/* * Copyright © 2014 Broadcom * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. */ #include "util/ralloc.h" #include "util/register_allocate.h" #include "vc4_context.h" #include "vc4_qir.h" #include "vc4_qpu.h" #define QPU_R(file, index) { QPU_MUX_##file, index } static const struct qpu_reg vc4_regs[] = { { QPU_MUX_R0, 0}, { QPU_MUX_R1, 0}, { QPU_MUX_R2, 0}, { QPU_MUX_R3, 0}, { QPU_MUX_R4, 0}, QPU_R(A, 0), 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 ACC_COUNT 5 #define AB_INDEX (ACC_INDEX + ACC_COUNT) #define AB_COUNT 64 static void vc4_alloc_reg_set(struct vc4_context *vc4) { 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), true); /* The physical regfiles split us into two classes, with [0] being the * whole space and [1] being the bottom half (for threaded fragment * shaders). */ for (int i = 0; i < 2; i++) { vc4->reg_class_any[i] = ra_alloc_reg_class(vc4->regs); vc4->reg_class_a_or_b[i] = ra_alloc_reg_class(vc4->regs); vc4->reg_class_a_or_b_or_acc[i] = ra_alloc_reg_class(vc4->regs); vc4->reg_class_r4_or_a[i] = ra_alloc_reg_class(vc4->regs); vc4->reg_class_a[i] = ra_alloc_reg_class(vc4->regs); } vc4->reg_class_r0_r3 = ra_alloc_reg_class(vc4->regs); /* r0-r3 */ for (uint32_t i = ACC_INDEX; i < ACC_INDEX + 4; i++) { ra_class_add_reg(vc4->regs, vc4->reg_class_r0_r3, i); ra_class_add_reg(vc4->regs, vc4->reg_class_a_or_b_or_acc[0], i); ra_class_add_reg(vc4->regs, vc4->reg_class_a_or_b_or_acc[1], i); } /* R4 gets a special class because it can't be written as a general * purpose register. (it's TMU_NOSWAP as a write address). */ for (int i = 0; i < 2; i++) { ra_class_add_reg(vc4->regs, vc4->reg_class_r4_or_a[i], ACC_INDEX + 4); ra_class_add_reg(vc4->regs, vc4->reg_class_any[i], ACC_INDEX + 4); } /* A/B */ for (uint32_t i = AB_INDEX; i < AB_INDEX + 64; i ++) { /* Reserve ra14/rb14 for spilling fixup_raddr_conflict() in * vc4_qpu_emit.c */ if (vc4_regs[i].addr == 14) continue; ra_class_add_reg(vc4->regs, vc4->reg_class_any[0], i); ra_class_add_reg(vc4->regs, vc4->reg_class_a_or_b[0], i); ra_class_add_reg(vc4->regs, vc4->reg_class_a_or_b_or_acc[0], i); if (vc4_regs[i].addr < 16) { ra_class_add_reg(vc4->regs, vc4->reg_class_any[1], i); ra_class_add_reg(vc4->regs, vc4->reg_class_a_or_b[1], i); ra_class_add_reg(vc4->regs, vc4->reg_class_a_or_b_or_acc[1], i); } /* A only */ if (((i - AB_INDEX) & 1) == 0) { ra_class_add_reg(vc4->regs, vc4->reg_class_a[0], i); ra_class_add_reg(vc4->regs, vc4->reg_class_r4_or_a[0], i); if (vc4_regs[i].addr < 16) { ra_class_add_reg(vc4->regs, vc4->reg_class_a[1], i); ra_class_add_reg(vc4->regs, vc4->reg_class_r4_or_a[1], 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 (1 << 1) #define CLASS_BIT_R4 (1 << 2) #define CLASS_BIT_R0_R3 (1 << 4) struct vc4_ra_select_callback_data { uint32_t next_acc; uint32_t next_ab; }; static unsigned int vc4_ra_select_callback(struct ra_graph *g, BITSET_WORD *regs, void *data) { struct vc4_ra_select_callback_data *vc4_ra = data; /* If r4 is available, always choose it -- few other things can go * there, and choosing anything else means inserting a mov. */ if (BITSET_TEST(regs, ACC_INDEX + 4)) return ACC_INDEX + 4; /* Choose an accumulator if possible (no delay between write and * read), but round-robin through them to give post-RA instruction * selection more options. */ for (int i = 0; i < ACC_COUNT; i++) { int acc_off = (vc4_ra->next_acc + i) % ACC_COUNT; int