lima/ppir: implement discard and discard_if

This commit also adds codegen for branch since we need it
for discard_if.

Reviewed-by: Qiang Yu <yuq825@gmail.com>
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>

src/gallium/drivers/lima/ir/pp/codegen.c

@@ -507,6 +507,42 @@ static void ppir_codegen_encode_const(ppir_const *constant, uint16_t *code)
       code[i] = util_float_to_half(constant->value[i].f);
 }
 
+static void ppir_codegen_encode_discard(ppir_node *node, void *code)
+{
+   ppir_codegen_field_branch *b = code;
+   assert(node->op = ppir_op_discard);
+
+   b->discard.word0 = PPIR_CODEGEN_DISCARD_WORD0;
+   b->discard.word1 = PPIR_CODEGEN_DISCARD_WORD1;
+   b->discard.word2 = PPIR_CODEGEN_DISCARD_WORD2;
+}
+
+static void ppir_codegen_encode_branch(ppir_node *node, void *code)
+{
+   ppir_codegen_field_branch *b = code;
+   ppir_branch_node *branch;
+   ppir_instr *target_instr;
+   if (node->op == ppir_op_discard) {
+      ppir_codegen_encode_discard(node, code);
+      return;
+   }
+
+   assert(node->op = ppir_op_branch);
+   branch = ppir_node_to_branch(node);
+
+   b->branch.unknown_0 = 0x0;
+   b->branch.arg0_source = ppir_target_get_src_reg_index(&branch->src[0]);
+   b->branch.arg1_source = ppir_target_get_src_reg_index(&branch->src[1]);
+   b->branch.cond_gt = branch->cond_gt;
+   b->branch.cond_eq = branch->cond_eq;
+   b->branch.cond_lt = branch->cond_lt;
+   b->branch.unknown_1 = 0x0;
+   b->branch.unknown_2 = 0x3;
+
+   target_instr = list_first_entry(&branch->target->instr_list, ppir_instr, list);
+   b->branch.target = target_instr->offset - node->instr->offset;
+}
+
 typedef void (*ppir_codegen_instr_slot_encode_func)(ppir_node *, void *);
 
 static const ppir_codegen_instr_slot_encode_func
@@ -520,6 +556,7 @@ ppir_codegen_encode_slot[PPIR_INSTR_SLOT_NUM] = {
    [PPIR_INSTR_SLOT_ALU_SCL_ADD] = ppir_codegen_encode_scl_add,
    [PPIR_INSTR_SLOT_ALU_COMBINE] = ppir_codegen_encode_combine,
    [PPIR_INSTR_SLOT_STORE_TEMP] = ppir_codegen_encode_store_temp,
+   [PPIR_INSTR_SLOT_BRANCH] = ppir_codegen_encode_branch,
 };
 
 static const int ppir_codegen_field_size[] = {
@@ -634,7 +671,7 @@ static void ppir_codegen_print_prog(ppir_compiler *comp)
    printf("========ppir codegen========\n");
    list_for_each_entry(ppir_block, block, &comp->block_list, list) {
       list_for_each_entry(ppir_instr, instr, &block->instr_list, list) {
-         printf("%03d: ", instr->index);
+         printf("%03d (@%6ld): ", instr->index, instr->offset);
          int n = prog[0] & 0x1f;
          for (int i = 0; i < n; i++) {
             if (i && i % 6 == 0)
@@ -655,6 +692,7 @@ bool ppir_codegen_prog(ppir_compiler *comp)
    int size = 0;
    list_for_each_entry(ppir_block, block, &comp->block_list, list) {
       list_for_each_entry(ppir_instr, instr, &block->instr_list, list) {
+         instr->offset = size;
          size += get_instr_encode_size(instr);
       }
    }

src/gallium/drivers/lima/ir/pp/instr.c

@@ -135,6 +135,20 @@ static bool ppir_instr_insert_const(ppir_const *dst, const ppir_const *src,
    return true;
 }
 
+static void ppir_update_src_pipeline(ppir_pipeline pipeline, ppir_src *src,
+                                     ppir_dest *dest, uint8_t *swizzle)
+{
+   if (ppir_node_target_equal(src, dest)) {
+      src->type = ppir_target_pipeline;
+      src->pipeline = pipeline;
+
+      if (swizzle) {
+         for (int k = 0; k < 4; k++)
+            src->swizzle[k] = swizzle[src->swizzle[k]];
+      }
+   }
+}
+
 /* make alu node src reflact the pipeline reg */
 static void ppir_instr_update_src_pipeline(ppir_instr *instr, ppir_pipeline pipeline,
                                            ppir_dest *dest, uint8_t *swizzle)
@@ -146,15 +160,16 @@ static void ppir_instr_update_src_pipeline(ppir_instr *instr, ppir_pipeline pipe
       ppir_alu_node *alu = ppir_node_to_alu(instr->slots[i]);
       for (int j = 0; j < alu->num_src; j++) {
          ppir_src *src = alu->src + j;
-         if (ppir_node_target_equal(src, dest)) {
-            src->type = ppir_target_pipeline;
-            src->pipeline = pipeline;
+         ppir_update_src_pipeline(pipeline, src, dest, swizzle);
+      }
+   }
 
