This patch is a second attempt at fixing a link error for MSVC
entry points when calling conventions are specified using a flag.
Calling conventions specified using flags should not be applied to MSVC
entry points. The default calling convention is set in this case. The
default calling convention for MSVC entry points main and wmain is cdecl.
For WinMain, wWinMain and DllMain, the default calling convention is
stdcall on 32 bit Windows.
Explicitly specified calling conventions are applied to MSVC entry points.
For MinGW, the default calling convention for all MSVC entry points is
cdecl.
First attempt: 4cff1b40da
Revert of first attempt: bebfc3b92d
Differential Revision: https://reviews.llvm.org/D97941
This reverts commit 809a1e0ffd.
Mach-O doesn't support dso_local and this change broke XNU because of the use of dso_local.
Differential Revision: https://reviews.llvm.org/D98458
The condition variable is in scope in the loop increment, so we need to
emit the jump destination from wthin the scope of the condition
variable.
For GCC compatibility (and compatibility with real-world 'FOR_EACH'
macros), 'continue' is permitted in a statement expression within the
condition of a for loop, though, so there are two cases here:
* If the for loop has no condition variable, we can emit the jump
destination before emitting the condition.
* If the for loop has a condition variable, we must defer emitting the
jump destination until after emitting the variable. We diagnose a
'continue' appearing in the initializer of the condition variable,
because it would jump past the initializer into the scope of that
variable.
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D98816
This was motivated by the fact that constructor type homing (debug info
optimization that we want to turn on by default) drops some libc++ types,
so an attribute would allow us to override constructor homing and emit
them anyway. I'm currently looking into the particular libc++ issue, but
even if we do fix that, this issue might come up elsewhere and it might be
nice to have this.
As I've implemented it now, the attribute isn't specific to the
constructor homing optimization and overrides all of the debug info
optimizations.
Open to discussion about naming, specifics on what the attribute should do, etc.
Differential Revision: https://reviews.llvm.org/D97411
Commit 1b04bdc2f3 added support for
capturing the 'this' pointer in a SEH context (__finally or __except),
But the case in which the 'this' pointer is part of a lambda capture
was not handled properly
Differential Revision: https://reviews.llvm.org/D97687
This patch implements the conditional select operator for
ext_vector_types in C++. It does so by using the same semantics as for
C.
D71463 added support for the conditional select operator for VectorType
in C++. Unfortunately the semantics between ext_vector_type in C are
different to VectorType in C++. Select for ext_vector_type is based on
the MSB of the condition vector, whereas for VectorType it is `!= 0`.
This unfortunately means that the behavior is inconsistent between
ExtVectorType and VectorType, but I think using the C semantics for
ExtVectorType in C++ as well should be less surprising for users.
Reviewed By: erichkeane, aaron.ballman
Differential Revision: https://reviews.llvm.org/D98055
Background:
Wasm EH, while using Windows EH (catchpad/cleanuppad based) IR, uses
Itanium-based libraries and ABIs with some modifications.
`__clang_call_terminate` is a wrapper generated in Clang's Itanium C++
ABI implementation. It contains this code, in C-style pseudocode:
```
void __clang_call_terminate(void *exn) {
__cxa_begin_catch(exn);
std::terminate();
}
```
So this function is a wrapper to call `__cxa_begin_catch` on the
exception pointer before termination.
In Itanium ABI, this function is called when another exception is thrown
while processing an exception. The pointer for this second, violating
exception is passed as the argument of this `__clang_call_terminate`,
which calls `__cxa_begin_catch` with that pointer and calls
`std::terminate` to terminate the program.
The spec (https://libcxxabi.llvm.org/spec.html) for `__cxa_begin_catch`
says,
```
When the personality routine encounters a termination condition, it
will call __cxa_begin_catch() to mark the exception as handled and then
call terminate(), which shall not return to its caller.
```
In wasm EH's Clang implementation, this function is called from
cleanuppads that terminates the program, which we also call terminate
pads. Cleanuppads normally don't access the thrown exception and the
wasm backend converts them to `catch_all` blocks. But because we need
the exception pointer in this cleanuppad, we generate
`wasm.get.exception` intrinsic (which will eventually be lowered to
`catch` instruction) as we do in the catchpads. But because terminate
pads are cleanup pads and should run even when a foreign exception is
thrown, so what we have been doing is:
1. In `WebAssemblyLateEHPrepare::ensureSingleBBTermPads()`, we make sure
terminate pads are in this simple shape:
```
%exn = catch
call @__clang_call_terminate(%exn)
unreachable
```
2. In `WebAssemblyHandleEHTerminatePads` pass at the end of the
pipeline, we attach a `catch_all` to terminate pads, so they will be in
this form:
```
%exn = catch
call @__clang_call_terminate(%exn)
unreachable
catch_all
call @std::terminate()
unreachable
```
In `catch_all` part, we don't have the exception pointer, so we call
`std::terminate()` directly. The reason we ran HandleEHTerminatePads at
the end of the pipeline, separate from LateEHPrepare, was it was
convenient to assume there was only a single `catch` part per `try`
during CFGSort and CFGStackify.
