This introduces a function annotation that disables TSan checking for the
function at run time. The benefit over attribute((no_sanitize("thread")))
is that the accesses within the callees will also be suppressed.
The motivation for this attribute is a guarantee given by the objective C
language that the calls to the reference count decrement and object
deallocation will be synchronized. To model this properly, we would need to
intercept all ref count decrement calls (which are very common in ObjC due
to use of ARC) and also every single message send. Instead, we propose to
just ignore all accesses made from within dealloc at run time. The main
downside is that this still does not introduce any synchronization, which
means we might still report false positives if the code that relies on this
synchronization is not executed from within dealloc. However, we have not
seen this in practice so far and think these cases will be very rare.
(This problem is similar in nature to https://reviews.llvm.org/D21609;
unfortunately, the same solution does not apply here.)
Differential Revision: https://reviews.llvm.org/D25857
llvm-svn: 286672
can be used to improve the locations when generating remarks for loops.
Depends on the companion LLVM change r286227.
Patch by Florian Hahn.
Differential Revision: https://reviews.llvm.org/D25764
llvm-svn: 286456
Summary:
Current generation of lifetime intrinsics does not handle cases like:
```
{
char x;
l1:
bar(&x, 1);
}
goto l1;
```
We will get code like this:
```
%x = alloca i8, align 1
call void @llvm.lifetime.start(i64 1, i8* nonnull %x)
br label %l1
l1:
%call = call i32 @bar(i8* nonnull %x, i32 1)
call void @llvm.lifetime.end(i64 1, i8* nonnull %x)
br label %l1
```
So the second time bar was called for x which is marked as dead.
Lifetime markers here are misleading so it's better to remove them at all.
This type of bypasses are rare, e.g. code detects just 8 functions building
clang (2329 targets).
PR28267
Reviewers: eugenis
Subscribers: beanz, mgorny, cfe-commits
Differential Revision: https://reviews.llvm.org/D24693
llvm-svn: 285176
Summary: D24693 will need access to it from other places
Reviewers: eugenis
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D24695
llvm-svn: 285158
* recurse through intermediate LabelStmts and AttributedStmts when checking
whether a statement inside a switch declares a variable
* if the end of a compound statement is reachable from the chosen case label,
and the compound statement contains a variable declaration, it's not valid
to just emit the contents of the compound statement -- we must emit the
statement itself or we lose the scope (and thus end lifetimes at the wrong
point)
llvm-svn: 281797
We also need to add ObjCTypeParamTypeLoc. ObjCTypeParamType supports the
representation of "T <protocol>" where T is a type parameter. Before this,
we use TypedefType to represent the type parameter for ObjC.
ObjCTypeParamType has "ObjCTypeParamDecl *OTPDecl" and it extends from
ObjCProtocolQualifiers. It is a non-canonical type and is canonicalized
to the underlying type with the protocol qualifiers.
rdar://24619481
rdar://25060179
Differential Revision: http://reviews.llvm.org/D23079
llvm-svn: 281355
Summary:
Remove access qualifiers on images in arg info metadata:
* kernel_arg_type
* kernel_arg_base_type
Image access qualifiers are inseparable from type in clang implementation,
but OpenCL spec provides a special query to get access qualifier
via clGetKernelArgInfo with CL_KERNEL_ARG_ACCESS_QUALIFIER.
Besides that OpenCL conformance test_api get_kernel_arg_info expects
image types without access qualifier.
Patch by Evgeniy Tyurin.
Reviewers: bader, yaxunl, Anastasia
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D23915
llvm-svn: 280699
Since some profiling tools, such as gprof, ftrace, and uftrace, use
-pg option to generate a mcount function call at the entry of each
function. Function invocation can be detected by this hook function.
But mcount insertion is done before function inlining phase in clang,
sometime a function that already has a mcount call can be inlined in the
middle of another function.
This patch adds an attribute "counting-function" to each function
rather than emitting the mcount call directly in frontend so that this
attribute can be processed in backend. Then the mcount calls can be
properly inserted in backend after all the other optimizations are
completed.
