runtime.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

/*#@(#)runtime.c	4.1	Ultrix	7/17/90*/

/* Copyright (c) 1982 Regents of the University of California */

static char sccsid[] = "@(#)runtime.c 1.8 8/10/83";

static char rcsid[] = "$Header: runtime.c,v 1.3 84/03/27 10:23:40 linton Exp $";

/*
 * Runtime organization dependent routines, mostly dealing with
 * activation records.
 */

#include "defs.h"
#include "runtime.h"
#include "process.h"
#include "machine.h"
#include "events.h"
#include "mappings.h"
#include "symbols.h"
#include "tree.h"
#include "eval.h"
#include "operators.h"
#include "object.h"
#include <sys/param.h>

#ifndef public
typedef struct Frame *Frame;

#include "machine.h"
#endif

#define NSAVEREG 12

struct Frame {
    Integer condition_handler;
    Integer mask;
    Address save_ap;		/* argument pointer */
    Address save_fp;		/* frame pointer */
    Address save_pc;		/* program counter */
    Word save_reg[NSAVEREG];	/* not necessarily there */
};

private Frame curframe = nil;
private struct Frame curframerec;
private Boolean walkingstack = false;

#define frameeq(f1, f2) ((f1)->save_fp == (f2)->save_fp)

/*
 * Set a frame to the current activation record.
 */

private getcurframe(frp)
register Frame frp;
{
    register int i;

    checkref(frp);
    frp->mask = reg(NREG);
    frp->save_ap = reg(ARGP);
    frp->save_fp = reg(FRP);
    frp->save_pc = reg(PROGCTR) + 1;
    for (i = 0; i < NSAVEREG; i++) {
	frp->save_reg[i] = reg(i);
    }
}

/*
 * Return a pointer to the next activation record up the stack.
 * Return nil if there is none.
 * Writes over space pointed to by given argument.
 */

#define bis(b, n) ((b & (1 << (n))) != 0)

private Frame nextframe(frp)
Frame frp;
{
    register Frame newfrp;
    struct Frame frame;
    register Integer i, j, mask;
    Address prev_frame, callpc; 
    static Integer ntramp = 0;

    newfrp = frp;
    prev_frame = frp->save_fp;

/*
 *  The check for interrupt generated frames is taken from adb with only
 *  partial understanding.  If you're in "sub" and on a sigxxx "sigsub"
 *  gets control, then the stack does NOT look like <main, sub, sigsub>.
 *
 *  As best I can make out it looks like:
 *
 *     <main, (machine check exception block + sub), sysframe, sigsub>.
 *
 *  When the signal occurs an exception block and a frame for the routine
 *  in which it occured are pushed on the user stack.  Then another frame
 *  is pushed corresponding to a call from the kernel to sigsub.
 *
 *  The addr in sub at which the exception occured is not in sub.save_pc
 *  but in the machine check exception block.  It is at the magic address
 *  fp + 84.
 *
 *  The current approach ignores the sys_frame (what adb reports as sigtramp)
 *  and takes the pc for sub from the exception block.  This allows the
 *  "where" command to report <main, sub, sigsub>, which seems reasonable.
 */

nextf:
    dread(&frame, prev_frame, sizeof(struct Frame));
    if (ntramp == 1) {
	dread(&callpc, prev_frame + 84, sizeof(callpc));
    } else {
	callpc = frame.save_pc;
    }
    if (frame.save_fp == nil) {
	newfrp = nil;
    } else if (callpc > 0x80000000 - 0x200 * UPAGES ) {
	 ntramp++;
	 prev_frame = frame.save_fp;
	 goto nextf;
    } else {
	frame.save_pc = callpc;
        ntramp = 0;
	mask = ((frame.mask >> 16) & 0x0fff);
	j = 0;
	for (i = 0; i < NSAVEREG; i++) {
	    if (bis(mask, i)) {
		newfrp->save_reg[i] = frame.save_reg[j];
		++j;
	    }
	}
	newfrp->condition_handler = frame.condition_handler;
	newfrp->mask = mask;
	newfrp->save_ap = frame.save_ap;
	newfrp->save_fp = frame.save_fp;
	newfrp->save_pc = frame.save_pc;
    }
    return newfrp;
}

/*
 * Get the current frame information in the given Frame and store the
 * associated function in the given value-result parameter.
 */

private getcurfunc (frp, fp)
Frame frp;
Symbol *fp;
{
    getcurframe(frp);
    *fp = whatblock(frp->save_pc);
}

/*
 * Return the frame associated with the next function up the call stack, or
 * nil if there is none.  The function is returned in a value-result parameter.
 * For "inline" functions the statically outer function and same frame
 * are returned.
 */

private Frame nextfunc (frp, fp)
Frame frp;
Symbol *fp;
{
    Symbol t;
    Frame nfrp;

    t = *fp;
    checkref(t);
    if (isinline(t)) {
	t = container(t);
	nfrp = frp;
    } else {
	nfrp = nextframe(frp);
	if (nfrp == nil) {
	    t = nil;
	} else {
	    t = whatblock(nfrp->save_pc);
	}
    }
    *fp = t;
    return nfrp;
}

