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477 lines
10 KiB
C
477 lines
10 KiB
C
/*
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* sched.c - O(n) ... O(n^2) scheduler
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*
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* Written 2011 by Werner Almesberger
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*
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* Based on gfpus.c
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* Copyright (C) 2007, 2008, 2009, 2010 Sebastien Bourdeauducq
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 3 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <fpvm/is.h>
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#include <fpvm/fpvm.h>
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#include <fpvm/pfpu.h>
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#include <fpvm/gfpus.h>
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#include <hw/pfpu.h>
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#define MAX_LATENCY 8 /* maximum latency; okay to make this bigger */
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#define Dprintf(...)
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struct list {
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struct list *next, *prev;
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};
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static struct insn {
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struct list more; /* more insns on same schedule */
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struct fpvm_instruction *vm_insn;
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struct data_ref {
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struct list more; /* more refs sharing the data */
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struct insn *insn; /* insn this is part of */
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struct insn *dep; /* insn we depend on */
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} opa, opb, dest, cond;
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int arity;
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int latency;
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int unresolved; /* number of data refs we need before we can sched */
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int earliest; /* earliest cycle dependencies seen so far are met */
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struct list dependants; /* list of dependencies (constant) */
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int num_dependants; /* number of unresolved dependencies */
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} insns[FPVM_MAXCODELEN];
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/* ----- Register initialization ------------------------------------------- */
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/*
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* Straight from gfpus.c, only with some whitespace changes.
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*/
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static void get_registers(struct fpvm_fragment *fragment,
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unsigned int *registers)
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{
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int i;
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union {
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float f;
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unsigned int n;
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} fconv;
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for(i = 0; i < fragment->nbindings; i++)
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if (fragment->bindings[i].isvar)
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registers[i] = 0;
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else {
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fconv.f = fragment->bindings[i].b.c;
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registers[i] = fconv.n;
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}
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for(; i < PFPU_REG_COUNT; i++)
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registers[i] = 0;
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}
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/* ----- Doubly-linked list ------------------------------------------------ */
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/*
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* Use naming conventions of include/linux/list.h
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*/
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static void list_init(struct list *list)
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{
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list->next = list->prev = list;
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}
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static void list_del(struct list *item)
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{
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item->prev->next = item->next;
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item->next->prev = item->prev;
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}
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static void *list_pop(struct list *list)
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{
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struct list *first;
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first = list->next;
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if (first == list)
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return NULL;
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list_del(first);
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return first;
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}
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static void list_add_tail(struct list *list, struct list *item)
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{
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item->next = list;
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item->prev = list->prev;
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list->prev->next = item;
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list->prev = item;
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}
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static void list_add(struct list *list, struct list *item)
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{
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item->next = list->next;
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item->prev = list;
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list->next->prev = item;
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list->next = item;
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}
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static void list_concat(struct list *a, struct list *b)
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{
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if (b->next != b) {
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a->prev->next = b->next;
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b->next->prev = a->prev;
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b->prev->next = a;
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a->prev = b->prev;
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}
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list_init(b);
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}
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/*
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* Do not delete elements from the list while traversing it with foreach !
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*/
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#define foreach(var, head) \
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for (var = (void *) ((struct list *) (head))->next; \
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(var) != (void *) (head); \
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var = (void *) ((struct list *) (var))->next)
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/* ----- Register management ----------------------------------------------- */
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static struct vm_reg {
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struct insn *setter; /* instruction setting it; NULL if none */
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int pfpu_reg; /* underlying PFPU register */
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int refs; /* usage count */
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} *regs;
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static struct list pfpu_regs[PFPU_REG_COUNT];
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static struct list unallocated; /* unallocated registers */
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static int nbindings; /* "public" bindings */
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static int reg2idx(int reg)
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{
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return reg >= 0 ? reg : nbindings-reg;
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}
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static int alloc_reg(struct insn *setter)
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{
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struct list *reg;
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int vm_reg, pfpu_reg, vm_idx;
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vm_reg = setter->vm_insn->dest;
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if (vm_reg >= 0)
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return vm_reg;
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reg = list_pop(&unallocated);
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if (!reg)
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abort();
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pfpu_reg = reg-pfpu_regs;
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Dprintf(" alloc reg %d -> %d\n", vm_reg, pfpu_reg);
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vm_idx = reg2idx(vm_reg);
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regs[vm_idx].setter = setter;
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regs[vm_idx].pfpu_reg = pfpu_reg;
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regs[vm_idx].refs = setter->num_dependants+1;
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return pfpu_reg;
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}
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static void put_reg(struct insn *setter)
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{
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int vm_reg, vm_idx;
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if (!setter)
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return;
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vm_reg = setter->vm_insn->dest;
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if (vm_reg >= 0)
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return;
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vm_idx = reg2idx(vm_reg);
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if (--regs[vm_idx].refs)
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return;
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Dprintf(" free reg %d\n", regs[vm_idx].pfpu_reg);
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/*
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* Prepend so that register numbers stay small and bugs reveal
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* themselves more rapidly.