Link: https://llvm.org/bugs/show_bug.cgi?id=28660
Reviewers: hans, rjmccall, hfinkel, rengolin, compnerd
Subscribers: shenhan, cfe-commits
Differential Revision: https://reviews.llvm.org/D22666
llvm-svn: 280355
-fxray-instrument: enables XRay annotation of IR
-fxray-instruction-threshold: configures the threshold for function size (looking at IR instructions), and allow LLVM to decide whether to add the nop sleds later on in the process.
Also implements the related xray_always_instrument and xray_never_instrument function attributes.
Patch by Dean Michael Berris.
llvm-svn: 275330
Improved test with user define structure pipe type case.
Reviewers: Anastasia, pxli168
Subscribers: yaxunl, cfe-commits
Differential revision: http://reviews.llvm.org/D21744
llvm-svn: 275259
Replace inheriting constructors implementation with new approach, voted into
C++ last year as a DR against C++11.
Instead of synthesizing a set of derived class constructors for each inherited
base class constructor, we make the constructors of the base class visible to
constructor lookup in the derived class, using the normal rules for
using-declarations.
For constructors, UsingShadowDecl now has a ConstructorUsingShadowDecl derived
class that tracks the requisite additional information. We create shadow
constructors (not found by name lookup) in the derived class to model the
actual initialization, and have a new expression node,
CXXInheritedCtorInitExpr, to model the initialization of a base class from such
a constructor. (This initialization is special because it performs real perfect
forwarding of arguments.)
In cases where argument forwarding is not possible (for inalloca calls,
variadic calls, and calls with callee parameter cleanup), the shadow inheriting
constructor is not emitted and instead we directly emit the initialization code
into the caller of the inherited constructor.
Note that this new model is not perfectly compatible with the old model in some
corner cases. In particular:
* if B inherits a private constructor from A, and C uses that constructor to
construct a B, then we previously required that A befriends B and B
befriends C, but the new rules require A to befriend C directly, and
* if a derived class has its own constructors (and so its implicit default
constructor is suppressed), it may still inherit a default constructor from
a base class
llvm-svn: 274049
Add support for /Ob1 (and equivalent -finline-hint-functions), which enable
inlining only for functions marked inline, either explicitly (via inline
keyword, for example), or implicitly (function definition in class body,
for example).
This works by enabling inlining pass, and adding noinline attribute to
every function not marked inline.
Patch by Rudy Pons <rudy.pons@ilod.org>!
Differential Revision: http://reviews.llvm.org/D20647
llvm-svn: 273440
This patch uses function metadata to represent reqd_work_group_size, work_group_size_hint and vector_type_hint kernel attributes and kernel argument info.
Differential Revision: http://reviews.llvm.org/D20979
llvm-svn: 273425
Summary:
This should have been a very simple change, but it was greatly
complicated by the construction of new Decls during IR generation.
In particular, we reconstruct the AST function type in order to get the
implicit 'this' parameter into C++ method types.
We also have to worry about FunctionDecls whose types are not
FunctionTypes because CGBlocks.cpp constructs some dummy FunctionDecls
with 'void' type.
Depends on D21114
Reviewers: aprantl, dblaikie
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D21141
llvm-svn: 272198
Revert the two changes to thread CodeGenOptions into the TargetInfo allocation
and to fix the layering violation by moving CodeGenOptions into Basic.
Code Generation is arguably not particularly "basic". This addresses Richard's
post-commit review comments. This change purely does the mechanical revert and
will be followed up with an alternate approach to thread the desired information
into TargetInfo.
llvm-svn: 265806
This is a mechanical move of CodeGenOptions from libFrontend to libBasic. This
fixes the layering violation introduced earlier by threading CodeGenOptions into
TargetInfo. It should also fix the modules based self-hosting builds. NFC.
llvm-svn: 265702
Add no-jump-tables flag to disable use of jump tables when lowering
switch statements
Reviewers: echristo, hans
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D18407
llvm-svn: 265425
Implement lambda capture of *this by copy.
For e.g.:
struct A {
int d = 10;
auto foo() { return [*this] (auto a) mutable { d+=a; return d; }; }
};
auto L = A{}.foo(); // A{}'s lifetime is gone.
// Below is still ok, because *this was captured by value.
assert(L(10) == 20);
assert(L(100) == 120);
If the capture was implicit, or [this] (i.e. *this was captured by reference), this code would be otherwise undefined.
