/* * Copyright (C) 2014 Rob Clark * * 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. * * Authors: * Rob Clark */ #include "util/u_math.h" #include "util/register_allocate.h" #include "util/ralloc.h" #include "util/bitset.h" #include "ir3.h" #include "ir3_compiler.h" #include "ir3_ra.h" #ifdef DEBUG #define RA_DEBUG (ir3_shader_debug & IR3_DBG_RAMSGS) #else #define RA_DEBUG 0 #endif #define d(fmt, ...) do { if (RA_DEBUG) { \ printf("RA: "fmt"\n", ##__VA_ARGS__); \ } } while (0) #define di(instr, fmt, ...) do { if (RA_DEBUG) { \ printf("RA: "fmt": ", ##__VA_ARGS__); \ ir3_print_instr(instr); \ } } while (0) /* * Register Assignment: * * Uses the register_allocate util, which implements graph coloring * algo with interference classes. To handle the cases where we need * consecutive registers (for example, texture sample instructions), * we model these as larger (double/quad/etc) registers which conflict * with the corresponding registers in other classes. * * Additionally we create additional classes for half-regs, which * do not conflict with the full-reg classes. We do need at least * sizes 1-4 (to deal w/ texture sample instructions output to half- * reg). At the moment we don't create the higher order half-reg * classes as half-reg frequently does not have enough precision * for texture coords at higher resolutions. * * There are some additional cases that we need to handle specially, * as the graph coloring algo doesn't understand "partial writes". * For example, a sequence like: * * add r0.z, ... * sam (f32)(xy)r0.x, ... * ... * sam (f32)(xyzw)r0.w, r0.x, ... ; 3d texture, so r0.xyz are coord * * In this scenario, we treat r0.xyz as class size 3, which is written * (from a use/def perspective) at the 'add' instruction and ignore the * subsequent partial writes to r0.xy. So the 'add r0.z, ...' is the * defining instruction, as it is the first to partially write r0.xyz. * * To address the fragmentation that this can potentially cause, a * two pass register allocation is used. After the first pass the * assignment of scalars is discarded, but the assignment of vecN (for * N > 1) is used to pre-color in the second pass, which considers * only scalars. * * Arrays of arbitrary size are handled via pre-coloring a consecutive * sequence of registers. Additional scalar (single component) reg * names are allocated starting at ctx->class_base[total_class_count] * (see arr->base), which are pre-colored. In the use/def graph direct * access is treated as a single element use/def, and indirect access * is treated as use or def of all array elements. (Only the first * def is tracked, in case of multiple indirect writes, etc.) * * TODO arrays that fit in one of the pre-defined class sizes should * not need to be pre-colored, but instead could be given a normal * vreg name. (Ignoring this for now since it is a good way to work * out the kinks with arbitrary sized arrays.) * * TODO might be easier for debugging to split this into two passes, * the first assigning vreg names in a way that we could ir3_print() * the result. */ static struct ir3_instruction * name_to_instr(struct ir3_ra_ctx *ctx, unsigned name); static bool name_is_array(struct ir3_ra_ctx *ctx, unsigned name); static struct ir3_array * name_to_array(struct ir3_ra_ctx *ctx, unsigned name); /* does it conflict? */ static inline bool intersects(unsigned a_start, unsigned a_end, unsigned b_start, unsigned b_end) { return !((a_start >= b_end) || (b_start >= a_end)); } static unsigned reg_size_for_array(struct ir3_array *arr) { if (arr->half) return DIV_ROUND_UP(arr->length, 2); return arr->length; } static bool instr_before(struct ir3_instruction *a, struct ir3_instruction *b) { if (a->flags & IR3_INSTR_UNUSED) return false; return (a->ip < b->ip); } static struct ir3_instruction * get_definer(struct ir3_ra_ctx *ctx, struct ir3_instruction *instr, int *sz, int *off) { struct ir3_ra_instr_data *id = &ctx->instrd[instr->ip]; struct ir3_instruction *d = NULL; if (ctx->scalar_pass) { id->defn = instr; id->off = 0; id->sz = 1; /* considering things as N scalar regs now */ } if (id->defn) { *sz = id->sz; *off = id->off; return id->defn; } if (instr->opc == OPC_META_COLLECT) { /* What about the case where collect is subset of array, we * need to find the distance between where actual array starts * and collect.. that probably doesn't happen currently. */ int dsz, doff; /* note: don't use foreach_ssa_src as this gets called once * while assigning regs (which clears SSA flag) */ foreach_src_n (src, n, instr) { struct ir3_instruction *dd; if (!src->instr) continue; dd = get_definer(ctx, src->instr, &dsz, &doff); if ((!d) || instr_before(dd, d)) { d = dd; *sz = dsz; *off = doff - n; } } } else if (instr->cp.right || instr->cp.left) { /* covers also the meta:fo case, which ends up w/ single * scalar instructions for each component: */ struct ir3_instruction *f = ir3_neighbor_first(instr); /* by definition, the entire sequence forms one linked list * of single scalar register nodes (even if some of them may * be splits from a texture sample (for example) instr. We * just need to walk the list finding the first element of * the group defined (lowest ip) */ int cnt = 0; /* need to skip over unused in the group: */ while (f && (f->flags & IR3_INSTR_UNUSED)) { f = f->cp.right; cnt++; } while (f) { if ((!d) || instr_before(f, d)) d = f; if (f == instr) *off = cnt; f = f->cp.right; cnt++; } *sz = cnt; } else { /* second case is looking directly at the instruction which * produces multiple values (eg, texture sample), rather * than the split nodes that point back to that instruction. * This isn't quite right, because it may be part of a larger * group, such as: * * sam (f32)(xyzw)r0.x, ... * add r1.x, ... * add r1.y, ... * sam (f32)(xyzw)r2.x, r0.w <-- (r0.w, r1.x, r1.y) * * need to come up with a better way to handle that case. */ if (instr->address) { *sz = instr->regs[0]->size; } else { *sz = util_last_bit(instr->regs[0]->wrmask); } *off = 0; d = instr; } if (d->opc == OPC_META_SPLIT) { struct ir3_instruction *dd; int dsz, doff; dd = get_definer(ctx, d->regs[1]->instr, &dsz, &doff); /* by definition, should come before: */ debug_assert(instr_before(dd, d)); *sz = MAX2(*sz, dsz); if (instr->opc == OPC_META_SPLIT) *off = MAX2(*off, instr->split.off); d = dd; } debug_assert(d->opc != OPC_META_SPLIT); id->defn = d; id->sz = *sz; id->off = *off; return d; } static void ra_block_find_definers(struct ir3_ra_ctx *ctx, struct ir3_block *block) { foreach_instr (instr, &block->instr_list) { struct ir3_ra_instr_data *id = &ctx->instrd[instr->ip]; if (instr->regs_count == 0) continue; /* couple special cases: */ if (writes_addr0(instr) || writes_addr1(instr) || writes_pred(instr)) { id->cls = -1; } else if (instr->regs[0]->flags & IR3_REG_ARRAY) { id->cls = total_class_count; } else { /* and the normal case: */ id->defn = get_definer(ctx, instr, &id->sz, &id->off); id->cls = ra_size_to_class(id->sz, is_half(id->defn), is_high(id->defn)); /* this is a bit of duct-tape.. if we have a scenario like: * * sam (f32)(x) out.x, ... * sam (f32)(x) out.y, ... * * Then the fanout/split meta instructions for the two different * tex instructions end up grouped as left/right neighbors. The * upshot is that in when you get_definer() on one of the meta:fo's * you get definer as the first sam with sz=2, but when you call * get_definer() on the either of the sam's you get itself as the * definer with sz=1. * * (We actually avoid this scenario exactly, the neighbor links * prevent one of the output mov's from being eliminated, so this * hack should be enough. But probably we need to rethink how we * find the "defining" instruction.) * * TODO how do we figure out offset properly... */ if (id->defn != instr) { struct ir3_ra_instr_data *did = &ctx->instrd[id->defn->ip]; if (did->sz < id->sz) { did->sz = id->sz; did->cls = id->cls; } } } } } /* give each instruction a name (and ip), and count up the # of names * of each class */ static void ra_block_name_instructions(struct ir3_ra_ctx *ctx, struct ir3_block *block) { foreach_instr (instr, &block->instr_list) { struct ir3_ra_instr_data *id = &ctx->instrd[instr->ip]; #ifdef DEBUG instr->name = ~0; #endif ctx->instr_cnt++; if (!writes_gpr(instr)) continue; if (id->defn != instr) continue; /* In scalar pass, collect/split don't get their own names, * but instead inherit them from their src(s): * * Possibly we don't need this because of scalar_name(), but * it does make the ir3_print() dumps easier to read. */ if (ctx->scalar_pass) { if (instr->opc == OPC_META_SPLIT) { instr->name = instr->regs[1]->instr->name + instr->split.off; continue; } if (instr->opc == OPC_META_COLLECT) { instr->name = instr->regs[1]->instr->name; continue; } } /* arrays which don't fit in one of the pre-defined class * sizes are pre-colored: */ if ((id->cls >= 0) && (id->cls < total_class_count)) { /* in the scalar pass, we generate a name for each * scalar component, instr->name is the name of the * first component. */ unsigned n = ctx->scalar_pass ? dest_regs(instr) : 1; instr->name = ctx->class_alloc_count[id->cls]; ctx->class_alloc_count[id->cls] += n; ctx->alloc_count += n; } } } /** * Set a value for max register target. * * Currently this just rounds up to a multiple of full-vec4 (ie. the * granularity that we configure the hw for.. there is no point to * using r3.x if you aren't going to make r3.yzw available). But * in reality there seems to be multiple thresholds that affect the * number of waves.. and we should round up the target to the next * threshold when we round-robin registers, to give postsched more * options. When we understand that better, this is where we'd * implement that. */ static void ra_set_register_target(struct ir3_ra_ctx *ctx, unsigned max_target) { const