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old-cross-binutils/gas/write.c
K. Richard Pixley fecd2382e7 Initial revision
1991-04-04 18:19:53 +00:00

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/* write.c - emit .o file
Copyright (C) 1986, 1987, 1990, 1991 Free Software Foundation, Inc.
This file is part of GAS, the GNU Assembler.
GAS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 1, or (at your option)
any later version.
GAS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GAS; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
/* static const char rcsid[] = "$Id$"; */
/*
This thing should be set up to do byteordering correctly. But...
In order to cross-assemble the target machine must have an a.out header
similar to the one in a.out.h on THIS machine. Byteorder doesn't matter,
we take special care of it, but the numbers must be the same SIZE (# of
bytes) and in the same PLACE. If this is not true, you will have some
trouble.
*/
#include "as.h"
#include "subsegs.h"
#include "obstack.h"
#include "output-file.h"
/* Hook for machine dependent relocation information output routine.
If not defined, the variable is allocated in BSS (Fortran common model).
If some other module defines it, we will see their value. */
void (*md_emit_relocations)();
/*
* In: length of relocation (or of address) in chars: 1, 2 or 4.
* Out: GNU LD relocation length code: 0, 1, or 2.
*/
unsigned char
nbytes_r_length [] = {
42, 0, 1, 42, 2
};
static struct frag *text_frag_root;
static struct frag *data_frag_root;
static struct frag *text_last_frag; /* Last frag in segment. */
static struct frag *data_last_frag; /* Last frag in segment. */
static object_headers headers;
long string_byte_count;
static char *the_object_file;
char *next_object_file_charP; /* Tracks object file bytes. */
int magic_number_for_object_file = DEFAULT_MAGIC_NUMBER_FOR_OBJECT_FILE;
/* static long length; JF unused */ /* String length, including trailing '\0'. */
#ifdef __STDC__
static int is_dnrange(struct frag *f1, struct frag *f2);
static long fixup_segment(fixS *fixP, segT this_segment_type);
static relax_addressT relax_align(relax_addressT address, long alignment);
static void relax_segment(struct frag *segment_frag_root, segT segment_type);
#else
static int is_dnrange();
static long fixup_segment();
static relax_addressT relax_align();
static void relax_segment();
#endif /* __STDC__ */
/*
* fix_new()
*
* Create a fixS in obstack 'notes'.
*/
fixS *fix_new(frag, where, size, add_symbol, sub_symbol, offset, pcrel, r_type)
fragS *frag; /* Which frag? */
int where; /* Where in that frag? */
short int size; /* 1, 2 or 4 usually. */
symbolS *add_symbol; /* X_add_symbol. */
symbolS *sub_symbol; /* X_subtract_symbol. */
long offset; /* X_add_number. */
int pcrel; /* TRUE if PC-relative relocation. */
enum reloc_type r_type; /* Relocation type */
{
register fixS * fixP;
fixP = (fixS *)obstack_alloc(&notes,sizeof(fixS));
fixP->fx_frag = frag;
fixP->fx_where = where;
fixP->fx_size = size;
fixP->fx_addsy = add_symbol;
fixP->fx_subsy = sub_symbol;
fixP->fx_offset = offset;
fixP->fx_pcrel = pcrel;
fixP->fx_r_type = r_type;
fixP->fx_next = NULL;
/* JF these 'cuz of the NS32K stuff */
fixP->fx_im_disp = 0;
fixP->fx_pcrel_adjust = 0;
fixP->fx_bsr = 0;
fixP->fx_bit_fixP = 0;
if (*seg_fix_tailP)
(*seg_fix_tailP)->fx_next = fixP;
else
*seg_fix_rootP = fixP;
*seg_fix_tailP = fixP;
fixP->fx_callj = 0;
return fixP;
}
void write_object_file() {
register struct frchain * frchainP; /* Track along all frchains. */
register fragS * fragP; /* Track along all frags. */
register struct frchain * next_frchainP;
register fragS * * prev_fragPP;
/* register char * name; */
/* symbolS *symbolP; */
/* register symbolS ** symbolPP; */
/* register fixS * fixP; JF unused */
unsigned int data_siz;
#ifdef DONTDEF
void gdb_emit();
void gdb_end();
#endif
long object_file_size;
#ifdef VMS
/*
* Under VMS we try to be compatible with VAX-11 "C". Thus, we
* call a routine to check for the definition of the procedure
* "_main", and if so -- fix it up so that it can be program
* entry point.
*/
VMS_Check_For_Main();
#endif /* VMS */
/*
* After every sub-segment, we fake an ".align ...". This conforms to BSD4.2
* brane-damage. We then fake ".fill 0" because that is the kind of frag
* that requires least thought. ".align" frags like to have a following
* frag since that makes calculating their intended length trivial.
