Sync VEX/LICENSE.GPL with top-level COPYING file. We used 3 different
addresses for writing to the FSF to receive a copy of the GPL. Replace
all different variants with an URL <http://www.gnu.org/licenses/>.
The following files might still have some slightly different (L)GPL
copyright notice because they were derived from other programs:
- files under coregrind/m_demangle which come from libiberty:
cplus-dem.c, d-demangle.c, demangle.h, rust-demangle.c,
safe-ctype.c and safe-ctype.h
- coregrind/m_demangle/dyn-string.[hc] derived from GCC.
- coregrind/m_demangle/ansidecl.h derived from glibc.
- VEX files for FMA detived from glibc:
host_generic_maddf.h and host_generic_maddf.c
- files under coregrin/m_debuginfo derived from LZO:
lzoconf.h, lzodefs.h, minilzo-inl.c and minilzo.h
- files under coregrind/m_gdbserver detived from GDB:
gdb/signals.h, inferiors.c, regcache.c, regcache.h,
regdef.h, remote-utils.c, server.c, server.h, signals.c,
target.c, target.h and utils.c
Plus the following test files:
- none/tests/ppc32/testVMX.c derived from testVMX.
- ppc tests derived from QEMU: jm-insns.c, ppc64_helpers.h
and test_isa_3_0.c
- tests derived from bzip2 (with embedded GPL text in code):
hackedbz2.c, origin5-bz2.c, varinfo6.c
- tests detived from glibc: str_tester.c, pth_atfork1.c
- test detived from GCC libgomp: tc17_sembar.c
- performance tests derived from bzip2 or tinycc (with embedded GPL
text in code): bz2.c, test_input_for_tinycc.c and tinycc.c
[This commit contains an implementation for all targets except amd64-solaris
and x86-solaris, which will be completed shortly.]
In the baseline simulator, jumps to guest code addresses that are not known at
JIT time have to be looked up in a guest->host mapping table. That means:
indirect branches, indirect calls and most commonly, returns. Since there are
huge numbers of these (often 10+ million/second) the mapping mechanism needs
to be extremely cheap.
Currently, this is implemented using a direct-mapped cache, VG_(tt_fast), with
2^15 (guest_addr, host_addr) pairs. This is queried in handwritten assembly
in VG_(disp_cp_xindir) in dispatch-<arch>-<os>.S. If there is a miss in the
cache then we fall back out to C land, and do a slow lookup using
VG_(search_transtab).
Given that the size of the translation table(s) in recent years has expanded
significantly in order to keep pace with increasing application sizes, two bad
things have happened: (1) the cost of a miss in the fast cache has risen
significantly, and (2) the miss rate on the fast cache has also increased
significantly. This means that large (~ one-million-basic-blocks-JITted)
applications that run for a long time end up spending a lot of time in
VG_(search_transtab).
The proposed fix is to increase associativity of the fast cache, from 1
(direct mapped) to 4. Simulations of various cache configurations using
indirect-branch traces from a large application show that is the best of
various configurations. In an extreme case with 5.7 billion indirect
branches:
* The increase of associativity from 1 way to 4 way, whilst keeping the
overall cache size the same (32k guest/host pairs), reduces the miss rate by
around a factor of 3, from 4.02% to 1.30%.
* The use of a slightly better hash function than merely slicing off the
bottom 15 bits of the address, reduces the miss rate further, from 1.30% to
0.53%.
Overall the VG_(tt_fast) miss rate is almost unchanged on small workloads, but
reduced by a factor of up to almost 8 on large workloads.
By implementing each (4-entry) cache set using a move-to-front scheme in the
case of hits in ways 1, 2 or 3, the vast majority of hits can be made to
happen in way 0. Hence the cost of having this extra associativity is almost
zero in the case of a hit. The improved hash function costs an extra 2 ALU
shots (a shift and an xor) but overall this seems performance neutral to a
win.
Explanation by Matthias Schwarzott:
The linker will request an executable stack as soon as at least one
object file, that is linked in, wants an executable stack.
And the absence of the
.section .note.GNU-stack."",@progbits
is enough to tell the linker that an executable stack is needed.
So even an empty asm-file must at least contain this statement to not
force executable stacks on the whole executable.
* Define a helper macro MARK_STACK_NO_EXEC that disables the
executable stack.
* Instantiate this macro unconditionally at the end of each asm file.
Patch by Matthias Schwarzott <zzam@gentoo.org>.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15692
way that the fast-path through VG_(disp_cp_xindir) only has to
increment a 32 bit counter, saving memory bandwidth on 32 bit
platforms compared to a 64-bit inc. The overall numbers of XIndirs
can still be 64 bit though.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@12527
so as to avoid a GSP-changed check in the common case. See vex r2155.
(amd64-darwin and x86-darwin are now temporarily unbuildable.)
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@11786
use test-based detection of GSP pointer changes.
Saves one load per SB.
dispatch-amd64-linux.S:
ditto
dispatch-amd64-linux.S:
use movabsq to get &VG_(tt_fast) into a register,
instead of an rsp-relative load from a constant pool.
Saves a second load per SB.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@11785
following improvements:
- Arch/OS/platform-specific files are now included/excluded via the
preprocessor, rather than via the build system. This is more consistent
(we use the pre-processor for small arch/OS/platform-specific chunks
within files) and makes the build system much simpler, as the sources for
all programs are the same on all platforms.
- Vast amounts of cut+paste Makefile.am code has been factored out. If a
new platform is implemented, you need to add 11 extra Makefile.am lines.
Previously it was over 100 lines.
- Vex has been autotoolised. Dependency checking now works in Vex (no more
incomplete builds). Parallel builds now also work. --with-vex no longer
works; it's little use and a pain to support. VEX/Makefile is still in
the Vex repository and gets overwritten at configure-time; it should
probably be renamed Makefile-gcc to avoid possible problems, such as
accidentally committing a generated Makefile. There's a bunch of hacky
copying to deal with the fact that autotools don't handle same-named files
in different directories. Julian plans to rename the files to avoid this
problem.
- Various small Makefile.am things have been made more standard automake
style, eg. the use of pkginclude/pkglib prefixes instead of rolling our
own.
- The existing five top-level Makefile.am include files have been
consolidated into three.
- Most Makefile.am files now are structured more clearly, with comment
headers separating sections, declarations relating to the same things next
to each other, better spacing and layout, etc.
- Removed the unused exp-ptrcheck/tests/x86 directory.
- Renamed some XML files.
- Factored out some duplicated dSYM handling code.
- Split auxprogs/ into auxprogs/ and mpi/, which allowed the resulting
Makefile.am files to be much more standard.
- Cleaned up m_coredump by merging a bunch of files that had been
overzealously separated.
The net result is 630 fewer lines of Makefile.am code, or 897 if you exclude
the added Makefile.vex.am, or 997 once the hacky file copying for Vex is
removed. And the build system is much simpler.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@10364
more cache friendly. This changes the mechanism from being a table of
pointers to (guest address, translated code pairs) to being a table of
pairs (guest address, pointer to translated code). The effect ranges
from zero up to about 20% performance improvement on memcheck, the
biggest effects being seen for programs which jump around a large
number of blocks of code and whose data set does not fit in L2.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@6582
Use 'ctr' rather than 'lr' for indirect jumps, so as not to trash the
branch predictor(s) for returns from generated code. Makes a big
difference on ppc970 (and POWER4).
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@6291
as requested by Greg Parker. (The ppc32/Darwin dispatch loop is
different to the ppc32/Linux one, for example.)
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@4843
