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refactor ElfObj::getsegment to allow lookup of existing sections
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- split into elf_addsectionname, elf_addsegment, and elf_getsegment
- add out parameter to addsectionname for newly added entries
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@MartinNowak
MartinNowak committed Aug 21, 2017
1 parent 7e648ce commit cebea44
Showing 1 changed file with 101 additions and 56 deletions.
157 changes: 101 additions & 56 deletions src/ddmd/backend/elfobj.c
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Original file line number Diff line number Diff line change
Expand Up @@ -339,8 +339,9 @@ int seg_max;
int seg_tlsseg = UNKNOWN;
int seg_tlsseg_bss = UNKNOWN;

int elf_getsegment2(IDXSEC shtidx, IDXSYM symidx, IDXSEC relidx);

static int elf_addsegment2(IDXSEC shtidx, IDXSYM symidx, IDXSEC relidx);
static int elf_addsegment(IDXSTR namidx, int type, int flags, int align);
static int elf_getsegment(IDXSTR namidx);

/*******************************
* Output a string into a string table
Expand Down Expand Up @@ -609,12 +610,18 @@ static IDXSEC elf_newsection2(
return section_cnt++;
}

static IDXSEC elf_newsection(const char *name, const char *suffix,
Elf32_Word type, Elf32_Word flags)
{
// dbg_printf("elf_newsection(%s,%s,type %d, flags x%x)\n",
// name?name:"",suffix?suffix:"",type,flags);
/**
Add a new section name or get the string table index of an existing entry.
Params:
name = name of section
suffix = append to name
padded = set to true when entry was newly added
Returns:
String index of new or existing section name.
*/
static IDXSEC elf_addsectionname(const char *name, const char *suffix = NULL, bool *padded = NULL)
{
IDXSTR namidx = section_names->size();
section_names->writeString(name);
if (suffix)
Expand All @@ -623,8 +630,25 @@ static IDXSEC elf_newsection(const char *name, const char *suffix,
section_names->writeString(suffix);
}
IDXSTR *pidx = (IDXSTR *)section_names_hashtable->get(&namidx);
assert(!*pidx); // must not already exist
*pidx = namidx;
if (*pidx)
{
// this section name already exists, remove addition
section_names->setsize(namidx);
return *pidx;
}
if (padded)
*padded = true;
return *pidx = namidx;
}

static IDXSEC elf_newsection(const char *name, const char *suffix,
Elf32_Word type, Elf32_Word flags)
{
// dbg_printf("elf_newsection(%s,%s,type %d, flags x%x)\n",
// name?name:"",suffix?suffix:"",type,flags);
bool added = false;
IDXSTR namidx = elf_addsectionname(name, suffix, &added);
assert(added);

return elf_newsection2(namidx,type,flags,0,0,0,0,0,0,0);
}
Expand Down Expand Up @@ -892,22 +916,22 @@ Obj *Obj::init(Outbuffer *objbuf, const char *filename, const char *csegname)

seg_count = 0;

elf_getsegment2(SHN_TEXT, STI_TEXT, SHN_RELTEXT);
elf_addsegment2(SHN_TEXT, STI_TEXT, SHN_RELTEXT);
assert(SegData[CODE]->SDseg == CODE);

elf_getsegment2(SHN_DATA, STI_DATA, SHN_RELDATA);
elf_addsegment2(SHN_DATA, STI_DATA, SHN_RELDATA);
assert(SegData[DATA]->SDseg == DATA);

elf_getsegment2(SHN_RODAT, STI_RODAT, 0);
elf_addsegment2(SHN_RODAT, STI_RODAT, 0);
assert(SegData[CDATA]->SDseg == CDATA);

elf_getsegment2(SHN_BSS, STI_BSS, 0);
elf_addsegment2(SHN_BSS, STI_BSS, 0);
assert(SegData[UDATA]->SDseg == UDATA);

elf_getsegment2(SHN_CDATAREL, STI_CDATAREL, 0);
elf_addsegment2(SHN_CDATAREL, STI_CDATAREL, 0);
assert(SegData[CDATAREL]->SDseg == CDATAREL);

elf_getsegment2(SHN_COM, STI_COM, 0);
elf_addsegment2(SHN_COM, STI_COM, 0);
assert(SegData[COMD]->SDseg == COMD);

dwarf_initfile(filename);
Expand Down Expand Up @@ -1903,17 +1927,7 @@ void addSegmentToComdat(segidx_t seg, segidx_t comdatseg)
addSectionToComdat(SegData[seg]->SDshtidx, comdatseg);
}

