In particular, pre-.init_array ELF uses the .ctors section mechanism.
MinGW COFF also uses .ctors, now that I think about it. Therefore,
restrict this optimization to the two platforms that are currently known
to work: ELF with .init_array and COFF with .CRT$XCU.
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The field is defined as:
If the third field is present, non-null, and points to a global variable or function, the initializer function will only run if the associated data from the current module is not discarded.
And without COMDATs we can't implement that.
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Clang can already handle
-------------------------------------------
struct S {
static const int x;
};
template<typename T> struct U {
static const int k;
};
template<typename T> const int U<T>::k = T::x;
const int S::x = 42;
extern const int *f();
const int *g() { return &U<S>::k; }
int main() {
return *f() + U<S>::k;
}
const int *f() { return &U<S>::k; }
-------------------------------------------
since r217264 which puts the .inint_array section in the same COMDAT
as the variable.
This patch allows the linker to more easily delete some dead code and data by
putting the guard variable and init function in the same COMDAT.
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Summary: When the main file is created from a membuffer, there is no file entry that can be retrieved. This uses "__GLOBAL_I_a" in that case which is what was always used before r208128.
Reviewers: majnemer, thakis
Reviewed By: thakis
Subscribers: yaron.keren, rsmith, cfe-commits
Differential Revision: http://reviews.llvm.org/D5043
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Summary:
This pragma is very rare. We could *hypothetically* lower some uses of
it down to @llvm.global_ctors, but given that GlobalOpt isn't able to
optimize prioritized global ctors today, there's really no point.
If we wanted to do this in the future, I would check if the section used
in the pragma started with ".CRT$XC" and had up to two characters after
it. Those two characters could form the 16-bit initialization priority
that we support in @llvm.global_ctors. We would have to teach LLVM to
lower prioritized global ctors on COFF as well.
This should let us compile some silly uses of this pragma in WebKit /
Blink.
Reviewers: rsmith, majnemer
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D4549
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Get rid of cached CodeGenModule::SanOpts, which was used to turn off
sanitizer codegen options if current LLVM Module is blacklisted, and use
plain LangOpts.Sanitize instead.
1) Some codegen decisions (turning TBAA or writable strings on/off)
shouldn't depend on the contents of blacklist.
2) llvm.asan.globals should *always* be created, even if the module
is blacklisted - soon Clang's CodeGen where we read sanitizer
blacklist files, so we should properly report which globals are
blacklisted to the backend.
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Initializers of global data that can appear multiple TUs (static data
members of class templates or __declspec(selectany) data) are now in a
comdat group keyed on the global variable being initialized. On
non-Windows platforms, this is a code size and startup time
optimization. On Windows, this is necessary for ABI compatibility with
MSVC.
Fixes PR16959.
Reviewers: rsmith
Differential Revision: http://reviews.llvm.org/D3811
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ensure that querying the first declaration for its most recent declaration
checks for redeclarations from the imported module.
This works as follows:
* The 'most recent' pointer on a canonical declaration grows a pointer to the
external AST source and a generation number (space- and time-optimized for
the case where there is no external source).
* Each time the 'most recent' pointer is queried, if it has an external source,
we check whether it's up to date, and update it if not.
* The ancillary data stored on the canonical declaration is allocated lazily
to avoid filling it in for declarations that end up being non-canonical.
We'll still perform a redundant (ASTContext) allocation if someone asks for
the most recent declaration from a decl before setPreviousDecl is called,
but such cases are probably all bugs, and are now easy to find.
Some finessing is still in order here -- in particular, we use a very general
mechanism for handling the DefinitionData pointer on CXXRecordData, and a more
targeted approach would be more compact.
Also, the MayHaveOutOfDateDef mechanism should now be expunged, since it was
addressing only a corner of the full problem space here. That's not covered
by this patch.
Early performance benchmarks show that this makes no measurable difference to
Clang performance without modules enabled (and fixes a major correctness issue
with modules enabled). I'll revert if a full performance comparison shows any
problems.
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This makes it easier to see where a global ctor comes from, and it also makes
ASan's init order analyzer output easier to understand. gcc does this too,
but only in -fPIC mode for some reason. Don't do this for constructors with
explicit init priority.
Also prepend "sub_" before the 'I', that way regular constructors stay
lexicographically after symbols with init priority (because
ord('s') > ord('I')). gold seems to ignore the name of constructor symbols,
and ld only looks at the symbol if it includes an init priority, which this
patch doesn't change.
Before: __GLOBAL_I_a
Now: __GLOBAL_sub_I_myfile.cc
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Summary:
A reference temporary should inherit the linkage of the variable it
initializes. Otherwise, we may hit cases where a reference temporary
wouldn't have the same value in all translation units.
Reviewers: rsmith
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D3515
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for CXXGlobalInit/Dtor helper functions.
This makes _GLOBAL__I_a regain its DW_AT_high/low_pc in the debug info.
