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code.c

/*    $Id: code.c,v 1.18 2011/04/07 18:50:15 ragge Exp $    */
/*
 * Copyright (c) 2003 Anders Magnusson (ragge@ludd.luth.se).
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


/*
 * MIPS port by Jan Enoksson (janeno-1@student.ltu.se) and
 * Simon Olsson (simols-1@student.ltu.se) 2005.
 */

#include <assert.h>
#include "pass1.h"

/*
 * Define everything needed to print out some data (or text).
 * This means segment, alignment, visibility, etc.
 */
void
defloc(struct symtab *sp)
{
      static char *loctbl[] = { "text", "data", "section .rodata" };
      static int lastloc = -1;
      TWORD t;
      char *n;
      int s;

      if (sp == NULL) {
            lastloc = -1;
            return;
      }
      t = sp->stype;
      s = ISFTN(t) ? PROG : ISCON(cqual(t, sp->squal)) ? RDATA : DATA;
      lastloc = s;
      if (s == PROG)
            return; /* text is written in prologue() */
      if (s != lastloc)
            printf("    .%s\n", loctbl[s]);
      printf("    .p2align %d\n", ispow2(talign(t, sp->sap)));
      n = sp->soname ? sp->soname : sp->sname;
      if (sp->sclass == EXTDEF)
            printf("    .globl %s\n", n);
      if (sp->slevel == 0) {
#ifdef USE_GAS
            printf("\t.type %s,@object\n", n);
            printf("\t.size %s," CONFMT "\n", n,
                tsize(sp->stype, sp->sdf, sp->sap));
#endif
            printf("%s:\n", n);
      } else
            printf(LABFMT ":\n", sp->soffset);
}


#ifdef notdef
/*
 * cause the alignment to become a multiple of n
 * never called for text segment.
 */
void
defalign(int n)
{
      n = ispow2(n / SZCHAR);
      if (n == -1)
            cerror("defalign: n != 2^i");
      printf("\t.p2align %d\n", n);
}

/*
 * define the current location as the name p->sname
 * never called for text segment.
 */
void
defnam(struct symtab *p)
{
      char *c = p->soname;

      if (p->sclass == EXTDEF)
            printf("\t.globl %s\n", c);
#ifdef USE_GAS
      printf("\t.type %s,@object\n", c);
      printf("\t.size %s," CONFMT "\n", c, tsize(p->stype, p->sdf, p->sap));
#endif
      printf("%s:\n", c);
}
#endif

static int rvnr;

/*
 * code for the end of a function
 * deals with struct return here
 */
void
efcode()
{
      NODE *p, *q;
      int tempnr;
      int ty;

      if (cftnsp->stype != STRTY+FTN && cftnsp->stype != UNIONTY+FTN)
            return;

      ty = cftnsp->stype - FTN;

      q = block(REG, NIL, NIL, INCREF(ty), 0, cftnsp->sap);
      q->n_rval = V0;
      p = tempnode(0, INCREF(ty), 0, cftnsp->sap);
      tempnr = regno(p);
      p = buildtree(ASSIGN, p, q);
      ecomp(p);

      q = tempnode(tempnr, INCREF(ty), 0, cftnsp->sap);
      q = buildtree(UMUL, q, NIL);

      p = tempnode(rvnr, INCREF(ty), 0, cftnsp->sap);
      p = buildtree(UMUL, p, NIL);

      p = buildtree(ASSIGN, p, q);
      ecomp(p);

      q = tempnode(rvnr, INCREF(ty), 0, cftnsp->sap);
      p = block(REG, NIL, NIL, INCREF(ty), 0, cftnsp->sap);
      p->n_rval = V0;
      p = buildtree(ASSIGN, p, q);
      ecomp(p);
}

/* Put a symbol in a temporary
 * used by bfcode() and its helpers */
static void
putintemp(struct symtab *sym)
{
      NODE *p;
      p = tempnode(0, sym->stype, sym->sdf, sym->sap);
      p = buildtree(ASSIGN, p, nametree(sym));
      sym->soffset = regno(p->n_left);
      sym->sflags |= STNODE;
      ecomp(p);
}