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*/
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list_add(&unallocated, pfpu_regs+regs[vm_idx].pfpu_reg);
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/* clear it for style only */
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regs[vm_idx].setter = NULL;
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regs[vm_idx].pfpu_reg = 0;
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}
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static int lookup_pfpu_reg(int vm_reg)
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{
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return vm_reg >= 0 ? vm_reg : regs[reg2idx(vm_reg)].pfpu_reg;
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}
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static void init_registers(struct fpvm_fragment *fragment,
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unsigned int *registers)
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{
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size_t regs_size;
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int i;
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get_registers(fragment, registers);
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nbindings = fragment->nbindings;
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regs_size = sizeof(struct vm_reg)*(nbindings-fragment->next_sur);
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regs = malloc(regs_size);
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memset(regs, 0, regs_size);
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list_init(&unallocated);
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for (i = fragment->nbindings; i != PFPU_REG_COUNT; i++)
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list_add_tail(&unallocated, pfpu_regs+i);
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/*
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* @@@ the rules are more complex, see use of dont_touch in
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* init_scheduler_state
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*/
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}
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/* ----- Instruction scheduler --------------------------------------------- */
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static struct list unscheduled; /* unscheduled insns */
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static struct list waiting; /* insns waiting to be scheduled */
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static struct list ready[PFPU_PROGSIZE]; /* insns ready at nth cycle */
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static struct insn *exits[PFPU_PROGSIZE+MAX_LATENCY];
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/* insn writing at nth cycle */
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static struct insn dummy_insn; /* dummy, to signal occupancy */
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static struct vm_reg *add_data_ref(struct insn *insn, struct data_ref *ref,
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int reg_num)
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{
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struct vm_reg *reg;
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reg = regs+reg2idx(reg_num);
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ref->insn = insn;
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ref->dep = reg->setter;
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if (ref->dep) {
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list_add_tail(&ref->dep->dependants, &ref->more);
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ref->dep->num_dependants++;
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insn->unresolved++;
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Dprintf("insn %lu: reg %d setter %lu unresolved %d\n",
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insn-insns, reg_num, reg->setter-insns, insn->unresolved);
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} else {
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list_init(&ref->more);
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}
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return reg;
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}
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int catch = 0;
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static void init_scheduler(struct fpvm_fragment *frag)
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{
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int i;
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struct insn *insn;
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list_init(&unscheduled);
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list_init(&waiting);
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for (i = 0; i != PFPU_PROGSIZE; i++)
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list_init(&ready[i]);
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#if 0
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if (frag->ninstructions > 10) {
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frag->ninstructions = 10;
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catch = 1;
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}
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#endif
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for (i = 0; i != frag->ninstructions; i++) {
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insn = insns+i;
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memset(insn, 0, sizeof(struct insn));
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insn->vm_insn = frag->code+i;
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insn->arity = fpvm_get_arity(frag->code[i].opcode);
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insn->latency = pfpu_get_latency(frag->code[i].opcode);
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list_init(&insn->dependants);
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switch (insn->arity) {
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case 3:
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add_data_ref(insn, &insn->opb, FPVM_REG_IFB);
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/* fall through */
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case 2:
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add_data_ref(insn, &insn->opb, frag->code[i].opb);
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/* fall through */
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case 1:
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add_data_ref(insn, &insn->opa, frag->code[i].opa);
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/* fall through */
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case 0:
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add_data_ref(insn,
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&insn->dest, frag->code[i].dest)->setter = insn;
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break;
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default:
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abort();
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}
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if (insn->unresolved)
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list_add_tail(&unscheduled, &insn->more);
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else
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list_add_tail(&ready[0], &insn->more);
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}
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/*
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* We add a few dummy instructions at the end so that we don't need to
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* check array boundaries for the unlikely case of overrunning the
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* schedule.