-            if (swizzle) {
-               for (int k = 0; k < 4; k++)
-                  src->swizzle[k] = swizzle[src->swizzle[k]];
-            }
-         }
+   ppir_node *branch_node = instr->slots[PPIR_INSTR_SLOT_BRANCH];
+   if (branch_node && (branch_node->type == ppir_node_type_branch)) {
+      ppir_branch_node *branch = ppir_node_to_branch(branch_node);
+      for (int j = 0; j < 2; j++) {
+         ppir_src *src = branch->src + j;
+         ppir_update_src_pipeline(pipeline, src, dest, swizzle);
       }
    }
 }
@@ -234,6 +249,7 @@ static struct {
    [PPIR_INSTR_SLOT_ALU_SCL_ADD] = { 4, "sadd" },
    [PPIR_INSTR_SLOT_ALU_COMBINE] = { 4, "comb" },
    [PPIR_INSTR_SLOT_STORE_TEMP] = { 4, "stor" },
+   [PPIR_INSTR_SLOT_BRANCH] = { 4, "brch" },
 };
 
 void ppir_instr_print_list(ppir_compiler *comp)

src/gallium/drivers/lima/ir/pp/lower.c

@@ -400,6 +400,40 @@ static bool ppir_lower_trunc(ppir_block *block, ppir_node *node)
    return true;
 }
 
+static bool ppir_lower_branch(ppir_block *block, ppir_node *node)
+{
+   ppir_branch_node *branch = ppir_node_to_branch(node);
+   ppir_const_node *zero = ppir_node_create(block, ppir_op_const, -1, 0);
+
+   if (!zero)
+      return false;
+
+   list_addtail(&zero->node.list, &node->list);
+
+   zero->constant.value[0].f = 0;
+   zero->constant.num = 1;
+   zero->dest.type = ppir_target_ssa;
+   zero->dest.ssa.num_components = 1;
+   zero->dest.ssa.live_in = INT_MAX;
+   zero->dest.ssa.live_out = 0;
+   zero->dest.write_mask = 0x01;
+
+   /* For now we're just comparing branch condition with 0,
+    * in future we should look whether it's possible to move
+    * comparision node into branch itself and use current
+    * way as a fallback for complex conditions.
+    */
+   branch->src[1].type = ppir_target_ssa;
+   branch->src[1].ssa = &zero->dest.ssa;
+
+   branch->cond_gt = true;
+   branch->cond_lt = true;
+
+   ppir_node_add_dep(&branch->node, &zero->node);
+
+   return true;
+}
+
 static bool (*ppir_lower_funcs[ppir_op_num])(ppir_block *, ppir_node *) = {
    [ppir_op_const] = ppir_lower_const,
    [ppir_op_dot2] = ppir_lower_dot,
@@ -417,6 +451,7 @@ static bool (*ppir_lower_funcs[ppir_op_num])(ppir_block *, ppir_node *) = {
    [ppir_op_load_texture] = ppir_lower_texture,
    [ppir_op_select] = ppir_lower_select,
    [ppir_op_trunc] = ppir_lower_trunc,
+   [ppir_op_branch] = ppir_lower_branch,
 };
 
 bool ppir_lower_prog(ppir_compiler *comp)

src/gallium/drivers/lima/ir/pp/nir.c

@@ -204,6 +204,57 @@ static ppir_node *ppir_emit_alu(ppir_block *block, nir_instr *ni)
    return &node->node;
 }
 