*/
#define SUB_SEGMENT_ALIGN (2)
for (frchainP = frchain_root; frchainP; frchainP = frchainP->frch_next) {
#ifdef VMS
/*
* Under VAX/VMS, the linker (and PSECT specifications)
* take care of correctly aligning the segments.
* Doing the alignment here (on initialized data) can
* mess up the calculation of global data PSECT sizes.
*/
#undef SUB_SEGMENT_ALIGN
#define SUB_SEGMENT_ALIGN ((frchainP->frch_seg != SEG_DATA) ? 2 : 0)
#endif /* VMS */
subseg_new (frchainP->frch_seg, frchainP->frch_subseg);
frag_align (SUB_SEGMENT_ALIGN, 0);
/* frag_align will have left a new frag. */
/* Use this last frag for an empty ".fill". */
/*
* For this segment ...
* Create a last frag. Do not leave a "being filled in frag".
*/
frag_wane (frag_now);
frag_now->fr_fix = 0;
know( frag_now->fr_next == NULL );
/* know( frags . obstack_c_base == frags . obstack_c_next_free ); */
/* Above shows we haven't left a half-completed object on obstack. */
} /* walk the frag chain */
/*
* From now on, we don't care about sub-segments.
* Build one frag chain for each segment. Linked thru fr_next.
* We know that there is at least 1 text frchain & at least 1 data frchain.
*/
prev_fragPP = &text_frag_root;
for (frchainP = frchain_root; frchainP; frchainP = next_frchainP) {
know( frchainP->frch_root );
* prev_fragPP = frchainP->frch_root;
prev_fragPP = & frchainP->frch_last->fr_next;
if (((next_frchainP = frchainP->frch_next) == NULL)
|| next_frchainP == data0_frchainP) {
prev_fragPP = & data_frag_root;
if (next_frchainP) {
text_last_frag = frchainP->frch_last;
} else {
data_last_frag = frchainP->frch_last;
}
}
} /* walk the frag chain */
/*
* We have two segments. If user gave -R flag, then we must put the
* data frags into the text segment. Do this before relaxing so
* we know to take advantage of -R and make shorter addresses.
*/
if (flagseen[ 'R' ]) {
fixS *tmp;
text_last_frag->fr_next = data_frag_root;
text_last_frag = data_last_frag;
data_last_frag = NULL;
data_frag_root = NULL;
if (text_fix_root) {
for (tmp = text_fix_root; tmp->fx_next; tmp = tmp->fx_next) ;;
tmp->fx_next=data_fix_root;
} else
text_fix_root=data_fix_root;
data_fix_root=NULL;
}
relax_segment(text_frag_root, SEG_TEXT);
relax_segment(data_frag_root, SEG_DATA);
/*
* Now the addresses of frags are correct within the segment.
*/
know(text_last_frag->fr_type == rs_fill && text_last_frag->fr_offset == 0);
H_SET_TEXT_SIZE(&headers,text_last_frag->fr_address);
text_last_frag->fr_address=H_GET_TEXT_SIZE(&headers);
/*
* Join the 2 segments into 1 huge segment.
* To do this, re-compute every rn_address in the SEG_DATA frags.
* Then join the data frags after the text frags.
*
* Determine a_data [length of data segment].
*/
if (data_frag_root) {
register relax_addressT slide;
know( text_last_frag->fr_type == rs_fill && text_last_frag->fr_offset == 0 );
H_SET_DATA_SIZE(&headers, data_last_frag->fr_address);
data_last_frag->fr_address = H_GET_DATA_SIZE(&headers);
slide = H_GET_TEXT_SIZE(&headers); /* & in file of the data segment. */
for (fragP = data_frag_root;
fragP;
fragP = fragP->fr_next)
{
fragP->fr_address += slide;
}
know( text_last_frag );
text_last_frag->fr_next = data_frag_root;
} else {
H_SET_DATA_SIZE(&headers,0);
data_siz = 0;
}
bss_address_frag.fr_address = H_GET_TEXT_SIZE(&headers) +
H_GET_DATA_SIZE(&headers);
H_SET_BSS_SIZE(&headers,local_bss_counter);
/*
*
* Crawl the symbol chain.
*
* For each symbol whose value depends on a frag, take the address of
* that frag and subsume it into the value of the symbol.
* After this, there is just one way to lookup a symbol value.
* Values are left in their final state for object file emission.
* We adjust the values of 'L' local symbols, even if we do
* not intend to emit them to the object file, because their values
* are needed for fix-ups.