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*/
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for (i = 0; i != PFPU_PROGSIZE; i++)
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exits[i] = NULL;
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for (; i != PFPU_PROGSIZE+MAX_LATENCY; i++)
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exits[i] = &dummy_insn;
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}
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static unsigned issue(struct insn *insn, int cycle)
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{
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pfpu_instruction code;
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struct data_ref *ref;
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int end;
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int nada = 0;
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end = cycle+insn->latency;
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exits[end] = insn;
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Dprintf("cycle %d: insn %lu L %d (A %d B %d)\n",
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cycle, insn-insns, insn->latency, insn->vm_insn->opa, insn->vm_insn->opb);
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switch (insn->arity) {
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case 3:
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/* fall through */
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case 2:
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code.i.opb = lookup_pfpu_reg(insn->vm_insn->opb);
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put_reg(insn->opb.dep);
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/* fall through */
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case 1:
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code.i.opa = lookup_pfpu_reg(insn->vm_insn->opa);
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put_reg(insn->opa.dep);
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break;
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case 0:
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break;
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default:
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abort();
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}
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code.i.dest = alloc_reg(insn);
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code.i.opcode = fpvm_to_pfpu(insn->vm_insn->opcode);
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foreach (ref, &insn->dependants) {
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if (ref->insn->earliest <= end)
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ref->insn->earliest = end+1;
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if (!--ref->insn->unresolved) {
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Dprintf(" unlocked %lu -> %u\n", ref->insn-insns, ref->insn->earliest);
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nada = 0;
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list_del(&ref->insn->more);
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list_add_tail(ready+ref->insn->earliest,
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&ref->insn->more);
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}
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}
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if (nada && catch) *(volatile int *) 0 = 1;
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return code.w;
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}
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static int count(const struct list *list)
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{
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int n = 0;
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const struct list *p;
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for (p = list->next; p != list; p = p->next)
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n++;
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return n;
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}
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static int schedule(struct fpvm_fragment *frag, unsigned int *code)
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{
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int remaining;
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int i, last, end;
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struct insn *insn;
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remaining = frag->ninstructions;
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for (i = 0; remaining; i++) {
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if (i == PFPU_PROGSIZE)
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return -1;
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Dprintf("@%d --- remaining %d, waiting %d + ready %d = ", i, remaining,
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count(&waiting), count(&ready[i]));
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list_concat(&waiting, &ready[i]);
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Dprintf("%d\n", count(&waiting));
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foreach (insn, &waiting)
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if (!exits[i+insn->latency]) {
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code[i] = issue(insn, i);
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list_del(&insn->more);
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remaining--;
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break;
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}
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if (exits[i])
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put_reg(exits[i]);
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}
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/*
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* Add NOPs to cover unfinished instructions.
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*/
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last = i;
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end = i+MAX_LATENCY;
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if (end > PFPU_PROGSIZE)
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end = PFPU_PROGSIZE;
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while (i != end) {
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if (exits[i])
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last = i+1; /* @@@ ? */
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i++;
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}
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return last;
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}
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int gfpus_schedule(struct fpvm_fragment *frag, unsigned int *code,
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unsigned int *reg)
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{
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pfpu_instruction vecout;
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int res;
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init_registers(frag, reg);
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memset(code, 0, PFPU_PROGSIZE*sizeof(*code));
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init_scheduler(frag);
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res = schedule(frag, code);
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free(regs);
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if (res < 0)
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return res;
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if (frag->vector_mode)
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return res;
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if (res == PFPU_PROGSIZE)
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return -1;
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vecout.w = 0;
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vecout.i.opcode = FPVM_OPCODE_VECTOUT;
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code[res] = vecout.w;
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return res+1;
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}
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