assert() that we can't reach two unreachable code paths

[perl5.git] / deb.c

/*    deb.c
 *
 *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999,
 *    2000, 2001, 2002, 2003, 2004, 2005, 2006, by Larry Wall and others
 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 */

/*
 * "Didst thou think that the eyes of the White Tower were blind?  Nay, I
 * have seen more than thou knowest, Gray Fool."  --Denethor
 */

/*
 * This file contains various utilities for producing debugging output
 * (mainly related to displaying the stack)
 */

#include "EXTERN.h"
#define PERL_IN_DEB_C
#include "perl.h"

#if defined(PERL_IMPLICIT_CONTEXT)
void
Perl_deb_nocontext(const char *pat, ...)
{
#ifdef DEBUGGING
    dTHX;
    va_list args;
    va_start(args, pat);
    vdeb(pat, &args);
    va_end(args);
#else
    PERL_UNUSED_ARG(pat);
#endif /* DEBUGGING */
}
#endif

void
Perl_deb(pTHX_ const char *pat, ...)
{
#ifdef DEBUGGING
    va_list args;
    va_start(args, pat);
    vdeb(pat, &args);
    va_end(args);
#else
    PERL_UNUSED_ARG(pat);
#endif /* DEBUGGING */
}

void
Perl_vdeb(pTHX_ const char *pat, va_list *args)
{
#ifdef DEBUGGING
    dVAR;
    const char* const file = OutCopFILE(PL_curcop);

    PerlIO_printf(Perl_debug_log, "(%s:%ld)\t", (file ? file : "<free>"),
		  (long)CopLINE(PL_curcop));
    (void) PerlIO_vprintf(Perl_debug_log, pat, *args);
#else
    PERL_UNUSED_ARG(pat);
    PERL_UNUSED_ARG(args);
#endif /* DEBUGGING */
}

I32
Perl_debstackptrs(pTHX)
{
#ifdef DEBUGGING
    dVAR;
    PerlIO_printf(Perl_debug_log,
		  "%8"UVxf" %8"UVxf" %8"IVdf" %8"IVdf" %8"IVdf"\n",
		  PTR2UV(PL_curstack), PTR2UV(PL_stack_base),
		  (IV)*PL_markstack_ptr, (IV)(PL_stack_sp-PL_stack_base),
		  (IV)(PL_stack_max-PL_stack_base));
    PerlIO_printf(Perl_debug_log,
		  "%8"UVxf" %8"UVxf" %8"UVuf" %8"UVuf" %8"UVuf"\n",
		  PTR2UV(PL_mainstack), PTR2UV(AvARRAY(PL_curstack)),
		  PTR2UV(PL_mainstack), PTR2UV(AvFILLp(PL_curstack)),
		  PTR2UV(AvMAX(PL_curstack)));
#endif /* DEBUGGING */
    return 0;
}


/* dump the contents of a particular stack
 * Display stack_base[stack_min+1 .. stack_max],
 * and display the marks whose offsets are contained in addresses
 * PL_markstack[mark_min+1 .. mark_max] and whose values are in the range
 * of the stack values being displayed
 *
 * Only displays top 30 max
 */

STATIC void
S_deb_stack_n(pTHX_ SV** stack_base, I32 stack_min, I32 stack_max,
	I32 mark_min, I32 mark_max)
{
#ifdef DEBUGGING
    dVAR;
    register I32 i = stack_max - 30;
    const I32 *markscan = PL_markstack + mark_min;
    if (i < stack_min)
	i = stack_min;
    
    while (++markscan <= PL_markstack + mark_max)
	if (*markscan >= i)
	    break;

    if (i > stack_min)
	PerlIO_printf(Perl_debug_log, "... ");

    if (stack_base[0] != &PL_sv_undef || stack_max < 0)
	PerlIO_printf(Perl_debug_log, " [STACK UNDERFLOW!!!]\n");
    do {
	++i;
	if (markscan <= PL_markstack + mark_max && *markscan < i) {
	    do {
		++markscan;
		PerlIO_putc(Perl_debug_log, '*');
	    }
	    while (markscan <= PL_markstack + mark_max && *markscan < i);
	    PerlIO_printf(Perl_debug_log, "  ");
	}
	if (i > stack_max)
	    break;
	PerlIO_printf(Perl_debug_log, "%-4s  ", SvPEEK(stack_base[i]));
    }
    while (1);
    PerlIO_printf(Perl_debug_log, "\n");
#else
    PERL_UNUSED_ARG(stack_base);
    PERL_UNUSED_ARG(stack_min);
    PERL_UNUSED_ARG(stack_max);
    PERL_UNUSED_ARG(mark_min);
    PERL_UNUSED_ARG(mark_max);
#endif /* DEBUGGING */
}


/* dump the current stack */

I32
Perl_debstack(pTHX)
{
#ifndef SKIP_DEBUGGING
    dVAR;
    if (CopSTASH_eq(PL_curcop, PL_debstash) && !DEBUG_J_TEST_)
	return 0;