/* setup the hidden pointer to struct return parameter
 * used by bfcode() */
static void
param_retptr(void)
{
      NODE *p, *q;

      p = tempnode(0, PTR+STRTY, 0, cftnsp->sap);
      rvnr = regno(p);
      q = block(REG, NIL, NIL, PTR+STRTY, 0, cftnsp->sap);
      q->n_rval = A0;
      p = buildtree(ASSIGN, p, q);
      ecomp(p);
}

/* setup struct parameter
 * push the registers out to memory
 * used by bfcode() */
static void
param_struct(struct symtab *sym, int *regp)
{
      int reg = *regp;
      NODE *p, *q;
      int navail;
      int sz;
      int off;
      int num;
      int i;

      navail = nargregs - (reg - A0);
      sz = tsize(sym->stype, sym->sdf, sym->sap) / SZINT;
      off = ARGINIT/SZINT + (reg - A0);
      num = sz > navail ? navail : sz;
      for (i = 0; i < num; i++) {
            q = block(REG, NIL, NIL, INT, 0, 0);
            q->n_rval = reg++;
            p = block(REG, NIL, NIL, INT, 0, 0);
            p->n_rval = FP;
            p = block(PLUS, p, bcon(4*off++), INT, 0, 0);
            p = block(UMUL, p, NIL, INT, 0, 0);
            p = buildtree(ASSIGN, p, q);
            ecomp(p);
      }

      *regp = reg;
}

/* setup a 64-bit parameter (double/ldouble/longlong)
 * used by bfcode() */
static void
param_64bit(struct symtab *sym, int *regp, int dotemps)
{
      int reg = *regp;
      NODE *p, *q;
      int navail;

      /* alignment */
      ++reg;
      reg &= ~1;

      navail = nargregs - (reg - A0);

      if (navail < 2) {
            /* would have appeared half in registers/half
             * on the stack, but alignment ensures it
             * appears on the stack */
            if (dotemps)
                  putintemp(sym);
            *regp = reg;
            return;
      }

      q = block(REG, NIL, NIL, sym->stype, sym->sdf, sym->sap);
      q->n_rval = A0A1 + (reg - A0);
      if (dotemps) {
            p = tempnode(0, sym->stype, sym->sdf, sym->sap);
            sym->soffset = regno(p);
            sym->sflags |= STNODE;
      } else {
            p = nametree(sym);
      }
      p = buildtree(ASSIGN, p, q);
      ecomp(p);
      *regp = reg + 2;
}

/* setup a 32-bit param on the stack
 * used by bfcode() */
static void
param_32bit(struct symtab *sym, int *regp, int dotemps)
{
      NODE *p, *q;

      q = block(REG, NIL, NIL, sym->stype, sym->sdf, sym->sap);
      q->n_rval = (*regp)++;
      if (dotemps) {
            p = tempnode(0, sym->stype, sym->sdf, sym->sap);
            sym->soffset = regno(p);
            sym->sflags |= STNODE;
      } else {
            p = nametree(sym);
      }
      p = buildtree(ASSIGN, p, q);
      ecomp(p);
}

/*
 * XXX This is a hack.  We cannot have (l)doubles in more than one
 * register class.  So we bounce them in and out of temps to
 * move them in and out of the right registers.
 */
static void
param_double(struct symtab *sym, int *regp, int dotemps)
{
      int reg = *regp;
      NODE *p, *q, *t;
      int navail;
      int tmpnr;

      /* alignment */
      ++reg;
      reg &= ~1;

      navail = nargregs - (reg - A0);

      if (navail < 2) {
            /* would have appeared half in registers/half
             * on the stack, but alignment ensures it
             * appears on the stack */
            if (dotemps)
                  putintemp(sym);
            *regp = reg;
            return;
      }

      t = tempnode(0, LONGLONG, 0, 0);
      tmpnr = regno(t);
      q = block(REG, NIL, NIL, LONGLONG, 0, 0);
      q->n_rval = A0A1 + (reg - A0);
      p = buildtree(ASSIGN, t, q);
      ecomp(p);

      if (dotemps) {
            sym->soffset = tmpnr;
            sym->sflags |= STNODE;
      } else {
            q = tempnode(tmpnr, sym->stype, sym->sdf, sym->sap);
            p = nametree(sym);
            p = buildtree(ASSIGN, p, q);
            ecomp(p);
      }
      *regp = reg + 2;
}