Thanks to echristo for catching this!
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are not associated with any source lines.
Previously, if the Location of a Decl was empty, EmitFunctionStart would
just keep using CurLoc, which would sometimes be correct (e.g., thunks)
but in other cases would just point to a hilariously random location.
This patch fixes this by completely eliminating all uses of CurLoc from
EmitFunctionStart and rather have clients explicitly pass in a
SourceLocation for the function header and the function body.
rdar://problem/14985269
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This fixes PR15768, where the sret parameter and the 'this' parameter
are in the wrong order.
Instance methods compiled by MSVC never return records in registers,
they always return indirectly through an sret pointer. That sret
pointer always comes after the 'this' parameter, for both __cdecl and
__thiscall methods.
Unfortunately, the same is true for other calling conventions, so we'll
have to change the overall approach here relatively soon.
Reviewers: rsmith
Differential Revision: http://llvm-reviews.chandlerc.com/D2664
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Static locals requiring initialization are not thread safe on Windows.
Unfortunately, it's possible to create static locals that are actually
externally visible with inline functions and templates. As a result, we
have to implement an initialization guard scheme that is compatible with
TUs built by MSVC, which makes thread safety prohibitively difficult.
MSVC's scheme is that every function that requires a guard gets an i32
bitfield. Each static local is assigned a bit that indicates if it has
been initialized, up to 32 bits, at which point a new bitfield is
created. MSVC rejects inline functions with more than 32 static locals,
and the externally visible mangling (?_B) only allows for one guard
variable per function.
On Eli's recommendation, I used MangleNumberingContext to track which
bit each static corresponds to.
Implements PR16888.
Reviewers: rjmccall, eli.friedman
Differential Revision: http://llvm-reviews.chandlerc.com/D1416
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I tried to implement this properly in r189051, but I didn't have enough
test coverage. Richard kindly provided more test cases than I could
possibly imagine and now we should have the correct condition.
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This reverts commit r189320.
Alexey Samsonov and Dmitry Vyukov presented some arguments for keeping
these around - though it still seems like those tasks could be solved by
a tool just using the symbol table. In a very small number of cases,
thunks may be inlined & debug info might be able to save profilers &
similar tools from misclassifying those cases as part of the caller.
The extra changes here plumb through the VarDecl for various cases to
CodeGenFunction - this provides better fidelity through a few APIs but
generally just causes the CGF::StartFunction to fallback to using the
name of the IR function as the name in the debug info.
The changes to debug-info-global-ctor-dtor.cpp seem like goodness. The
two names that go missing (in favor of only emitting those names as
linkage names) are names that can be demangled - emitting them only as
the linkage name should encourage tools to do just that.
Again, thanks to Dinesh Dwivedi for investigation/work on this issue.
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CodeGenFunction is run on only one function - a new object is made for
each new function. I would add an assertion/flag to this effect, but
there's an exception: ObjC properties involve emitting helper functions
that are all emitted by the same CodeGenFunction object, so such a check
is not possible/correct.
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Summary:
These typically come from static data members of class template
specializations. This accomplishes two things:
1. May expose GlobalOpt optimizations for Itanium C++ ABI code.
2. Works toward fixing double initialization in the Microsoft C++ ABI.
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1475
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declarations of reference type; they're handled by the general case handling of
MaterializeTemporaryExpr.
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Original commit message:
Emit the TLS intialization functions into a list.
Add the TLS initialization functions to a list of initialization functions. The
back-end takes this list and places the function pointers into the correct
section. This way they're called before `main().'
<rdar://problem/13733006>
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Add the TLS initialization functions to a list of initialization functions. The
back-end takes this list and places the function pointers into the correct
section. This way they're called before `main().'
<rdar://problem/13733006>
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non-constant constructors or non-trivial destructors. Plus bugfixes for
thread_local references bound to temporaries (the temporaries themselves are
lifetime-extended to become thread_local), and the corresponding case for
std::initializer_list.
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aggregate types in a profoundly wrong way that has to be
worked around in every call site, to getEvaluationKind,
which classifies and distinguishes between all of these
cases.
Also, normalize the API for loading and storing complexes.
I'm working on a larger patch and wanted to pull these
changes out, but it would have be annoying to detangle
them from each other.
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calls and declarations.
LLVM has a default CC determined by the target triple. This is
not always the actual default CC for the ABI we've been asked to
target, and so we sometimes find ourselves annotating all user
functions with an explicit calling convention. Since these
calling conventions usually agree for the simple set of argument
types passed to most runtime functions, using the LLVM-default CC
in principle has no effect. However, the LLVM optimizer goes
into histrionics if it sees this kind of formal CC mismatch,
since it has no concept of CC compatibility. Therefore, if this
module happens to define the "runtime" function, or got LTO'ed
with such a definition, we can miscompile; so it's quite
important to get this right.
Defining runtime functions locally is quite common in embedded
applications.
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These are two related changes (one in llvm, one in clang).
