source: mainline/uspace/app/pcc/arch/mips/code.c@ 087c27f6

/*      $Id: code.c,v 1.17 2010/09/19 14:01:35 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, MKAP(INT));
                q->n_rval = reg++;
                p = block(REG, NIL, NIL, INT, 0, MKAP(INT));
                p->n_rval = FP;
                p = block(PLUS, p, bcon(4*off++), INT, 0, MKAP(INT));
                p = block(UMUL, p, NIL, INT, 0, MKAP(INT));
                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, MKAP(LONGLONG));
        tmpnr = regno(t);
        q = block(REG, NIL, NIL, LONGLONG, 0, MKAP(LONGLONG));
        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, MKAP(INT));
        tmpnr = regno(t);
        q = block(REG, NIL, NIL, INT, 0, MKAP(INT));
        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, MKAP(INT));
                q->n_rval = reg++;
                p = block(REG, NIL, NIL, INT, 0, MKAP(INT));
                p->n_rval = FP;
                p = block(PLUS, p, bcon(4*off), INT, 0, MKAP(INT));
                p = block(UMUL, p, NIL, INT, 0, MKAP(INT));
                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, MKAP(PTR+ty));
                t = block(SCONV, t, NIL, PTR+INT, 0, MKAP(PTR+INT));
                t = block(PLUS, t, bcon(4*i), PTR+INT, 0, MKAP(PTR+INT));
                t = buildtree(UMUL, t, NIL);

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

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

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

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

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

        *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, MKAP(LONGLONG));
                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, MKAP(INT));
                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;
}