+static ppir_block *ppir_block_create(ppir_compiler *comp);
+
+static bool ppir_emit_discard_block(ppir_compiler *comp)
+{
+   ppir_block *block = ppir_block_create(comp);
+   ppir_discard_node *discard;
+   if (!block)
+      return false;
+
+   comp->discard_block = block;
+   block->comp  = comp;
+
+   discard = ppir_node_create(block, ppir_op_discard, -1, 0);
+   if (discard)
+      list_addtail(&discard->node.list, &block->node_list);
+   else
+      return false;
+
+   return true;
+}
+
+static ppir_node *ppir_emit_discard_if(ppir_block *block, nir_instr *ni)
+{
+   nir_intrinsic_instr *instr = nir_instr_as_intrinsic(ni);
+   ppir_node *node;
+   ppir_compiler *comp = block->comp;
+   ppir_branch_node *branch;
+
+   if (!comp->discard_block && !ppir_emit_discard_block(comp))
+      return NULL;
+
+   node = ppir_node_create(block, ppir_op_branch, -1, 0);
+   if (!node)
+      return NULL;
+   branch = ppir_node_to_branch(node);
+
+   /* second src and condition will be updated during lowering */
+   ppir_node_add_src(block->comp, node, &branch->src[0],
+                     &instr->src[0], u_bit_consecutive(0, instr->num_components));
+   branch->target = comp->discard_block;
+
+   return node;
+}
+
+static ppir_node *ppir_emit_discard(ppir_block *block, nir_instr *ni)
+{
+   ppir_node *node = ppir_node_create(block, ppir_op_discard, -1, 0);
+
+   return node;
+}
+
 static ppir_node *ppir_emit_intrinsic(ppir_block *block, nir_instr *ni)
 {
    nir_intrinsic_instr *instr = nir_instr_as_intrinsic(ni);
@@ -264,6 +315,12 @@ static ppir_node *ppir_emit_intrinsic(ppir_block *block, nir_instr *ni)
 
       return &snode->node;
 
+   case nir_intrinsic_discard:
+      return ppir_emit_discard(block, ni);
+
+   case nir_intrinsic_discard_if:
+      return ppir_emit_discard_if(block, ni);
+
    default:
       ppir_error("unsupported nir_intrinsic_instr %s\n",
                  nir_intrinsic_infos[instr->intrinsic].name);
@@ -452,6 +509,46 @@ static ppir_compiler *ppir_compiler_create(void *prog, unsigned num_reg, unsigne
    return comp;
 }
 
+static void ppir_add_ordering_deps(ppir_compiler *comp)
+{
+   /* Some intrinsics do not have explicit dependencies and thus depend
+    * on instructions order. Consider discard_if and store_ouput as
+    * example. If we don't add fake dependency of discard_if to store_output
+    * scheduler may put store_output first and since store_output terminates
+    * shader on Utgard PP, rest of it will never be executed.
+    * Add fake dependencies for discard/branch/store to preserve
+    * instruction order.
+    *
+    * TODO: scheduler should schedule discard_if as early as possible otherwise
+    * we may end up with suboptimal code for cases like this:
+    *
+    * s3 = s1 < s2
+    * discard_if s3
+    * s4 = s1 + s2
+    * store s4
+    *
+    * In this case store depends on discard_if and s4, but since dependencies can
+    * be scheduled in any order it can result in code like this:
+    *
+    * instr1: s3 = s1 < s3
+    * instr2: s4 = s1 + s2
+    * instr3: discard_if s3
+    * instr4: store s4
+    */
+   list_for_each_entry(ppir_block, block, &comp->block_list, list) {
+      ppir_node *prev_node = NULL;
+      list_for_each_entry(ppir_node, node, &block->node_list, list) {
+         if (node->type == ppir_node_type_discard ||
+             node->type == ppir_node_type_store ||
+             node->type == ppir_node_type_branch) {
+            if (prev_node)
+               ppir_node_add_dep(node, prev_node);
+            prev_node = node;
+         }
+      }
+   }
+}
+
 bool ppir_compile_nir(struct lima_fs_shader_state *prog, struct nir_shader *nir,
                       struct ra_regs *ra)
 {
@@ -477,6 +574,13 @@ bool ppir_compile_nir(struct lima_fs_shader_state *prog, struct nir_shader *nir,
 
    if (!ppir_emit_cf_list(comp, &func->body))
       goto err_out0;
+
+   /* If we have discard block add it to the very end */
+   if (comp->discard_block)
+      list_addtail(&comp->discard_block->list, &comp->block_list);
+
+   ppir_add_ordering_deps(comp);
+
    ppir_node_print_prog(comp);
 
    if (!ppir_lower_prog(comp))

src/gallium/drivers/lima/ir/pp/node.c

@@ -281,6 +281,20 @@ const ppir_op_info ppir_op_infos[] = {
          PPIR_INSTR_SLOT_STORE_TEMP, PPIR_INSTR_SLOT_END
       },
    },
+   [ppir_op_discard] = {
+      .name = "discard",
+      .type = ppir_node_type_discard,
+      .slots = (int []) {
+         PPIR_INSTR_SLOT_BRANCH, PPIR_INSTR_SLOT_END
+      },
+   },
+   [ppir_op_branch] = {
+      .name = "branch",
+      .type = ppir_node_type_branch,
+      .slots = (int []) {
+         PPIR_INSTR_SLOT_BRANCH, PPIR_INSTR_SLOT_END
+      },
+   },
 };
 
