520 lines
14 KiB
C
520 lines
14 KiB
C
/* obj-evax.c - EVAX (openVMS/Alpha) object file format.
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Copyright (C) 1996-2018 Free Software Foundation, Inc.
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Contributed by Klaus Kämpf (kkaempf@progis.de) of
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proGIS Software, Aachen, Germany.
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Extensively enhanced by Douglas Rupp of AdaCore.
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This file is part of GAS, the GNU Assembler
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GAS is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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GAS is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GAS; see the file COPYING. If not, write to
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the Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#define OBJ_HEADER "obj-evax.h"
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#include "as.h"
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#include "bfd.h"
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#include "vms.h"
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#include "subsegs.h"
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#include "struc-symbol.h"
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#include "safe-ctype.h"
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static void s_evax_weak (int);
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static unsigned int crc32 (unsigned char *, int);
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static char *encode_32 (unsigned int);
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static char *encode_16 (unsigned int);
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static int decode_16 (const char *);
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const pseudo_typeS obj_pseudo_table[] =
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{
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{ "weak", s_evax_weak, 0},
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{0, 0, 0},
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}; /* obj_pseudo_table */
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void obj_read_begin_hook () {}
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/* Handle the weak specific pseudo-op. */
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static void
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s_evax_weak (int ignore ATTRIBUTE_UNUSED)
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{
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char *name;
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int c;
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symbolS *symbolP;
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char *stop = NULL;
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char stopc;
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if (flag_mri)
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stop = mri_comment_field (&stopc);
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do
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{
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c = get_symbol_name (&name);
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symbolP = symbol_find_or_make (name);
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(void) restore_line_pointer (c);
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SKIP_WHITESPACE ();
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S_SET_WEAK (symbolP);
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if (c == ',')
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{
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input_line_pointer++;
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SKIP_WHITESPACE ();
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if (*input_line_pointer == '\n')
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c = '\n';
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}
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}
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while (c == ',');
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if (flag_mri)
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mri_comment_end (stop, stopc);
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demand_empty_rest_of_line ();
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}
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void
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evax_symbol_new_hook (symbolS *sym)
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{
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struct evax_private_udata_struct *udata;
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udata = XNEW (struct evax_private_udata_struct);
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udata->bsym = symbol_get_bfdsym (sym);
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udata->enbsym = NULL;
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udata->origname = xstrdup (S_GET_NAME (sym));
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udata->lkindex = 0;
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symbol_get_bfdsym(sym)->udata.p = (PTR) udata;
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}
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void
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evax_frob_symbol (symbolS *sym, int *punt)
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{
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const char *symname = S_GET_NAME (sym);
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int symlen = strlen (symname);
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asymbol *symbol = symbol_get_bfdsym (sym);
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if (symlen > 4
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&& strcmp (symname + symlen - 4, "..en") == 0
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&& S_GET_SEGMENT (sym) == undefined_section)
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{
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symbol_clear_used_in_reloc (sym);
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*punt = 1;
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}
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else if ((symbol->flags & BSF_GLOBAL) && (symbol->flags & BSF_FUNCTION))
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{
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struct evax_private_udata_struct *udata
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= (struct evax_private_udata_struct *)symbol->udata.p;
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/* Fix up equates of function definitions. */
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while (udata->enbsym == NULL)
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{
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/* ??? Equates have been resolved at this point so their
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expression is O_constant; but they previously were
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O_symbol and we hope the equated symbol is still there. */
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sym = symbol_get_value_expression (sym)->X_add_symbol;
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if (sym == NULL)
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{
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as_bad (_("no entry symbol for global function '%s'"), symname);
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return;
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}
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symbol = symbol_get_bfdsym (sym);
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udata->enbsym
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= ((struct evax_private_udata_struct *)symbol->udata.p)->enbsym;
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}
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}
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}
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void
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evax_frob_file_before_adjust (void)
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{
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struct alpha_linkage_fixups *l;
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segT current_section = now_seg;
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int current_subsec = now_subseg;
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segment_info_type *seginfo;
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int linkage_index = 1;
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subseg_set (alpha_link_section, 0);
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seginfo = seg_info (alpha_link_section);
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/* Handle .linkage fixups. */
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for (l = alpha_linkage_fixup_root; l != NULL; l = l->next)
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{
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if (S_GET_SEGMENT (l->fixp->fx_addsy) == alpha_link_section)
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{
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/* The symbol is defined in the file. The linkage entry decays to
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two relocs. */
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symbolS *entry_sym;
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fixS *fixpentry, *fixppdesc, *fixtail;
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fixtail = seginfo->fix_tail;
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/* Replace the linkage with the local symbols */
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entry_sym = symbol_find
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(((struct evax_private_udata_struct *)symbol_get_bfdsym (l->fixp->fx_addsy)->udata.p)->enbsym->name);
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if (!entry_sym)
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abort ();
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fixpentry = fix_new (l->fixp->fx_frag, l->fixp->fx_where, 8,
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entry_sym, l->fixp->fx_offset, 0,
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BFD_RELOC_64);
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fixppdesc = fix_new (l->fixp->fx_frag, l->fixp->fx_where + 8, 8,
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l->fixp->fx_addsy, l->fixp->fx_offset, 0,
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BFD_RELOC_64);
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l->fixp->fx_size = 0;
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l->fixp->fx_done = 1;