unsigned hvec4 = 4; const unsigned vec4 = 2 * hvec4; ctx->max_target = align(max_target, vec4); d("New max_target=%u", ctx->max_target); } static int pick_in_range(BITSET_WORD *regs, unsigned min, unsigned max) { for (unsigned i = min; i <= max; i++) { if (BITSET_TEST(regs, i)) { return i; } } return -1; } static int pick_in_range_rev(BITSET_WORD *regs, int min, int max) { for (int i = max; i >= min; i--) { if (BITSET_TEST(regs, i)) { return i; } } return -1; } /* register selector for the a6xx+ merged register file: */ static unsigned int ra_select_reg_merged(unsigned int n, BITSET_WORD *regs, void *data) { struct ir3_ra_ctx *ctx = data; unsigned int class = ra_get_node_class(ctx->g, n); bool half, high; int sz = ra_class_to_size(class, &half, &high); assert (sz > 0); /* dimensions within the register class: */ unsigned max_target, start; /* the regs bitset will include *all* of the virtual regs, but we lay * out the different classes consecutively in the virtual register * space. So we just need to think about the base offset of a given * class within the virtual register space, and offset the register * space we search within by that base offset. */ unsigned base; /* TODO I think eventually we want to round-robin in vector pass * as well, but needs some more work to calculate # of live vals * for this. (Maybe with some work, we could just figure out * the scalar target and use that, since that is what we care * about in the end.. but that would mean setting up use-def/ * liveranges for scalar pass before doing vector pass.) * * For now, in the vector class, just move assignments for scalar * vals higher to hopefully prevent them from limiting where vecN * values can be placed. Since the scalar values are re-assigned * in the 2nd pass, we don't really care where they end up in the * vector pass. */ if (!ctx->scalar_pass) { base = ctx->set->gpr_to_ra_reg[class][0]; if (high) { max_target = HIGH_CLASS_REGS(class - HIGH_OFFSET); } else if (half) { max_target = HALF_CLASS_REGS(class - HALF_OFFSET); } else { max_target = CLASS_REGS(class); } if ((sz == 1) && !high) { return pick_in_range_rev(regs, base, base + max_target); } else { return pick_in_range(regs, base, base + max_target); } } else { assert(sz == 1); } /* NOTE: this is only used in scalar pass, so the register * class will be one of the scalar classes (ie. idx==0): */ base = ctx->set->gpr_to_ra_reg[class][0]; if (high) { max_target = HIGH_CLASS_REGS(0); start = 0; } else if (half) { max_target = ctx->max_target; start = ctx->start_search_reg; } else { max_target = ctx->max_target / 2; start = ctx->start_search_reg; } /* For cat4 instructions, if the src reg is already assigned, and * avail to pick, use it. Because this doesn't introduce unnecessary * dependencies, and it potentially avoids needing (ss) syncs to * for write after read hazards: */ struct ir3_instruction *instr = name_to_instr(ctx, n); if (is_sfu(instr)) { struct ir3_register *src = instr->regs[1]; int src_n; if ((src->flags & IR3_REG_ARRAY) && !(src->flags & IR3_REG_RELATIV)) { struct ir3_array *arr = ir3_lookup_array(ctx->ir, src->array.id); src_n = arr->base + src->array.offset; } else { src_n = scalar_name(ctx, src->instr, 0); } unsigned reg = ra_get_node_reg(ctx->g, src_n); /* Check if the src register has been assigned yet: */ if (reg != NO_REG) { if (BITSET_TEST(regs, reg)) { return reg; } } } int r = pick_in_range(regs, base + start, base + max_target); if (r < 0) { /* wrap-around: */ r = pick_in_range(regs, base, base + start); } if (r < 0) { /* overflow, we need to increase max_target: */ ra_set_register_target(ctx, ctx->max_target + 1); return ra_select_reg_merged(n, regs, data); } if (class == ctx->set->half_classes[0]) { int n = r - base; ctx->start_search_reg = (n + 1) % ctx->max_target; } else if (class == ctx->set->classes[0]) { int n = (r - base) * 2; ctx->start_search_reg = (n + 1) % ctx->max_target; } return r; } static void ra_init(struct ir3_ra_ctx *ctx) { unsigned n, base; ir3_clear_mark(ctx->ir); n = ir3_count_instructions_ra(ctx->ir); ctx->instrd = rzalloc_array(NULL, struct ir3_ra_instr_data, n); foreach_block (block, &ctx->ir->block_list) { ra_block_find_definers(ctx, block); } foreach_block (block, &ctx->ir->block_list) { ra_block_name_instructions(ctx, block); } /* figure out the base register name for each class. The * actual ra name is class_base[cls] + instr->name; */ ctx->class_base[0] = 0; for (unsigned i = 1; i <= total_class_count; i++) { ctx->class_base[i] = ctx->class_base[i-1] + ctx->class_alloc_count[i-1]; } /* and vreg names for array elements: */ base = ctx->class_base[total_class_count]; foreach_array (arr, &ctx->ir->array_list) { arr->base = base; ctx->class_alloc_count[total_class_count] += reg_size_for_array(arr); base += reg_size_for_array(arr); } ctx->alloc_count += ctx->class_alloc_count[total_class_count]; /* Add vreg names for