*
* Unless we saw a -L flag, remove all symbols that begin with 'L'
* from the symbol chain. (They are still pointed to by the fixes.)
*
* Count the remaining symbols.
* Assign a symbol number to each symbol.
* Count the number of string-table chars we will emit.
* Put this info into the headers as appropriate.
*
*/
know(zero_address_frag.fr_address == 0);
string_byte_count = sizeof(string_byte_count);
obj_crawl_symbol_chain(&headers);
if (string_byte_count == sizeof(string_byte_count)) {
string_byte_count = 0;
} /* if no strings, then no count. */
H_SET_STRING_SIZE(&headers, string_byte_count);
/*
* Addresses of frags now reflect addresses we use in the object file.
* Symbol values are correct.
* Scan the frags, converting any ".org"s and ".align"s to ".fill"s.
* Also converting any machine-dependent frags using md_convert_frag();
*/
subseg_change(SEG_TEXT, 0);
for (fragP = text_frag_root; fragP; fragP = fragP->fr_next) {
switch (fragP->fr_type) {
case rs_align:
case rs_org:
fragP->fr_type = rs_fill;
know( fragP->fr_var == 1 );
know( fragP->fr_next );
fragP->fr_offset
= fragP->fr_next->fr_address
- fragP->fr_address
- fragP->fr_fix;
break;
case rs_fill:
break;
case rs_machine_dependent:
md_convert_frag (fragP);
/*
* After md_convert_frag, we make the frag into a ".space 0".
* Md_convert_frag() should set up any fixSs and constants
* required.
*/
frag_wane (fragP);
break;
#ifndef WORKING_DOT_WORD
case rs_broken_word: {
struct broken_word *lie;
extern md_short_jump_size;
extern md_long_jump_size;
if (fragP->fr_subtype) {
fragP->fr_fix+=md_short_jump_size;
for (lie=(struct broken_word *)(fragP->fr_symbol);lie && lie->dispfrag==fragP;lie=lie->next_broken_word)
if (lie->added==1)
fragP->fr_fix+=md_long_jump_size;
}
frag_wane(fragP);
}
break;
#endif
default:
BAD_CASE( fragP->fr_type );
break;
} /* switch (fr_type) */
} /* for each frag. */
#ifndef WORKING_DOT_WORD
{
struct broken_word *lie;
struct broken_word **prevP;
prevP= &broken_words;
for (lie=broken_words; lie; lie=lie->next_broken_word)
if (!lie->added) {
#ifdef TC_NS32K
fix_new_ns32k(lie->frag,
lie->word_goes_here - lie->frag->fr_literal,
2,
lie->add,
lie->sub,
lie->addnum,
0, 0, 2, 0, 0);
#else /* TC_NS32K */
fix_new( lie->frag, lie->word_goes_here - lie->frag->fr_literal,
2, lie->add,
lie->sub, lie->addnum,
0, NO_RELOC);
#endif /* TC_NS32K */
/* md_number_to_chars(lie->word_goes_here,
S_GET_VALUE(lie->add)
+ lie->addnum
- S_GET_VALUE(lie->sub),
2); */
*prevP=lie->next_broken_word;
} else
prevP= &(lie->next_broken_word);
for (lie=broken_words;lie;) {
struct broken_word *untruth;
char *table_ptr;
long table_addr;
long from_addr,
to_addr;
int n,
m;
extern md_short_jump_size;
extern md_long_jump_size;
fragP=lie->dispfrag;
/* Find out how many broken_words go here */
n=0;
for (untruth=lie;untruth && untruth->dispfrag==fragP;untruth=untruth->next_broken_word)
if (untruth->added==1)
n++;
table_ptr=lie->dispfrag->fr_opcode;
table_addr=lie->dispfrag->fr_address+(table_ptr - lie->dispfrag->fr_literal);
/* Create the jump around the long jumps */
/* This is a short jump from table_ptr+0 to table_ptr+n*long_jump_size */
from_addr=table_addr;
to_addr = table_addr + md_short_jump_size + n * md_long_jump_size;
md_create_short_jump(table_ptr, from_addr, to_addr, lie->dispfrag, lie->add);
table_ptr+=md_short_jump_size;
table_addr+=md_short_jump_size;
for (m=0;lie && lie->dispfrag==fragP;m++,lie=lie->next_broken_word) {
if (lie->added==2)
continue;
/* Patch the jump table */
/* This is the offset from ??? to table_ptr+0 */
to_addr = table_addr
- S_GET_VALUE(lie->sub);
md_number_to_chars(lie->word_goes_here,to_addr,2);
for (untruth=lie->next_broken_word;untruth && untruth->dispfrag==fragP;untruth=untruth->next_broken_word) {
if (untruth->use_jump==lie)
md_number_to_chars(untruth->word_goes_here,to_addr,2);
}
/* Install the long jump */
/* this is a long jump from table_ptr+0 to the final target */
from_addr=table_addr;
to_addr=S_GET_VALUE(lie->add) + lie->addnum;
md_create_long_jump(table_ptr,from_addr,to_addr,lie->dispfrag,lie->add);
table_ptr+=md_long_jump_size;
table_addr+=md_long_jump_size;
}
}
}
#endif /* not WORKING_DOT_WORD */
#ifndef VMS
{ /* not vms */
/*
* Scan every FixS performing fixups. We had to wait until now to do
* this because md_convert_frag() may have made some fixSs.
