375 lines
9.6 KiB
C
375 lines
9.6 KiB
C
/*
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* Copyright (c) 2002-2010 Stephen Williams (steve@icarus.com)
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*
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* This source code is free software; you can redistribute it
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* and/or modify it in source code form under the terms of the GNU
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* General Public License as published by the Free Software
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* Foundation; either version 2 of the License, or (at your option)
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* any later version.
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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, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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# include "vvp_priv.h"
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# include <assert.h>
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/* Maximum vector bits in a thread. If a thread co-processor is
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* implemented, this value may need to be reduced. At that time
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* wider operations will need to be partitioned. For example
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* shift operations on WIDE (say > 64k bit) registers.
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*/
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#define MAX_VEC (256*1024)
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static struct allocation_score_s {
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ivl_expr_t exp;
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ivl_signal_t sig;
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unsigned sig_word;
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unsigned exp_bit : 24;
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unsigned sig_bit : 24;
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unsigned alloc : 8;
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} allocation_map[MAX_VEC] = { {0} };
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/* This is the largest bit to have lookaside values. */
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static unsigned lookaside_top = 0;
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static __inline__ ivl_expr_t peek_exp(unsigned addr)
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{
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return allocation_map[addr].exp;
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}
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static __inline__ unsigned peek_exp_bit(unsigned addr)
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{
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return allocation_map[addr].exp_bit;
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}
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static __inline__ void set_exp(unsigned addr, ivl_expr_t expr, unsigned ebit)
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{
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allocation_map[addr].exp = expr;
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allocation_map[addr].exp_bit = ebit;
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}
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static __inline__ void set_sig(unsigned addr, ivl_signal_t expr,
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unsigned sig_word, unsigned ebit)
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{
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allocation_map[addr].sig = expr;
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allocation_map[addr].sig_word = sig_word;
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allocation_map[addr].sig_bit = ebit;
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}
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/*
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* This clears a vector that was previously allocated by
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* allocate_vector. That is, it unmarks all the bits of the map that
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* represent this vector.
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*
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* If the vector is based in one of 4 constant bit values, then there
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* are no bits to clear. If the vector is based in the 4-8 result
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* area, then someone is broken.
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*/
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void clr_vector(struct vector_info vec)
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{
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unsigned idx;
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if (vec.base < 4)
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return;
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assert(vec.base >= 8);
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for (idx = 0 ; idx < vec.wid ; idx += 1) {
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assert( allocation_map[vec.base+idx].alloc > 0);
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allocation_map[vec.base+idx].alloc -= 1;
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}
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}
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static unsigned allocate_vector_no_lookaside(unsigned wid, int skip_lookaside)
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{
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unsigned base = 8;
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unsigned idx = 0;
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while (idx < wid) {
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if (base+idx >= MAX_VEC)
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return 0;
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assert((base + idx) < MAX_VEC);
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if ((allocation_map[base+idx].alloc > 0)
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|| (skip_lookaside && peek_exp(base+idx))) {
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base = base + idx + 1;
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idx = 0;
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} else {
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idx += 1;
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}
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}
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for (idx = 0 ; idx < wid ; idx += 1) {
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allocation_map[base+idx].alloc += 1;
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set_exp(base+idx, 0, 0);
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set_sig(base+idx, 0, 0, 0);
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}
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return base;
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}
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/*
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* This unconditionally allocates a stretch of bits from the register
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* set. It never returns a bit addressed <8 (0-3 are constant, 4-7 are
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* condition codes).
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*
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* First try to allocate a vector without interfering with any bits
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* cached by the lookaside buffer. If that doesn't work, then try
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* again without worrying about trashing lookaside results. This
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* should lead to preferentially allocating new bits instead of
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* constantly overwriting intermediate results.
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*
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* If there is no space for a vector of the given width, then give up
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* and return 0.
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*/
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unsigned allocate_vector(unsigned wid)
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{
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unsigned base = allocate_vector_no_lookaside(wid, 1);
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if (base == 0)
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base = allocate_vector_no_lookaside(wid, 0);
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return base;
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}
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/*
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* This clears the expression cache of the allocation map. It is
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* called to prevent reuse of existing expressions, normally at the
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* start of a basic block, but also at the end of thread processing.
