diff options
Diffstat (limited to 'alloca.c')
| -rw-r--r-- | alloca.c | 492 |
1 files changed, 0 insertions, 492 deletions
diff --git a/alloca.c b/alloca.c deleted file mode 100644 index ec432dfc..00000000 --- a/alloca.c +++ /dev/null @@ -1,492 +0,0 @@ -/* alloca.c -- allocate automatically reclaimed memory - (Mostly) portable public-domain implementation -- D A Gwyn - - This implementation of the PWB library alloca function, - which is used to allocate space off the run-time stack so - that it is automatically reclaimed upon procedure exit, - was inspired by discussions with J. Q. Johnson of Cornell. - J.Otto Tennant <jot@cray.com> contributed the Cray support. - - There are some preprocessor constants that can - be defined when compiling for your specific system, for - improved efficiency; however, the defaults should be okay. - - The general concept of this implementation is to keep - track of all alloca-allocated blocks, and reclaim any - that are found to be deeper in the stack than the current - invocation. This heuristic does not reclaim storage as - soon as it becomes invalid, but it will do so eventually. - - As a special case, alloca(0) reclaims storage without - allocating any. It is a good idea to use alloca(0) in - your main control loop, etc. to force garbage collection. */ - -#ifdef HAVE_CONFIG_H -#include "config.h" -#endif - -#ifdef emacs -#include "blockinput.h" -#endif - -/* If compiling with GCC 2, this file's not needed. */ -#if !defined (__GNUC__) || __GNUC__ < 2 - -/* If someone has defined alloca as a macro, - there must be some other way alloca is supposed to work. */ -#ifndef alloca - -#ifdef emacs -#ifdef static -/* actually, only want this if static is defined as "" - -- this is for usg, in which emacs must undefine static - in order to make unexec workable - */ -#ifndef STACK_DIRECTION -you -lose --- must know STACK_DIRECTION at compile-time -#endif /* STACK_DIRECTION undefined */ -#endif /* static */ -#endif /* emacs */ - -/* If your stack is a linked list of frames, you have to - provide an "address metric" ADDRESS_FUNCTION macro. */ - -#if defined (CRAY) && defined (CRAY_STACKSEG_END) -long i00afunc (); -#define ADDRESS_FUNCTION(arg) (char *) i00afunc (&(arg)) -#else -#define ADDRESS_FUNCTION(arg) &(arg) -#endif - -#if __STDC__ -typedef void *pointer; -#else -typedef char *pointer; -#endif - -#define NULL 0 - -/* Different portions of Emacs need to call different versions of - malloc. The Emacs executable needs alloca to call xmalloc, because - ordinary malloc isn't protected from input signals. On the other - hand, the utilities in lib-src need alloca to call malloc; some of - them are very simple, and don't have an xmalloc routine. - - Non-Emacs programs expect this to call use xmalloc. - - Callers below should use malloc. */ - -#ifndef emacs -#define malloc xmalloc -#endif -extern pointer malloc (); - -/* Define STACK_DIRECTION if you know the direction of stack - growth for your system; otherwise it will be automatically - deduced at run-time. - - STACK_DIRECTION > 0 => grows toward higher addresses - STACK_DIRECTION < 0 => grows toward lower addresses - STACK_DIRECTION = 0 => direction of growth unknown */ - -#ifndef STACK_DIRECTION -#define STACK_DIRECTION 0 /* Direction unknown. */ -#endif - -#if STACK_DIRECTION != 0 - -#define STACK_DIR STACK_DIRECTION /* Known at compile-time. */ - -#else /* STACK_DIRECTION == 0; need run-time code. */ - -static int stack_dir; /* 1 or -1 once known. */ -#define STACK_DIR stack_dir - -static void -find_stack_direction () -{ - static char *addr = NULL; /* Address of first `dummy', once known. */ - auto char dummy; /* To get stack address. */ - - if (addr == NULL) - { /* Initial entry. */ - addr = ADDRESS_FUNCTION (dummy); - - find_stack_direction (); /* Recurse once. */ - } - else - { - /* Second entry. */ - if (ADDRESS_FUNCTION (dummy) > addr) - stack_dir = 1; /* Stack grew upward. */ - else - stack_dir = -1; /* Stack grew downward. */ - } -} - -#endif /* STACK_DIRECTION == 0 */ - -/* An "alloca header" is used to: - (a) chain together all alloca'ed blocks; - (b) keep track of stack depth. - - It is very important that sizeof(header) agree with malloc - alignment chunk size. The following default should work okay. */ - -#ifndef ALIGN_SIZE -#define ALIGN_SIZE sizeof(double) -#endif - -typedef union hdr -{ - char align[ALIGN_SIZE]; /* To force sizeof(header). */ - struct - { - union hdr *next; /* For chaining headers. */ - char *deep; /* For stack depth measure. */ - } h; -} header; - -static header *last_alloca_header = NULL; /* -> last alloca header. */ - -/* Return a pointer