Currently we emit DeferredDeclsToEmit in reverse order. This patch changes that.
The advantages of the change are that
* The output order is a bit closer to the source order. The change to
test/CodeGenCXX/pod-member-memcpys.cpp is a good example.
* If we decide to deffer more, it will not cause as large changes in the
estcases as it would without this patch.
llvm-svn: 226751
The llvm IR until recently had no support for comdats. This was a problem when
targeting C++ on ELF/COFF as just using weak linkage would cause quite a bit of
dead bits to remain on the executable (unless -ffunction-sections,
-fdata-sections and --gc-sections were used).
To fix the problem, llvm's codegen will just assume that any weak or linkonce
that is not in an explicit comdat should be output in one with the same name as
the global.
This unfortunately breaks cases like pr19848 where a weak symbol is not
xpected to be part of any comdat.
Now that we have explicit comdats in the IR, we can finally get both cases
right.
This first patch just makes clang give explicit comdats to GlobalValues where
t is allowed to.
A followup patch to llvm will then stop implicitly producing comdats.
llvm-svn: 225705
The variable (and the GV) is only ever used if the function is. Putting it
in the function's comdat make it easier for the linker to discard them.
The motivating example is
struct S {
static const int x;
};
// const int S::x = 42;
inline const int *f() {
static const int y = S::x;
return &y;
}
const int *g() { return f(); }
With S::x commented out, _ZZ1fvE1y is a variable with a guard variable
that is initialized by f.
With S::x present, _ZZ1fvE1y is a constant.
llvm-svn: 224369
Clang can already handle
-------------------------------------------
struct S {
static const int x;
};
template<typename T> struct U {
static const int k;
};
template<typename T> const int U<T>::k = T::x;
const int S::x = 42;
extern const int *f();
const int *g() { return &U<S>::k; }
int main() {
return *f() + U<S>::k;
}
const int *f() { return &U<S>::k; }
-------------------------------------------
since r217264 which puts the .inint_array section in the same COMDAT
as the variable.
This patch allows the linker to more easily delete some dead code and data by
putting the guard variable and init function in the same COMDAT.
This is a fixed version of r218089.
llvm-svn: 218141
With this patch we output the in the order
C2
C1
D2
D1
D0
Which means that a destructor or constructor that call another is output after
the callee. This is a bit easier to read IHMO and a tiny bit more efficient
as we don't put a decl in DeferredDeclsToEmit.
llvm-svn: 196784
initialize an array of unsigned char. Outside C++11 mode, this bug was benign,
and just resulted in us emitting a constant which was double the required
length, padded with 0s. In C++11, it resulted in us generating an array whose
first element was something like i8 ptrtoint ([n x i8]* @str to i8).
llvm-svn: 154756
global destructor entry. For some reason this isn't enabled for
apple-kexts; it'd be good to have documentation for that.
Based on a patch by Nakamura Takumi!
llvm-svn: 154191
the function body, but do so in a way that doesn't make any assumptions
about the static local actually having a proper, unique mangling,
since apparently we don't do that correctly at all.
llvm-svn: 153776
These patches cause us to miscompile and/or reject code with static
function-local variables in an extern-C context. Previously, we were
papering over this as long as the variables are within the same
translation unit, and had not seen any failures in the wild. We still
need a proper fix, which involves mangling static locals inside of an
extern-C block (as GCC already does), but this patch causes pretty
widespread regressions. Firefox, and many other applications no longer
build.
Lots of test cases have been posted to the list in response to this
commit, so there should be no problem reproducing the issues.
llvm-svn: 153768
the case that the variable already exists. Partly this is just
protection against people making crazy declarations with custom
asm labels or extern "C" names that intentionally collide with
the manglings of such variables, but the main reason is that we
can actually emit a static local variable twice with the
requirement that it match up. There may be other cases with
(e.g.) the various nested functions, but the main exemplar is
with constructor variants, where we can be forced into
double-emitting the function body under certain circumstances
like (currently) the presence of virtual bases.
llvm-svn: 153723
variables should have that linkage. Otherwise, its static local
variables should have internal linkage. To avoid computing this excessively,
set a function's linkage before we emit code for it.
Previously we were assigning weak linkage to the static variables of
static inline functions in C++, with predictably terrible results. This
fixes that and also gives better linkage than 'weak' when merging is required.
llvm-svn: 104581
destructors, place the __cxa_atexit call after the __cxa_guard_release
call, mimicking GCC/LLVM-GCC behavior. Noticed while debugging
something related.
llvm-svn: 103088
- This is designed to make it obvious that %clang_cc1 is a "test variable"
which is substituted. It is '%clang_cc1' instead of '%clang -cc1' because it
can be useful to redefine what gets run as 'clang -cc1' (for example, to set
a default target).
llvm-svn: 91446
David Blaikie