/*
 * Return the frame associated with the given function.
 * If the function is nil, return the most recently activated frame.
 *
 * Static allocation for the frame.
 */

public Frame findframe(f)
Symbol f;
{
    register Frame frp;
    static struct Frame frame;
    Symbol p;
    Boolean done;

    frp = &frame;
    getcurframe(frp);
    if (f != nil) {
	if (f == curfunc and curframe != nil) {
	    *frp = *curframe;
	} else {
	    done = false;
	    p = whatblock(frp->save_pc);
	    do {
		if (p == f) {
		    done = true;
		} else if (p == program) {
		    done = true;
		    frp = nil;
		} else {
		    frp = nextfunc(frp, &p);
		    if (frp == nil) {
			done = true;
		    }
		}
	    } while (not done);
	}
    }
    return frp;
}

/*
 * Find the return address of the current procedure/function.
 */

public Address return_addr()
{
    Frame frp;
    Address addr;
    struct Frame frame;

    frp = &frame;
    getcurframe(frp);
    frp = nextframe(frp);
    if (frp == nil) {
	addr = 0;
    } else {
	addr = frp->save_pc;
    }
    return addr;
}

/*
 * Push the value associated with the current function.
 */

public pushretval(len, isindirect)
Integer len;
Boolean isindirect;
{
    Word r0;

    r0 = reg(0);
    if (isindirect) {
	rpush((Address) r0, len);
    } else {
	switch (len) {
	    case sizeof(char):
		push(char, r0);
		break;

	    case sizeof(short):
		push(short, r0);
		break;

	    default:
		if (len == sizeof(Word)) {
		    push(Word, r0);
		} else if (len == 2*sizeof(Word)) {
		    push(Word, r0);
		    push(Word, reg(1));
		} else {
		    panic("not indirect in pushretval?");
		}
		break;
	}
    }
}

/*
 * Return the base address for locals in the given frame.
 */

public Address locals_base(frp)
register Frame frp;
{
    return (frp == nil) ? reg(FRP) : frp->save_fp;
}

/*
 * Return the base address for arguments in the given frame.
 */

public Address args_base(frp)
register Frame frp;
{
    return (frp == nil) ? reg(ARGP) : frp->save_ap;
}

/*
 * Return saved register n from the given frame.
 */

public Word savereg(n, frp)
register Integer n;
register Frame frp;
{
    register Word w;

    if (frp == nil) {
	w = reg(n);
    } else {
	switch (n) {
	    case ARGP:
		w = frp->save_ap;
		break;

	    case FRP:
		w = frp->save_fp;
		break;

	    case STKP:
		w = reg(STKP);
		break;

	    case PROGCTR:
		w = frp->save_pc;
		break;

	    default:
		assert(n >= 0 and n < NSAVEREG);
		w = frp->save_reg[n];
		break;
	}
    }
    return w;
}

/*
 * Return the nth argument to the current procedure.
 */

public Word argn(n, frp)
Integer n;
Frame frp;
{
    Word w;

    dread(&w, args_base(frp) + (n * sizeof(Word)), sizeof(w));
    return w;
}

/*
 * Calculate the entry address for a procedure or function parameter,
 * given the address of the descriptor.
 */

public Address fparamaddr(a)
Address a;
{
    Address r;

    dread(&r, a, sizeof(r));
    return r;
}

/*
 * Print a list of currently active blocks starting with most recent.
 */

public wherecmd()
{
    walkstack(false);
}

/*
 * Dump the world to the given file.
 * Like "where", but variables are dumped also.
 */

public dump()
{
    walkstack(true);
}

/*
 * Walk the stack of active procedures printing information
 * about each active procedure.
 */

private walkstack(dumpvariables)
Boolean dumpvariables;
{
    register Frame frp;
    register Boolean save;
    register Lineno line;
    Symbol f;
    struct Frame frame;

    if (notstarted(process)) {
	error("program is not active");
    } else {
	save = walkingstack;
	walkingstack = true;
	frp = &frame;
	getcurfunc(frp, &f);
	do {
	    printf("%s", symname(f));
	    if (not isinline(f)) {
		printparams(f, frp);
	    }
	    line = srcline(frp->save_pc - 1);
	    if (line != 0) {
		printf(", line %d", line);
		printf(" in \"%s\"\n", srcfilename(frp->save_pc - 1));
	    } else {
		printf(" at 0x%x\n", frp->save_pc);
	    }
	    if (dumpvariables) {
		dumpvars(f, frp);
		putchar('\n');
	    }
	    frp = nextfunc(frp, &f);
	} while (frp != nil and f != program);
	if (dumpvariables) {
	    printf("in \"%s\":\n", symname(program));
	    dumpvars(program, nil);
	    putchar('\n');
	}
	walkingstack = save;
    }
}

/*