to at least SIZE bytes of storage, - which will be automatically reclaimed upon exit from - the procedure that called alloca. Originally, this space - was supposed to be taken from the current stack frame of the - caller, but that method cannot be made to work for some - implementations of C, for example under Gould's UTX/32. */ - -pointer -alloca (size) - unsigned size; -{ - auto char probe; /* Probes stack depth: */ - register char *depth = ADDRESS_FUNCTION (probe); - -#if STACK_DIRECTION == 0 - if (STACK_DIR == 0) /* Unknown growth direction. */ - find_stack_direction (); -#endif - - /* Reclaim garbage, defined as all alloca'd storage that - was allocated from deeper in the stack than currently. */ - - { - register header *hp; /* Traverses linked list. */ - -#ifdef emacs - BLOCK_INPUT; -#endif - - for (hp = last_alloca_header; hp != NULL;) - if ((STACK_DIR > 0 && hp->h.deep > depth) - || (STACK_DIR < 0 && hp->h.deep < depth)) - { - register header *np = hp->h.next; - - free ((pointer) hp); /* Collect garbage. */ - - hp = np; /* -> next header. */ - } - else - break; /* Rest are not deeper. */ - - last_alloca_header = hp; /* -> last valid storage. */ - -#ifdef emacs - UNBLOCK_INPUT; -#endif - } - - if (size == 0) - return NULL; /* No allocation required. */ - - /* Allocate combined header + user data storage. */ - - { - register pointer new = malloc (sizeof (header) + size); - /* Address of header. */ - - ((header *) new)->h.next = last_alloca_header; - ((header *) new)->h.deep = depth; - - last_alloca_header = (header *) new; - - /* User storage begins just after header. */ - - return (pointer) ((char *) new + sizeof (header)); - } -} - -#if defined (CRAY) && defined (CRAY_STACKSEG_END) - -#ifdef DEBUG_I00AFUNC -#include <stdio.h> -#endif - -#ifndef CRAY_STACK -#define CRAY_STACK -#ifndef CRAY2 -/* Stack structures for CRAY-1, CRAY X-MP, and CRAY Y-MP */ -struct stack_control_header - { - long shgrow:32; /* Number of times stack has grown. */ - long shaseg:32; /* Size of increments to stack. */ - long shhwm:32; /* High water mark of stack. */ - long shsize:32; /* Current size of stack (all segments). */ - }; - -/* The stack segment linkage control information occurs at - the high-address end of a stack segment. (The stack - grows from low addresses to high addresses.) The initial - part of the stack segment linkage control information is - 0200 (octal) words. This provides for register storage - for the routine which overflows the stack. */ - -struct stack_segment_linkage - { - long ss[0200]; /* 0200 overflow words. */ - long sssize:32; /* Number of words in this segment. */ - long ssbase:32; /* Offset to stack base. */ - long:32; - long sspseg:32; /* Offset to linkage control of previous - segment of stack. */ - long:32; - long sstcpt:32; /* Pointer to task common address block. */ - long sscsnm; /* Private control structure number for - microtasking. */ - long ssusr1; /* Reserved for user. */ - long ssusr2; /* Reserved for user. */ - long sstpid; /* Process ID for pid based multi-tasking. */ - long ssgvup; /* Pointer to multitasking thread giveup. */ - long sscray[7]; /* Reserved for Cray Research. */ - long ssa0; - long ssa1; - long ssa2; - long ssa3; - long ssa4; - long ssa5; - long ssa6; - long ssa7; - long sss0; - long sss1; - long sss2; - long sss3; - long sss4; - long sss5; - long sss6; - long sss7; - }; - -#else /* CRAY2 */ -/* The following structure defines the vector of words - returned by the STKSTAT library routine. */ -struct stk_stat - { - long now; /* Current total stack size. */ - long maxc; /* Amount of contiguous space which would - be required to satisfy the maximum - stack demand to date. */ - long high_water; /* Stack high-water mark. */ - long overflows; /* Number of stack overflow ($STKOFEN) calls. */ - long hits; /* Number of internal buffer hits. */ - long extends; /* Number of block extensions. */ - long stko_mallocs; /* Block allocations by $STKOFEN. */ - long underflows; /* Number of stack underflow calls ($STKRETN). */ - long stko_free; /* Number of deallocations by $STKRETN. */ - long stkm_free; /* Number of deallocations by $STKMRET. */ - long segments; /* Current number of stack segments. */ - long maxs; /* Maximum number of stack segments so far. */ - long pad_size; /* Stack pad size. */ - long current_address; /* Current stack segment address. */ - long current_size; /* Current stack segment size. This - number is actually corrupted by STKSTAT to - include the fifteen word trailer area. */ - long initial_address; /* Address of initial segment. */ - long initial_size; /* Size of initial segment. */ - }; - -/* The