r0.xyz */ ctx->r0_xyz_nodes = ctx->alloc_count; ctx->alloc_count += 3; ctx->hr0_xyz_nodes = ctx->alloc_count; ctx->alloc_count += 3; /* Add vreg name for prefetch-exclusion range: */ ctx->prefetch_exclude_node = ctx->alloc_count++; ctx->g = ra_alloc_interference_graph(ctx->set->regs, ctx->alloc_count); ralloc_steal(ctx->g, ctx->instrd); ctx->def = rzalloc_array(ctx->g, unsigned, ctx->alloc_count); ctx->use = rzalloc_array(ctx->g, unsigned, ctx->alloc_count); /* TODO add selector callback for split (pre-a6xx) register file: */ if (ctx->ir->compiler->gpu_id >= 600) { ra_set_select_reg_callback(ctx->g, ra_select_reg_merged, ctx); if (ctx->scalar_pass) { ctx->name_to_instr = _mesa_hash_table_create(ctx->g, _mesa_hash_int, _mesa_key_int_equal); } } } /* Map the name back to instruction: */ static struct ir3_instruction * name_to_instr(struct ir3_ra_ctx *ctx, unsigned name) { assert(!name_is_array(ctx, name)); struct hash_entry *entry = _mesa_hash_table_search(ctx->name_to_instr, &name); if (entry) return entry->data; unreachable("invalid instr name"); return NULL; } static bool name_is_array(struct ir3_ra_ctx *ctx, unsigned name) { return name >= ctx->class_base[total_class_count]; } static struct ir3_array * name_to_array(struct ir3_ra_ctx *ctx, unsigned name) { assert(name_is_array(ctx, name)); foreach_array (arr, &ctx->ir->array_list) { unsigned sz = reg_size_for_array(arr); if (name < (arr->base + sz)) return arr; } unreachable("invalid array name"); return NULL; } static void ra_destroy(struct ir3_ra_ctx *ctx) { ralloc_free(ctx->g); } static void __def(struct ir3_ra_ctx *ctx, struct ir3_ra_block_data *bd, unsigned name, struct ir3_instruction *instr) { debug_assert(name < ctx->alloc_count); /* split/collect do not actually define any real value */ if ((instr->opc == OPC_META_SPLIT) || (instr->opc == OPC_META_COLLECT)) return; /* defined on first write: */ if (!ctx->def[name]) ctx->def[name] = instr->ip; ctx->use[name] = MAX2(ctx->use[name], instr->ip); BITSET_SET(bd->def, name); } static void __use(struct ir3_ra_ctx *ctx, struct ir3_ra_block_data *bd, unsigned name, struct ir3_instruction *instr) { debug_assert(name < ctx->alloc_count); ctx->use[name] = MAX2(ctx->use[name], instr->ip); if (!BITSET_TEST(bd->def, name)) BITSET_SET(bd->use, name); } static void ra_block_compute_live_ranges(struct ir3_ra_ctx *ctx, struct ir3_block *block) { struct ir3_ra_block_data *bd; unsigned bitset_words = BITSET_WORDS(ctx->alloc_count); #define def(name, instr) __def(ctx, bd, name, instr) #define use(name, instr) __use(ctx, bd, name, instr) bd = rzalloc(ctx->g, struct ir3_ra_block_data); bd->def = rzalloc_array(bd, BITSET_WORD, bitset_words); bd->use = rzalloc_array(bd, BITSET_WORD, bitset_words); bd->livein = rzalloc_array(bd, BITSET_WORD, bitset_words); bd->liveout = rzalloc_array(bd, BITSET_WORD, bitset_words); block->data = bd; struct ir3_instruction *first_non_input = NULL; foreach_instr (instr, &block->instr_list) { if (instr->opc != OPC_META_INPUT) { first_non_input = instr; break; } } foreach_instr (instr, &block->instr_list) { foreach_def (name, ctx, instr) { if (name_is_array(ctx, name)) { struct ir3_array *arr = name_to_array(ctx, name); arr->start_ip = MIN2(arr->start_ip, instr->ip); arr->end_ip = MAX2(arr->end_ip, instr->ip); for (unsigned i = 0; i < arr->length; i++) { unsigned name = arr->base + i; if(arr->half) ra_set_node_class(ctx->g, name, ctx->set->half_classes[0]); else ra_set_node_class(ctx->g, name, ctx->set->classes[0]); } } else { struct ir3_ra_instr_data *id = &ctx->instrd[instr->ip]; if (is_high(instr)) { ra_set_node_class(ctx->g, name, ctx->set->high_classes[id->cls - HIGH_OFFSET]); } else if (is_half(instr)) { ra_set_node_class(ctx->g, name, ctx->set->half_classes[id->cls - HALF_OFFSET]); } else { ra_set_node_class(ctx->g, name, ctx->set->classes[id->cls]); } } def(name, instr); if ((instr->opc == OPC_META_INPUT) && first_non_input) use(name, first_non_input); /* Texture instructions with writemasks can be treated as smaller * vectors (or just scalars!) to allocate knowing that the * masked-out regs won't be written, but we need to make sure that * the start of the vector doesn't come before the first register * or we'll wrap. */ if (is_tex_or_prefetch(instr)) { int writemask_skipped_regs = ffs(instr->regs[0]->wrmask) - 1; int r0_xyz = is_half(instr) ? ctx->hr0_xyz_nodes : ctx->r0_xyz_nodes; for (int i = 0; i < writemask_skipped_regs; i++) ra_add_node_interference(ctx->g, name, r0_xyz + i); } /* Pre-fetched textures have a lower limit for bits to encode dst * register, so add additional interference with registers above * that limit. */ if (instr->opc == OPC_META_TEX_PREFETCH) { ra_add_node_interference(ctx->g, name, ctx->prefetch_exclude_node); } } foreach_use (name, ctx, instr) { if (name_is_array(ctx, name)) { struct ir3_array *arr = name_to_array(ctx, name); arr->start_ip = MIN2(arr->start_ip, instr->ip); arr->end_ip = MAX2(arr->end_ip, instr->ip); /* NOTE: arrays are not SSA so unconditionally * set use bit: */ BITSET_SET(bd->use, name); } use(name, instr); } foreach_name (name, ctx, instr) { /* split/collect instructions have duplicate names * as real instructions, so they skip the hashtable: */ if (ctx->name_to_instr && !