Clang generates copy and dispose helper functions for each block literal
on the stack. Often these functions are equivalent for different blocks.
This commit makes changes to merge equivalent copy and dispose helper
functions and reduce code size.
To enable merging equivalent copy/dispose functions, the captured object
infomation is encoded into the helper function name. This allows IRGen
to check whether an equivalent helper function has already been emitted
and reuse the function instead of generating a new helper function
whenever a block is defined. In addition, the helper functions are
marked as linkonce_odr to enable merging helper functions that have the
same name across translation units and marked as unnamed_addr to enable
the linker's deduplication pass to merge functions that have different
names but the same content.
rdar://problem/42640608
Differential Revision: https://reviews.llvm.org/D50152
llvm-svn: 339438
blocks.
r302270 made changes to avoid emitting clang.arc.use at -O0 and instead
emit @objc_release. We also have to emit @objc_retain for the captured
variable at -O0 to match the @objc_release instead of just storing the
pointer to the capture field.
llvm-svn: 302495
creation that are const-qualified.
When a block captures an ObjC object pointer, clang retains the pointer
to prevent prematurely destroying the object the pointer points to
before the block is called or copied.
When the captured object pointer is const-qualified, we can avoid
emitting the retain/release pair since the pointer variable cannot be
modified in the scope in which the block literal is introduced.
For example:
void test(const id x) {
callee(^{ (void)x; });
}
This patch implements that optimization.
rdar://problem/28894510
Differential Revision: https://reviews.llvm.org/D32601
llvm-svn: 301667
CodeGenFunction::EmitObjCForCollectionStmt currently emits lifetime markers for the loop variable in an inconsistent way: lifetime.start is emitted before the loop is entered, but lifetime.end is emitted inside the loop. AddressSanitizer uses these markers to track out-of-scope accesses to local variables, and we get false positives in Obj-C foreach loops (in the 2nd iteration of the loop). This patch keeps the loop variable alive for the whole loop by extending ForScope and registering the cleanup function inside EmitAutoVarAlloca.
Differential Revision: https://reviews.llvm.org/D32029
llvm-svn: 300340
routines for objects that are captured with the __unsafe_unretained
ownership qualifier
This is a preparation commit that improves code-coverage in code that emits
block copy/dispose routines.
llvm-svn: 296048
Much to my surprise, '-disable-llvm-optzns' which I thought was the
magical flag I wanted to get at the raw LLVM IR coming out of Clang
deosn't do that. It still runs some passes over the IR. I don't want
that, I really want the *raw* IR coming out of Clang and I strongly
suspect everyone else using it is in the same camp.
There is actually a flag that does what I want that I didn't know about
called '-disable-llvm-passes'. I suspect many others don't know about it
either. It both does what I want and is much simpler.
This removes the confusing version and makes that spelling of the flag
an alias for '-disable-llvm-passes'. I've also moved everything in Clang
to use the 'passes' spelling as it seems both more accurate (*all* LLVM
passes are disabled, not just optimizations) and much easier to remember
and spell correctly.
This is part of simplifying how Clang drives LLVM to make it cleaner to
wire up to the new pass manager.
Differential Revision: https://reviews.llvm.org/D28047
llvm-svn: 290392
CGBlocks.cpp.
This commit fixes a bug in clang's code-gen where it creates the
following functions but doesn't attach function attributes to them:
__copy_helper_block_
__destroy_helper_block_
__Block_byref_object_copy_
__Block_byref_object_dispose_
rdar://problem/20828324
Differential Revision: http://reviews.llvm.org/D13525
llvm-svn: 249735
This reverts commit r234700. It turns out that the lifetime markers
were not the cause of Chromium failing but a bug which was uncovered by
optimizations exposed by the markers.
llvm-svn: 235553
Now that TailRecursionElimination has been fixed with r222354, the
threshold on size for lifetime marker insertion can be removed. This
only affects named temporary though, as the patch for unnamed temporaries
is still in progress.