 void *ppir_node_create(ppir_block *block, ppir_op op, int index, unsigned mask)
@@ -292,6 +306,8 @@ void *ppir_node_create(ppir_block *block, ppir_op op, int index, unsigned mask)
       [ppir_node_type_load] = sizeof(ppir_load_node),
       [ppir_node_type_store] = sizeof(ppir_store_node),
       [ppir_node_type_load_texture] = sizeof(ppir_load_texture_node),
+      [ppir_node_type_discard] = sizeof(ppir_discard_node),
+      [ppir_node_type_branch] = sizeof(ppir_branch_node),
    };
 
    ppir_node_type type = ppir_op_infos[op].type;

src/gallium/drivers/lima/ir/pp/node_to_instr.c

@@ -93,7 +93,8 @@ static bool insert_to_each_succ_instr(ppir_block *block, ppir_node *node)
 
    ppir_node_foreach_succ_safe(node, dep) {
       ppir_node *succ = dep->succ;
-      assert(succ->type == ppir_node_type_alu);
+      assert(succ->type == ppir_node_type_alu ||
+             succ->type == ppir_node_type_branch);
 
       if (!ppir_instr_insert_node(succ->instr, node)) {
          /* create a move node to insert for failed node */
@@ -323,6 +324,15 @@ static bool ppir_do_node_to_instr(ppir_block *block, ppir_node *node)
       node = move;
       break;
    }
+   case ppir_node_type_discard:
+      if (!create_new_instr(block, node))
+         return false;
+      node->instr->is_end = true;
+      break;
+   case ppir_node_type_branch:
+      if (!create_new_instr(block, node))
+         return false;
+      break;
    default:
       return false;
    }

src/gallium/drivers/lima/ir/pp/ppir.h

@@ -108,6 +108,9 @@ typedef enum {
 
    ppir_op_const,
 
+   ppir_op_discard,
+   ppir_op_branch,
+
    ppir_op_num,
 } ppir_op;
 
@@ -117,6 +120,8 @@ typedef enum {
    ppir_node_type_load,
    ppir_node_type_store,
    ppir_node_type_load_texture,
+   ppir_node_type_discard,
+   ppir_node_type_branch,
 } ppir_node_type;
 
 typedef struct {
@@ -254,6 +259,10 @@ typedef struct {
    int sampler_dim;
 } ppir_load_texture_node;
 
+typedef struct {
+   ppir_node node;
+} ppir_discard_node;
+
 enum ppir_instr_slot {
    PPIR_INSTR_SLOT_VARYING,
    PPIR_INSTR_SLOT_TEXLD,
@@ -264,6 +273,7 @@ enum ppir_instr_slot {
    PPIR_INSTR_SLOT_ALU_SCL_ADD,
    PPIR_INSTR_SLOT_ALU_COMBINE,
    PPIR_INSTR_SLOT_STORE_TEMP,
+   PPIR_INSTR_SLOT_BRANCH,
    PPIR_INSTR_SLOT_NUM,
    PPIR_INSTR_SLOT_END,
    PPIR_INSTR_SLOT_ALU_START = PPIR_INSTR_SLOT_ALU_VEC_MUL,
@@ -287,6 +297,7 @@ typedef struct ppir_instr {
    int est; /* earliest start time */
    int parent_index;
    bool scheduled;
+   off_t offset;
 } ppir_instr;
 
 typedef struct ppir_block {
@@ -300,6 +311,15 @@ typedef struct ppir_block {
    int sched_instr_base;
 } ppir_block;
 
+typedef struct {
+   ppir_node node;
+   ppir_src src[2];
+   bool cond_gt;
+   bool cond_eq;
+   bool cond_lt;
+   ppir_block *target;
+} ppir_branch_node;
+
 struct ra_regs;
 struct lima_fs_shader_state;
 
@@ -322,6 +342,8 @@ typedef struct ppir_compiler {
 
    /* for regalloc spilling debug */
    int force_spilling;
+
+   ppir_block *discard_block;
 } ppir_compiler;
 
 void *ppir_node_create(ppir_block *block, ppir_op op, int index, unsigned mask);
@@ -377,6 +399,8 @@ static inline ppir_node *ppir_node_first_pred(ppir_node *node)
 #define ppir_node_to_load(node) ((ppir_load_node *)(node))
 #define ppir_node_to_store(node) ((ppir_store_node *)(node))
 #define ppir_node_to_load_texture(node) ((ppir_load_texture_node *)(node))
+#define ppir_node_to_discard(node) ((ppir_discard_node *)(node))
+#define ppir_node_to_branch(node) ((ppir_branch_node *)(node))
 
 static inline ppir_dest *ppir_node_get_dest(ppir_node *node)
 {