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subsections: don't lose the offset in the parent section

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We don't want to lose the offset into the parent section when we
create a subsection, at least not for the MachO backend which is
currently the only user of subsections. Allow ofmt->herelabel() to set
a flag to copy the section offset from the previous section.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin (Intel)
2018-06-27 20:20:21 -07:00
parent 12810fac92
commit d644119ded
4 changed files with 26 additions and 8 deletions
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12
asm/labels.c
View File

@@ -351,15 +351,23 @@ handle_herelabel(union label *lptr, int32_t *segment, int64_t *offset)
if (oldseg == location.segment && *offset == location.offset) {
/* This label is defined at this location */
int32_t newseg;
bool copyoffset = false;
nasm_assert(lptr->defn.mangled);
newseg = ofmt->herelabel(lptr->defn.mangled, lptr->defn.type,
oldseg, &lptr->defn.subsection);
oldseg, &lptr->defn.subsection, &copyoffset);
if (likely(newseg == oldseg))
return;
*segment = newseg;
*offset = switch_segment(newseg);
if (copyoffset) {
/* Maintain the offset from the old to the new segment */
switch_segment(newseg);
location.offset = *offset;
} else {
/* Keep a separate offset for the new segment */
*offset = switch_segment(newseg);
}
}
}

7
include/nasm.h
View File

@@ -911,9 +911,14 @@ struct ofmt {
* The offset isn't passed; and may not be stable at this point.
* The subsection number is a field available for use by the
* backend. It is initialized to NO_SEG.
*
* If "copyoffset" is set by the backend then the offset is
* copied from the previous segment, otherwise the new segment
* is treated as a new segment the normal way.
*/
int32_t (*herelabel)(const char *name, enum label_type type,
int32_t seg, int32_t *subsection);
int32_t seg, int32_t *subsection,
bool *copyoffset);
/*
* This procedure is called to modify section alignment,

7
output/outdbg.c
View File

@@ -137,14 +137,17 @@ static int32_t dbg_section_names(char *name, int pass, int *bits)
}
static int32_t dbg_herelabel(const char *name, enum label_type type,
int32_t oldseg, int32_t *subsection)
int32_t oldseg, int32_t *subsection,
bool *copyoffset)
{
int32_t newseg = oldseg;
if (subsections_via_symbols && type != LBL_LOCAL) {
newseg = *subsection;
if (newseg == NO_SEG)
if (newseg == NO_SEG) {
newseg = *subsection = seg_alloc();
*copyoffset = true; /* Minic MachO for now */
}
}
fprintf(ofile, "herelabel %s type %d (seg %08x) -> %08x\n",
name, type, oldseg, newseg);

8
output/outmacho.c
View File

@@ -1018,7 +1018,8 @@ static int32_t macho_section(char *name, int pass, int *bits)
}
static int32_t macho_herelabel(const char *name, enum label_type type,
int32_t section, int32_t *subsection)
int32_t section, int32_t *subsection,
bool *copyoffset)
{
struct section *s;
int32_t subsec;
@@ -1043,6 +1044,7 @@ static int32_t macho_herelabel(const char *name, enum label_type type,
}
s->subsection = subsec;
*copyoffset = true; /* Maintain previous offset */
return subsec;
}
@@ -1055,8 +1057,8 @@ static void macho_symdef(char *name, int32_t section, int64_t offset,
#if defined(DEBUG) && DEBUG>2
nasm_error(ERR_DEBUG,
" macho_symdef: %s, sec=%"PRIx32", off=%"PRIx64", is_global=%d, %s\n",
name, section, offset, is_global, special);
" macho_symdef: %s, pass0=%d, passn=%"PRId64", sec=%"PRIx32", off=%"PRIx64", is_global=%d, %s\n",
name, pass0, passn, section, offset, is_global, special);
#endif
if (is_global == 3) {