There are two things in a C++ program that need to read the vtable pointer:
Constructors and destructors. (A few other operations -- virtual calls,
dynamic cast, rtti -- read the vtable pointer off a this pointer, but for
this they don't need the vtable symbol.) Implicit constructors and destructors
and explicit constructors already marked the vtable as used, but explicit
destructors didn't.
Note that the only thing sema's "mark a class's vtable used" does is to mark all
final overriders of the class as referenced, it does _not_ cause emission of
the vtable itself. This is done on demand by codegen, independent of sema,
since sema might emit functions that are not referenced. (The exception are
vtables that are forced via key functions -- these are forced onto codegen
by sema.)
This bug went unnoticed for years because it doesn't have observable effects
(yet -- I want to change this in PR20337, which is why I noticed this).
r213109 made it so that _calls_ to constructors don't mark the vtable used.
Currently, _calls_ to destructors still mark the vtable used. If that
wasn't the case, this program would tickle the problem:
test.h:
template <typename T>
struct B {
int* p;
virtual ~B() { delete p; }
virtual void f() {}
};
struct __attribute__((visibility("default"))) C {
C();
B<int> m;
};
test2.cc:
#include "test.h"
int main() {
C* c = new C;
delete c;
}
test3.cc:
#include "test.h"
C::C() {}
# This bin/clang++ binary doesn't MarkVTableUsed() for virtual dtor calls:
$ bin/clang++ -shared test3.cc -std=c++11 -O2 -fvisibility=hidden \
-fvisibility-inlines-hidden -o libtest3.dylib
$ bin/clang++ test2.cc -std=c++11 -O2 -fvisibility=hidden \
-fvisibility-inlines-hidden libtest3.dylib
Undefined symbols for architecture x86_64:
"B<int>::f()", referenced from:
vtable for B<int> in test2-af8f4f.o
ld: symbol(s) not found for architecture x86_64
What's happening here is that there's a copy of B's vtable hidden in
libtest3.dylib, because C's constructor caused an implicit instantiation of that
(and implicit constructors generate vtables).
test2.cc calls C's destructDr, which destroys the B<int> member,
which wants to overwrite the vtable back to B (think of B as the base of a class
hierarchy, and of hierarchical destruction -- maybe we shouldn't do the vtable
writing in destructors of final classes), but there's nothing in test2.cc that
marks B's vtable used. So codegen writes out the vtable, but since it wasn't
marked used, sema didn't mark all the virtual functions (in particular f())
as used.
Note that this change makes us reject programs we didn't reject before (see
the included Sema test case), but both gcc and cl also reject this code, and
clang used to reject it before r213109.
llvm-svn: 225761
The functions {pred,succ,use,user}_{begin,end} exist, but many users
have to check *_begin() with *_end() by hand to determine if the
BasicBlock or User is empty. Fix this with a standard *_empty(),
demonstrating a few usecases.
llvm-svn: 225760
AAELF specifies a number of ELF specific relocation types which have custom
prefixes for the symbol reference. Switch the parser to be more table driven
with an idea of file formats for which they apply. NFC.
llvm-svn: 225758
template.
This consolidates three copies of nearly the same core logic. It adds
"complexity" to the ModuleAnalysisManager in that it makes it possible
to share a ModuleAnalysisManager across multiple modules... But it does
so by deleting *all of the code*, so I'm OK with that. This will
naturally make fixing bugs in this code much simpler, etc.
The only down side here is that we have to use 'typename' and 'this->'
in various places, and the implementation is lifted into the header.
I'll take that for the code size reduction.
The convenient names are still typedef-ed and used throughout so that
users can largely ignore this aspect of the implementation.
The follow-up change to this will do the exact same refactoring for the
PassManagers. =D
It turns out that the interesting different code is almost entirely in
the adaptors. At the end, that should be essentially all that is left.
llvm-svn: 225757
This name is less descriptive, but it sort of puts things in the
'llvm.frame...' namespace, relating it to frameallocate and
frameaddress. It also avoids using "allocate" and "allocation" together.
llvm-svn: 225752
even though every basic source character literal has the same numerical value
as a narrow or wide character literal.
It appears that the FreeBSD folks are trying to use this macro to mean
something other than what the relevant standards say it means, but their usage
is conforming, so put up with it.
llvm-svn: 225751
The terminal window will be opened under the ownership
of the real userid and it won't be able to open the
socket talking back to lldb -- the testsuite will hang
here.