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/* If not already at the tail, splice the new fixups into
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the chain right after the one we are nulling out */
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if (fixtail != l->fixp)
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{
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fixppdesc->fx_next = l->fixp->fx_next;
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l->fixp->fx_next = fixpentry;
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fixtail->fx_next = 0;
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seginfo->fix_tail = fixtail;
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}
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}
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else
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{
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/* Assign a linkage index. */
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((struct evax_private_udata_struct *)
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symbol_get_bfdsym (l->label)->udata.p)->lkindex = linkage_index;
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l->fixp->fx_addnumber = linkage_index;
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linkage_index += 2;
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}
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}
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subseg_set (current_section, current_subsec);
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}
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void
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evax_frob_file_before_fix (void)
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{
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/* Now that the fixups are done earlier, we need to transfer the values
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into the BFD symbols before calling fix_segment (ideally should not
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be done also later). */
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if (symbol_rootP)
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{
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symbolS *symp;
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/* Set the value into the BFD symbol. Up til now the value
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has only been kept in the gas symbolS struct. */
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for (symp = symbol_rootP; symp; symp = symbol_next (symp))
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symbol_get_bfdsym (symp)->value = S_GET_VALUE (symp);
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}
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}
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/* The length is computed from the maximum allowable length of 64 less the
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4 character ..xx extension that must be preserved (removed before
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crunching and appended back on afterwards). The $<nnn>.. prefix is
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also removed and prepened back on, but doesn't enter into the length
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computation because symbols with that prefix are always resolved
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by the assembler and will never appear in the symbol table. At least
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I hope that's true, TBD. */
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#define MAX_LABEL_LENGTH 60
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static char *shorten_identifier (char *);
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static int is_truncated_identifier (char *);
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char *
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evax_shorten_name (char *id)
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{
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int prefix_dotdot = 0;
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char prefix [64];
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int len = strlen (id);
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int suffix_dotdot = len;
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char suffix [64];
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char *base_id;
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/* This test may be too conservative. */
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if (len <= MAX_LABEL_LENGTH)
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return id;
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suffix [0] = 0;
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prefix [0] = 0;
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/* Check for ..xx suffix and save it. */
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if (strncmp (&id[len-4], "..", 2) == 0)
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{
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suffix_dotdot = len - 4;
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strncpy (suffix, &id[len-4], 4);
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suffix [4] = 0;
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}
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/* Check for $<nnn>.. prefix and save it. */
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if ((id[0] == '$') && ISDIGIT (id[1]))
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{
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int i;
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for (i=2; i < len; i++)
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{
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if (!ISDIGIT (id[i]))
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{
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if (id[i] == '.' && id [i+1] == '.')
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{
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prefix_dotdot = i+2;
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strncpy (prefix, id, prefix_dotdot);
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prefix [prefix_dotdot] = 0;
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}
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break;
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}
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}
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}
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/* We only need worry about crunching the base symbol. */
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base_id = xmemdup0 (&id[prefix_dotdot], suffix_dotdot - prefix_dotdot);
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if (strlen (base_id) > MAX_LABEL_LENGTH)
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{
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char new_id [4096];
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char *return_id;
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strcpy (new_id, base_id);
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/* Shorten it. */
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strcpy (new_id, shorten_identifier (new_id));
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/* Prepend back the prefix if there was one. */
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if (prefix_dotdot)
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{
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memmove (&new_id [prefix_dotdot], new_id, strlen (new_id) + 1);
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strncpy (new_id, prefix, prefix_dotdot);
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}
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/* Append back the suffix if there was one. */
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if (strlen (suffix))
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strcat (new_id, suffix);
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/* Save it on the heap and return. */
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return_id = xstrdup (new_id);
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return return_id;
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}
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else
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return id;
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}
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/* The code below implements a mechanism for truncating long
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identifiers to an arbitrary length (set by MAX_LABEL_LENGTH).
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It attempts to make each truncated identifier unique by replacing
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part of the identifier with an encoded 32-bit CRC and an associated
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checksum (the checksum is used as a way to determine that the name
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was truncated).
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Note that both a portion of the start and of the end of the
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identifier may be kept. The macro ID_SUFFIX_LENGTH will return the
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number of characters in the suffix of the identifier that should be
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kept.
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The portion of the identifier that is going to be removed is
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checksummed. The checksum is then encoded as a 5-character string,
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the characters of which are then summed. This sum is then encoded
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as a 3-character string. Finally, the original length of the
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identifier is encoded as a 3-character string.
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These three strings are then concatenated together (along with an _h
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which further designates that the name was truncated):
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"original_identifier"_haaaaabbbccc
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aaaaa = 32-bit CRC
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bbb = length of original identifier
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ccc = sum of 32-bit CRC characters
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The resulting identifier will be MAX_LABEL_LENGTH characters long.