Implementation Strategy:
- amend the parser to accept *this in the lambda introducer
- add a new king of capture LCK_StarThis
- teach Sema::CheckCXXThisCapture to handle by copy captures of the
enclosing object (i.e. *this)
- when CheckCXXThisCapture does capture by copy, the corresponding
initializer expression for the closure's data member
direct-initializes it thus making a copy of '*this'.
- in codegen, when assigning to CXXThisValue, if *this was captured by
copy, make sure it points to the corresponding field member, and
not, unlike when captured by reference, what the field member points
to.
- mark feature as implemented in svn
Much gratitude to Richard Smith for his carefully illuminating reviews!
llvm-svn: 263921
Summary:
This flag is enabled by default in the driver when NDEBUG is set. It
is forwarded on the LLVMContext to discard all value names (but
GlobalValue) for performance purpose.
This an improved version of D18024
Reviewers: echristo, chandlerc
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D18127
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 263394
commit 60d9845f6a037122d9be9a6d92d4de617ef45b04
Author: Mehdi Amini <mehdi.amini@apple.com>
Date: Fri Mar 11 18:48:02 2016 +0000
Fix clang crash: when CodeGenAction is initialized without a
context, use the member and not the parameter
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@263273
91177308-0d34-0410-b5e6-96231b3b80d8
commit af7ce3bf04a75ad5124b457b805df26006bd215b
Author: Mehdi Amini <mehdi.amini@apple.com>
Date: Fri Mar 11 17:32:58 2016 +0000
Fix build: use -> with pointers and not .
Silly typo.
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@263267
91177308-0d34-0410-b5e6-96231b3b80d8
commit d0eea119192814954e7368c77d0dc5a9eeec1fbb
Author: Mehdi Amini <mehdi.amini@apple.com>
Date: Fri Mar 11 17:15:44 2016 +0000
Remove compile time PreserveName switch based on NDEBUG
Summary:
Following r263086, we are now relying on a flag on the Context to
discard Value names in release builds.
Reviewers: chandlerc
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D18024
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@263257
91177308-0d34-0410-b5e6-96231b3b80d8
until we can fix the Release builds.
This reverts commits 263257, 263267, 263273
llvm-svn: 263320
Summary:
Following r263086, we are now relying on a flag on the Context to
discard Value names in release builds.
Reviewers: chandlerc
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D18024
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 263257
We'd lose track of the parent CodeGenFunction, leading us to get
confused with regard to which function a nested finally belonged to.
Differential Revision: http://reviews.llvm.org/D17752
llvm-svn: 262379
Summary:
OpenCL access qualifiers are now not only used for image types, refine it to avoid misleading,
Add semacheck for OpenCL access qualifier as well as test caees.
Reviewers: pekka.jaaskelainen, Anastasia, aaron.ballman
Subscribers: aaron.ballman, cfe-commits
Differential Revision: http://reviews.llvm.org/D16040
llvm-svn: 261961
This patch changes cc1 option -fprofile-instr-generate to an enum option
-fprofile-instrument={clang|none}. It also changes cc1 options
-fprofile-instr-generate= to -fprofile-instrument-path=.
The driver level option -fprofile-instr-generate and -fprofile-instr-generate=
remain intact. This change will pave the way to integrate new PGO
instrumentation in IR level.
Review: http://reviews.llvm.org/D16730
llvm-svn: 259811
This is part of a new statistics gathering feature for the sanitizers.
See clang/docs/SanitizerStats.rst for further info and docs.
Differential Revision: http://reviews.llvm.org/D16175
llvm-svn: 257971
Summary:
Support for OpenCL 2.0 pipe type.
This is a bug-fix version for bader's patch reviews.llvm.org/D14441
Reviewers: pekka.jaaskelainen, Anastasia
Subscribers: bader, Anastasia, cfe-commits
Differential Revision: http://reviews.llvm.org/D15603
llvm-svn: 257254
Constructors and destructors may be represented by several functions
in IR. Only base structors correspond to source code, others are
small pieces of code and eventually call the base variant. In this
case instrumentation of non-base structors has little sense, this
fix remove it. Now profile data of a declaration corresponds to
exactly one function in IR, it agrees with the current logic of the
profile data loading.
This change fixes PR24996.
