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overview
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This commit introduces an optimisation that speeds up Memcheck by roughly
-3 -- 28%, and Addrcheck by 1 -- 36%, at least for the SPEC2000 benchmarks on
my 1400MHz Athlon.
Basic idea: that handling of A/V bit updates on %esp-adjustments was quite
sub-optimal -- for each "PUT ESP", a function was called that computed the
delta from the old and new ESPs, and then called a looping function to deal
with it.
Improvements:
1. most of the time, the delta can be seen from the code. So there's no need
to compute it.
2. when the delta is known, we can directly call a skin function to handle it.
3. we can specialise for certain common cases (eg. +/- 4, 8, 12, 16, 32),
including having unrolled loops for these.
This slightly bloats UCode because of setting up args for the call, and for
updating ESP in code (previously was done in the called C function). Eg. for
`date' the code expansion ratio goes from 14.2 --> 14.6. But it's much faster.
Note that skins don't have to use the specialised cases, they can just
define the ordinary case if they want; the specialised cases are only used
if present.
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details
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Removed addrcheck/ac_common.c, put its (minimal) contents in ac_main.c.
Updated the major interface version, because this change isn't binary
compatible with the old core/skin interface.
Removed the hooks {new,die}_mem_stack_aligned, replaced with the better
{new,die}_mem_stack_{4,8,12,16,32}. Still have the generic {die,new}_mem_stack
hooks. These are called directly from UCode, thanks to a new pass that occurs
between instrumentation and register allocation (but only if the skin uses
these stack-adjustment hooks). VG_(unknown_esp_update)() is called from UCode
for the generic case; it determines if it's a stack switch, and calls the
generic {new,die}_stack_mem hooks accordingly. This meant
synth_handle_esp_assignment() could be removed.
The new %esp-delta computation phase is in vg_translate.c.
In Memcheck and Addrcheck, added functions for updating the A and V bits of a
single aligned word and a single aligned doubleword. These are called from the
specialised functions new_mem_stack_4, etc. Could remove the one for the old
hooks new_mem_stack_aligned and die_mem_stack_aligned.
In mc_common.h, added a big macro containing the definitions of new_mem_stack_4
et al. It's ``instantiated'' separately by Memcheck and Addrcheck. The macro
is a bit klugey, but I did it that way because speed is vital for these
functions, so eg. a function pointer would have slowed things down.
Updated the built-in profiling events appropriately for the changes (removed
one old event, added a new one; finding their names is left as an exercise for
the reader).
Fixed memory event profiling in {Addr,Mem}check, which had rotted.
A few other minor things.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@1510 a5019735-40e9-0310-863c-91ae7b9d1cf9
17 files changed