On Mon, 26 Jun 2023 at 23:24, Jan Hubicka <hubi...@ucw.cz> wrote: > > > > +simple_object_write_add_symbol(simple_object_write *sobj, const char > > > *name, > > > > +size_t size, unsigned int align); > > > > > > Symbols has much more properties in addition to sizes and alignments. > > > We will eventually need to get dwarf writting, so we will need to > > > support them. However right now we only do these fake lto object > > > symbols, so perhaps for start we could kep things simple and assume > that > > > size is always 0 and align always 1 or so. > > > > > > Overall this looks like really good start to me (both API and > > > imllementation looks reasonable to me and it is good that you follow > the > > > coding convention). I guess you can create a branch (see git info on > > > the gcc homepage) and put the patch there? > > > > > I can, but I don't have write access to git. Also, for the next part, I > am > This is easy to fix. Follow instructions here > https://gcc.gnu.org/gitwrite.html > and add me as sponsor. There are also instructions how to produce a > branch on git correctly. > Ok.
> > thinking of properly configuring the driver > > to directly produce an executable or adding debug info. What do you > think? > > I think we should try to aim to something that can be tested. If we add > symbol table and get the ELF header right, linker should accept the > object files and properly recognize them as LTO. > I have done some testing, readelf can read the symbol table and display it correctly ( using your updated patch to produce object files: https://gcc.gnu.org/pipermail/gcc/2022-May/238670.html). Apart from this, I also ran GCC LTO's test suite, and all test cases passed as expected. I am also able to produce an executable and run it. The only thing I might be missing is producing the ELF header directly instead of reading it from crtbegin.o. I am thinking about it but can't think where to find architecture and header's field details without crtbegin.o. What exactly you mean by configuring the driver? > I was talking about right now in the patch, to produce an executable, we have to stop before the assembly step(-S flag) and then invoke the linker. I am thinking of fixing it. -- Regards Rishi > > Honza > > -- > > Regards > > Rishi > > > > > > > > I am also adding Ian to CC as he is maintainer of the simple-object and > > > he may have some ideas. > > > > > > Honza > > > > > > > > /* Release all resources associated with SIMPLE_OBJECT, including > any > > > > simple_object_write_section's that may have been created. */ > > > > diff --git a/libiberty/simple-object-common.h > > > > b/libiberty/simple-object-common.h > > > > index b9d10550d88..df99c9d85ac 100644 > > > > --- a/libiberty/simple-object-common.h > > > > +++ b/libiberty/simple-object-common.h > > > > @@ -58,6 +58,24 @@ struct simple_object_write_struct > > > > simple_object_write_section *last_section; > > > > /* Private data for the object file format. */ > > > > void *data; > > > > + /*The start of the list of symbols.*/ > > > > + simple_object_symbol *symbols; > > > > + /*The last entry in the list of symbols*/ > > > > + simple_object_symbol *last_symbol; > > > > +}; > > > > + > > > > +/*A symbol in object file being created*/ > > > > +struct simple_object_symbol_struct > > > > +{ > > > > + /*Next in the list of symbols attached to an > > > > + simple_object_write*/ > > > > + simple_object_symbol *next; > > > > + /*The name of this symbol. */ > > > > + char *name; > > > > + /* Symbol value */ > > > > + unsigned int align; > > > > + /* Symbol size */ > > > > + size_t size; > > > > }; > > > > > > > > /* A section in an object file being created. */ > > > > diff --git a/libiberty/simple-object-elf.c > > > b/libiberty/simple-object-elf.c > > > > index eee07039984..cbba88186bd 100644 > > > > --- a/libiberty/simple-object-elf.c > > > > +++ b/libiberty/simple-object-elf.c > > > > @@ -787,9 +787,9 @@ simple_object_elf_write_ehdr (simple_object_write > > > > *sobj, int descriptor, > > > > ++shnum; > > > > if (shnum > 0) > > > > { > > > > - /* Add a section header for the