/********************************
* Get a segment for a segment name.
* Input:
* name name of segment, if NULL then revert to default name
* suffix append to name
* align alignment
* Returns:
* segment index of found or newly created segment
*/

int elf_getsegment2(IDXSEC shtidx, IDXSYM symidx, IDXSEC relidx)
static int elf_addsegment2(IDXSEC shtidx, IDXSYM symidx, IDXSEC relidx)
{
//printf("SegData = %p\n", SegData);
int seg = ++seg_count;
Expand Down Expand Up @@ -1955,45 +1969,76 @@ int elf_getsegment2(IDXSEC shtidx, IDXSYM symidx, IDXSEC relidx)
return seg;
}

int ElfObj::getsegment(const char *name, const char *suffix, int type, int flags,
int align)
/********************************
* Add a new section and get corresponding seg_data entry.
*
* Input:
* nameidx = string index of section name
* type = section header type, e.g. SHT_PROGBITS
* flags = section header flags, e.g. SHF_ALLOC
* align = section alignment
* Returns:
* SegData index of newly created section.
*/
static int elf_addsegment(IDXSTR namidx, int type, int flags, int align)
{
//printf("ElfObj::getsegment(%s,%s,flags %x, align %d)\n",name,suffix,flags,align);

// Add name~suffix to the section_names table
IDXSTR namidx = section_names->size();
section_names->writeString(name);
if (suffix)
{ // Append suffix string
section_names->setsize(section_names->size() - 1); // back up over terminating 0
section_names->writeString(suffix);
}
IDXSTR *pidx = (IDXSTR *)section_names_hashtable->get(&namidx);
if (*pidx)
{ // this section name already exists
section_names->setsize(namidx); // remove addition
namidx = *pidx;
for (int seg = CODE; seg <= seg_count; seg++)
{ // should be in segment table
if (MAP_SEG2SEC(seg)->sh_name == namidx)
{
return seg; // found section for segment
}
}
assert(0); // but it's not a segment
// FIX - should be an error message conflict with section names
}
*pidx = namidx;

//dbg_printf("\tNew segment - %d size %d\n", seg,SegData[seg]->SDbuf);
IDXSEC shtidx = elf_newsection2(namidx,type,flags,0,0,0,0,0,0,0);
SecHdrTab[shtidx].sh_addralign = align;
IDXSYM symidx = elf_addsym(0, 0, 0, STT_SECTION, STB_LOCAL, shtidx);
int seg = elf_getsegment2(shtidx, symidx, 0);
int seg = elf_addsegment2(shtidx, symidx, 0);
//printf("-ElfObj::getsegment() = %d\n", seg);
return seg;
}

/********************************
* Find corresponding seg_data entry for existing section.
*
* Input:
* nameidx = string index of section name
* Returns:
* SegData index of found section or 0 if none was found.
*/
static int elf_getsegment(IDXSTR namidx)
{
// find existing section
for (int seg = CODE; seg <= seg_count; seg++)
{ // should be in segment table
if (MAP_SEG2SEC(seg)->sh_name == namidx)
{
return seg; // found section for segment
}
}
return 0;
}

/********************************
* Get corresponding seg_data entry for an existing or newly added section.
*
* Input:
* name = name of section
* suffix = append to name
* type = section header type, e.g. SHT_PROGBITS
* flags = section header flags, e.g. SHF_ALLOC
* align = section alignment
* Returns:
* SegData index of found or newly created section.
*/
int ElfObj::getsegment(const char *name, const char *suffix, int type, int flags,
int align)
{
//printf("ElfObj::getsegment(%s,%s,flags %x, align %d)\n",name,suffix,flags,align);
bool added = false;
IDXSEC namidx = elf_addsectionname(name, suffix, &added);
if (!added)
{
int seg = elf_getsegment(namidx);
assert(seg);
return seg;
}
return elf_addsegment(namidx, type, flags, align);
}

/**********************************
* Reset code seg to existing seg.
* Used after a COMDAT for a function is done.
Expand Down

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