acc = ACC_INDEX + acc_off; if (BITSET_TEST(regs, acc)) { vc4_ra->next_acc = acc_off + 1; return acc; } } for (int i = 0; i < AB_COUNT; i++) { int ab_off = (vc4_ra->next_ab + i) % AB_COUNT; int ab = AB_INDEX + ab_off; if (BITSET_TEST(regs, ab)) { vc4_ra->next_ab = ab_off + 1; return ab; } } unreachable("RA must pass us at least one possible reg."); } /** * Returns a mapping from QFILE_TEMP indices to struct qpu_regs. * * The return value should be freed by the caller. */ struct qpu_reg * vc4_register_allocate(struct vc4_context *vc4, struct vc4_compile *c) { 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)); struct vc4_ra_select_callback_data callback_data = { .next_acc = 0, .next_ab = 0, }; /* If things aren't ever written (undefined values), just read from * r0. */ for (uint32_t i = 0; i < c->num_temps; i++) temp_registers[i] = qpu_rn(0); vc4_alloc_reg_set(vc4); struct ra_graph *g = ra_alloc_interference_graph(vc4->regs, c->num_temps); /* Compute the live ranges so we can figure out interference. */ qir_calculate_live_intervals(c); ra_set_select_reg_callback(g, vc4_ra_select_callback, &callback_data); 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. */ memset(class_bits, CLASS_BIT_A | CLASS_BIT_B | CLASS_BIT_R4 | CLASS_BIT_R0_R3, sizeof(class_bits)); 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; } /* If we're doing a conditional write of something * writing R4 (math, tex results), then make sure that * we store in a temp so that we actually * conditionally move the result. */ if (inst->cond != QPU_COND_ALWAYS) class_bits[inst->dst.index] &= ~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: 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: ra_set_node_reg(g, temp_to_node[inst->dst.index], AB_INDEX + QPU_R_FRAG_PAYLOAD_ZW * 2); break; case QOP_ROT_MUL: assert(inst->src[0].file == QFILE_TEMP); class_bits[inst->src[0].index] &= CLASS_BIT_R0_R3; break; case QOP_THRSW: /* All accumulators are invalidated across a thread * switch. */ 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_R0_R3 | CLASS_BIT_R4); } break; default: 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; } /* 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_nsrc(inst); 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 | CLASS_BIT_R4 | CLASS_BIT_R0_R3: ra_set_node_class(g, node, vc4->reg_class_any[c->fs_threaded]); break; case CLASS_BIT_A | CLASS_BIT_B: ra_set_node_class(g, node, vc4->reg_class_a_or_b[c->fs_threaded]); break; case CLASS_BIT_A | CLASS_BIT_B | CLASS_BIT_R0_R3: ra_set_node_class(g, node, vc4->reg_class_a_or_b_or_acc[c->fs_threaded]); break; case CLASS_BIT_A | CLASS_BIT_R4: ra_set_node_class(g, node, vc4->reg_class_r4_or_a[c->fs_threaded]); break; case CLASS_BIT_A: ra_set_node_class(g, node, vc4->reg_class_a[c->fs_threaded]); break; case CLASS_BIT_R0_R3: ra_set_node_class(g, node, vc4->reg_class_r0_r3); break; default: /* DDX/DDY used across thread switched might get us * here. */ if (c->fs_threaded) { c->failed = true; free(temp_registers); return NULL; } 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 (!(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); if (!ok) { if (!c->fs_threaded) { fprintf(stderr, "Failed to register allocate:\n"); qir_dump(c); } c->failed = true; free(temp_registers); return NULL; } 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); return temp_registers; }