In the medany code model the compiler generates PCREL_HI20+PCREL_LO12
relocation pairs against local symbols because HI20+LO12 relocations
can't reach high addresses. We relax HI20+LO12 pairs to GPREL
relocations when possible, which is an important optimization for
Dhrystone. Without this commit we are unable to relax
PCREL_HI20+PCREL_LO12 pairs to GPREL when possible, causing a 10%
permormance hit on Dhrystone on Rocket.
Note that we'll now relax
la gp, __global_pointer$
to
mv gp, gp
which probably isn't what you want in your entry code. Users who want
gp-relative symbols to continue to resolve should add ".option norelax"
accordingly. Due to this, the assembler now pairs PCREL relocations
with RELAX relocations when they're expected to be relaxed just like
every other relaxable relocation.
bfd/ChangeLog
2017-10-19 Palmer Dabbelt <palmer@dabbelt.com>
* elfnn-riscv.c (riscv_pcgp_hi_reloc): New structure.
(riscv_pcgp_lo_reloc): Likewise.
(riscv_pcgp_relocs): Likewise.
(riscv_init_pcgp_relocs): New function.
(riscv_free_pcgp_relocs): Likewise.
(riscv_record_pcgp_hi_reloc): Likewise.
(riscv_record_pcgp_lo_reloc): Likewise.
(riscv_delete_pcgp_hi_reloc): Likewise.
(riscv_use_pcgp_hi_reloc): Likewise.
(riscv_record_pcgp_lo_reloc): Likewise.
(riscv_find_pcgp_lo_reloc): Likewise.
(riscv_delete_pcgp_lo_reloc): Likewise.
(_bfd_riscv_relax_pc): Likewise.
(_bfd_riscv_relax_section): Handle R_RISCV_PCREL_* relocations
via the new functions above.
gas/ChangeLog
2017-10-19 Palmer Dabbelt <palmer@dabbelt.com>
* config/tc-riscv.c (md_apply_fix): Mark
BFD_RELOC_RISCV_PCREL_HI20 as relaxable when relaxations are
enabled.
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BFD is an object file library. It permits applications to use the
same routines to process object files regardless of their format.
BFD is used by the GNU debugger, assembler, linker, and the binary
utilities.
The documentation on using BFD is scanty and may be occasionally
incorrect. Pointers to documentation problems, or an entirely
rewritten manual, would be appreciated.
There is some BFD internals documentation in doc/bfdint.texi which may
help programmers who want to modify BFD.
BFD is normally built as part of another package. See the build
instructions for that package, probably in a README file in the
appropriate directory.
BFD supports the following configure options:
--target=TARGET
The default target for which to build the library. TARGET is
a configuration target triplet, such as sparc-sun-solaris.
--enable-targets=TARGET,TARGET,TARGET...
Additional targets the library should support. To include
support for all known targets, use --enable-targets=all.
--enable-64-bit-bfd
Include support for 64 bit targets. This is automatically
turned on if you explicitly request a 64 bit target, but not
for --enable-targets=all. This requires a compiler with a 64
bit integer type, such as gcc.
--enable-shared
Build BFD as a shared library.
--with-mmap
Use mmap when accessing files. This is faster on some hosts,
but slower on others. It may not work on all hosts.
Report bugs with BFD to bug-binutils@gnu.org.
Patches are encouraged. When sending patches, always send the output
of diff -u or diff -c from the original file to the new file. Do not
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the original file. Remember that any patch must not break other
systems. Remember that BFD must support cross compilation from any
host to any target, so patches which use ``#ifdef HOST'' are not
acceptable. Please also read the ``Reporting Bugs'' section of the
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Bug reports without patches will be remembered, but they may never get
fixed until somebody volunteers to fix them.
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Copying and distribution of this file, with or without modification,
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