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https://github.com/netwide-assembler/nasm.git
synced 2025-03-31 18:20:22 +08:00
outmacho: don't do encoding magic in the segment index
Encoding magic (in this case, subsection number) by bitfields in the segment index has several problems: 1. It limits the number of *external symbols* as well as segments/subsections. 2. It is inefficient for the assembler (creates a very large RAA). This is also a really good opportunity for removing linear lookups in the MachO backend. We now use an RAA to do look up segment by index, and a hash table to look up segment by name. Subsections are simply handled by allocating a new index using seg_alloc() but still point it to the same section structure in the index RAA. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
H. Peter Anvin
parent
29695c85fb
commit
b91b63d164
@ -51,6 +51,7 @@
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#include "saa.h"
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#include "raa.h"
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#include "rbtree.h"
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#include "hashtbl.h"
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#include "outform.h"
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#include "outlib.h"
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#include "ver.h"
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@ -153,13 +154,14 @@ struct section {
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/* nasm internal data */
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struct section *next;
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struct SAA *data;
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uint16_t index; /* Main section index */
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uint16_t subsection; /* Current subsection */
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int32_t index; /* Main section index */
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int32_t subsection; /* Current subsection index */
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int32_t fileindex;
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struct reloc *relocs;
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struct rbtree *syms[2]; /* All/global symbols symbols in section */
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int align;
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bool by_name; /* This section was specified by full MachO name */
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char namestr[34]; /* segment,section as a C string */
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/* data that goes into the file */
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char sectname[16]; /* what this section is called */
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@ -310,29 +312,58 @@ static uint64_t rel_padcnt = 0;
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#define alignptr(x) \
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ALIGN(x, fmt.ptrsize) /* align x to output format width */
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static struct section *get_section_by_name(const char *segname,
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const char *sectname)
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{
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struct section *s;
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static struct hash_table section_by_name;
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static struct RAA *section_by_index;
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for (s = sects; s != NULL; s = s->next)
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if (!xstrncmp(s->segname, segname) && !xstrncmp(s->sectname, sectname))
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break;
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static struct section * never_null
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find_or_add_section(const char *segname, const char *sectname)
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{
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struct hash_insert hi;
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void **sp;
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struct section *s;
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char sect[34];
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snprintf(sect, sizeof sect, "%-16s,%-16s", segname, sectname);
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sp = hash_find(§ion_by_name, sect, &hi);
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if (sp)
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return (struct section *)(*sp);
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s = nasm_zalloc(sizeof *s);
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xstrncpy(s->segname, segname);
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xstrncpy(s->sectname, sectname);
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xstrncpy(s->namestr, sect);
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hash_add(&hi, s->namestr, s);
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s->index = s->subsection = seg_alloc();
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section_by_index = raa_write_ptr(section_by_index, s->index >> 1, s);
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return s;
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}
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static inline bool is_new_section(const struct section *s)
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{
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return !s->data;
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}
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static struct section *get_section_by_name(const char *segname,
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const char *sectname)
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{
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char sect[34];
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void **sp;
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snprintf(sect, sizeof sect, "%-16s,%-16s", segname, sectname);
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sp = hash_find(§ion_by_name, sect, NULL);
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return sp ? (struct section *)(*sp) : NULL;
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}
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static struct section *get_section_by_index(int32_t index)
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{
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struct section *s;
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if (index < 0 || index >= SEG_ABS || (index & 1))
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return NULL;
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index &= 0x4000fffe; /* Strip subsection but not absolute flag */
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for (s = sects; s != NULL; s = s->next)
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if (index == s->index)
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break;
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return s;
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return (struct section *)raa_read(section_by_index, index >> 1);
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}
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struct dir_list {
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@ -405,6 +436,9 @@ static void macho_init(void)
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extsyms = raa_init();
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strs = saa_init(1L);
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section_by_index = raa_init();
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hash_init(§ion_by_name, HASH_MEDIUM);
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/* string table starts with a zero byte so index 0 is an empty string */
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saa_wbytes(strs, zero_buffer, 1);
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strslen = 1;
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@ -412,15 +446,6 @@ static void macho_init(void)
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/* add special symbol for TLVP */
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macho_tlvp_sect = seg_alloc() + 1;
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backend_label("..tlvp", macho_tlvp_sect, 0L);
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}
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static void macho_reset(void)
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{
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/* Reset all subsection numbers */
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struct section *s;
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for (s = sects; s != NULL; s = s->next)