Differential Revision: http://reviews.llvm.org/D15158
llvm-svn: 254876
`pass_object_size` is our way of enabling `__builtin_object_size` to
produce high quality results without requiring inlining to happen
everywhere.
A link to the design doc for this attribute is available at the
Differential review link below.
Differential Revision: http://reviews.llvm.org/D13263
llvm-svn: 254554
target attribute, don't include "negative" subtarget features in the
list of required features. Builtins are positive by default so don't
need this change, but we pull the default list of features from the
command line and so need to make sure that we only include features
that are turned on for code generation in our error.
llvm-svn: 253242
The C++ spec (3.6.1.3) says "The function `main` shall not be used within a program". This implies that it cannot recurse, so add the norecurse attribute to help the midend out a bit.
llvm-svn: 252902
target features that the caller function doesn't provide. This matches
the existing backend failure to inline functions that don't have
matching target features - and diagnoses earlier in the case of
always_inline.
Fix up a few test cases that were, in fact, invalid if you tried
to generate code from the backend with the specified target features
and add a couple of tests to illustrate what's going on.
This should fix PR25246.
llvm-svn: 252834
Summary: It breaks the build for the ASTMatchers
Subscribers: klimek, cfe-commits
Differential Revision: http://reviews.llvm.org/D13893
llvm-svn: 250827
Summary:
This change adds support for `__builtin_ms_va_list`, a GCC extension for
variadic `ms_abi` functions. The existing `__builtin_va_list` support is
inadequate for this because `va_list` is defined differently in the Win64
ABI vs. the System V/AMD64 ABI.
Depends on D1622.
Reviewers: rsmith, rnk, rjmccall
CC: cfe-commits
Differential Revision: http://reviews.llvm.org/D1623
llvm-svn: 247941
The type of a member pointer is incomplete if it has no inheritance
model. This lets us reuse more general logic already embedded in clang.
llvm-svn: 247346
Introduce an Address type to bundle a pointer value with an
alignment. Introduce APIs on CGBuilderTy to work with Address
values. Change core APIs on CGF/CGM to traffic in Address where
appropriate. Require alignments to be non-zero. Update a ton
of code to compute and propagate alignment information.
As part of this, I've promoted CGBuiltin's EmitPointerWithAlignment
helper function to CGF and made use of it in a number of places in
the expression emitter.
The end result is that we should now be significantly more correct
when performing operations on objects that are locally known to
be under-aligned. Since alignment is not reliably tracked in the
type system, there are inherent limits to this, but at least we
are no longer confused by standard operations like derived-to-base
conversions and array-to-pointer decay. I've also fixed a large
number of bugs where we were applying the complete-object alignment
to a pointer instead of the non-virtual alignment, although most of
these were hidden by the very conservative approach we took with
member alignment.
Also, because IRGen now reliably asserts on zero alignments, we
should no longer be subject to an absurd but frustrating recurring
bug where an incomplete type would report a zero alignment and then
we'd naively do a alignmentAtOffset on it and emit code using an
alignment equal to the largest power-of-two factor of the offset.
We should also now be emitting much more aggressive alignment
attributes in the presence of over-alignment. In particular,
field access now uses alignmentAtOffset instead of min.
Several times in this patch, I had to change the existing
code-generation pattern in order to more effectively use
the Address APIs. For the most part, this seems to be a strict
improvement, like doing pointer arithmetic with GEPs instead of
ptrtoint. That said, I've tried very hard to not change semantics,
but it is likely that I've failed in a few places, for which I
apologize.
ABIArgInfo now always carries the assumed alignment of indirect and
indirect byval arguments. In order to cut down on what was already
a dauntingly large patch, I changed the code to never set align
attributes in the IR on non-byval indirect arguments. That is,
we still generate code which assumes that indirect arguments have
the given alignment, but we don't express this information to the
backend except where it's semantically required (i.e. on byvals).
This is likely a minor regression for those targets that did provide
this information, but it'll be trivial to add it back in a later
patch.
I partially punted on applying this work to CGBuiltin. Please
do not add more uses of the CreateDefaultAligned{Load,Store}
APIs; they will be going away eventually.
llvm-svn: 246985
This patch depends on r246688 (D12341).