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*/
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void clear_expression_lookaside(void)
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{
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unsigned idx;
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for (idx = 0 ; idx < lookaside_top ; idx += 1) {
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set_exp(idx, 0, 0);
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set_sig(idx, 0, 0, 0);
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}
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lookaside_top = 0;
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}
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static int test_expression_savable(ivl_expr_t expr)
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{
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switch (ivl_expr_type(expr)) {
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case IVL_EX_NUMBER:
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case IVL_EX_STRING:
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return 1;
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default:
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return 0;
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}
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}
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void save_expression_lookaside(unsigned addr, ivl_expr_t expr, unsigned wid)
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{
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unsigned idx;
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assert(addr >= 8);
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assert((addr+wid) <= MAX_VEC);
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/* When saving an expression to the lookaside, also clear the
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signal saved in the lookaside for these bits. The reason is
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that an expression calculation will replace any signal
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bits. */
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for (idx = 0 ; idx < wid ; idx += 1)
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set_sig(addr+idx, 0, 0, 0);
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/* Only certain types of expressions are savable. */
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if ( ! test_expression_savable(expr))
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return;
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for (idx = 0 ; idx < wid ; idx += 1) {
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set_exp(addr+idx, expr, idx);
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}
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if ((addr+wid) > lookaside_top)
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lookaside_top = addr+wid;
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}
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static void clear_signal_lookaside_bit(unsigned idx, ivl_signal_t sig, unsigned sig_word)
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{
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if (allocation_map[idx].alloc > 0)
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return;
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if (allocation_map[idx].sig != sig)
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return;
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if (allocation_map[idx].sig_word != sig_word)
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return;
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set_sig(idx, 0, 0, 0);
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}
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void save_signal_lookaside(unsigned addr, ivl_signal_t sig, unsigned sig_word, unsigned wid)
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{
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unsigned idx;
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/* Don't bind any of the low bits to a signal. */
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if (addr < 8 && wid > 0)
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return;
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assert((addr+wid) <= MAX_VEC);
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for (idx = 8 ; idx < addr ; idx += 1)
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clear_signal_lookaside_bit(idx, sig, sig_word);
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for (idx = 0 ; idx < wid ; idx += 1)
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set_sig(addr+idx, sig, sig_word, idx);
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if ((addr+wid) > lookaside_top)
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lookaside_top = addr+wid;
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for (idx = addr+wid ; idx < lookaside_top ; idx += 1)
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clear_signal_lookaside_bit(idx, sig, sig_word);
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}
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static int compare_exp(ivl_expr_t l, ivl_expr_t r)
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{
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if (! (l && r))
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return 0;
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if (l == r)
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return 1;
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if (ivl_expr_type(l) != ivl_expr_type(r))
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return 0;
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switch (ivl_expr_type(l)) {
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case IVL_EX_NUMBER:
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if (ivl_expr_width(l) != ivl_expr_width(r))
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return 0;
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{ const char*bitl = ivl_expr_bits(l);
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const char*bitr = ivl_expr_bits(r);
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unsigned idx;
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for (idx = 0 ; idx < ivl_expr_width(l) ; idx += 1) {
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if (bitl[idx] != bitr[idx])
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return 0;
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}
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}
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return 1;
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case IVL_EX_SELECT:
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if (! compare_exp(ivl_expr_oper1(l), ivl_expr_oper1(r)))
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return 0;
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if (ivl_expr_oper2(l) == 0 && ivl_expr_oper1(r) == 0)
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return 1;
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if (! compare_exp(ivl_expr_oper2(l), ivl_expr_oper2(r)))
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return 0;
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return 1;
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case IVL_EX_SIGNAL:
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if (ivl_expr_signal(l) != ivl_expr_signal(r))
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return 0;
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if (ivl_expr_width(l) != ivl_expr_width(r))
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return 0;
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/* Don't match array words. */
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if (ivl_expr_oper1(l) || ivl_expr_oper1(r))
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return 0;
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return 1;
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default:
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break;
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}
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return 0;
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}
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static unsigned find_expression_lookaside(ivl_expr_t expr, unsigned wid)
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{
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unsigned idx, match;
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ivl_signal_t sig;
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if (lookaside_top <= wid)
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return 0;
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/* Look in the expression lookaside for this expression. */
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assert(expr);
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match = 0;
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for (idx = 8 ; idx < lookaside_top ; idx += 1) {
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if (! compare_exp(allocation_map[idx].exp, expr)) {
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match = 0;
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continue;
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}
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if (allocation_map[idx].exp_bit != match) {
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match = 0;
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continue;
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}
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match += 1;
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if (match == wid)
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return idx-match+1;
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}
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/* The general expression lookup failed. If this is an
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IVL_EX_SIGNAL, then look again in the variable lookaside
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(which is saved l-values) for the expression. */
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if (ivl_expr_type(expr) != IVL_EX_SIGNAL)
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return 0;
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sig = ivl_expr_signal(expr);
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/* Only reg signals (variables) will be in the signal
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lookaside, because only blocking assigned values are in the
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signal lookaside. */
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if (ivl_signal_type(sig) != IVL_SIT_REG)
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return 0;
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/* Now look for signal value matches in the signal lookaside. */
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match = 0;
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for (idx = 8 ; idx < lookaside_top ; idx += 1) {
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if (sig != allocation_map[idx].sig) {
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match = 0;
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continue;
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}
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if (allocation_map[idx].sig_bit != match) {
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match = 0;
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continue;
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}
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match += 1;
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if (match == wid)
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return idx-match+1;
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}
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return 0;
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}
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/*
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* Look for the expression in the expression lookaside table. If it is
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* there, then allocate it and return the base. In this case the
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* caller will not need to evaluate the expression. If this function
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* returns 0, then the expression is not found and nothing is allocated.
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*/
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unsigned allocate_vector_exp(ivl_expr_t expr, unsigned wid,
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int exclusive_flag)
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{
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unsigned idx;
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unsigned la = find_expression_lookaside(expr, wid);
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if (la == 0)
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return 0;
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if (exclusive_flag) {
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/* If the caller is requesting exclusive allocation of
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the expression, then return not-found if a lookup
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already matched the expression. */
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for (idx = 0 ; idx < wid ; idx += 1)
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if (allocation_map[la+idx].alloc)
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return 0;
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}
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for (idx = 0 ; idx < wid ; idx += 1)
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allocation_map[la+idx].alloc += 1;
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return la;
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}
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