---
Problem:
While it thinks terminate pads could have been possibly split or calls
to `__clang_call_terminate` could have been duplicated,
`WebAssemblyLateEHPrepare::ensureSingleBBTermPads()` assumes terminate
pads contain no more than calls to `__clang_call_terminate` and
`unreachable` instruction. I assumed that because in LLVM very limited
forms of transformations are done to catchpads and cleanuppads to
maintain the scoping structure. But it turned out to be incorrect;
passes can merge cleanuppads into one, including terminate pads, as long
as the new code has a correct scoping structure. One pass that does this
I observed was `SimplifyCFG`, but there can be more. After this
transformation, a single cleanuppad can contain any number of other
instructions with the call to `__clang_call_terminate` and can span many
BBs. It wouldn't be practical to duplicate all these BBs within the
cleanuppad to generate the equivalent `catch_all` blocks, only with
calls to `__clang_call_terminate` replaced by calls to `std::terminate`.
Unless we do more complicated transformation to split those calls to
`__clang_call_terminate` into a separate cleanuppad, it is tricky to
solve.
---
Solution (?):
This CL just disables the generation and use of `__clang_call_terminate`
and calls `std::terminate()` directly in its place.
The possible downside of this approach can be, because the Itanium ABI
intended to "mark" the violating exception handled, we don't do that
anymore. What `__cxa_begin_catch` actually does is increment the
exception's handler count and decrement the uncaught exception count,
which in my opinion do not matter much given that we are about to
terminate the program anyway. Also it does not affect info like stack
traces that can be possibly shown to developers.
And while we use a variant of Itanium EH ABI, we can make some
deviations if we choose to; we are already different in that in the
current version of the EH spec we don't support two-phase unwinding. We
can possibly consider a more complicated transformation later to
reenable this, but I don't think that has high priority.
Changes in this CL contains:
- In Clang, we don't generate a call to `wasm.get.exception()` intrinsic
and `__clang_call_terminate` function in terminate pads anymore; we
simply generate calls to `std::terminate()`, which is the default
implementation of `CGCXXABI::emitTerminateForUnexpectedException`.
- Remove `WebAssembly::ensureSingleBBTermPads() function and
`WebAssemblyHandleEHTerminatePads` pass, because terminate pads are
already `catch_all` now (because they don't need the exception
pointer) and we don't need these transformations anymore.
- Change tests to use `std::terminate` directly. Also removes tests that
tested `LateEHPrepare::ensureSingleBBTermPads` and
`HandleEHTerminatePads` pass.
- Drive-by fix: Add some function attributes to EH intrinsic
declarations
Fixes https://github.com/emscripten-core/emscripten/issues/13582.
Reviewed By: dschuff, tlively
Differential Revision: https://reviews.llvm.org/D97834
Use a WeakTrackingVH to cope with the stmt emission logic that cleans up
unreachable blocks. This invalidates the reference to the deferred
replacement placeholder. Cope with it.
Fixes PR25102 (from 2015!)
`GetAddrOfGlobalTemporary` previously tried to emit the initializer of
a global temporary before updating the global temporary map. Emitting the
initializer could recurse back into `GetAddrOfGlobalTemporary` for the same
temporary, resulting in an infinite recursion.
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D97733
Simply make sure that the CodeGenFunction::CXXThisValue and CXXABIThisValue
are correctly initialized to the recovered value.
For lambda capture, we also need to make sure to fill the LambdaCaptureFields
Differential Revision: https://reviews.llvm.org/D97534
For ELF targets, GCC 11 will set SHF_GNU_RETAIN on the section of a
`__attribute__((retain))` function/variable to prevent linker garbage
collection. (See AttrDocs.td for the linker support).
This patch adds `retain` functions/variables to the `llvm.used` list, which has
the desired linker GC semantics. Note: `retain` does not imply `used`,
so an unused function/variable can be dropped by Sema.
Before 'retain' was introduced, previous ELF solutions require inline asm or
linker tricks, e.g. `asm volatile(".reloc 0, R_X86_64_NONE, target");`
(architecture dependent) or define a non-local symbol in the section and use
`ld -u`. There was no elegant source-level solution.
With D97448, `__attribute__((retain))` will set `SHF_GNU_RETAIN` on ELF targets.
Differential Revision: https://reviews.llvm.org/D97447
An global value in the `llvm.used` list does not have GC root semantics on ELF targets.
This will be changed in a subsequent backend patch.