The goal is to make LLVM generate different code for these functions for a target that
has cheap branches (see PR23827 for more details):
int foo();
int normal(int x, int y, int z) {
if (x != 0 && y != 0) return foo();
return 1;
}
int crazy(int x, int y) {
if (__builtin_unpredictable(x != 0 && y != 0)) return foo();
return 1;
}
Differential Revision: http://reviews.llvm.org/D12458
llvm-svn: 246699
The new EH instructions make it possible for LLVM to generate .xdata
tables that the MSVC personality routines will be happy about. Because
this is experimental, hide it behind a -cc1 flag (-fnew-ms-eh).
Differential Revision: http://reviews.llvm.org/D11405
llvm-svn: 243767
This reverts commit r241244, but restricts SEH support to Win64.
This way, Chromium builds will still fall back on TUs with SEH, and
Clang developers can work on this incrementally upstream while patching
this small predicate locally. It'll also make it easier to review small
fixes.
llvm-svn: 241533
This is needed to use clang's command line option "-ftrap-function" for LTO and
enable changing the trap function name on a per-call-site basis.
rdar://problem/21225723
Differential Revision: http://reviews.llvm.org/D10831
llvm-svn: 241306
This re-lands r236052 and adds support for __exception_code().
In 32-bit SEH, the exception code is not available in eax. It is only
available in the filter function, and now we arrange to load it and
store it into an escaped variable in the parent frame.
As a consequence, we have to disable the "catch i8* null" optimization
on 32-bit and always generate a filter function. We can re-enable the
optimization if we detect an __except block that doesn't use the
exception code, but this probably isn't worth optimizing.
Reviewers: majnemer
Differential Revision: http://reviews.llvm.org/D10852
llvm-svn: 241171
This patch adds initial support for the -fsanitize=kernel-address flag to Clang.
Right now it's quite restricted: only out-of-line instrumentation is supported, globals are not instrumented, some GCC kasan flags are not supported.
Using this patch I am able to build and boot the KASan tree with LLVMLinux patches from github.com/ramosian-glider/kasan/tree/kasan_llvmlinux.
To disable KASan instrumentation for a certain function attribute((no_sanitize("kernel-address"))) can be used.
llvm-svn: 240131
This patch adds the -fsanitize=safe-stack command line argument for clang,
which enables the Safe Stack protection (see http://reviews.llvm.org/D6094
for the detailed description of the Safe Stack).
This patch is our implementation of the safe stack on top of Clang. The
patches make the following changes:
- Add -fsanitize=safe-stack and -fno-sanitize=safe-stack options to clang
to control safe stack usage (the safe stack is disabled by default).
- Add __attribute__((no_sanitize("safe-stack"))) attribute to clang that can be
used to disable the safe stack for individual functions even when enabled
globally.
Original patch by Volodymyr Kuznetsov and others at the Dependable Systems
Lab at EPFL; updates and upstreaming by myself.
Differential Revision: http://reviews.llvm.org/D6095
llvm-svn: 239762
- added -fcuda-include-gpubinary option to incorporate results of
device-side compilation into host-side one.
- generate code to register GPU binaries and associated kernels
with CUDA runtime and clean-up on exit.
- added test case for init/deinit code generation.
Differential Revision: http://reviews.llvm.org/D9507
llvm-svn: 236765
The fact that PGO has a say in how these branch weights are determined
isn't interesting to most of CodeGen, so it makes more sense for this
API to be accessible via CodeGenFunction rather than CodeGenPGO.
llvm-svn: 236380
This is just the clang-side of 32-bit SEH. LLVM still needs work, and it
will determinstically fail to compile until it's feature complete.
On x86, all outlined handlers have no parameters, but they do implicitly
take the EBP value passed in and use it to address locals of the parent
frame. We model this with llvm.frameaddress(1).
This works (mostly), but __finally block inlining can break it. For now,
we apply the 'noinline' attribute. If we really want to inline __finally
blocks on 32-bit x86, we should teach the inliner how to untangle
frameescape and framerecover.
