/* $Id$ */ /* * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands. * See the copyright notice in the ACK home directory, in the file "Copyright". */ /* S T R E N G T H R E D U C T I O N * * S R _ X F O R M . C * */ #include #include #include #include #include "../share/types.h" #include "sr.h" #include "../share/debug.h" #include "../share/global.h" #include "../share/alloc.h" #include "../share/def.h" #include "../share/get.h" #include "sr_aux.h" #include "../share/lset.h" #include "../share/aux.h" #include "sr_xform.h" /* Transformations on EM texts */ line_p move_pointer(offset tmp, int dir) { /* Generate EM code to load/store a pointer variable * onto/from the stack, depending on dir(ection). * We accept all kinds of pointer sizes. */ line_p l; l = int_line(tmp); if (ps == ws) { /* pointer fits in a word */ l->l_instr = (dir == LOAD ? op_lol : op_stl); } else { if (ps == 2 * ws) { /* pointer fits in a double word */ l->l_instr = (dir == LOAD ? op_ldl : op_sdl); } else { /* very large pointer size, generate code: * LAL tmp ; LOI/STI ps */ l->l_instr = op_lal; l->l_next = newline(OPSHORT); SHORT(l->l_next) = ps; l->l_next->l_instr = (dir == LOAD ? op_loi : op_sti); PREV(l->l_next) = l; } } return l; } /* make_header */ static void copy_loops(bblock_p b1, bblock_p b2, loop_p except) { /* Copy the loopset of b2 to b1, except for 'except' */ Lindex i; loop_p lp; for (i = Lfirst(b2->b_loops); i != (Lindex) 0; i = Lnext(i,b2->b_loops)) { lp = (loop_p) Lelem(i); if (lp != except) { Ladd(lp,&b1->b_loops); } } } static lab_id label(bblock_p b) { /* Find the label at the head of block b. If there is * no such label yet, create one. */ line_p l; if (b->b_start && INSTR(b->b_start) == op_lab) { return INSTRLAB(b->b_start); } /* The block has no label yet. */ l = newline(OPINSTRLAB); l->l_instr = op_lab; INSTRLAB(l) = freshlabel(); if (b->b_start) { DLINK(l,b->b_start); /* doubly link them */ } b->b_start = l; return INSTRLAB(l); } static void adjust_jump(bblock_p newtarg, bblock_p oldtarg, bblock_p c) { /* If the last instruction of c is a jump to the * old target, then change it into a jump to the * start of the new target. */ line_p l = last_instr(c); assert(l != (line_p) 0); if (INSTR(oldtarg->b_start) == op_lab) { /* If old target has no label, it cannot be jumped to */ if (TYPE(l) == OPINSTRLAB && INSTRLAB(l) == INSTRLAB(oldtarg->b_start)) { INSTRLAB(l) = label(newtarg); } } if (c->b_next == oldtarg && INSTR(l) != op_bra) { line_p new = newline(OPINSTRLAB); INSTRLAB(new) = label(newtarg); new->l_instr = op_bra; DLINK(l, new); } } void make_header(loop_p lp) { /* Make sure that the loop has a header block, i.e. a block * has the loop entry block as its only successor and * that dominates the loop entry block. * If there is no header yet, create one. */ bblock_p b,c,entry; Lindex i,next; if (lp->LP_HEADER != (bblock_p) 0) return; OUTTRACE("creating a new header block",0); /* The loop has no header yet. The main problem is to * keep all relations (SUCC, PRED, NEXT, IDOM, LOOPS) * up to date. */ b = freshblock(); /* new block with new b_id */ entry = lp->lp_entry; /* update succ/pred. Also take care that any jump from outside * the loop to the entry block now goes to b. */ b->b_succ = Lempty_set(); b->b_pred = Lempty_set(); for (i = Lfirst(entry->b_pred); i != (Lindex) 0; i = next ) { next = Lnext(i,entry->b_pred); c = (bblock_p) Lelem(i); /* c is a predecessor of the entry block */ if (!Lis_elem(c,lp->LP_BLOCKS)) { /* c is outside the loop */ Lremove(c,&entry->b_pred); Lremove(entry,&c->b_succ); Ladd(b,&c->b_succ); Ladd(c,&b->b_pred); adjust_jump(b,entry,c); } } assert(lp->LP_INSTR == 0); lp->LP_INSTR = b->b_start; Ladd(b,&entry->b_pred); Ladd(entry,&b->b_succ); /* put header block at end of procedure */ for (c = curproc->p_start; c->b_next != 0; c = c->b_next); c->b_next = b; /* b->b_next = 0; */ copy_loops(b,entry,lp); b->b_idom = entry->b_idom; entry->b_idom = b; lp->LP_HEADER = b; }