[PATCH] MIPS support for --hash-style=gnu

[Huang Pei]

Hi, everybody,

     On N64, the layout of .gnu.xhash cause unaligned access at bitmask 
field, so I suggest we remove ngnusyms at the header of the .gnu.xhash 
to avoid the unaligned access. Since MIPS ELF requires DT_MIPS_SYMTABNO 
Tag is present with
dynsymcount, so I think ngnusyms can be taken by dynsymcount - symndx

     // Part 0: .gnu.hash header
     Elf32_Word  nbuckets;  // number of hash table buckets
     Elf32_Word  symndx;  // number of initial .dynsym entires skipped 
in chains[] (and xlat[])
     Elf32_Word  maskwords; // number of ElfW(Addr) words in bitmask
     Elf32_Word  shift2;  // bit shift of hashval for second Bloom 
filter bit
     // Part 1: .gnu.hash Bloom filter
     ElfW(Addr)  bitmask[maskwords];  // 2 bit Bloom filter on hashval
     // Part 2: .gnu.hash buckets
     Elf32_Word  buckets[nbuckets];  // indices into chains[]
     // Part 3: .gnu.hash chains
     Elf32_Word  chains[ngnusyms];  // consecutive hashvals in a given 
bucket; last entry in chain has LSB set
     // Part 4: .gnu.xhash translation table
     Elf32_Word  xlat[ngnusyms];  // parallel to chains[]; index into 
.dynsym

below is the patch removing ngnusyms

https://github.com/heiher/binutils-mips/commit/ceefe8ac5f52285d2c98a43a66c2d7d31574b3f4

https://github.com/heiher/glibc-mips/commit/db33de9af675f9851c0941ca186baf87c79d8ab9

any suggestion?
........

In practice, though, the .gnu.xhash section is virtually identical to 
.gnu.hash. [9]

     // Part 0: .gnu.xhash header
     Elf32_Word  ngnusyms;  // number of entries in chains (and xlat); 
dynsymcount=symndx+ngnusyms
     // Part 1: .gnu.hash header
     Elf32_Word  nbuckets;  // number of hash table buckets
     Elf32_Word  symndx;  // number of initial .dynsym entires skipped 
in chains[] (and xlat[])
     Elf32_Word  maskwords; // number of ElfW(Addr) words in bitmask
     Elf32_Word  shift2;  // bit shift of hashval for second Bloom 
filter bit
     // Part 2: .gnu.hash Bloom filter
     ElfW(Addr)  bitmask[maskwords];  // 2 bit Bloom filter on hashval
     // Part 3: .gnu.hash buckets
     Elf32_Word  buckets[nbuckets];  // indices into chains[]
     // Part 4: .gnu.hash chains
     Elf32_Word  chains[ngnusyms];  // consecutive hashvals in a given 
bucket; last entry in chain has LSB set
     // Part 5: .gnu.xhash translation table
     Elf32_Word  xlat[ngnusyms];  // parallel to chains[]; index into 
.dynsym
..........