dummy section and one for > > > > - .shstrtab. */ > > > > - shnum += 2; > > > > + /* Add a section header for the dummy section, > > > > + .shstrtab, .symtab and .strtab. */ > > > > + shnum += 4; > > > > } > > > > > > > > ehdr_size = (cl == ELFCLASS32 > > > > @@ -882,6 +882,51 @@ simple_object_elf_write_shdr > (simple_object_write > > > > *sobj, int descriptor, > > > > errmsg, err); > > > > } > > > > > > > > +/* Write out an ELF Symbol*/ > > > > + > > > > +static int > > > > +simple_object_elf_write_symbol(simple_object_write *sobj, int > > > descriptor, > > > > + off_t offset, unsigned int st_name, unsigned int > st_value, > > > > size_t st_size, > > > > + unsigned char st_info, unsigned char st_other, unsigned > int > > > > st_shndx, > > > > + const char **errmsg, int *err) > > > > +{ > > > > + struct simple_object_elf_attributes *attrs = > > > > + (struct simple_object_elf_attributes *) sobj->data; > > > > + const struct elf_type_functions* fns; > > > > + unsigned char cl; > > > > + size_t sym_size; > > > > + unsigned char buf[sizeof (Elf64_External_Shdr)]; > > > > + > > > > + fns = attrs->type_functions; > > > > + cl = attrs->ei_class; > > > > + > > > > + sym_size = (cl == ELFCLASS32 > > > > + ? sizeof (Elf32_External_Shdr) > > > > + : sizeof (Elf64_External_Shdr)); > > > > + memset (buf, 0, sizeof (Elf64_External_Shdr)); > > > > + > > > > + if(cl==ELFCLASS32) > > > > + { > > > > + ELF_SET_FIELD(fns, cl, Sym, buf, st_name, Elf_Word, st_name); > > > > + ELF_SET_FIELD(fns, cl, Sym, buf, st_value, Elf_Addr, st_value); > > > > + ELF_SET_FIELD(fns, cl, Sym, buf, st_size, Elf_Addr, st_size); > > > > + buf[4]=st_info; > > > > + buf[5]=st_other; > > > > + ELF_SET_FIELD(fns, cl, Sym, buf, st_shndx, Elf_Half, st_shndx); > > > > + } > > > > + else > > > > + { > > > > + ELF_SET_FIELD(fns, cl, Sym, buf, st_name, Elf_Word, st_name); > > > > + buf[4]=st_info; > > > > + buf[5]=st_other; > > > > + ELF_SET_FIELD(fns, cl, Sym, buf, st_shndx, Elf_Half, st_shndx); > > > > + ELF_SET_FIELD(fns, cl, Sym, buf, st_value, Elf_Addr, st_value); > > > > + ELF_SET_FIELD(fns, cl, Sym, buf, st_size, Elf_Addr, st_size); > > > > + } > > > > + return simple_object_internal_write(descriptor, > offset,buf,sym_size, > > > > + errmsg,err); > > > > +} > > > > + > > > > /* Write out a complete ELF file. > > > > Ehdr > > > > initial dummy Shdr > > > > @@ -932,8 +977,8 @@ simple_object_elf_write_to_file > (simple_object_write > > > > *sobj, int descriptor, > > > > if (shnum == 0) > > > > return NULL; > > > > > > > > - /* Add initial dummy Shdr and .shstrtab. */ > > > > - shnum += 2; > > > > + /* Add initial dummy Shdr, .shstrtab, .symtab and .strtab. */ > > > > + shnum += 4; > > > > > > > > shdr_offset = ehdr_size; > > > > sh_offset = shdr_offset + shnum * shdr_size; > > > > @@ -1036,6 +1081,70 @@ simple_object_elf_write_to_file > > > (simple_object_write > > > > *sobj, int descriptor, > > > > sh_offset += sh_size; > > > > } > > > > > > > > + unsigned int num_sym=1; > > > > + simple_object_symbol *symbol; > > > > + > > > > + for(symbol=sobj->symbols;symbol!=NULL;symbol=symbol->next) > > > > + { > > > > + ++num_sym; > > > > + } > > > > + > > > > + size_t > > > > > > > > sym_size=cl==ELFCLASS32?sizeof(Elf32_External_Sym):sizeof(Elf64_External_Sym); > > > > + size_t sh_addralign=cl==ELFCLASS32?0x04:0x08; > > > > + size_t sh_entsize=sym_size; > > > > + size_t sh_size=num_sym*sym_size; > > > > + unsigned int sh_info=2; > > > > + if (!simple_object_elf_write_shdr (sobj, descriptor, shdr_offset, > > > > + sh_name, SHT_SYMTAB, 0, 0, sh_offset, > > > > + sh_size, shnum-2, sh_info, > > > > + sh_addralign,sh_entsize, &errmsg, err)) > > > > + return errmsg; > > > > + shdr_offset += shdr_size; > > > > + sh_name+=strlen(".symtab")+1; > > > > + /*Writes out the dummy symbol */ > > > > + > > > > + if(!simple_object_elf_write_symbol(sobj, descriptor, sh_offset, > > > > + 0,0,0,0,0,SHN_UNDEF,&errmsg,err)) > > > > + return errmsg; > > > > + sh_offset+=sym_size; > > > > + unsigned int st_name=1; > > > > + for(symbol=sobj->symbols;symbol!