*/
H_SET_RELOCATION_SIZE(&headers,
md_reloc_size * fixup_segment(text_fix_root, SEG_TEXT),
md_reloc_size * fixup_segment(data_fix_root, SEG_DATA));
/* FIXME move this stuff into the pre-write-hook */
H_SET_MAGIC_NUMBER(&headers, magic_number_for_object_file);
H_SET_ENTRY_POINT(&headers,0);
#ifdef EXEC_MACHINE_TYPE
H_SET_MACHINE_TYPE(&headers,EXEC_MACHINE_TYPE);
#endif
#ifdef EXEC_VERSION
H_SET_VERSION(&headers,EXEC_VERSION);
#endif
obj_pre_write_hook(&headers); /* extra coff stuff */
if ((had_warnings() && flagseen['Z'])
|| had_errors() > 0) {
if (flagseen['Z']) {
as_warn("%d error%s, %d warning%s, generating bad object file.\n",
had_errors(), had_errors() == 1 ? "" : "s",
had_warnings(), had_warnings() == 1 ? "" : "s");
} else {
as_fatal("%d error%s, %d warning%s, no object file generated.\n",
had_errors(), had_errors() == 1 ? "" : "s",
had_warnings(), had_warnings() == 1 ? "" : "s");
} /* on want output */
} /* on error condition */
object_file_size = H_GET_FILE_SIZE(&headers);
next_object_file_charP = the_object_file = xmalloc(object_file_size);
output_file_create(out_file_name);
obj_header_append(&next_object_file_charP, &headers);
/*
* Emit code.
*/
for (fragP = text_frag_root; fragP; fragP = fragP->fr_next) {
register long count;
register char * fill_literal;
register long fill_size;
know( fragP->fr_type == rs_fill );
append (& next_object_file_charP, fragP->fr_literal, (unsigned long)fragP->fr_fix);
fill_literal= fragP->fr_literal + fragP->fr_fix;
fill_size = fragP->fr_var;
know( fragP->fr_offset >= 0 );
for (count = fragP->fr_offset; count; count --)
append (& next_object_file_charP, fill_literal, (unsigned long)fill_size);
} /* for each code frag. */
/*
* Emit relocations.
*/
obj_emit_relocations(&next_object_file_charP, text_fix_root, (relax_addressT)0);
#ifdef TC_I960
/* Make addresses in data relocation directives relative to beginning of
* first data fragment, not end of last text fragment: alignment of the
* start of the data segment may place a gap between the segments.
*/
obj_emit_relocations(&next_object_file_charP, data_fix_root, data0_frchainP->frch_root->fr_address);
#else /* TC_I960 */
obj_emit_relocations(&next_object_file_charP, data_fix_root, text_last_frag->fr_address);
#endif /* TC_I960 */
/*
* Emit line number entries.
*/
OBJ_EMIT_LINENO(&next_object_file_charP, lineno_rootP, the_object_file);
/*
* Emit symbols.
*/
obj_emit_symbols(&next_object_file_charP, symbol_rootP);
/*
* Emit strings.
*/
if (string_byte_count > 0) {
obj_emit_strings(&next_object_file_charP);
} /* only if we have a string table */
know(next_object_file_charP == the_object_file + object_file_size);
/* Write the data to the file */
output_file_append(the_object_file,object_file_size,out_file_name);
#ifdef DONTDEF
if (flagseen['G']) /* GDB symbol file to be appended? */
{
gdb_emit (out_file_name);
gdb_end ();
}
#endif /* DONTDEF */
output_file_close(out_file_name);
} /* non vms output */
#else /* VMS */
/*
* Now do the VMS-dependent part of writing the object file
*/
VMS_write_object_file(text_siz, data_siz, text_frag_root, data_frag_root);
#endif /* VMS */
} /* write_object_file() */
/*
* relax_segment()
*
* Now we have a segment, not a crowd of sub-segments, we can make fr_address
* values.
*
* Relax the frags.