The same thing probably should be done for lldb when run
on a remote system over ssh. I added a line for that
but commented it out for now because I haven't
tested it.
llvm-svn: 225748
These intrinsics allow multiple functions to share a single stack
allocation from one function's call frame. The function with the
allocation may only perform one allocation, and it must be in the entry
block.
Functions accessing the allocation call llvm.recoverframeallocation with
the function whose frame they are accessing and a frame pointer from an
active call frame of that function.
These intrinsics are very difficult to inline correctly, so the
intention is that they be introduced rarely, or at least very late
during EH preparation.
Reviewers: echristo, andrew.w.kaylor
Differential Revision: http://reviews.llvm.org/D6493
llvm-svn: 225746
This adds back the testcase from r225738, and adds to it. Looks like we
need both sides for now (the assertion was incorrect both ways, and
although it seemed reasonable (when written correctly) it wasn't
particularly important).
llvm-svn: 225745
so has clang-format. Notably, this fixes a bunch of formatting in the
CGSCC pass manager side of things that has been improved in clang-format
recently.
llvm-svn: 225743
This reverts commit r225738. Maybe the assertion is just plain wrong,
but this version fails on WAY more bots. I'll make sure both ways work
in a follow-up but I want to get bots green in the meantime.
llvm-svn: 225742
Templates don't have key functions (cf computeKeyFunction() in
RecordLayoutBuilder.cpp), so don't have something that looks like one.
Also, instead of a vcall to force generation of the vtable, just construct
the object. This is how the repro on PR5557 (what the test is for) worked too.
llvm-svn: 225741
Instead, just present the command for committing it. This way,
the user can test the merge locally, resolve conflicts, etc.
before committing, which seems much safer to me.
llvm-svn: 225737
Move the declaration of DebugLocDwarfExpression into DwarfExpression.h
because it needs to be accessed from AsmPrinterDwarf.cpp and DwarfDebug.cpp
NFC.
llvm-svn: 225734
Otherwise we'll attempt to forward ECX, EDX, and EAX for cdecl and
stdcall thunks, leaving us with no scratch registers for indirect call
targets.
Fixes PR22052.
llvm-svn: 225729
templated interface.
So far, every single IR unit I can come up with has address-identity.
That is, when two units of IR are both active in LLVM, their addresses
will be distinct of the IR is distinct. This is clearly true for
Modules, Functions, BasicBlocks, and Instructions. It turns out that the
only practical way to make the CGSCC stuff work the way we want is to
make it true for SCCs as well. I expect this pattern to continue.
When first designing the pass manager code, I kept this dimension of
freedom in the type parameters, essentially allowing for a wrapper-type
whose address did not form identity. But that really no longer makes
sense and is making the code more complex or subtle for no gain. If we
ever have an actual use case for this, we can figure out what makes
sense then and there. It will be better because then we will have the
actual example in hand.
While the simplifications afforded in this patch are fairly small
(mostly sinking the '&' out of many type parameters onto a few
interfaces), it would have become much more pronounced with subsequent
changes. I have a sequence of changes that will completely remove the
code duplication that currently exists between all of the pass managers
and analysis managers. =] Should make things much cleaner and avoid bug
fixing N times for the N pass managers.
llvm-svn: 225723
Introduce the following -fsanitize-recover flags:
- -fsanitize-recover=<list>: Enable recovery for selected checks or
group of checks. It is forbidden to explicitly list unrecoverable
sanitizers here (that is, "address", "unreachable", "return").
- -fno-sanitize-recover=<list>: Disable recovery for selected checks or
group of checks.
- -f(no-)?sanitize-recover is now a synonym for
-f(no-)?sanitize-recover=undefined,integer and will soon be deprecated.
These flags are parsed left to right, and mask of "recoverable"
sanitizer is updated accordingly, much like what we do for -fsanitize= flags.
-fsanitize= and -fsanitize-recover= flag families are independent.
CodeGen change: If there is a single UBSan handler function, responsible
for implementing multiple checks, which have different recoverable setting,
then we emit two handler calls instead of one:
the first one for the set of "unrecoverable" checks, another one - for
set of "recoverable" checks. If all checks implemented by a handler have the
same recoverability setting, then the generated code will be the same.
llvm-svn: 225719
r225551 vector byte shuffle optimization caused an assertion as fully zeroable vectors can be produced under certain circumstances. This fix drops the assert and returns a zero vector where the assert would have failed.
llvm-svn: 225718
Rui Ueyama