vc4: Add support for emitting NIR IF nodes.
[mesa.git] / src / gallium / drivers / vc4 / vc4_register_allocate.c
index 204c080467e194fa3c8573a1c12839cf2d3963ce..203b459abf89ddf8c33646982540ad725b9c509b 100644 (file)
@@ -36,110 +36,135 @@ static const struct qpu_reg vc4_regs[] = {
         { QPU_MUX_R3, 0},
         { QPU_MUX_R4, 0},
         QPU_R(A, 0),
-        QPU_R(A, 1),
-        QPU_R(A, 2),
-        QPU_R(A, 3),
-        QPU_R(A, 4),
-        QPU_R(A, 5),
-        QPU_R(A, 6),
-        QPU_R(A, 7),
-        QPU_R(A, 8),
-        QPU_R(A, 9),
-        QPU_R(A, 10),
-        QPU_R(A, 11),
-        QPU_R(A, 12),
-        QPU_R(A, 13),
-        QPU_R(A, 14),
-        QPU_R(A, 15),
-        QPU_R(A, 16),
-        QPU_R(A, 17),
-        QPU_R(A, 18),
-        QPU_R(A, 19),
-        QPU_R(A, 20),
-        QPU_R(A, 21),
-        QPU_R(A, 22),
-        QPU_R(A, 23),
-        QPU_R(A, 24),
-        QPU_R(A, 25),
-        QPU_R(A, 26),
-        QPU_R(A, 27),
-        QPU_R(A, 28),
-        QPU_R(A, 29),
-        QPU_R(A, 30),
-        QPU_R(A, 31),
         QPU_R(B, 0),
+        QPU_R(A, 1),
         QPU_R(B, 1),
+        QPU_R(A, 2),
         QPU_R(B, 2),
+        QPU_R(A, 3),
         QPU_R(B, 3),
+        QPU_R(A, 4),
         QPU_R(B, 4),
+        QPU_R(A, 5),
         QPU_R(B, 5),
+        QPU_R(A, 6),
         QPU_R(B, 6),
+        QPU_R(A, 7),
         QPU_R(B, 7),
+        QPU_R(A, 8),
         QPU_R(B, 8),
+        QPU_R(A, 9),
         QPU_R(B, 9),
+        QPU_R(A, 10),
         QPU_R(B, 10),
+        QPU_R(A, 11),
         QPU_R(B, 11),
+        QPU_R(A, 12),
         QPU_R(B, 12),
+        QPU_R(A, 13),
         QPU_R(B, 13),
+        QPU_R(A, 14),
         QPU_R(B, 14),
+        QPU_R(A, 15),
         QPU_R(B, 15),
+        QPU_R(A, 16),
         QPU_R(B, 16),
+        QPU_R(A, 17),
         QPU_R(B, 17),
+        QPU_R(A, 18),
         QPU_R(B, 18),
+        QPU_R(A, 19),
         QPU_R(B, 19),
+        QPU_R(A, 20),
         QPU_R(B, 20),
+        QPU_R(A, 21),
         QPU_R(B, 21),
+        QPU_R(A, 22),
         QPU_R(B, 22),
+        QPU_R(A, 23),
         QPU_R(B, 23),
+        QPU_R(A, 24),
         QPU_R(B, 24),
+        QPU_R(A, 25),
         QPU_R(B, 25),
+        QPU_R(A, 26),
         QPU_R(B, 26),
+        QPU_R(A, 27),
         QPU_R(B, 27),
+        QPU_R(A, 28),
         QPU_R(B, 28),
+        QPU_R(A, 29),
         QPU_R(B, 29),
+        QPU_R(A, 30),
         QPU_R(B, 30),
+        QPU_R(A, 31),
         QPU_R(B, 31),
 };
 #define ACC_INDEX     0
-#define A_INDEX       (ACC_INDEX + 5)
-#define B_INDEX       (A_INDEX + 32)
+#define AB_INDEX      (ACC_INDEX + 5)
 