following structure describes the data structure which trails - any stack segment. I think that the description in 'asdef' is - out of date. I only describe the parts that I am sure about. */ - -struct stk_trailer - { - long this_address; /* Address of this block. */ - long this_size; /* Size of this block (does not include - this trailer). */ - long unknown2; - long unknown3; - long link; /* Address of trailer block of previous - segment. */ - long unknown5; - long unknown6; - long unknown7; - long unknown8; - long unknown9; - long unknown10; - long unknown11; - long unknown12; - long unknown13; - long unknown14; - }; - -#endif /* CRAY2 */ -#endif /* not CRAY_STACK */ - -#ifdef CRAY2 -/* Determine a "stack measure" for an arbitrary ADDRESS. - I doubt that "lint" will like this much. */ - -static long -i00afunc (long *address) -{ - struct stk_stat status; - struct stk_trailer *trailer; - long *block, size; - long result = 0; - - /* We want to iterate through all of the segments. The first - step is to get the stack status structure. We could do this - more quickly and more directly, perhaps, by referencing the - $LM00 common block, but I know that this works. */ - - STKSTAT (&status); - - /* Set up the iteration. */ - - trailer = (struct stk_trailer *) (status.current_address - + status.current_size - - 15); - - /* There must be at least one stack segment. Therefore it is - a fatal error if "trailer" is null. */ - - if (trailer == 0) - abort (); - - /* Discard segments that do not contain our argument address. */ - - while (trailer != 0) - { - block = (long *) trailer->this_address; - size = trailer->this_size; - if (block == 0 || size == 0) - abort (); - trailer = (struct stk_trailer *) trailer->link; - if ((block <= address) && (address < (block + size))) - break; - } - - /* Set the result to the offset in this segment and add the sizes - of all predecessor segments. */ - - result = address - block; - - if (trailer == 0) - { - return result; - } - - do - { - if (trailer->this_size <= 0) - abort (); - result += trailer->this_size; - trailer = (struct stk_trailer *) trailer->link; - } - while (trailer != 0); - - /* We are done. Note that if you present a bogus address (one - not in any segment), you will get a different number back, formed - from subtracting the address of the first block. This is probably - not what you want. */ - - return (result); -} - -#else /* not CRAY2 */ -/* Stack address function for a CRAY-1, CRAY X-MP, or CRAY Y-MP. - Determine the number of the cell within the stack, - given the address of the cell. The purpose of this - routine is to linearize, in some sense, stack addresses - for alloca. */ - -static long -i00afunc (long address) -{ - long stkl = 0; - - long size, pseg, this_segment, stack; - long result = 0; - - struct stack_segment_linkage *ssptr; - - /* Register B67 contains the address of the end of the - current stack segment. If you (as a subprogram) store - your registers on the stack and find that you are past - the contents of B67, you have overflowed the segment. - - B67 also points to the stack segment linkage control - area, which is what we are really interested in. */ - - stkl = CRAY_STACKSEG_END (); - ssptr = (struct stack_segment_linkage *) stkl; - - /* If one subtracts 'size' from the end of the segment, - one has the address of the first word of the segment. - - If this is not the first segment, 'pseg' will be - nonzero. */ - - pseg = ssptr->sspseg; - size = ssptr->sssize; - - this_segment = stkl - size; - - /* It is possible that calling this routine itself caused - a stack overflow. Discard stack segments which do not - contain the target address. */ - - while (!(this_segment <= address && address <= stkl)) - { -#ifdef DEBUG_I00AFUNC - fprintf (stderr, "%011o %011o %011o\n", this_segment, address, stkl); -#endif - if (pseg == 0) - break; - stkl = stkl - pseg; - ssptr = (struct stack_segment_linkage *) stkl; - size = ssptr->sssize; - pseg = ssptr->sspseg; - this_segment = stkl - size; - } - - result = address - this_segment; - - /* If you subtract pseg from the current end of the stack, - you get the address of the previous stack segment's end. - This seems a little convoluted to me, but I'll bet you save - a cycle somewhere. */ - - while (pseg != 0) - { -#ifdef DEBUG_I00AFUNC - fprintf (stderr, "%011o %011o\n", pseg, size); -#endif - stkl = stkl - pseg; - ssptr = (struct stack_segment_linkage *) stkl; - size = ssptr->sssize; - pseg = ssptr->sspseg; - result += size; - } - return (result); -} - -#endif /* not CRAY2 */ -#endif /* CRAY */ - -#endif /* no alloca */ -#endif /* not GCC version 2 */ |