=NULL;symbol=symbol->next) > > > > + { > > > > + unsigned int st_value=1; > > > > + unsigned int st_size=1; > > > > + unsigned char st_info=17; > > > > + if(!simple_object_elf_write_symbol(sobj, descriptor, sh_offset, > > > > + st_name,st_value,st_size,st_info,0,SHN_COMMON,&errmsg,err)) > > > > + return errmsg; > > > > + sh_offset+=sym_size; > > > > + st_name+=strlen(symbol->name)+1; > > > > + > > > > + } > > > > + > > > > + if (!simple_object_elf_write_shdr (sobj, descriptor, shdr_offset, > > > > + sh_name, SHT_STRTAB, 0, 0, sh_offset, > > > > + st_name, 0, 0, > > > > + 1, 0, &errmsg, err)) > > > > + return errmsg; > > > > + shdr_offset += shdr_size; > > > > + sh_name+=strlen(".strtab")+1; > > > > + /*.strtab has a leading zero byte*/ > > > > + zero = 0; > > > > + if (!simple_object_internal_write (descriptor, sh_offset, &zero, > 1, > > > > + &errmsg, err)) > > > > + return errmsg; > > > > + ++sh_offset; > > > > + > > > > + for(symbol=sobj->symbols;symbol!=NULL;symbol=symbol->next) > > > > + { > > > > + size_t len=strlen(symbol->name)+1; > > > > + if (!simple_object_internal_write (descriptor, sh_offset, > > > > + (const unsigned char *) symbol->name, > > > > + len, &errmsg, err)) > > > > + return errmsg; > > > > + sh_offset += len; > > > > + > > > > + } > > > > if (!simple_object_elf_write_shdr (sobj, descriptor, shdr_offset, > > > > sh_name, SHT_STRTAB, 0, 0, sh_offset, > > > > sh_name + strlen (".shstrtab") + 1, 0, 0, > > > > @@ -1060,7 +1169,16 @@ simple_object_elf_write_to_file > > > (simple_object_write > > > > *sobj, int descriptor, > > > > return errmsg; > > > > sh_offset += len; > > > > } > > > > - > > > > + if (!simple_object_internal_write (descriptor, sh_offset, > > > > + (const unsigned char *) ".symtab", > > > > + strlen (".symtab") + 1, &errmsg, err)) > > > > + return errmsg; > > > > + sh_offset+=strlen(".symtab")+1; > > > > + if (!simple_object_internal_write (descriptor, sh_offset, > > > > + (const unsigned char *) ".strtab", > > > > + strlen (".strtab") + 1, &errmsg, err)) > > > > + return errmsg; > > > > + sh_offset+=strlen(".strtab")+1; > > > > if (!simple_object_internal_write (descriptor, sh_offset, > > > > (const unsigned char *) ".shstrtab", > > > > strlen (".shstrtab") + 1, &errmsg, err)) > > > > diff --git a/libiberty/simple-object.c b/libiberty/simple-object.c > > > > index 163e58a2f3b..73622160248 100644 > > > > --- a/libiberty/simple-object.c > > > > +++ b/libiberty/simple-object.c > > > > @@ -455,6 +455,8 @@ simple_object_start_write > (simple_object_attributes > > > > *attrs, > > > > ret->sections = NULL; > > > > ret->last_section = NULL; > > > > ret->data = data; > > > > + ret->symbols=NULL; > > > > + ret->last_symbol=NULL; > > > > return ret; > > > > } > > > > > > > > @@ -538,6 +540,28 @@ simple_object_write_to_file (simple_object_write > > > > *sobj, int descriptor, > > > > { > > > > return sobj->functions->write_to_file (sobj, descriptor, err); > > > > } > > > > +/*Adds a symbol in to common*/ > > > > +void > > > > +simple_object_write_add_symbol(simple_object_write *sobj, const char > > > *name, > > > > +size_t size, unsigned int align) > > > > +{ > > > > + simple_object_symbol *symbol; > > > > + symbol=XNEW(simple_object_symbol); > > > > + symbol->next=NULL; > > > > + symbol->name=xstrdup(name); > > > > + symbol->align=align; > > > > + symbol->size=size; > > > > + if(sobj->last_symbol==NULL) > > > > + { > > > > + sobj->symbols=symbol; > > > > + sobj->last_symbol=symbol; > > > > + } > > > > + else > > > > + { > > > > + sobj->last_symbol->next=symbol; > > > > + sobj->last_symbol=symbol; > > > > + } > > > > +} > > > > > > > > /* Release an simple_object_write. */ > > > > > > > > @@ -571,6 +595,14 @@ simple_object_release_write (simple_object_write > > > *sobj) > > > > XDELETE (section); > > > > section = next_section; > > > > } > > > > + simple_object_symbol *symbol; > > > > + symbol=sobj->symbols; > > > > + while(symbol!=NULL) > > > > + { > > > > + free(symbol->name); > > > > + XDELETE(symbol); > > > > + symbol=symbol->next; > > > > + } > > > > > > > > sobj->functions->release_write (sobj->data); > > > > XDELETE (sobj); > > > > -- > > > > 2.40.1 > > > >