((instr->opc == OPC_META_SPLIT) || (instr->opc == OPC_META_COLLECT))) { /* this is slightly annoying, we can't just use an * integer on the stack */ unsigned *key = ralloc(ctx->name_to_instr, unsigned); *key = name; debug_assert(!_mesa_hash_table_search(ctx->name_to_instr, key)); _mesa_hash_table_insert(ctx->name_to_instr, key, instr); } } } } static bool ra_compute_livein_liveout(struct ir3_ra_ctx *ctx) { unsigned bitset_words = BITSET_WORDS(ctx->alloc_count); bool progress = false; foreach_block (block, &ctx->ir->block_list) { struct ir3_ra_block_data *bd = block->data; /* update livein: */ for (unsigned i = 0; i < bitset_words; i++) { /* anything used but not def'd within a block is * by definition a live value coming into the block: */ BITSET_WORD new_livein = (bd->use[i] | (bd->liveout[i] & ~bd->def[i])); if (new_livein & ~bd->livein[i]) { bd->livein[i] |= new_livein; progress = true; } } /* update liveout: */ for (unsigned j = 0; j < ARRAY_SIZE(block->successors); j++) { struct ir3_block *succ = block->successors[j]; struct ir3_ra_block_data *succ_bd; if (!succ) continue; succ_bd = succ->data; for (unsigned i = 0; i < bitset_words; i++) { /* add anything that is livein in a successor block * to our liveout: */ BITSET_WORD new_liveout = (succ_bd->livein[i] & ~bd->liveout[i]); if (new_liveout) { bd->liveout[i] |= new_liveout; progress = true; } } } } return progress; } static void print_bitset(const char *name, BITSET_WORD *bs, unsigned cnt) { bool first = true; debug_printf("RA: %s:", name); for (unsigned i = 0; i < cnt; i++) { if (BITSET_TEST(bs, i)) { if (!first) debug_printf(","); debug_printf(" %04u", i); first = false; } } debug_printf("\n"); } /* size of one component of instruction result, ie. half vs full: */ static unsigned live_size(struct ir3_instruction *instr) { if (is_half(instr)) { return 1; } else if (is_high(instr)) { /* doesn't count towards footprint */ return 0; } else { return 2; } } static unsigned name_size(struct ir3_ra_ctx *ctx, unsigned name) { if (name_is_array(ctx, name)) { struct ir3_array *arr = name_to_array(ctx, name); return arr->half ? 1 : 2; } else { struct ir3_instruction *instr = name_to_instr(ctx, name); /* in scalar pass, each name represents on scalar value, * half or full precision */ return live_size(instr); } } static unsigned ra_calc_block_live_values(struct ir3_ra_ctx *ctx, struct ir3_block *block) { struct ir3_ra_block_data *bd = block->data; unsigned name; assert(ctx->name_to_instr); /* TODO this gets a bit more complicated in non-scalar pass.. but * possibly a lowball estimate is fine to start with if we do * round-robin in non-scalar pass? Maybe we just want to handle * that in a different fxn? */ assert(ctx->scalar_pass); BITSET_WORD *live = rzalloc_array(bd, BITSET_WORD, BITSET_WORDS(ctx->alloc_count)); /* Add the live input values: */ unsigned livein = 0; BITSET_FOREACH_SET (name, bd->livein, ctx->alloc_count) { livein += name_size(ctx, name); BITSET_SET(live, name); } d("---------------------"); d("block%u: LIVEIN: %u", block_id(block), livein); unsigned max = livein; int cur_live = max; /* Now that we know the live inputs to the block, iterate the * instructions adjusting the current # of live values as we * see their last use: */ foreach_instr (instr, &block->instr_list) { if (RA_DEBUG) print_bitset("LIVE", live, ctx->alloc_count); di(instr, "CALC"); unsigned new_live = 0; /* newly live values */ unsigned new_dead = 0; /* newly no-longer live values */ unsigned next_dead = 0; /* newly dead following this instr */ foreach_def (name, ctx, instr) { /* NOTE: checking ctx->def filters out things like split/ * collect which are just redefining existing live names * or array writes to already live array elements: */ if (ctx->def[name] != instr->ip) continue; new_live += live_size(instr); d("NEW_LIVE: %u (new_live=%u, use=%u)", name, new_live, ctx->use[name]); BITSET_SET(live, name); /* There can be cases where this is *also* the last use * of a value, for example instructions that write multiple * values, only some of which are used. These values are * dead *after* (rather than during) this instruction. */ if (ctx->use[name] != instr->ip) continue; next_dead += live_size(instr); d("NEXT_DEAD: %u (next_dead=%u)", name, next_dead); BITSET_CLEAR(live, name); } /* To be more resilient against special cases where liverange * is extended (like first_non_input), rather than using the * foreach_use() iterator, we iterate the current live values * instead: */ BITSET_FOREACH_SET (name, live, ctx->alloc_count) { /* Is