/*
 * XXX This is a hack.  We cannot have floats in more than one
 * register class.  So we bounce them in and out of temps to
 * move them in and out of the right registers.
 */
static void
param_float(struct symtab *sym, int *regp, int dotemps)
{
      NODE *p, *q, *t;
      int tmpnr;

      t = tempnode(0, INT, 0, 0);
      tmpnr = regno(t);
      q = block(REG, NIL, NIL, INT, 0, 0);
      q->n_rval = (*regp)++;
      p = buildtree(ASSIGN, t, q);
      ecomp(p);

      if (dotemps) {
            sym->soffset = tmpnr;
            sym->sflags |= STNODE;
      } else {
            q = tempnode(tmpnr, sym->stype, sym->sdf, sym->sap);
            p = nametree(sym);
            p = buildtree(ASSIGN, p, q);
            ecomp(p);
      }
}

/*
 * code for the beginning of a function; a is an array of
 * indices in symtab for the arguments; n is the number
 */
void
bfcode(struct symtab **sp, int cnt)
{
      union arglist *usym;
      int lastreg = A0 + nargregs - 1;
      int saveallargs = 0;
      int i, reg;

      /*
       * Detect if this function has ellipses and save all
       * argument register onto stack.
       */
      usym = cftnsp->sdf->dfun;
      while (usym && usym->type != TNULL) {
            if (usym->type == TELLIPSIS) {
                  saveallargs = 1;
                  break;
            }
            ++usym;
      }

      reg = A0;

      /* assign hidden return structure to temporary */
      if (cftnsp->stype == STRTY+FTN || cftnsp->stype == UNIONTY+FTN) {
            param_retptr();
            ++reg;
      }

        /* recalculate the arg offset and create TEMP moves */
        for (i = 0; i < cnt; i++) {

            if ((reg > lastreg) && !xtemps)
                  break;
            else if (reg > lastreg) 
                  putintemp(sp[i]);
            else if (sp[i]->stype == STRTY || sp[i]->stype == UNIONTY)
                  param_struct(sp[i], &reg);
            else if (DEUNSIGN(sp[i]->stype) == LONGLONG)
                  param_64bit(sp[i], &reg, xtemps && !saveallargs);
            else if (sp[i]->stype == DOUBLE || sp[i]->stype == LDOUBLE)
                  param_double(sp[i], &reg, xtemps && !saveallargs);
            else if (sp[i]->stype == FLOAT)
                  param_float(sp[i], &reg, xtemps && !saveallargs);
            else
                  param_32bit(sp[i], &reg, xtemps && !saveallargs);
      }

      /* if saveallargs, save the rest of the args onto the stack */
      if (!saveallargs)
            return;
      while (reg <= lastreg) {
            NODE *p, *q;
            int off = ARGINIT/SZINT + (reg - A0);
            q = block(REG, NIL, NIL, INT, 0, 0);
            q->n_rval = reg++;
            p = block(REG, NIL, NIL, INT, 0, 0);
            p->n_rval = FP;
            p = block(PLUS, p, bcon(4*off), INT, 0, 0);
            p = block(UMUL, p, NIL, INT, 0, 0);
            p = buildtree(ASSIGN, p, q);
            ecomp(p);
      }

}


/*
 * by now, the automatics and register variables are allocated
 */
void
bccode()
{
      SETOFF(autooff, SZINT);
}

/* called just before final exit */
/* flag is 1 if errors, 0 if none */
void
ejobcode(int flag )
{
}

void
bjobcode()
{
      printf("\t.section .mdebug.abi32\n");
      printf("\t.previous\n");
      printf("\t.abicalls\n");
}