Promote the error diagnostic from codegen to sema. It now rejects SEH on
non-Windows platforms. LLVM doesn't implement SEH on non-x86 Windows
platforms, but there's nothing preventing it.
llvm-svn: 236052
The RegionCounter type does a lot of legwork, but most of it is only
meaningful within the implementation of CodeGenPGO. The uses elsewhere
in CodeGen generally just want to increment or read counters, so do
that directly.
llvm-svn: 235664
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
Even though these symbols are in a comdat group, the Microsoft linker
really wants them to have internal linkage.
I'm planning to tweak the mangling in a follow-up change. This is a
straight revert with a 1-line fix.
llvm-svn: 234613
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
WinEHPrepare was going to have to pattern match the control flow merge
and split that the old lowering used, and that wasn't really feasible.
Now we can teach WinEHPrepare to pattern match this, which is much
simpler:
%fp = call i8* @llvm.frameaddress(i32 0)
call void @func(iN [01], i8* %fp)
This prototype happens to match the prototype used by the Win64 SEH
personality function, so this is really simple.
llvm-svn: 234532
The driver currently accepts but ignores the -freciprocal-math flag.
This patch passes the flag through and enables 'arcp' fast-math-flag
generation in IR.
Note that this change does not actually enable the optimization for
any target. The reassociation optimization that this flag specifies
was implemented by http://reviews.llvm.org/D6334 :
http://llvm.org/viewvc/llvm-project?view=revision&revision=222510
Because the optimization is done in the backend rather than IR,
the backend must be modified to understand instruction-level
fast-math-flags or a new function-level attribute must be created.
Also note that -freciprocal-math is independent of any target-specific
usage of reciprocal estimate hardware instructions. That requires
its own flag ('-mrecip').
https://llvm.org/bugs/show_bug.cgi?id=20912
llvm-svn: 234493
The test should be fixed. It was failing in NDEBUG builds due to a
missing '*' character in a regex. In asserts builds, the pattern matched
a single digit value, which became a double digit value in NDEBUG
builds. Go figure.
This reverts commit r234261.
llvm-svn: 234447
While capturing filters aren't very common, we'd like to outline
__finally blocks in the frontend to simplify -O0 EH preparation and
reduce code size. Finally blocks are usually have captures, and this is
the first step towards that.
Currently we don't support capturing 'this' or VLAs.
Reviewers: majnemer
Differential Revision: http://reviews.llvm.org/D8825
llvm-svn: 234261
There are no widely deployed standard libraries providing sized
deallocation functions, so we have to punt and ask the user if they want
us to use sized deallocation. In the future, when such libraries are
deployed, we can teach the driver to detect them and enable this
feature.
N3536 claimed that a weak thunk from sized to unsized deallocation could
be emitted to avoid breaking backwards compatibility with standard
libraries not providing sized deallocation. However, this approach and
other variations don't work in practice.
With the weak function approach, the thunk has to have default
visibility in order to ensure that it is overridden by other DSOs
providing sized deallocation. Weak, default visibility symbols are
particularly expensive on MachO, so John McCall was considering
disabling this feature by default on Darwin. It also changes behavior
ELF linking behavior, causing certain otherwise unreferenced object
files from an archive to be pulled into the link.
Our second approach was to use an extern_weak function declaration and
do an inline conditional branch at the deletion call site. This doesn't
work because extern_weak only works on MachO if you have some archive
providing the default value of the extern_weak symbol. Arranging to
provide such an archive has the same challenges as providing the symbol
in the standard library. Not to mention that extern_weak doesn't really
work on COFF.
Reviewers: rsmith, rjmccall
Differential Revision: http://reviews.llvm.org/D8467
llvm-svn: 232788
Previously we would simply double-emit the body of the __finally block,
but that doesn't work when it contains any kind of Decl, which we can't
double emit.
This fixes that by emitting the block once and branching into a shared
code region and then branching back out.
llvm-svn: 228222
Now if you break on a dtor and go 'up' in your debugger (or you get an
asan failure in a dtor) during an exception unwind, you'll have more
context. Instead of all dtors appearing to be called from the '}' of the
function, they'll be attributed to the end of the scope of the variable,
the same as the non-exceptional dtor call.
This doesn't /quite/ remove all uses of CurEHLocation (which might be
nice to remove, for a few reasons) - it's still used to choose the
location for some other work in the landing pad. It'd be nice to
attribute that code to the same location as the exception calls within
the block and to remove CurEHLocation.
llvm-svn: 228181