this the last use? */ if (ctx->use[name] != instr->ip) continue; new_dead += name_size(ctx, name); d("NEW_DEAD: %u (new_dead=%u)", name, new_dead); BITSET_CLEAR(live, name); } cur_live += new_live; cur_live -= new_dead; assert(cur_live >= 0); d("CUR_LIVE: %u", cur_live); max = MAX2(max, cur_live); /* account for written values which are not used later, * but after updating max (since they are for one cycle * live) */ cur_live -= next_dead; assert(cur_live >= 0); if (RA_DEBUG) { unsigned cnt = 0; BITSET_FOREACH_SET (name, live, ctx->alloc_count) { cnt += name_size(ctx, name); } assert(cur_live == cnt); } } d("block%u max=%u", block_id(block), max); /* the remaining live should match liveout (for extra sanity testing): */ if (RA_DEBUG) { unsigned new_dead = 0; BITSET_FOREACH_SET (name, live, ctx->alloc_count) { /* Is this the last use? */ if (ctx->use[name] != block->end_ip) continue; new_dead += name_size(ctx, name); d("NEW_DEAD: %u (new_dead=%u)", name, new_dead); BITSET_CLEAR(live, name); } unsigned liveout = 0; BITSET_FOREACH_SET (name, bd->liveout, ctx->alloc_count) { liveout += name_size(ctx, name); BITSET_CLEAR(live, name); } if (cur_live != liveout) { print_bitset("LEAKED", live, ctx->alloc_count); /* TODO there are a few edge cases where live-range extension * tells us a value is livein. But not used by the block or * liveout for the block. Possibly a bug in the liverange * extension. But for now leave the assert disabled: assert(cur_live == liveout); */ } } ralloc_free(live); return max; } static unsigned ra_calc_max_live_values(struct ir3_ra_ctx *ctx) { unsigned max = 0; foreach_block (block, &ctx->ir->block_list) { unsigned block_live = ra_calc_block_live_values(ctx, block); max = MAX2(max, block_live); } return max; } static void ra_add_interference(struct ir3_ra_ctx *ctx) { struct ir3 *ir = ctx->ir; /* initialize array live ranges: */ foreach_array (arr, &ir->array_list) { arr->start_ip = ~0; arr->end_ip = 0; } /* set up the r0.xyz precolor regs. */ for (int i = 0; i < 3; i++) { ra_set_node_reg(ctx->g, ctx->r0_xyz_nodes + i, i); ra_set_node_reg(ctx->g, ctx->hr0_xyz_nodes + i, ctx->set->first_half_reg + i); } /* pre-color node that conflict with half/full regs higher than what * can be encoded for tex-prefetch: */ ra_set_node_reg(ctx->g, ctx->prefetch_exclude_node, ctx->set->prefetch_exclude_reg); /* compute live ranges (use/def) on a block level, also updating * block's def/use bitmasks (used below to calculate per-block * livein/liveout): */ foreach_block (block, &ir->block_list) { ra_block_compute_live_ranges(ctx, block); } /* update per-block livein/liveout: */ while (ra_compute_livein_liveout(ctx)) {} if (RA_DEBUG) { d("AFTER LIVEIN/OUT:"); foreach_block (block, &ir->block_list) { struct ir3_ra_block_data *bd = block->data; d("block%u:", block_id(block)); print_bitset(" def", bd->def, ctx->alloc_count); print_bitset(" use", bd->use, ctx->alloc_count); print_bitset(" l/i", bd->livein, ctx->alloc_count); print_bitset(" l/o", bd->liveout, ctx->alloc_count); } foreach_array (arr, &ir->array_list) { d("array%u:", arr->id); d(" length: %u", arr->length); d(" start_ip: %u", arr->start_ip); d(" end_ip: %u", arr->end_ip); } d("INSTRUCTION VREG NAMES:"); foreach_block (block, &ctx->ir->block_list) { foreach_instr (instr, &block->instr_list) { if (!ctx->instrd[instr->ip].defn) continue; if (!writes_gpr(instr)) continue; di(instr, "%04u", scalar_name(ctx, instr, 0)); } } d("ARRAY VREG NAMES:"); foreach_array (arr, &ctx->ir->array_list) { d("%04u: arr%u", arr->base, arr->id); } } /* extend start/end ranges based on livein/liveout info from cfg: */ foreach_block (block, &ir->block_list) { struct ir3_ra_block_data *bd = block->data; for (unsigned i = 0; i < ctx->alloc_count; i++) { if (BITSET_TEST(bd->livein, i)) { ctx->def[i] = MIN2(ctx->def[i], block->start_ip); ctx->use[i] = MAX2(ctx->use[i], block->start_ip); } if (BITSET_TEST(bd->liveout, i)) { ctx->def[i] = MIN2(ctx->def[i], block->end_ip); ctx->use[i] = MAX2(ctx->use[i], block->end_ip); } } foreach_array (arr, &ctx->ir->array_list) { for (unsigned i = 0; i < arr->length; i++) { if (BITSET_TEST(bd->livein, i + arr->base)) { arr->start_ip = MIN2(arr->start_ip, block->start_ip); } if (BITSET_TEST(bd->liveout, i + arr->base)) { arr->end_ip = MAX2(arr->end_ip, block->end_ip); } } } } if (ctx->name_to_instr) { unsigned max = ra_calc_max_live_values(ctx); ra_set_register_target(ctx, max); } for (unsigned i = 0; i < ctx->alloc_count; i++) { for (unsigned j = 0; j < ctx->alloc_count; j++) { if (intersects(ctx->def[i], ctx->use[i], ctx->def[j], ctx->use[j])) { ra_add_node_interference(ctx->g, i, j); } } } } /* NOTE: instr could be NULL for IR3_REG_ARRAY case, for the first * array access(es) which do not have any previous access to depend * on from scheduling point of view */ static void reg_assign(struct ir3_ra_ctx *ctx, struct ir3_register *reg, struct