*
* After this, all frags in this segment have addresses that are correct
* within the segment. Since segments live in different file addresses,
* these frag addresses may not be the same as final object-file addresses.
*/
#ifndef VMS
static
#endif /* not VMS */
void relax_segment(segment_frag_root, segment_type)
struct frag * segment_frag_root;
segT segment_type; /* SEG_DATA or SEG_TEXT */
{
register struct frag * fragP;
register relax_addressT address;
/* register relax_addressT old_address; JF unused */
/* register relax_addressT new_address; JF unused */
know( segment_type == SEG_DATA || segment_type == SEG_TEXT );
/* In case md_estimate_size_before_relax() wants to make fixSs. */
subseg_change(segment_type, 0);
/*
* For each frag in segment: count and store (a 1st guess of) fr_address.
*/
address = 0;
for ( fragP = segment_frag_root; fragP; fragP = fragP->fr_next )
{
fragP->fr_address = address;
address += fragP->fr_fix;
switch (fragP->fr_type)
{
case rs_fill:
address += fragP->fr_offset * fragP->fr_var;
break;
case rs_align:
address += relax_align(address, fragP->fr_offset);
break;
case rs_org:
/*
* Assume .org is nugatory. It will grow with 1st relax.
*/
break;
case rs_machine_dependent:
address += md_estimate_size_before_relax(fragP, segment_type);
break;
#ifndef WORKING_DOT_WORD
/* Broken words don't concern us yet */
case rs_broken_word:
break;
#endif
default:
BAD_CASE( fragP->fr_type );
break;
} /* switch(fr_type) */
} /* for each frag in the segment */
/*
* Do relax().
*/
{
register long stretch; /* May be any size, 0 or negative. */
/* Cumulative number of addresses we have */
/* relaxed this pass. */
/* We may have relaxed more than one address. */
register long stretched; /* Have we stretched on this pass? */
/* This is 'cuz stretch may be zero, when,
in fact some piece of code grew, and
another shrank. If a branch instruction
doesn't fit anymore, we could be scrod */
do
{
stretch = stretched = 0;
for (fragP = segment_frag_root; fragP; fragP = fragP->fr_next)
{
register long growth = 0;
register unsigned long was_address;
/* register long var; */
register long offset;
register symbolS *symbolP;
register long target;
register long after;
register long aim;
was_address = fragP->fr_address;
address = fragP->fr_address += stretch;
symbolP = fragP->fr_symbol;
offset = fragP->fr_offset;
/* var = fragP->fr_var; */
switch (fragP->fr_type)
{
case rs_fill: /* .fill never relaxes. */
growth = 0;
break;
#ifndef WORKING_DOT_WORD
/* JF: This is RMS's idea. I do *NOT* want to be blamed
for it I do not want to write it. I do not want to have
anything to do with it. This is not the proper way to
implement this misfeature. */
case rs_broken_word:
{
struct broken_word *lie;
struct broken_word *untruth;
extern int md_short_jump_size;
extern int md_long_jump_size;
/* Yes this is ugly (storing the broken_word pointer
in the symbol slot). Still, this whole chunk of
code is ugly, and I don't feel like doing anything
about it. Think of it as stubbornness in action */
growth=0;
for (lie=(struct broken_word *)(fragP->fr_symbol);
lie && lie->dispfrag==fragP;
lie=lie->next_broken_word) {
if (lie->added)
continue;
offset= lie->add->sy_frag->fr_address+ S_GET_VALUE(lie->add) + lie->addnum -
(lie->sub->sy_frag->fr_address+ S_GET_VALUE(lie->sub));
if (offset<=-32768 || offset>=32767) {
if (flagseen['k'])
as_warn(".word %s-%s+%ld didn't fit",
S_GET_NAME(lie->add),
S_GET_NAME(lie->sub),
lie->addnum);
lie->added=1;
if (fragP->fr_subtype==0) {
fragP->fr_subtype++;
growth+=md_short_jump_size;
}
for (untruth=lie->next_broken_word;untruth && untruth->dispfrag==lie->dispfrag;untruth=untruth->next_broken_word)
if ((untruth->add->sy_frag == lie->add->sy_frag)
&& S_GET_VALUE(untruth->add) == S_GET_VALUE(lie->add)) {
untruth->added=2;
untruth->use_jump=lie;
}
growth+=md_long_jump_size;
}
}
}
break;
#endif
case rs_align:
growth = relax_align ((relax_addressT)(address + fragP->fr_fix), offset)
- relax_align ((relax_addressT)(was_address + fragP->fr_fix), offset);
break;
case rs_org:
target = offset;
if (symbolP)
{
know((S_GET_SEGMENT(symbolP) == SEG_ABSOLUTE) ||