    PerlIO_printf(Perl_debug_log, "    =>  ");
    deb_stack_n(PL_stack_base,
		0,
		PL_stack_sp - PL_stack_base,
		PL_curstackinfo->si_markoff,
		PL_markstack_ptr - PL_markstack);


#endif /* SKIP_DEBUGGING */
    return 0;
}


#ifdef DEBUGGING
static const char * const si_names[] = {
    "UNKNOWN",
    "UNDEF",
    "MAIN",
    "MAGIC",
    "SORT",
    "SIGNAL",
    "OVERLOAD",
    "DESTROY",
    "WARNHOOK",
    "DIEHOOK",
    "REQUIRE"
};
#endif

/* display all stacks */


void
Perl_deb_stack_all(pTHX)
{
#ifdef DEBUGGING
    dVAR;
    I32 si_ix;
    const PERL_SI *si;

    /* rewind to start of chain */
    si = PL_curstackinfo;
    while (si->si_prev)
	si = si->si_prev;

    si_ix=0;
    for (;;)
    {
        const int si_name_ix = si->si_type+1; /* -1 is a valid index */
        const char * const si_name = (si_name_ix>= sizeof(si_names)) ? "????" : si_names[si_name_ix];
	I32 ix;
	PerlIO_printf(Perl_debug_log, "STACK %"IVdf": %s\n",
						(IV)si_ix, si_name);

	for (ix=0; ix<=si->si_cxix; ix++) {

	    const PERL_CONTEXT * const cx = &(si->si_cxstack[ix]);
	    PerlIO_printf(Perl_debug_log,
		    "  CX %"IVdf": %-6s => ",
		    (IV)ix, PL_block_type[CxTYPE(cx)]
	    );
	    /* substitution contexts don't save stack pointers etc) */
	    if (CxTYPE(cx) == CXt_SUBST)
		PerlIO_printf(Perl_debug_log, "\n");
	    else {

		/* Find the the current context's stack range by searching
		 * forward for any higher contexts using this stack; failing
		 * that, it will be equal to the size of the stack for old
		 * stacks, or PL_stack_sp for the current stack
		 */

		I32 i, stack_min, stack_max, mark_min, mark_max;
		const PERL_CONTEXT *cx_n;
		const PERL_SI *si_n;

		cx_n = Null(PERL_CONTEXT*);

		/* there's a separate stack per SI, so only search
		 * this one */

		for (i=ix+1; i<=si->si_cxix; i++) {
		    if (CxTYPE(cx) == CXt_SUBST)
			continue;
		    cx_n = &(si->si_cxstack[i]);
		    break;
		}

		stack_min = cx->blk_oldsp;

		if (cx_n) {
		    stack_max = cx_n->blk_oldsp;
		}
		else if (si == PL_curstackinfo) {
		    stack_max = PL_stack_sp - AvARRAY(si->si_stack);
		}
		else {
		    stack_max = AvFILLp(si->si_stack);
		}

		/* for the other stack types, there's only one stack
		 * shared between all SIs */

		si_n = si;
		i = ix;
		cx_n = Null(PERL_CONTEXT*);
		for (;;) {
		    i++;
		    if (i > si_n->si_cxix) {
			if (si_n == PL_curstackinfo)
			    break;
			else {
			    si_n = si_n->si_next;
			    i = 0;
			}
		    }
		    if (CxTYPE(&(si_n->si_cxstack[i])) == CXt_SUBST)
			continue;
		    cx_n = &(si_n->si_cxstack[i]);
		    break;
		}

		mark_min  = cx->blk_oldmarksp;
		if (cx_n) {
		    mark_max  = cx_n->blk_oldmarksp;
		}
		else {
		    mark_max = PL_markstack_ptr - PL_markstack;
		}

		deb_stack_n(AvARRAY(si->si_stack),
			stack_min, stack_max, mark_min, mark_max);

		if (CxTYPE(cx) == CXt_EVAL || CxTYPE(cx) == CXt_SUB
			|| CxTYPE(cx) == CXt_FORMAT)
		{
		    const OP * const retop = (CxTYPE(cx) == CXt_EVAL)
			    ? cx->blk_eval.retop : cx->blk_sub.retop;

		    PerlIO_printf(Perl_debug_log, "  retop=%s\n",
			    retop ? OP_NAME(retop) : "(null)"
		    );
		}
	    }
	} /* next context */


	if (si == PL_curstackinfo)
	    break;
	si = si->si_next;
	si_ix++;
	if (!si)
	    break; /* shouldn't happen, but just in case.. */
    } /* next stackinfo */

    PerlIO_printf(Perl_debug_log, "\n");
#endif /* DEBUGGING */
}

/*
 * Local variables:
 * c-indentation-style: bsd
 * c-basic-offset: 4
 * indent-tabs-mode: t
 * End:
 *
 * ex: set ts=8 sts=4 sw=4 noet:
 */