 static void
 vc4_alloc_reg_set(struct vc4_context *vc4)
 {
-        assert(vc4_regs[A_INDEX].addr == 0);
-        assert(vc4_regs[B_INDEX].addr == 0);
-        STATIC_ASSERT(ARRAY_SIZE(vc4_regs) == B_INDEX + 32);
+        assert(vc4_regs[AB_INDEX].addr == 0);
+        assert(vc4_regs[AB_INDEX + 1].addr == 0);
+        STATIC_ASSERT(ARRAY_SIZE(vc4_regs) == AB_INDEX + 64);
 
         if (vc4->regs)
                 return;
 
-        vc4->regs = ra_alloc_reg_set(vc4, ARRAY_SIZE(vc4_regs));
+        vc4->regs = ra_alloc_reg_set(vc4, ARRAY_SIZE(vc4_regs), true);
 
         vc4->reg_class_any = ra_alloc_reg_class(vc4->regs);
+        vc4->reg_class_a_or_b_or_acc = ra_alloc_reg_class(vc4->regs);
+        vc4->reg_class_r4_or_a = ra_alloc_reg_class(vc4->regs);
+        vc4->reg_class_a = ra_alloc_reg_class(vc4->regs);
         for (uint32_t i = 0; i < ARRAY_SIZE(vc4_regs); i++) {
-                /* Reserve r3 for now, since we're using it for spilling-like
-                 * operations in vc4_qpu_emit.c
+                /* Reserve ra31/rb31 for spilling fixup_raddr_conflict() in
+                 * vc4_qpu_emit.c
                  */
-                if (vc4_regs[i].mux == QPU_MUX_R3)
+                if (vc4_regs[i].addr == 31)
                         continue;
 
                 /* R4 can't be written as a general purpose register. (it's
                  * TMU_NOSWAP as a write address).
                  */
-                if (vc4_regs[i].mux == QPU_MUX_R4)
+                if (vc4_regs[i].mux == QPU_MUX_R4) {
+                        ra_class_add_reg(vc4->regs, vc4->reg_class_r4_or_a, i);
+                        ra_class_add_reg(vc4->regs, vc4->reg_class_any, i);
                         continue;
+                }
 
                 ra_class_add_reg(vc4->regs, vc4->reg_class_any, i);
+                ra_class_add_reg(vc4->regs, vc4->reg_class_a_or_b_or_acc, i);
         }
 
-        vc4->reg_class_a = ra_alloc_reg_class(vc4->regs);
-        for (uint32_t i = A_INDEX; i < A_INDEX + 32; i++)
+        for (uint32_t i = AB_INDEX; i < AB_INDEX + 64; i += 2) {
                 ra_class_add_reg(vc4->regs, vc4->reg_class_a, i);
+                ra_class_add_reg(vc4->regs, vc4->reg_class_r4_or_a, i);
+        }
 
         ra_set_finalize(vc4->regs, NULL);
 }
 
+struct node_to_temp_map {
+        uint32_t temp;
+        uint32_t priority;
+};
+
+static int
+node_to_temp_priority(const void *in_a, const void *in_b)
+{
+        const struct node_to_temp_map *a = in_a;
+        const struct node_to_temp_map *b = in_b;
+
+        return a->priority - b->priority;
+}
+
+#define CLASS_BIT_A                    (1 << 0)
+#define CLASS_BIT_B_OR_ACC             (1 << 1)
+#define CLASS_BIT_R4                   (1 << 2)
+
 /**
  * Returns a mapping from QFILE_TEMP indices to struct qpu_regs.
  *
@@ -148,13 +173,11 @@ vc4_alloc_reg_set(struct vc4_context *vc4)
 struct qpu_reg *
 vc4_register_allocate(struct vc4_context *vc4, struct vc4_compile *c)
 {
-        struct simple_node *node;
-        uint32_t def[c->num_temps];
-        uint32_t use[c->num_temps];
+        struct node_to_temp_map map[c->num_temps];
+        uint32_t temp_to_node[c->num_temps];
+        uint8_t class_bits[c->num_temps];
         struct qpu_reg *temp_registers = calloc(c->num_temps,
                                                 sizeof(*temp_registers));
-        memset(def, 0, sizeof(def));
-        memset(use, 0, sizeof(use));
 