Change some `llvm.used` in the ELF code path to use `llvm.compiler.used` to
prevent undesired GC root semantics.
Change one extern "C" alias (due to `__attribute__((used))` in extern "C") to use `llvm.compiler.used` on all targets.
GNU ld has a rule "`__start_/__stop_` references from a live input section retain the associated C identifier name sections",
which LLD may drop entirely (currently refined to exclude SHF_LINK_ORDER/SHF_GROUP) in a future release (the rule makes it clumsy to GC metadata sections; D96914 added a way to try the potential future behavior).
For `llvm.used` global values defined in a C identifier name section, keep using `llvm.used` so that
the future LLD change will not affect them.
rnk kindly categorized the changes:
```
ObjC/blocks: this wants GC root semantics, since ObjC mainly runs on Mac.
MS C++ ABI stuff: wants GC root semantics, no change
OpenMP: unsure, but GC root semantics probably don't hurt
CodeGenModule: affected in this patch to *not* use GC root semantics so that __attribute__((used)) behavior remains the same on ELF, plus two other minor use cases that don't want GC semantics
Coverage: Probably want GC root semantics
CGExpr.cpp: refers to LTO, wants GC root
CGDeclCXX.cpp: one is MS ABI specific, so yes GC root, one is some other C++ init functionality, which should form GC roots (C++ initializers can have side effects and must run)
CGDecl.cpp: Changed in this patch for __attribute__((used))
```
Differential Revision: https://reviews.llvm.org/D97446
It would be beneficial to allow not_tail_called attribute to be applied to
virtual functions. I don't see any drawback of allowing this.
Differential Revision: https://reviews.llvm.org/D96832
Patch takes advantage of the implicit default behavior to reduce the number of attributes, which in turns reduces compilation time.
Reviewed By: serge-sans-paille
Differential Revision: https://reviews.llvm.org/D97116
Follow-up to fe2dcd89ac.
Update test per review comments, restoring the "D" type to its
original state, and adding new "L" type. (Sorry, this was intended to
be included in the prior commit)
Differential Revision: https://reviews.llvm.org/D96044
Previously, the definition was so-marked, but the declaration was
not. This resulted in LLVM's dwarf emission treating the function as
being external, and incorrectly emitting DW_AT_external.
Differential Revision: https://reviews.llvm.org/D96044
When WPD is enabled, via WholeProgramVTables, emit type metadata for
available_externally vtables. Additionally, add the vtables to the
llvm.compiler.used global so that they are not prematurely eliminated
(before *LTO analysis).
This is needed to avoid devirtualizing calls to a function overriding a
class defined in a header file but with a strong definition in a shared
library. Without type metadata on the available_externally vtables from
the header, the WPD analysis never sees what a derived class is
overriding. Even if the available_externally base class functions are
pure virtual, because shared library definitions are already treated
conservatively (committed patches D91583, D96721, and D96722) we will
not devirtualize, which would be unsafe since the library might contain
overrides that aren't visible to the LTO unit.
An example is std::error_category, which is overridden in LLVM
and causing failures after a self build with WPD enabled, because
libstdc++ contains hidden overrides of the virtual base class methods.
Differential Revision: https://reviews.llvm.org/D96919
This patch generates the `-f[no-]finite-loops` arguments from `CompilerInvocation` (added in D96419), fixing test failures of Clang built with `-DCLANG_ROUND_TRIP_CC1_ARGS=ON`.
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D96761
This patch ensures that vector predication and vectorization width
pragmas work together correctly/as expected. Specifically, this patch
fixes the issue that when vectorization_width > 1, the vector
predication behaviour (this would matter if it has NOT been disabled
explicitly by a pragma) was getting ignored, which was incorrect.
The fix here removes the dependence of vector predication on the
vectorization width. The loop metadata corresponding to clang loop
pragma vectorize_predicate is always emitted, if the pragma is
specified, even if vectorization is disabled by vectorize_width(1)
or vectorize(disable) since the option is also used for interleaving
by the LoopVectorize pass.
Reviewed By: dmgreen, Meinersbur
Differential Revision: https://reviews.llvm.org/D94779
This patch adds 2 new options to control when Clang adds `mustprogress`:
1. -ffinite-loops: assume all loops are finite; mustprogress is added
to all loops, regardless of the selected language standard.
2. -fno-finite-loops: assume no loop is finite; mustprogress is not
added to any loop or function. We could add mustprogress to
functions without loops, but we would have to detect that in Clang,
which is probably not worth it.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D96419
class types.
The goal is to provide a way to bypass constructor homing when emitting
class definitions and force class definitions in the debug info.
Not sure about the wording of the attribute, or whether it should be
specific to classes with constructors
The ability to specify alignment was recently added, and it's an
important property which we should ensure is set as expected by
Clang. (Especially before making further changes to Clang's code in
this area.) But, because it's on the end of the lines, the existing
tests all ignore it.