(S_GET_SEGMENT(symbolP) == SEG_DATA) ||
(S_GET_SEGMENT(symbolP) == SEG_TEXT));
know(symbolP->sy_frag);
know(!(S_GET_SEGMENT(symbolP) == SEG_ABSOLUTE) ||
symbolP->sy_frag==&zero_address_frag );
target +=
S_GET_VALUE(symbolP)
+ symbolP->sy_frag->fr_address;
}
know( fragP->fr_next );
after = fragP->fr_next->fr_address;
growth = ((target - after ) > 0) ? (target - after) : 0;
/* Growth may be -ve, but variable part */
/* of frag cannot have < 0 chars. */
/* That is, we can't .org backwards. */
growth -= stretch; /* This is an absolute growth factor */
break;
case rs_machine_dependent:
{
register const relax_typeS * this_type;
register const relax_typeS * start_type;
register relax_substateT next_state;
register relax_substateT this_state;
start_type = this_type
= md_relax_table + (this_state = fragP->fr_subtype);
target = offset;
if (symbolP)
{
know((S_GET_SEGMENT(symbolP) == SEG_ABSOLUTE) ||
(S_GET_SEGMENT(symbolP) == SEG_DATA) ||
(S_GET_SEGMENT(symbolP) == SEG_TEXT));
know(symbolP->sy_frag);
know(!(S_GET_SEGMENT(symbolP) == SEG_ABSOLUTE) ||
symbolP->sy_frag==&zero_address_frag );
target +=
S_GET_VALUE(symbolP)
+ symbolP->sy_frag->fr_address;
/* If frag has yet to be reached on this pass,
assume it will move by STRETCH just as we did.
If this is not so, it will be because some frag
between grows, and that will force another pass. */
/* JF was just address */
/* JF also added is_dnrange hack */
/* There's gotta be a better/faster/etc way
to do this. . . */
/* gnu@cygnus.com: I changed this from > to >=
because I ran into a zero-length frag (fr_fix=0)
which was created when the obstack needed a new
chunk JUST AFTER the opcode of a branch. Since
fr_fix is zero, fr_address of this frag is the same
as fr_address of the next frag. This
zero-length frag was variable and jumped to .+2
(in the next frag), but since the > comparison
below failed (the two were =, not >), "stretch"
was not added to the target. Stretch was 178, so
the offset appeared to be .-176 instead, which did
not fit into a byte branch, so the assembler
relaxed the branch to a word. This didn't compare
with what happened when the same source file was
assembled on other machines, which is how I found it.
You might want to think about what other places have
trouble with zero length frags... */
if (symbolP->sy_frag->fr_address >= was_address && is_dnrange(fragP,symbolP->sy_frag))
target += stretch;
}
aim = target - address - fragP->fr_fix;
/* The displacement is affected by the instruction size
* for the 32k architecture. I think we ought to be able
* to add fragP->fr_pcrel_adjust in all cases (it should be
* zero if not used), but just in case it breaks something
* else we'll put this inside #ifdef NS32K ... #endif
*/
#ifdef TC_NS32K
aim += fragP->fr_pcrel_adjust;
#endif /* TC_NS32K */
if (aim < 0)
{
/* Look backwards. */
for (next_state = this_type->rlx_more; next_state; )
{
if (aim >= this_type->rlx_backward)
next_state = 0;
else
{ /* Grow to next state. */
this_type = md_relax_table + (this_state = next_state);
next_state = this_type->rlx_more;
}
}
}
else
{
#ifdef DONTDEF
/* JF these next few lines of code are for the mc68020 which can't handle short
offsets of zero in branch instructions. What a kludge! */
if (aim==0 && this_state==(1<<2+0)) { /* FOO hard encoded from m.c */
aim=this_type->rlx_forward+1; /* Force relaxation into word mode */
}
#endif
/* JF end of 68020 code */
/* Look forwards. */
for (next_state = this_type->rlx_more; next_state; )
{
if (aim <= this_type->rlx_forward)
next_state = 0;
else
{ /* Grow to next state. */
this_type = md_relax_table + (this_state = next_state);
next_state = this_type->rlx_more;
}
}
}
if ((growth = this_type->rlx_length - start_type->rlx_length) != 0)
fragP->fr_subtype = this_state;
}
break;
default:
BAD_CASE( fragP->fr_type );
break;
}
if (growth) {
stretch += growth;
stretched++;
}
} /* For each frag in the segment. */
} while (stretched); /* Until nothing further to relax. */
}
/*
* We now have valid fr_address'es for each frag.
*/
/*
* All fr_address's are correct, relative to their own segment.
* We have made all the fixS we will ever make.