ir3_instruction *instr) { struct ir3_ra_instr_data *id; if (reg->flags & IR3_REG_ARRAY) { struct ir3_array *arr = ir3_lookup_array(ctx->ir, reg->array.id); unsigned name = arr->base + reg->array.offset; unsigned r = ra_get_node_reg(ctx->g, name); unsigned num = ctx->set->ra_reg_to_gpr[r]; if (reg->flags & IR3_REG_RELATIV) { reg->array.offset = num; } else { reg->num = num; reg->flags &= ~IR3_REG_SSA; } reg->flags &= ~IR3_REG_ARRAY; } else if ((id = &ctx->instrd[instr->ip]) && id->defn) { unsigned first_component = 0; /* Special case for tex instructions, which may use the wrmask * to mask off the first component(s). In the scalar pass, * this means the masked off component(s) are not def'd/use'd, * so we get a bogus value when we ask the register_allocate * algo to get the assigned reg for the unused/untouched * component. So we need to consider the first used component: */ if (ctx->scalar_pass && is_tex_or_prefetch(id->defn)) { unsigned n = ffs(id->defn->regs[0]->wrmask); debug_assert(n > 0); first_component = n - 1; } unsigned name = scalar_name(ctx, id->defn, first_component); unsigned r = ra_get_node_reg(ctx->g, name); unsigned num = ctx->set->ra_reg_to_gpr[r] + id->off; debug_assert(!(reg->flags & IR3_REG_RELATIV)); debug_assert(num >= first_component); if (is_high(id->defn)) num += FIRST_HIGH_REG; reg->num = num - first_component; reg->flags &= ~IR3_REG_SSA; if (is_half(id->defn)) reg->flags |= IR3_REG_HALF; } } /* helper to determine which regs to assign in which pass: */ static bool should_assign(struct ir3_ra_ctx *ctx, struct ir3_instruction *instr) { if ((instr->opc == OPC_META_SPLIT) && (util_bitcount(instr->regs[1]->wrmask) > 1)) return !ctx->scalar_pass; if ((instr->opc == OPC_META_COLLECT) && (util_bitcount(instr->regs[0]->wrmask) > 1)) return !ctx->scalar_pass; return ctx->scalar_pass; } static void ra_block_alloc(struct ir3_ra_ctx *ctx, struct ir3_block *block) { foreach_instr (instr, &block->instr_list) { if (writes_gpr(instr)) { if (should_assign(ctx, instr)) { reg_assign(ctx, instr->regs[0], instr); } } foreach_src_n (reg, n, instr) { struct ir3_instruction *src = reg->instr; if (src && !should_assign(ctx, src) && !should_assign(ctx, instr)) continue; if (src && should_assign(ctx, instr)) reg_assign(ctx, src->regs[0], src); /* Note: reg->instr could be null for IR3_REG_ARRAY */ if (src || (reg->flags & IR3_REG_ARRAY)) reg_assign(ctx, instr->regs[n+1], src); } } /* We need to pre-color outputs for the scalar pass in * ra_precolor_assigned(), so we need to actually assign * them in the first pass: */ if (!ctx->scalar_pass) { foreach_input (in, ctx->ir) { reg_assign(ctx, in->regs[0], in); } foreach_output (out, ctx->ir) { reg_assign(ctx, out->regs[0], out); } } } static void assign_arr_base(struct ir3_ra_ctx *ctx, struct ir3_array *arr, struct ir3_instruction **precolor, unsigned nprecolor) { unsigned base = 0; /* figure out what else we conflict with which has already * been assigned: */ retry: foreach_array (arr2, &ctx->ir->array_list) { if (arr2 == arr) break; if (arr2->end_ip == 0) continue; /* if it intersects with liverange AND register range.. */ if (intersects(arr->start_ip, arr->end_ip, arr2->start_ip, arr2->end_ip) && intersects(base, base + reg_size_for_array(arr), arr2->reg, arr2->reg + reg_size_for_array(arr2))) { base = MAX2(base, arr2->reg + reg_size_for_array(arr2)); goto retry; } } /* also need to not conflict with any pre-assigned inputs: */ for (unsigned i = 0; i < nprecolor; i++) { struct ir3_instruction *instr = precolor[i]; if (!instr || (instr->flags & IR3_INSTR_UNUSED)) continue; struct ir3_ra_instr_data *id = &ctx->instrd[instr->ip]; /* only consider the first component: */ if (id->off > 0) continue; unsigned name = ra_name(ctx, id); unsigned regid = instr->regs[0]->num; /* Check if array intersects with liverange AND register * range of the input: */ if (intersects(arr->start_ip, arr->end_ip, ctx->def[name], ctx->use[name]) && intersects(base, base + reg_size_for_array(arr), regid, regid + class_sizes[id->cls])) { base = MAX2(base, regid + class_sizes[id->cls]); goto retry; } } arr->reg = base; } /* handle pre-colored registers. This includes "arrays" (which could be of * length 1, used for phi webs lowered to registers in nir), as well as * special shader input values that need to be pinned to certain registers. */ static void ra_precolor(struct ir3_ra_ctx *ctx, struct ir3_instruction **precolor, unsigned nprecolor) { for (unsigned i = 0; i < nprecolor; i++) { if (precolor[i] && !(precolor[i]->flags & IR3_INSTR_UNUSED)) { struct ir3_instruction *instr = precolor[i]; if (instr->regs[0]->num == INVALID_REG) continue; struct ir3_ra_instr_data *id = &ctx->instrd[instr->ip]; debug_assert(!