0, 0, 0 },
+   { NV_OP_RCP, "rcp", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 1, 0, 0, 0 },
+   { NV_OP_RSQ, "rsqrt", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 1, 0, 0, 0 },
+   { NV_OP_LG2, "lg2", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 1, 0, 0, 0 },
+   { NV_OP_SIN, "sin", NV_TYPE_F32, 0, 0, 0, 0, 1, 0, 0, 0 },
+   { NV_OP_COS, "cos", NV_TYPE_F32, 0, 0, 0, 0, 1, 0, 0, 0 },
+   { NV_OP_EX2, "ex2", NV_TYPE_F32, 0, 0, 0, 0, 1, 0, 0, 0 },
+   { NV_OP_PRESIN, "presin", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 1, 0, 0, 0 },
+   { NV_OP_PREEX2, "preex2", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 1, 0, 0, 0 },
    { NV_OP_SAT, "sat", NV_TYPE_F32, 0, 0, 0, 0, 1, 0, 0, 0 },
 
    { NV_OP_SET_F32_AND, "and set", NV_TYPE_F32, 0, 0, 0, 0, 1, 0, 0, 0 },
@@ -369,7 +369,7 @@ struct nv_op_info nvc0_op_info_table[NV_OP_COUNT + 1] =
 
    { NV_OP_ADD, "sub", NV_TYPE_F32, 0, 0, 0, 0, 1, 0, 1, 0 },
 
-   { NV_OP_SET, "fset", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 1, 0, 0, 2 },
+   { NV_OP_SET, "fset", NV_TYPE_F32, NV_MOD_SGN, 0, 0, 0, 1, 0, 2, 2 },
 
    { NV_OP_TXG, "texgrad", NV_TYPE_F32, 0, 0, 0, 1, 1, 0, 0, 0 },
 
diff --git a/src/gallium/drivers/nvc0/nvc0_tgsi_to_nc.c b/src/gallium/drivers/nvc0/nvc0_tgsi_to_nc.c
index 43c27fd8906..72bfcd0c95f 100644
--- a/src/gallium/drivers/nvc0/nvc0_tgsi_to_nc.c
+++ b/src/gallium/drivers/nvc0/nvc0_tgsi_to_nc.c
@@ -659,7 +659,7 @@ bld_kil(struct bld_context *bld, struct nv_value *src)
 
 static void
 bld_flow(struct bld_context *bld, uint opcode,
-         struct nv_value *src, struct nv_basic_block *target,
+         struct nv_value *pred, uint8_t cc, struct nv_basic_block *target,
          boolean reconverge)
 {
    struct nv_instruction *nvi;
@@ -670,8 +670,10 @@ bld_flow(struct bld_context *bld, uint opcode,
    nvi = new_instruction(bld->pc, opcode);
    nvi->target = target;
    nvi->terminator = 1;
-   if (src)
-      bld_src_predicate(bld, nvi, 0, src);
+   if (pred) {
+      nvi->cc = cc;
+      bld_src_predicate(bld, nvi, 0, pred);
+   }
 }
 
 static ubyte
@@ -1584,6 +1586,7 @@ bld_instruction(struct bld_context *bld,
    case TGSI_OPCODE_IF:
    {
       struct nv_basic_block *b = new_basic_block(bld->pc);
+      struct nv_value *pred = emit_fetch(bld, insn, 0, 0);
 
       assert(bld->cond_lvl < BLD_MAX_COND_NESTING);
 
@@ -1592,10 +1595,19 @@ bld_instruction(struct bld_context *bld,
       bld->join_bb[bld->cond_lvl] = bld->pc->current_block;
       bld->cond_bb[bld->cond_lvl] = bld->pc->current_block;
 
-      src1 = bld_setp(bld, NV_OP_SET_U32, NV_CC_EQ,
-                      emit_fetch(bld, insn, 0, 0), bld->zero);
+      if (pred->insn && NV_BASEOP(pred->insn->opcode) == NV_OP_SET) {
+         pred = bld_clone(bld, pred->insn);
+         pred->reg.size = 1;
+         pred->reg.file = NV_FILE_PRED;
+         if (pred->insn->opcode == NV_OP_FSET_F32)
+            pred->insn->opcode = NV_OP_SET_F32;
+      } else {
+         pred = bld_setp(bld, NV_OP_SET_U32, NV_CC_NE | NV_CC_U,
+                         pred, bld->zero);
+      }
+      assert(!mask);
 
-      bld_flow(bld, NV_OP_BRA, src1, NULL, (bld->cond_lvl == 0));
+      bld_flow(bld, NV_OP_BRA, pred, NV_CC_NOT_P, NULL, (bld->cond_lvl == 0));
 
       ++bld->cond_lvl;
       bld_new_block(bld, b);
@@ -1661,7 +1673,7 @@ bld_instruction(struct bld_context *bld,
    {
       struct nv_basic_block *bb = bld->brkt_bb[bld->loop_lvl - 1];
 
-      bld_flow(bld, NV_OP_BRA, NULL, bb, FALSE);
+      bld_flow(bld, NV_OP_BRA, NULL, NV_CC_P, bb, FALSE);
 
       if (bld->out_kind == CFG_EDGE_FORWARD) /* else we already had BRK/CONT */
          nvc0_bblock_attach(bld->pc->current_block, bb, CFG_EDGE_LOOP_LEAVE);
@@ -1673,7 +1685,7 @@ bld_instruction(struct bld_context *bld,
    {
       struct nv_basic_block *bb = bld->loop_bb[bld->loop_lvl - 1];
 
-      bld_flow(bld, NV_OP_BRA, NULL, bb, FALSE);
+      bld_flow(bld, NV_OP_BRA, NULL, NV_CC_P, bb, FALSE);
 
       nvc0_bblock_attach(bld->pc->current_block, bb, CFG_EDGE_BACK);
 
@@ -1689,7 +1701,7 @@ bld_instruction(struct bld_context *bld,
       struct nv_basic_block *bb = bld->loop_bb[bld->loop_lvl - 1];
 
       if (bld->out_kind != CFG_EDGE_FAKE) { /* else we already had BRK/CONT */
-         bld_flow(bld, NV_OP_BRA, NULL, bb, FALSE);
+         bld_flow(bld, NV_OP_BRA, NULL, NV_CC_P, bb, FALSE);
 
          nvc0_bblock_attach(bld->pc->current_block, bb, CFG_EDGE_BACK);
       }