Changed beforeinstall rule to use `install -C' instead of `cmp -s'
and `install -c'. `install -C' has exactly the right semantics
for installing headers and should be used elsewhere.
vector. Now it is called the "symbol caching" vector. This was made
possible and unconfusing by other changes that allowed me to localize
everything having to do with the caching vector in the function
reloc_map().
Switched to alloca() for allocating the caching vector, and eliminated
the special mmap-based allocation routines. Although this was motivated
by performance reasons, it led to significant simplification of the
code, and made it possible to confine the symbol caching code to the
single function reloc_map().
Got rid of the unnecessary and inefficient division loop at the
beginning of rtld().
Reduced the number of calls to getenv("LD_LIBRARY_PATH") to just 1, on
suggestion from <davidg@root.com>.
Added breaks out of the relocation loops when the relocation address is
found to be 0. A relocation address of 0 is caused by an unused
relocation entry. Unused relocation entries are caused by linking a
shared object with the "-Bsymbolic" switch. The runtime linker itself
is linked that way, and the last 40% of its relocation entries are
unused. Thus, breaking out of the loop on the first such entry is a
performance win when ld.so relocates itself. As a side benefit, it
permits removing a test from md_relocate_simple() in
../i386/md-static-funcs.c.
Unused relocation entries in other shared objects (linked with
"-Bsymbolic") caused even bigger problems in previous versions of the
runtime linker. The runtime linker interpreted the unused entries as if
they were valid. That caused it to perform repeated relocations of the
first byte of the shared object. In order to do that, it had to remap
the text segment writable. Breaking out of the loop on the first unused
relocation entry solves that.
Submitted by: John Polstra <jdp@polstra.com>
them. Good greif! This was causing an unimaginable amount of brain-damage!
The mere fact that I griped about $ Log $ in a previous commit (misspelled
deliberately here) meant that the blasted thing was being expanded from the
middle of the log entry as well as the beginning, and using " * All these"
as the comment leader.. AARGH!!!! We *really* need to prevent these from
being expanded! (or remove the magic identifier from the source).
All those $Log$ entries, combined with the whitespace changes are a real
pain.
I'm committing this now, before it's completely finished to get it compiling
and working again ASAP. Some of the FreeBSD specific features are not working
in this commit yet (mainly rlog stuff and $FreeBSD$ support)
This is going to be pretty messy.... Although the vendor import was correct,
both the vendor and release tags are the same "gnu"... :-/
Getting cvs to choose the correct one might be rather interesting...
Note, this is going to be messy.. 2.3 was vendor-branch imported, while
2.6 was done as a delta. Sigh. I'm importing this on a vendor branch so
that it will be easier to deal with next time..
(cvs-1.6 wants rcs-5.7, and rcs-5.7 suggests diffutils-2.7)
Implemented symbol memorizing to reduce the number of calls to lookup(),
making relocation go faster. While relocating a given shared object,
the dynamic linker maintains a memorizing vector that is directly
indexed by the symbol number in the relocation entry. The first time a
given symbol is looked up, the memorizing vector is filled in with a
pointer to the symbol table entry, and a pointer to the so_map of the
shared object in which the symbol was defined. On subsequent uses of
the same symbol, that information is retrieved directly from the
memorizing vector, without calling lookup() again.
A symbol that is referenced in a relocation entry is typically
referenced in many relocation entries, so this memorizing reduces the
number of calls to lookup() dramatically. The overall improvement in
the speed of dynamic linking is also dramatic -- as much as a factor of
three for programs that use many shared libaries.
Submitted by: jdp@polstra.com "John Polstra"