#ifdef notdef
/*
 * Print character t at position i in one string, until t == -1.
 * Locctr & label is already defined.
 */
void
bycode(int t, int i)
{
      static int lastoctal = 0;

      /* put byte i+1 in a string */

      if (t < 0) {
            if (i != 0)
                  puts("\\000\"");
      } else {
            if (i == 0)
                  printf("\t.ascii \"");
            if (t == 0)
                  return;
            else if (t == '\\' || t == '"') {
                  lastoctal = 0;
                  putchar('\\');
                  putchar(t);
            } else if (t == 011) {
                  printf("\\t");
            } else if (t == 012) {
                  printf("\\n");
            } else if (t < 040 || t >= 0177) {
                  lastoctal++;
                  printf("\\%o",t);
            } else if (lastoctal && '0' <= t && t <= '9') {
                  lastoctal = 0;
                  printf("\"\n\t.ascii \"%c", t);
            } else {    
                  lastoctal = 0;
                  putchar(t);
            }
      }
}
#endif

/*
 * return the alignment of field of type t
 */
int
fldal(unsigned int t)
{
      uerror("illegal field type");
      return(ALINT);
}

/* fix up type of field p */
void
fldty(struct symtab *p)
{
}

/*
 * XXX - fix genswitch.
 */
int
mygenswitch(int num, TWORD type, struct swents **p, int n)
{
      return 0;
}


/* setup call stack with a structure */
/* called from moveargs() */
static NODE *
movearg_struct(NODE *p, NODE *parent, int *regp)
{
      int reg = *regp;
      NODE *l, *q, *t, *r;
      int tmpnr;
      int navail;
      int off;
      int num;
        int sz;
      int ty;
      int i;

      navail = nargregs - (reg - A0);
      sz = tsize(p->n_type, p->n_df, p->n_ap) / SZINT;
      num = sz > navail ? navail : sz;

      l = p->n_left;
      nfree(p);
      ty = l->n_type;
      t = tempnode(0, l->n_type, l->n_df, l->n_ap);
      tmpnr = regno(t);
      l = buildtree(ASSIGN, t, l);

      if (p != parent) {
            q = parent->n_left;
      } else
            q = NULL;

      /* copy structure into registers */
      for (i = 0; i < num; i++) {
            t = tempnode(tmpnr, ty, 0, 0);
            t = block(SCONV, t, NIL, PTR+INT, 0, 0);
            t = block(PLUS, t, bcon(4*i), PTR+INT, 0, 0);
            t = buildtree(UMUL, t, NIL);

            r = block(REG, NIL, NIL, INT, 0, 0);
            r->n_rval = reg++;

                  r = buildtree(ASSIGN, r, t);
            if (q == NULL)
                  q = r;
            else 
                  q = block(CM, q, r, INT, 0, 0);
      }
      off = ARGINIT/SZINT + nargregs;
      for (i = num; i < sz; i++) {
            t = tempnode(tmpnr, ty, 0, 0);
            t = block(SCONV, t, NIL, PTR+INT, 0, 0);
            t = block(PLUS, t, bcon(4*i), PTR+INT, 0, 0);
            t = buildtree(UMUL, t, NIL);

            r = block(REG, NIL, NIL, INT, 0, 0);
            r->n_rval = FP;
            r = block(PLUS, r, bcon(4*off++), INT, 0, 0);
            r = block(UMUL, r, NIL, INT, 0, 0);

                  r = buildtree(ASSIGN, r, t);
            if (q == NULL)
                  q = r;
            else
                  q = block(CM, q, r, INT, 0, 0);
      }

      if (parent->n_op == CM) {
            parent->n_left = q;
            q = l;
      } else {
            q = block(CM, q, l, INT, 0, 0);
      }

      *regp = reg;
      return q;
}

/* setup call stack with 64-bit argument */
/* called from moveargs() */
static NODE *
movearg_64bit(NODE *p, int *regp)
{
      int reg = *regp;
      NODE *q;
      int lastarg;