(instr->regs[0]->flags & (IR3_REG_HALF | IR3_REG_HIGH))); /* only consider the first component: */ if (id->off > 0) continue; if (ctx->scalar_pass && !should_assign(ctx, instr)) continue; /* 'base' is in scalar (class 0) but we need to map that * the conflicting register of the appropriate class (ie. * input could be vec2/vec3/etc) * * Note that the higher class (larger than scalar) regs * are setup to conflict with others in the same class, * so for example, R1 (scalar) is also the first component * of D1 (vec2/double): * * Single (base) | Double * --------------+--------------- * R0 | D0 * R1 | D0 D1 * R2 | D1 D2 * R3 | D2 * .. and so on.. */ unsigned regid = instr->regs[0]->num; unsigned reg = ctx->set->gpr_to_ra_reg[id->cls][regid]; unsigned name = ra_name(ctx, id); ra_set_node_reg(ctx->g, name, reg); } } /* pre-assign array elements: * * TODO this is going to need some work for half-precision.. possibly * this is easier on a6xx, where we can just divide array size by two? * But on a5xx and earlier it will need to track two bases. */ foreach_array (arr, &ctx->ir->array_list) { if (arr->end_ip == 0) continue; if (!ctx->scalar_pass) assign_arr_base(ctx, arr, precolor, nprecolor); unsigned base = arr->reg; for (unsigned i = 0; i < arr->length; i++) { unsigned name, reg; if (arr->half) { /* Doesn't need to do this on older generations than a6xx, * since there's no conflict between full regs and half regs * on them. * * TODO Presumably "base" could start from 0 respectively * for half regs of arrays on older generations. */ unsigned base_half = base * 2 + i; reg = ctx->set->gpr_to_ra_reg[0+HALF_OFFSET][base_half]; base = base_half / 2 + 1; } else { reg = ctx->set->gpr_to_ra_reg[0][base++]; } name = arr->base + i; ra_set_node_reg(ctx->g, name, reg); } } if (ir3_shader_debug & IR3_DBG_OPTMSGS) { foreach_array (arr, &ctx->ir->array_list) { unsigned first = arr->reg; unsigned last = arr->reg + arr->length - 1; debug_printf("arr[%d] at r%d.%c->r%d.%c\n", arr->id, (first >> 2), "xyzw"[first & 0x3], (last >> 2), "xyzw"[last & 0x3]); } } } static void precolor(struct ir3_ra_ctx *ctx, struct ir3_instruction *instr) { struct ir3_ra_instr_data *id = &ctx->instrd[instr->ip]; unsigned n = dest_regs(instr); for (unsigned i = 0; i < n; i++) { /* tex instructions actually have a wrmask, and * don't touch masked out components. So we * shouldn't precolor them:: */ if (is_tex_or_prefetch(instr) && !(instr->regs[0]->wrmask & (1 << i))) continue; unsigned name = scalar_name(ctx, instr, i); unsigned regid = instr->regs[0]->num + i; if (instr->regs[0]->flags & IR3_REG_HIGH) regid -= FIRST_HIGH_REG; unsigned vreg = ctx->set->gpr_to_ra_reg[id->cls][regid]; ra_set_node_reg(ctx->g, name, vreg); } } /* pre-color non-scalar registers based on the registers assigned in previous * pass. Do this by looking actually at the fanout instructions. */ static void ra_precolor_assigned(struct ir3_ra_ctx *ctx) { debug_assert(ctx->scalar_pass); foreach_block (block, &ctx->ir->block_list) { foreach_instr (instr, &block->instr_list) { if (!writes_gpr(instr)) continue; if (should_assign(ctx, instr)) continue; precolor(ctx, instr); foreach_src (src, instr) { if (!src->instr) continue; precolor(ctx, src->instr); } } } } static int ra_alloc(struct ir3_ra_ctx *ctx) { if (!ra_allocate(ctx->g)) return -1; foreach_block (block, &ctx->ir->block_list) { ra_block_alloc(ctx, block); } return 0; } /* if we end up with split/collect instructions with non-matching src * and dest regs, that means something has gone wrong. Which makes it * a pretty good sanity check. */ static void ra_sanity_check(struct ir3 *ir) { foreach_block (block, &ir->block_list) { foreach_instr (instr, &block->instr_list) { if (instr->opc == OPC_META_SPLIT) { struct ir3_register *dst = instr->regs[0]; struct ir3_register *src = instr->regs[1]; debug_assert(dst->num == (src->num + instr->split.off)); } else if (instr->opc == OPC_META_COLLECT) { struct ir3_register *dst = instr->regs[0]; foreach_src_n (src, n, instr) { debug_assert(dst->num == (src->num - n)); } } } } } static int ir3_ra_pass(struct ir3_shader_variant *v, struct ir3_instruction **precolor, unsigned nprecolor, bool scalar_pass) { struct ir3_ra_ctx ctx = { .v = v, .ir = v->ir, .set = v->ir->compiler->set, .scalar_pass = scalar_pass, }; int ret; ra_init(&ctx); ra_add_interference(&ctx); ra_precolor(&ctx, precolor, nprecolor); if (scalar_pass) ra_precolor_assigned(&ctx); ret = ra_alloc(&ctx); ra_destroy(&ctx); return ret; } int ir3_ra(struct ir3_shader_variant *v, struct ir3_instruction **precolor, unsigned nprecolor) { int ret; /* First pass, assign the vecN (non-scalar) registers: */ ret = ir3_ra_pass(v, precolor, nprecolor, false); if (ret) return ret; ir3_debug_print(v->ir, "AFTER: ir3_ra (1st pass)"); /* Second pass, assign the scalar registers: */ ret = ir3_ra_pass(v, precolor, nprecolor, true); if (ret) return ret; ir3_debug_print(v->ir, "AFTER: ir3_ra (2st pass)"); #ifdef DEBUG # define SANITY_CHECK DEBUG #else # define SANITY_CHECK 0 #endif if (SANITY_CHECK) ra_sanity_check(v->ir); return ret; }