LLVM:
- rename address_safety => sanitize_address (the enum value is the same, so we preserve binary compatibility with old bitcode)
- rename thread_safety => sanitize_thread
- rename no_uninitialized_checks -> sanitize_memory
CLANG:
- add __attribute__((no_sanitize_address)) as a synonym for __attribute__((no_address_safety_analysis))
- add __attribute__((no_sanitize_thread))
- add __attribute__((no_sanitize_memory))
for S in address thread memory
If -fsanitize=S is present and __attribute__((no_sanitize_S)) is not
set llvm attribute sanitize_S
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uncovered.
This required manually correcting all of the incorrect main-module
headers I could find, and running the new llvm/utils/sort_includes.py
script over the files.
I also manually added quite a few missing headers that were uncovered by
shuffling the order or moving headers up to be main-module-headers.
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if (CGM.getModuleDebugInfo())
DebugInfo = CGM.getModuleDebugInfo()
into a call:
maybeInitializeDebugInfo();
This is a simplification for a possible future fix of PR13942.
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variables that have static storage duration, it removes debug info on the
emitted initializer function but not all debug info about this variable.
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and only consider using __cxa_atexit in the Itanium logic. The
default logic is to use atexit().
Emit "guarded" initializers in Microsoft mode unconditionally.
This is definitely not correct, but it's closer to correct than
just not emitting the initializer.
Based on a patch by Timur Iskhodzhanov!
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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!
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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.
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a complete object, the memcpy needs to use the data size of
the structure instead of its sizeof() value. Fixes PR12204.
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The member variable is always "LangOpts" and the member function is always "getLangOpts".
Reviewed by Chris Lattner
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variable ends, if the variable has a trivial destructor and no mutable
subobjects then emit an llvm.invariant.start call for it. globalopt knows to
make the variable const when evaluating this.
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optional argument passed through the variadic ellipsis)
potentially affects how we need to lower it. Propagate
this information down to the various getFunctionInfo(...)
overloads on CodeGenTypes. Furthermore, rename those
overloads to clarify their distinct purposes, and make
sure we're calling the right one in the right place.
This has a nice side-effect of making it easier to construct
a function type, since the 'variadic' bit is no longer
separable.
This shouldn't really change anything for our existing
platforms, with one minor exception --- we should now call
variadic ObjC methods with the ... in the "right place"
(see the test case), which I guess matters for anyone
running GNUStep on MIPS. Mostly it's just a substantial
clean-up.
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constructor, and that constructor is used to initialize an object of static
storage duration such that all members and bases are initialized by constant
expressions, constant initialization is performed. In this case, the object
can still have a non-trivial destructor, and if it does, we must emit a dynamic
initializer which performs no initialization and instead simply registers that
destructor.
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builtin types (When requested). This is another step toward making
ASTUnit build the ASTContext as needed when loading an AST file,
rather than doing so after the fact. No actual functionality change (yet).
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emit call results into potentially aliased slots. This allows us
to properly mark indirect return slots as noalias, at the cost
of requiring an extra memcpy when assigning an aggregate call
result into a l-value. It also brings us into compliance with
the x86-64 ABI.
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initializer. Previously, we only used guard variables for weak static
data members. Fixes <rdar://problem/9692249>.
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Language-design credit goes to a lot of people, but I particularly want
to single out Blaine Garst and Patrick Beard for their contributions.
Compiler implementation credit goes to Argyrios, Doug, Fariborz, and myself,
in no particular order.
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This enables incremental codegen, where the initializer array can be removed from the module, such that only new initializers will be emitted and run.
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weak linkage. Also, fix a problem where global weak variables
with non-trivial initializers were getting guard variables, or at
least were checking for them and then crashing.
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Issue this as an IR-gen error; it's not really worthwhile doing this
"right", i.e. in Sema, because IR gen knows a lot of tricks beyond
what the constant evaluator knows.
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simplify the logic of initializing function parameters so that we don't need
both a variable declaration and a type in FunctionArgList. This also means
that we need to propagate the CGFunctionInfo down in a lot of places rather
than recalculating it from the FAL. There's more we can do to eliminate
redundancy here, and I've left FIXMEs behind to do it.
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Block{Function,Module} base class. Minor other refactorings.
Fixed a few address-space bugs while I was there.
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data members by delaying the emission of the initializer until after
linkage and visibility have been set on the global. Also, don't
emit a guard unless the variable actually ends up with vague linkage,
and don't use thread-safe statics in any case.
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on if its linkage is weak. Currently this is the
case but may change in the future. (part of radar
8562966).
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slot. The easiest way to do that was to bundle up the information
we care about for aggregate slots into a new structure which demands
that its creators at least consider the question.
I could probably be convinced that the ObjC 'needs GC' bit should
be rolled into this structure.
Implement generalized copy elision. The main obstacle here is that
IR-generation must be much more careful about making sure that exactly
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Reid Kleckner