         /* If things aren't ever written (undefined values), just read from
          * r0.
@@ -167,70 +190,138 @@ vc4_register_allocate(struct vc4_context *vc4, struct vc4_compile *c)
         struct ra_graph *g = ra_alloc_interference_graph(vc4->regs,
                                                          c->num_temps);
 
-        for (uint32_t i = 0; i < c->num_temps; i++)
-                ra_set_node_class(g, i, vc4->reg_class_any);
+        /* Compute the live ranges so we can figure out interference. */
+        qir_calculate_live_intervals(c);
 
-        /* Compute the live ranges so we can figure out interference, and
-         * figure out our register classes and preallocated registers.
+        for (uint32_t i = 0; i < c->num_temps; i++) {
+                map[i].temp = i;
+                map[i].priority = c->temp_end[i] - c->temp_start[i];
+        }
+        qsort(map, c->num_temps, sizeof(map[0]), node_to_temp_priority);
+        for (uint32_t i = 0; i < c->num_temps; i++) {
+                temp_to_node[map[i].temp] = i;
+        }
+
+        /* Figure out our register classes and preallocated registers.  We
+         * start with any temp being able to be in any file, then instructions
+         * incrementally remove bits that the temp definitely can't be in.
          */
-        uint32_t ip = 0;
-        foreach(node, &c->instructions) {
-                struct qinst *inst = (struct qinst *)node;
+        memset(class_bits,
+               CLASS_BIT_A | CLASS_BIT_B_OR_ACC | CLASS_BIT_R4,
+               sizeof(class_bits));
 
-                if (inst->dst.file == QFILE_TEMP) {
-                        def[inst->dst.index] = ip;
-                        use[inst->dst.index] = ip;
-                }
-
-                for (int i = 0; i < qir_get_op_nsrc(inst->op); i++) {
-                        if (inst->src[i].file == QFILE_TEMP)
-                                use[inst->src[i].index] = ip;
+        int ip = 0;
+        qir_for_each_inst_inorder(inst, c) {
+                if (qir_writes_r4(inst)) {
+                        /* This instruction writes r4 (and optionally moves
+                         * its result to a temp), so nothing else can be
+                         * stored in r4 across it.
+                         */
+                        for (int i = 0; i < c->num_temps; i++) {
+                                if (c->temp_start[i] < ip && c->temp_end[i] > ip)
+                                        class_bits[i] &= ~CLASS_BIT_R4;
+                        }
+                } else {
+                        /* R4 can't be written as a general purpose
+                         * register. (it's TMU_NOSWAP as a write address).
+                         */
+                        if (inst->dst.file == QFILE_TEMP)
+                                class_bits[inst->dst.index] &= ~CLASS_BIT_R4;
                 }
 
                 switch (inst->op) {
                 case QOP_FRAG_Z:
-                        def[inst->dst.index] = 0;
-                        ra_set_node_reg(g, inst->dst.index,
-                                        B_INDEX + QPU_R_FRAG_PAYLOAD_ZW);
+                        ra_set_node_reg(g, temp_to_node[inst->dst.index],
+                                        AB_INDEX + QPU_R_FRAG_PAYLOAD_ZW * 2 + 1);
                         break;
 
                 case QOP_FRAG_W:
-                        def[inst->dst.index] = 0;
-                        ra_set_node_reg(g, inst->dst.index,
-                                        A_INDEX + QPU_R_FRAG_PAYLOAD_ZW);
+                        ra_set_node_reg(g, temp_to_node[inst->dst.index],
+                                        AB_INDEX + QPU_R_FRAG_PAYLOAD_ZW * 2);
                         break;
 
