/* $Id$ */ /* * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands. * See the copyright notice in the ACK home directory, in the file "Copyright". */ /* C O M M O N S U B E X P R E S S I O N E L I M I N A T I O N */ #include #include #include "../share/types.h" #include "../share/lset.h" #include "../share/debug.h" #include "../share/go.h" #include "cs.h" #include "cs_aux.h" #include "cs_avail.h" #include "cs_debug.h" #include "cs_elim.h" #include "cs_entity.h" #include "cs_profit.h" #include "cs_stack.h" #include "cs_vnm.h" int Scs; /* Number of optimizations found. */ STATIC cs_clear() { clr_avails(); clr_entities(); clr_stack(); start_valnum(); } STATIC cs_optimize(p) proc_p p; { /* Optimize all basic blocks of one procedure. */ register bblock_p rbp, bdone; if (IS_ENTERED_WITH_GTO(p)) return; avails = (avail_p) 0; entities = Lempty_set(); cs_clear(); rbp = p->p_start; while (rbp != (bblock_p) 0) { /* First we build a list of common expressions with the * value numbering algorithm. We take blocks in textual order * as long as the next block can only be reached through the * block we have just done. Note that if a block is preceded * by itself, the number of predecessors is greater than 1, * but the previous block can still be its immediate dominator. */ do { vnm(rbp); bdone = rbp; OUTTRACE("basic block %d processed", bdone->b_id); rbp = rbp->b_next; } while (rbp != (bblock_p) 0 && rbp->b_idom == bdone && Lnrelems(rbp->b_pred) == 1 ); OUTTRACE("value numbering completed", 0); OUTAVAILS(); OUTENTITIES(); /* Now we put out the instructions without common * subexpressions but with the use of temporaries, * which will be local variables of procedure p. */ eliminate(p); cs_clear(); } } main(argc, argv) int argc; char *argv[]; { Scs = 0; go(argc, argv, no_action, cs_optimize, cs_machinit, no_action); report("Duplicate expressions eliminated", Scs); exit(0); }