Commit Graph

9 Commits

Author SHA1 Message Date
Dmitri Gribenko 3e1551c96f Provide the same ABI regardless of NDEBUG
For projects depending on LLVM, I find it very useful to combine a
release-no-asserts build of LLVM with a debug+asserts build of the dependent
project.  The motivation is that when developing a dependent project, you are
debugging that project itself, not LLVM.  In my usecase, a significant part of
the runtime is spent in LLVM optimization passes, so I would like to build LLVM
without assertions to get the best performance from this combination.

Currently, `lib/Support/Debug.cpp` changes the set of symbols it provides
depending on NDEBUG, while `include/llvm/Support/Debug.h` requires extra
symbols when NDEBUG is not defined.  Thus, it is not possible to enable
assertions in an external project that uses facilities of `Debug.h`.

This patch changes `Debug.cpp` and `Valgrind.cpp` to always define the symbols
that other code may depend on when #including LLVM headers without NDEBUG.

http://reviews.llvm.org/D7662

llvm-svn: 229819
2015-02-19 05:30:16 +00:00
Chandler Carruth a48ecb7639 Don't mark the declarations of the TSan annotation functions as weak.
That causes references to them to be weak references which can collapse
to null if no definition is provided. We call these functions
unconditionally, so a definition *must* be provided. Make the
definitions provided in the .cpp file weak by re-declaring them as weak
just prior to defining them. This should keep compilers which cannot
attach the weak attribute to the definition happy while actually
resolving the symbols correctly during the link.

You might ask yourself upon reading this commit log: how did *any* of
this work before? Well, fun story. It turns out we have some code in
Support (BumpPtrAllocator) which both uses virtual dispatch and has
out-of-line vtables used by that virtual dispatch. If you move the
virtual dispatch into its header in *just* the right way, the optimizer
gets to devirtualize, and remove all references to the vtable. Then the
sad part: the references to this one vtable were the only strong symbol
uses in the support library for llvm-tblgen AFAICT. At least, after
doing something just like this, these symbols stopped getting their weak
definition and random calls to them would segfault instead.

Yay software.

llvm-svn: 205137
2014-03-30 11:20:25 +00:00
Nick Lewycky 76c6299f88 Don't define these unless we plan to use them.
llvm-svn: 145289
2011-11-28 22:14:02 +00:00
Nick Lewycky 6804d27048 Move WEAK marking to the declaration.
llvm-svn: 144603
2011-11-15 01:23:22 +00:00
Nick Lewycky b2489b7484 Fix linking for some users who already have tsan enabled code and are trying to
link it against llvm code, by making our definitions weak. "Some users."

llvm-svn: 144596
2011-11-15 00:14:04 +00:00
Nick Lewycky fe856110aa Add support for tsan annotations (thread sanitizer, a valgrind-based tool).
These annotations are disabled entirely when either ENABLE_THREADS is off, or
building a release build. When enabled, they add calls to functions with no
statements to ManagedStatic's getters.

Use these annotations to inform tsan that the race used inside ManagedStatic
initialization is actually benign. Thanks to Kostya Serebryany for helping
write this patch!

llvm-svn: 144567
2011-11-14 20:50:16 +00:00
Duncan Sands a1c44332e5 Revert previous commit. It seems that whether casting to void
is valid or not depends on which system you build.

llvm-svn: 134321
2011-07-02 13:14:22 +00:00
Duncan Sands dda99eef54 Supress gcc-4.5 warning about the result not being used.
llvm-svn: 134319
2011-07-02 13:06:23 +00:00
Michael J. Spencer 447762da85 Merge System into Support.
llvm-svn: 120298
2010-11-29 18:16:10 +00:00