-                case QOP_TEX_RESULT:
-                case QOP_TLB_COLOR_READ:
-                        assert(vc4_regs[ACC_INDEX + 4].mux == QPU_MUX_R4);
-                        ra_set_node_reg(g, inst->dst.index,
-                                        ACC_INDEX + 4);
+                default:
                         break;
+                }
 
-                case QOP_PACK_SCALED:
-                        /* The pack flags require an A-file dst register. */
-                        ra_set_node_class(g, inst->dst.index, vc4->reg_class_a);
-                        break;
+                if (inst->dst.pack && !qir_is_mul(inst)) {
+                        /* The non-MUL pack flags require an A-file dst
+                         * register.
+                         */
+                        class_bits[inst->dst.index] &= CLASS_BIT_A;
+                }
 
-                default:
-                        break;
+                /* Apply restrictions for src unpacks.  The integer unpacks
+                 * can only be done from regfile A, while float unpacks can be
+                 * either A or R4.
+                 */
+                for (int i = 0; i < qir_get_op_nsrc(inst->op); i++) {
+                        if (inst->src[i].file == QFILE_TEMP &&
+                            inst->src[i].pack) {
+                                if (qir_is_float_input(inst)) {
+                                        class_bits[inst->src[i].index] &=
+                                                CLASS_BIT_A | CLASS_BIT_R4;
+                                } else {
+                                        class_bits[inst->src[i].index] &=
+                                                CLASS_BIT_A;
+                                }
+                        }
                 }
 
                 ip++;
         }
 
+        for (uint32_t i = 0; i < c->num_temps; i++) {
+                int node = temp_to_node[i];
+
+                switch (class_bits[i]) {
+                case CLASS_BIT_A | CLASS_BIT_B_OR_ACC | CLASS_BIT_R4:
+                        ra_set_node_class(g, node, vc4->reg_class_any);
+                        break;
+                case CLASS_BIT_A | CLASS_BIT_B_OR_ACC:
+                        ra_set_node_class(g, node, vc4->reg_class_a_or_b_or_acc);
+                        break;
+                case CLASS_BIT_A | CLASS_BIT_R4:
+                        ra_set_node_class(g, node, vc4->reg_class_r4_or_a);
+                        break;
+                case CLASS_BIT_A:
+                        ra_set_node_class(g, node, vc4->reg_class_a);
+                        break;
+                default:
+                        fprintf(stderr, "temp %d: bad class bits: 0x%x\n",
+                                i, class_bits[i]);
+                        abort();
+                        break;
+                }
+        }
+
         for (uint32_t i = 0; i < c->num_temps; i++) {
                 for (uint32_t j = i + 1; j < c->num_temps; j++) {
-                        if (!(def[i] >= use[j] || def[j] >= use[i]))
-                                ra_add_node_interference(g, i, j);
+                        if (!(c->temp_start[i] >= c->temp_end[j] ||
+                              c->temp_start[j] >= c->temp_end[i])) {
+                                ra_add_node_interference(g,
+                                                         temp_to_node[i],
+                                                         temp_to_node[j]);
+                        }
                 }
         }
 
         bool ok = ra_allocate(g);
-        assert(ok);
+        if (!ok) {
+                fprintf(stderr, "Failed to register allocate:\n");
+                qir_dump(c);
+                abort();
+        }
 
-        for (uint32_t i = 0; i < c->num_temps; i++)
-                temp_registers[i] = vc4_regs[ra_get_node_reg(g, i)];
+        for (uint32_t i = 0; i < c->num_temps; i++) {
+                temp_registers[i] = vc4_regs[ra_get_node_reg(g, temp_to_node[i])];
+
+                /* If the value's never used, just write to the NOP register
+                 * for clarity in debug output.
+                 */
+                if (c->temp_start[i] == c->temp_end[i])
+                        temp_registers[i] = qpu_ra(QPU_W_NOP);
+        }
 
         ralloc_free(g);