      /* alignment */
      ++reg;
      reg &= ~1;

      lastarg = A0 + nargregs - 1;
      if (reg > lastarg) {
            *regp = reg;
            return block(FUNARG, p, NIL, p->n_type, p->n_df, p->n_ap);
      }

      q = block(REG, NIL, NIL, p->n_type, p->n_df, p->n_ap);
      q->n_rval = A0A1 + (reg - A0);
      q = buildtree(ASSIGN, q, p);

      *regp = reg + 2;
      return q;
}

/* setup call stack with 32-bit argument */
/* called from moveargs() */
static NODE *
movearg_32bit(NODE *p, int *regp)
{
      int reg = *regp;
      NODE *q;

      q = block(REG, NIL, NIL, p->n_type, p->n_df, p->n_ap);
      q->n_rval = reg++;
      q = buildtree(ASSIGN, q, p);

      *regp = reg;
      return q;
}

static NODE *
moveargs(NODE *p, int *regp)
{
        NODE *r, **rp;
      int lastreg;
      int reg;

        if (p->n_op == CM) {
                p->n_left = moveargs(p->n_left, regp);
                r = p->n_right;
            rp = &p->n_right;
        } else {
            r = p;
            rp = &p;
      }

      lastreg = A0 + nargregs - 1;
        reg = *regp;

      if (reg > lastreg && r->n_op != STARG)
            *rp = block(FUNARG, r, NIL, r->n_type, r->n_df, r->n_ap);
      else if (r->n_op == STARG) {
            *rp = movearg_struct(r, p, regp);
      } else if (DEUNSIGN(r->n_type) == LONGLONG) {
            *rp = movearg_64bit(r, regp);
      } else if (r->n_type == DOUBLE || r->n_type == LDOUBLE) {
            /* XXX bounce in and out of temporary to change to longlong */
            NODE *t1 = tempnode(0, LONGLONG, 0, 0);
            int tmpnr = regno(t1);
            NODE *t2 = tempnode(tmpnr, r->n_type, r->n_df, r->n_ap);
            t1 =  movearg_64bit(t1, regp);
            r = block(ASSIGN, t2, r, r->n_type, r->n_df, r->n_ap);
            if (p->n_op == CM) {
                  p->n_left = buildtree(CM, p->n_left, t1);
                  p->n_right = r;
            } else {
                  p = buildtree(CM, t1, r);
            }
      } else if (r->n_type == FLOAT) {
            /* XXX bounce in and out of temporary to change to int */
            NODE *t1 = tempnode(0, INT, 0, 0);
            int tmpnr = regno(t1);
            NODE *t2 = tempnode(tmpnr, r->n_type, r->n_df, r->n_ap);
            t1 =  movearg_32bit(t1, regp);
            r = block(ASSIGN, t2, r, r->n_type, r->n_df, r->n_ap);
            if (p->n_op == CM) {
                  p->n_left = buildtree(CM, p->n_left, t1);
                  p->n_right = r;
            } else {
                  p = buildtree(CM, t1, r);
            }
      } else {
            *rp = movearg_32bit(r, regp);
      }

      return p;
}

/*
 * Called with a function call with arguments as argument.
 * This is done early in buildtree() and only done once.
 */
NODE *
funcode(NODE *p)
{
      int regnum = A0;
      NODE *l, *r, *t, *q;
      int ty;

      l = p->n_left;
      r = p->n_right;

      /*
       * if returning a structure, make the first argument
       * a hidden pointer to return structure.
       */
      ty = DECREF(l->n_type);
      if (ty == STRTY+FTN || ty == UNIONTY+FTN) {
            ty = DECREF(l->n_type) - FTN;
            q = tempnode(0, ty, l->n_df, l->n_ap);
            q = buildtree(ADDROF, q, NIL);
            if (r->n_op != CM) {
                  p->n_right = block(CM, q, r, INCREF(ty),
                      l->n_df, l->n_ap);
            } else {
                  for (t = r; t->n_left->n_op == CM; t = t->n_left)
                        ;
                  t->n_left = block(CM, q, t->n_left, INCREF(ty),
                      l->n_df, l->n_ap);
            }
      }

      p->n_right = moveargs(p->n_right, &regnum);

      return p;
}

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