*/
} /* relax_segment() */
/*
* Relax_align. Advance location counter to next address that has 'alignment'
* lowest order bits all 0s.
*/
/* How many addresses does the .align take? */
static relax_addressT relax_align(address, alignment)
register relax_addressT address; /* Address now. */
register long alignment; /* Alignment (binary). */
{
relax_addressT mask;
relax_addressT new_address;
mask = ~ ( (~0) << alignment );
new_address = (address + mask) & (~ mask);
return (new_address - address);
} /* relax_align() */
/* fixup_segment()
Go through all the fixS's in a segment and see which ones can be
handled now. (These consist of fixS where we have since discovered
the value of a symbol, or the address of the frag involved.)
For each one, call md_apply_fix to put the fix into the frag data.
Result is a count of how many relocation structs will be needed to
handle the remaining fixS's that we couldn't completely handle here.
These will be output later by emit_relocations(). */
static long fixup_segment(fixP, this_segment_type)
register fixS * fixP;
segT this_segment_type; /* N_TYPE bits for segment. */
{
register long seg_reloc_count;
register symbolS *add_symbolP;
register symbolS *sub_symbolP;
register long add_number;
register int size;
register char *place;
register long where;
register char pcrel;
register fragS *fragP;
register segT add_symbol_segment = SEG_ABSOLUTE;
fixS *topP = fixP;
seg_reloc_count = 0;
for ( ; fixP; fixP = fixP->fx_next) {
fragP = fixP->fx_frag;
know(fragP);
where = fixP->fx_where;
place = fragP->fr_literal + where;
size = fixP->fx_size;
add_symbolP = fixP->fx_addsy;
#ifdef TC_I960
if (fixP->fx_callj && TC_S_IS_CALLNAME(add_symbolP)) {
/* Relocation should be done via the
associated 'bal' entry point
symbol. */
if (!TC_S_IS_BALNAME(tc_get_bal_of_call(add_symbolP))) {
as_bad("No 'bal' entry point for leafproc %s",
S_GET_NAME(add_symbolP));
continue;
}
fixP->fx_addsy = add_symbolP = tc_get_bal_of_call(add_symbolP);
} /* callj relocation */
#endif
sub_symbolP = fixP->fx_subsy;
add_number = fixP->fx_offset;
pcrel = fixP->fx_pcrel;
if (add_symbolP) {
add_symbol_segment = S_GET_SEGMENT(add_symbolP);
} /* if there is an addend */
if (sub_symbolP) {
if (!add_symbolP) {
/* Its just -sym */
if (S_GET_SEGMENT(sub_symbolP) != SEG_ABSOLUTE) {
as_bad("Negative of non-absolute symbol %s", S_GET_NAME(sub_symbolP));
} /* not absolute */
add_number -= S_GET_VALUE(sub_symbolP);
/* if sub_symbol is in the same segment that add_symbol
and add_symbol is either in DATA, TEXT, BSS or ABSOLUTE */
} else if ((S_GET_SEGMENT(sub_symbolP) == add_symbol_segment)
&& ((add_symbol_segment == SEG_DATA)
|| (add_symbol_segment == SEG_TEXT)
|| (add_symbol_segment == SEG_BSS)
|| (add_symbol_segment == SEG_ABSOLUTE))) {
/* Difference of 2 symbols from same segment. */
/* Can't make difference of 2 undefineds: 'value' means */
/* something different for N_UNDF. */
#ifdef TC_I960
/* Makes no sense to use the difference of 2 arbitrary symbols
* as the target of a call instruction.
*/
if (fixP->fx_callj) {
as_bad("callj to difference of 2 symbols");
}
#endif /* TC_I960 */
add_number += S_GET_VALUE(add_symbolP) -
S_GET_VALUE(sub_symbolP);
add_symbolP = NULL;
fixP->fx_addsy = NULL;
} else {
/* Different segments in subtraction. */
know(!(S_IS_EXTERNAL(sub_symbolP) && (S_GET_SEGMENT(sub_symbolP) == SEG_ABSOLUTE)));
if ((S_GET_SEGMENT(sub_symbolP) == SEG_ABSOLUTE)) {
add_number -= S_GET_VALUE(sub_symbolP);
} else {
as_bad("Can't emit reloc {- %s-seg symbol \"%s\"} @ file address %d.",
segment_name(S_GET_SEGMENT(sub_symbolP)),
S_GET_NAME(sub_symbolP), fragP->fr_address + where);
} /* if absolute */
}
} /* if sub_symbolP */
if (add_symbolP) {
if (add_symbol_segment == this_segment_type && pcrel) {
/*
* This fixup was made when the symbol's segment was
* SEG_UNKNOWN, but it is now in the local segment.