Therefore, update all the tests to also verify the expected alignment
for atomicrmw and cmpxchg. While I was in there, I also updated uses
of 'load atomic' and 'store atomic', and added the memory ordering,
where that was missing.
variable's destruction if it didn't do so during construction.
The standard doesn't give any guidance as to what to do here, but this
approach seems reasonable and conservative, and has been proposed to the
standard committee.
As Itanium ABI[http://itanium-cxx-abi.github.io/cxx-abi/abi.html#once-ctor]
points out:
"The size of the guard variable is 64 bits. The first byte (i.e. the byte at
the address of the full variable) shall contain the value 0 prior to
initialization of the associated variable, and 1 after initialization is complete."
Differential Revision: https://reviews.llvm.org/D95822
doubly-nested implicit CXXConstructExprs.
Ensure that we transform the parameter initializer using
TransformInitializer rather than TransformExpr so that we properly strip
down and rebuild the initialization, including any necessary
CXXBindTemporaryExprs. Otherwise we can end up forgetting to destroy
temporary objects used to construct a constructor parameter.
Normally, Clang will not make dllimport functions available for inlining
if they reference non-imported symbols, as this can lead to confusing
link errors. But if the function is marked always_inline, the user
presumably knows what they're doing and the attribute should be honored.
Differential revision: https://reviews.llvm.org/D95673
with fix to test case and stringrefs.
Currently (for codeview) lambdas have a string like `<lambda_0>` in
their mangled name, and don't have any display name. This change uses the
`<lambda_0>` as the display name, which helps distinguish between lambdas
in -gline-tables-only, since there are no linkage names there.
It also changes how we display lambda names; previously we used
`<unnamed-tag>`; now it will show `<lambda_0>`.
I added a function to the mangling context code to create this string;
for Itanium it just returns an empty string.
Bug: https://bugs.llvm.org/show_bug.cgi?id=48432
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D95187
This reverts 9b21d4b943
Currently (for codeview) lambdas have a string like `<lambda_0>` in
their mangled name, and don't have any display name. This change uses the
`<lambda_0>` as the display name, which helps distinguish between lambdas
in -gline-tables-only, since there are no linkage names there.
It also changes how we display lambda names; previously we used
`<unnamed-tag>`; now it will show `<lambda_0>`.
I added a function to the mangling context code to create this string;
for Itanium it just returns an empty string.
Bug: https://bugs.llvm.org/show_bug.cgi?id=48432
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D95187
The only test that needed change had 'QUAL' as an unused prefix. The
rest of the changes are to simplify the prefix lists.
Differential Revision: https://reviews.llvm.org/D95499
If an initial value is given for a bitfield that does not fit in the
bitfield, the value should be truncated. Constant folding for
expressions did not account for this truncation in the case of union
member functions, despite a warning being emitted. In some contexts,
evaluation of expressions was not enabled unless C++11, ROPI or RWPI
was enabled.
Differential Revision: https://reviews.llvm.org/D93101
The Clang enable_if extension is mangled as an <extended-qualifier>,
which is supposed to contain <template-args>. However, we were
unconditionally emitting X/E around its arguments, neglecting the fact
that <expr-primary> should be emitted directly without the surrounding
X/E.
Differential Revision: https://reviews.llvm.org/D95488
Previously, we were emitting an extraneous X .. E in <template-arg>
around an <expr-primary> if the template argument was constructed from
an expression (rather than an already-evaluated literal value). In
such a case, we would then e.g. emit 'XLi0EE' instead of 'Li0E'.
We had one special-case for DeclRefExpr expressions, in particular, to
omit them the mangled-name without the surrounding X/E. However,
unfortunately, that special case also triggered for ParmVarDecl (a
subtype of VarDecl), and _incorrectly_ emitted 'L_Z .. E' instead of
the proper 'Xfp_E'.
This change causes mangleExpression itself to be responsible for
emitting X/E around non-primary expressions, which removes the
special-case, and corrects both these problems.
Differential Revision: https://reviews.llvm.org/D95487
The two operations have acted differently since Clang 8, but were
unfortunately mangled the same. The new mangling uses new "vendor
extended expression" syntax proposed in
https://github.com/itanium-cxx-abi/cxx-abi/issues/112
GCC had the same mangling problem, https://gcc.gnu.org/PR88115, and
will hopefully be switching to the same mangling as implemented here.
Additionally, fix the mangling of `__uuidof` to use the new extension
syntax, instead of its previous nonstandard special-case.
Adjusts the demangler accordingly.
Differential Revision: https://reviews.llvm.org/D93922
The test ms-lookup-template-base-classes.cpp added in d972d4c749
is failing on some builtbot that don't include x86.
This patch should fix that (following the patterns in the test directory).
Elizabeth Andrews