My previous commit (r222993) was not handling debuginfo correctly, but
this could only be seen with some asan tests. Basically, lifetime markers
are just instrumentation for the compiler's usage and should not affect
debug information; however, the cleanup infrastructure was assuming it
contained only destructors, i.e. actual code to be executed, and was
setting the breakpoint for the end of the function to the closing '}', and
not the return statement, in order to show some destructors have been
called when leaving the function. This is wrong when the cleanups are only
lifetime markers, and this is now fixed.
llvm-svn: 234581
Now that TailRecursionElimination has been fixed with r222354, the
threshold on size for lifetime marker insertion can be removed. This
only affects named temporary though, as the patch for unnamed temporaries
is still in progress.
llvm-svn: 222993
Boostrapping LLVM+Clang+LLDB without threshold on object size for
lifetime markers insertion has shown there was no significant change
in compile time, so let the stack slot colorizer do its optimization
for all slots.
llvm-svn: 219303
to an out-parameter using the indirect-writeback conversion,
and we copied the current value of the variable to the temporary,
make sure that we register an intrinsic use of that value with
the optimizer so that the value won't get released until we have
a chance to retain it.
rdar://13195034
llvm-svn: 177813
arguments in function prologue is done
with objc_StoreStrong to pair it with
similar objc_StoreStrong for release in function
epilogue. This is done with -O0 only.
// rdar://13145317
llvm-svn: 175698
call sites as tail calls unconditionally. While it's theoretically true that
this is just an optimization, it's an optimization that we very much want to
happen even at -O0, or else ARC applications become substantially harder to
debug. See r169796 for the llvm/fast-isel side of things.
rdar://12553082
llvm-svn: 169996
objc_loadWeak. This retains and autorelease the weakly-refereced
object. This hidden autorelease sometimes makes __weak variable alive even
after the weak reference is erased, because the object is still referenced
by an autorelease pool. This patch overcomes this behavior by loading a
weak object via call to objc_loadWeakRetained(), followng it by objc_release
at appropriate place, thereby removing the hidden autorelease. // rdar://10849570
llvm-svn: 168740
generation for captured block variables in arc mode. This includes
inlined version of the meta-data when it can be done. It also includes
severat tests. This is wip. // rdar://12184410.
llvm-svn: 167241
combination of a load+objc_release; this is generally better
for tools that try to track why values are retained and
released. Also use objc_storeStrong when copying a block
(again, only at -O0), which requires us to do a preliminary
store of null in order to compensate for objc_storeStrong's
assign semantics.
llvm-svn: 166085
into the enclosing scope; this is a more accurate model but is
(I believe) unnecessary in my test case due to other flaws.
However, one of those flaws is now intentional: blocks which
appear in return statements can be trivially observed to not
extend in lifetime past the return, and so we can allow a jump
past them. Do the necessary magic in IR-generation to make
this work.
llvm-svn: 164589
literal helper functions. All helper functions (global
and locals) use block_invoke as their prefix. Local literal
helper names are prefixed by their enclosing mangled function
names. Blocks in non-local initializers (e.g. a global variable
or a C++11 field) are prefixed by their mangled variable name.
The descriminator number added to end of the name starts off
with blank (for first block) and _<N> (for the N+2-th block).
llvm-svn: 159206
initializer need be null initialized before initializer takes
hold, just like any other initialized retainable object pointer.
// rdar://11016025
llvm-svn: 158738
need to provide a 'dominating IP' which is guaranteed to
dominate the (de)activation point but which cannot be avoided
along any execution path from the (de)activation point to
the push-point of the cleanup. Using the entry block is
bad mojo.
llvm-svn: 144276
a previously-inactive cleanup, not only do we need a
flag variable, but we should also force the cleanup to
query the flag variable. However, we only need to do
this when we're activating in a context that's
conditionally executed; otherwise, we may safely
assume that the cleanup is dominated by the activation
point.
llvm-svn: 144271
full-expression. Naturally they're inactive before we enter
the block literal expression. This restores the intended
behavior that blocks belong to their enclosing scope.
There's a useful -O0 / compile-time optimization that we're
missing here with activating cleanups following straight-line
code from their inactive beginnings.
llvm-svn: 144268
block-typed __block variables using objc_retainBlock
and objc_dispose. Previously we were using
_Block_object_assign and _Block_object_destroy
with BLOCK_BYREF_CALLER, which causes the runtime
to completely ignore the retain and release.
In most cases this doesn't cause catastrophe
because the retain/release are balanced and
because the block in the variable was copied
upon assignment there. However, the stack
copy of the variable will be released when
it goes out of scope, which is a problem if
that value was released due to an assignment
to the heap copy. Similarly, a leak can occur
if the variable is assigned after the copy to
the heap.
llvm-svn: 144162
Akira Hatanaka