* So we know how to do the address without relocation.
*/
#ifdef TC_I960
/* reloc_callj() may replace a 'call' with a 'calls' or a 'bal',
* in which cases it modifies *fixP as appropriate. In the case
* of a 'calls', no further work is required, and *fixP has been
* set up to make the rest of the code below a no-op.
*/
reloc_callj(fixP);
#endif /* TC_I960 */
add_number += S_GET_VALUE(add_symbolP);
add_number -= md_pcrel_from (fixP);
pcrel = 0; /* Lie. Don't want further pcrel processing. */
fixP->fx_addsy = NULL; /* No relocations please. */
} else {
switch (add_symbol_segment) {
case SEG_ABSOLUTE:
#ifdef TC_I960
reloc_callj(fixP); /* See comment about reloc_callj() above*/
#endif /* TC_I960 */
add_number += S_GET_VALUE(add_symbolP);
fixP->fx_addsy = NULL;
add_symbolP = NULL;
break;
case SEG_BSS:
case SEG_DATA:
case SEG_TEXT:
seg_reloc_count ++;
add_number += S_GET_VALUE(add_symbolP);
break;
case SEG_UNKNOWN:
#ifdef TC_I960
if ((int)fixP->fx_bit_fixP == 13) {
/* This is a COBR instruction. They have only a
* 13-bit displacement and are only to be used
* for local branches: flag as error, don't generate
* relocation.
*/
as_bad("can't use COBR format with external label");
fixP->fx_addsy = NULL; /* No relocations please. */
continue;
} /* COBR */
#endif /* TC_I960 */
/* FIXME-SOON: I think this is trash, but I'm not sure. xoxorich. */
#ifdef comment
#ifdef OBJ_COFF
if (S_IS_COMMON(add_symbolP))
add_number += S_GET_VALUE(add_symbolP);
#endif /* OBJ_COFF */
#endif /* comment */
++seg_reloc_count;
break;
default:
BAD_CASE(add_symbol_segment);
break;
} /* switch on symbol seg */
} /* if not in local seg */
} /* if there was a + symbol */
if (pcrel) {
add_number -= md_pcrel_from(fixP);
if (add_symbolP == 0) {
fixP->fx_addsy = & abs_symbol;
++seg_reloc_count;
} /* if there's an add_symbol */
} /* if pcrel */
if (!fixP->fx_bit_fixP) {
if ((size==1 &&
(add_number& ~0xFF) && (add_number&~0xFF!=(-1&~0xFF))) ||
(size==2 &&
(add_number& ~0xFFFF) && (add_number&~0xFFFF!=(-1&~0xFFFF)))) {
as_bad("Value of %d too large for field of %d bytes at 0x%x",
add_number, size, fragP->fr_address + where);
} /* generic error checking */
} /* not a bit fix */
md_apply_fix(fixP, add_number);
} /* For each fixS in this segment. */
#ifdef OBJ_COFF
#ifdef TC_I960
/* two relocs per callj under coff. */
for (fixP = topP; fixP; fixP = fixP->fx_next) {
if (fixP->fx_callj && fixP->fx_addsy != 0) {
++seg_reloc_count;
} /* if callj and not already fixed. */
} /* for each fix */
#endif /* TC_I960 */
#endif /* OBJ_COFF */
return(seg_reloc_count);
} /* fixup_segment() */
static int is_dnrange(f1,f2)
struct frag *f1;
struct frag *f2;
{
while (f1) {
if (f1->fr_next==f2)
return 1;
f1=f1->fr_next;
}
return 0;
} /* is_dnrange() */
/* Append a string onto another string, bumping the pointer along. */
void
append (charPP, fromP, length)
char **charPP;
char *fromP;
unsigned long length;
{
if (length) { /* Don't trust bcopy() of 0 chars. */
bcopy(fromP, *charPP, (int) length);
*charPP += length;
}
}
int section_alignment[SEG_MAXIMUM_ORDINAL];
/*
* This routine records the largest alignment seen for each segment.
* If the beginning of the segment is aligned on the worst-case
* boundary, all of the other alignments within it will work. At
* least one object format really uses this info.
*/
void record_alignment(seg, align)
segT seg; /* Segment to which alignment pertains */
int align; /* Alignment, as a power of 2
* (e.g., 1 => 2-byte boundary, 2 => 4-byte boundary, etc.)
*/
{
if ( align > section_alignment[(int) seg] ){
section_alignment[(int) seg] = align;
} /* if highest yet */
return;
} /* record_alignment() */
/*
* Local Variables:
* comment-column: 0
* fill-column: 131
* End:
*/
/* end of write.c */
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