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*/
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/* Table used to convert an integer into a string. */
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static const char codings[] = {
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'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
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'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
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'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '_'};
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/* The number of codings in the above table. */
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static const int number_of_codings = sizeof (codings) / sizeof (char);
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/* Table used by decode_16 () to convert an encoded string back into
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an integer. */
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static char decodings[256];
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/* Table used by the crc32 function to calculate the checksum. */
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static unsigned int crc32_table[256] = {0, 0};
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/* Given a string in BUF, calculate a 32-bit CRC for it.
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This is used as a reasonably unique hash for the given string. */
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static unsigned int
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crc32 (unsigned char *buf, int len)
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{
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unsigned int crc = 0xffffffff;
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if (! crc32_table[1])
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{
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/* Initialize the CRC table and the decoding table. */
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int i, j;
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unsigned int c;
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for (i = 0; i < 256; i++)
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{
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for (c = i << 24, j = 8; j > 0; --j)
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c = c & 0x80000000 ? (c << 1) ^ 0x04c11db7 : (c << 1);
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crc32_table[i] = c;
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decodings[i] = 0;
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}
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for (i = 0; i < number_of_codings; i++)
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decodings[codings[i] & 255] = i;
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}
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while (len--)
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{
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crc = (crc << 8) ^ crc32_table[(crc >> 24) ^ *buf];
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buf++;
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}
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return crc;
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}
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/* Encode the lower 32 bits of VALUE as a 5-character string. */
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static char *
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encode_32 (unsigned int value)
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{
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static char res[6];
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int x;
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res[5] = 0;
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for(x = 0; x < 5; x++)
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{
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res[x] = codings[value % number_of_codings];
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value = value / number_of_codings;
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}
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return res;
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}
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/* Encode the lower 16 bits of VALUE as a 3-character string. */
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static char *
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encode_16 (unsigned int value)
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{
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static char res[4];
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int x;
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res[3] = 0;
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for(x = 0; x < 3; x++)
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{
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res[x] = codings[value % number_of_codings];
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value = value / number_of_codings;
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}
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return res;
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}
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/* Convert the encoded string obtained from encode_16 () back into a
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16-bit integer. */
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static int
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decode_16 (const char *string)
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{
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return decodings[(int) string[2]] * number_of_codings * number_of_codings
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+ decodings[(int) string[1]] * number_of_codings
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+ decodings[(int) string[0]];
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}
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/* ID_SUFFIX_LENGTH is used to determine how many characters in the
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suffix of the identifier are to be preserved, if any. */
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#ifndef ID_SUFFIX_LENGTH
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#define ID_SUFFIX_LENGTH(ID) (0)
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#endif
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/* Return a reasonably-unique version of NAME that is less than or
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equal to MAX_LABEL_LENGTH characters long. The string returned from
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this function may be a copy of NAME; the function will never
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actually modify the contents of NAME. */
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static char newname[MAX_LABEL_LENGTH + 1];
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static char *
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shorten_identifier (char *name)
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{
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int crc, len, sum, x, final_len;
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char *crc_chars;
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int suffix_length = ID_SUFFIX_LENGTH (name);
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if ((len = strlen (name)) <= MAX_LABEL_LENGTH)
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return name;
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final_len = MAX_LABEL_LENGTH - 2 - 5 - 3 - 3 - suffix_length;
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crc = crc32 ((unsigned char *)name + final_len,
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len - final_len - suffix_length);
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crc_chars = encode_32 (crc);
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sum = 0;
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for (x = 0; x < 5; x++)
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sum += crc_chars [x];
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strncpy (newname, name, final_len);
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newname [MAX_LABEL_LENGTH] = 0;
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/* Now append the suffix of the original identifier, if any. */
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if (suffix_length)
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strncpy (newname + MAX_LABEL_LENGTH - suffix_length,
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name + len - suffix_length,
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suffix_length);
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strncpy (newname + final_len, "_h", 2);
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strncpy (newname + final_len + 2 , crc_chars, 5);
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strncpy (newname + final_len + 2 + 5, encode_16 (len), 3);
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strncpy (newname + final_len + 2 + 5 + 3, encode_16 (sum), 3);
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if (!is_truncated_identifier (newname))
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abort ();
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return newname;
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}
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/* Determine whether or not ID is a truncated identifier, and return a
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non-zero value if it is. */
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static int
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is_truncated_identifier (char *id)
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{
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char *ptr;
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int len = strlen (id);
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/* If it's not exactly MAX_LABEL_LENGTH characters long, it can't be
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a truncated identifier. */
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if (len != MAX_LABEL_LENGTH)
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return 0;
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/* Start scanning backwards for a _h. */
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len = len - 3 - 3 - 5 - 2;
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ptr = id + len;
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while (ptr >= id)
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{
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if (ptr[0] == '_' && ptr[1] == 'h')
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{
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/* Now see if the sum encoded in the identifier matches. */
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int x, sum;
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sum = 0;
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for (x = 0; x < 5; x++)
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sum += ptr[x + 2];
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/* If it matches, this is probably a truncated identifier. */
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if (sum == decode_16 (ptr + 5 + 2 + 3))
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return 1;
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}
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ptr--;
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}
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return 0;
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}
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/* end of obj-evax.c */
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