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s->subsection = 0;
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}
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static void sect_write(struct section *sect,
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@ -480,9 +505,7 @@ static int64_t add_reloc(struct section *sect, int32_t section,
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r->pcrel = 0;
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r->snum = R_ABS;
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s = NULL;
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if (section != NO_SEG)
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s = get_section_by_index(section);
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s = get_section_by_index(section);
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fi = s ? s->fileindex : NO_SECT;
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/* absolute relocation */
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@ -620,14 +643,13 @@ static void macho_output(int32_t secto, const void *data,
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}
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s = get_section_by_index(secto);
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if (s == NULL) {
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if (!s) {
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nasm_error(ERR_WARNING, "attempt to assemble code in"
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" section %d: defaulting to `.text'", secto);
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s = get_section_by_name("__TEXT", "__text");
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/* should never happen */
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if (s == NULL)
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if (!s)
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nasm_panic(0, "text section not found");
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}
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@ -904,32 +926,25 @@ static int32_t macho_section(char *name, int pass, int *bits)
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}
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found:
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/* try to find section with that name */
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s = get_section_by_name(segment, section);
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/* try to find section with that name, or create it */
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s = find_or_add_section(segment, section);
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new_seg = is_new_section(s);
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/* create it if it doesn't exist yet */
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if (!s) {
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new_seg = true;
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s = *sectstail = nasm_zalloc(sizeof(struct section));
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/* initialize it if it is a brand new section */
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if (new_seg) {
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*sectstail = s;
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sectstail = &s->next;
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s->data = saa_init(1L);
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s->index = seg_alloc();
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s->subsection = 0;
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s->fileindex = ++seg_nsects;
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s->align = -1;
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s->pad = -1;
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s->offset = -1;
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s->by_name = false;
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xstrncpy(s->segname, segment);
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xstrncpy(s->sectname, section);
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s->size = 0;
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s->nreloc = 0;
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s->flags = flags;
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} else {
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new_seg = false;
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}
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if (comma)
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@ -999,16 +1014,16 @@ static int32_t macho_section(char *name, int pass, int *bits)
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s->flags |= flags & ~S_NASM_TYPE_MASK;
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}
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return s->index | (s->subsection << 16);
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return s->subsection;
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}
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static int32_t macho_herelabel(const char *name, enum label_type type,
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int32_t section, int32_t *subsection)
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{
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struct section *s;
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int32_t subsec;
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(void)name;
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(void)subsection;
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if (!(head_flags & MH_SUBSECTIONS_VIA_SYMBOLS))
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return section;
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@ -1020,8 +1035,15 @@ static int32_t macho_herelabel(const char *name, enum label_type type,
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if (!s)
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return section;
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s->subsection++;
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return s->index | (s->subsection << 16);
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subsec = *subsection;
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if (subsec == NO_SEG) {
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/* Allocate a new subsection index */
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subsec = *subsection = seg_alloc();
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section_by_index = raa_write_ptr(section_by_index, subsec >> 1, s);
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}
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s->subsection = subsec;
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return subsec;
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}
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static void macho_symdef(char *name, int32_t section, int64_t offset,
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@ -1786,6 +1808,8 @@ static void macho_cleanup(void)
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nasm_free(extdefsyms);
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nasm_free(undefsyms);
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nasm_free(sectstab);
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raa_free(section_by_index);
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hash_free(§ion_by_name);
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}
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static bool macho_set_section_attribute_by_symbol(const char *label, uint32_t flags)
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@ -2363,7 +2387,7 @@ const struct ofmt of_macho32 = {
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&macho32_df_dwarf,
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macho_stdmac,
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macho32_init,
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macho_reset,
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null_reset,
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nasm_do_legacy_output,
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macho_output,
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macho_symdef,
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@ -2430,7 +2454,7 @@ const struct ofmt of_macho64 = {
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&macho64_df_dwarf,
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macho_stdmac,
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macho64_init,
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macho_reset,
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null_reset,
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nasm_do_legacy_output,
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macho_output,
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macho_symdef,
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