Summary:
Right now we annotate C++'s `operator new` with `noalias` attribute,
which very much is healthy for optimizations.
However as per [[ http://eel.is/c++draft/basic.stc.dynamic.allocation | `[basic.stc.dynamic.allocation]` ]],
there are more promises on global `operator new`, namely:
* non-`std::nothrow_t` `operator new` *never* returns `nullptr`
* If `std::align_val_t align` parameter is taken, the pointer will also be `align`-aligned
* ~~global `operator new`-returned pointer is `__STDCPP_DEFAULT_NEW_ALIGNMENT__`-aligned ~~ It's more caveated than that.
Supplying this information may not cause immediate landslide effects
on any specific benchmarks, but it for sure will be healthy for optimizer
in the sense that the IR will better reflect the guarantees provided in the source code.
The caveat is `-fno-assume-sane-operator-new`, which currently prevents emitting `noalias`
attribute, and is automatically passed by Sanitizers ([[ https://bugs.llvm.org/show_bug.cgi?id=16386 | PR16386 ]]) - should it also cover these attributes?
The problem is that the flag is back-end-specific, as seen in `test/Modules/explicit-build-flags.cpp`.
But while it is okay to add `noalias` metadata in backend, we really should be adding at least
the alignment metadata to the AST, since that allows us to perform sema checks on it.
Reviewers: erichkeane, rjmccall, jdoerfert, eugenis, rsmith
Reviewed By: rsmith
Subscribers: xbolva00, jrtc27, atanasyan, nlopes, cfe-commits
Tags: #llvm, #clang
Differential Revision: https://reviews.llvm.org/D73380
Summary:
Depends on https://reviews.llvm.org/D71902.
The last in a series of six patches that ports the LLVM coroutines
passes to the new pass manager infrastructure.
This patch has Clang schedule the new coroutines passes when the
`-fexperimental-new-pass-manager` option is used. With this and the
previous 5 patches, Clang is capable of building and successfully
running the test suite of large coroutines projects such as
https://github.com/lewissbaker/cppcoro with
`ENABLE_EXPERIMENTAL_NEW_PASS_MANAGER=On`.
Reviewers: GorNishanov, lewissbaker, chandlerc, junparser
Subscribers: EricWF, cfe-commits, llvm-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D71903
Summary:
Clang -fpic defaults to -fno-semantic-interposition (GCC -fpic defaults
to -fsemantic-interposition).
Users need to specify -fsemantic-interposition to get semantic
interposition behavior.
Semantic interposition is currently a best-effort feature. There may
still be some cases where it is not handled well.
Reviewers: peter.smith, rnk, serge-sans-paille, sfertile, jfb, jdoerfert
Subscribers: dschuff, jyknight, dylanmckay, nemanjai, jvesely, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, arphaman, PkmX, jocewei, jsji, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D73865
For consistency with normal instructions and clarity when reading IR,
it's best to print the %0, %1, ... names of function arguments in
definitions.
Also modifies the parser to accept IR in that form for obvious reasons.
llvm-svn: 367755
This reverts commit https://reviews.llvm.org/rL344150 which causes
MachineOutliner related failures on the ppc64le multistage buildbot.
llvm-svn: 344526
This is currently a clang extension and a resolution
of the defect report in the C++ Standard.
Differential Revision: https://reviews.llvm.org/D46441
llvm-svn: 344150
Summary:
In his review of https://reviews.llvm.org/D45860, @GorNishanov suggested
avoiding generating additional exception-handling IR in the case that
the resume function was marked as 'noexcept', and exceptions could not
occur. This implements that suggestion.
Test Plan: `check-clang`
Reviewers: GorNishanov, EricWF
Reviewed By: GorNishanov
Subscribers: cfe-commits, GorNishanov
Differential Revision: https://reviews.llvm.org/D47673
llvm-svn: 335422
Summary:
http://wg21.link/P0664r2 section "Evolution/Core Issues 24" describes a
proposed change to Coroutines TS that would have any exceptions thrown
after the initial suspend point of a coroutine be caught by the handler
specified by the promise type's 'unhandled_exception' member function.
This commit provides a sample implementation of the specified behavior.
Test Plan: `check-clang`
Reviewers: GorNishanov, EricWF
Reviewed By: GorNishanov
Subscribers: cfe-commits, lewissbaker, eric_niebler
Differential Revision: https://reviews.llvm.org/D45860
llvm-svn: 331519
A recent addition to Coroutines TS (https://wg21.link/p0913) adds a pre-defined
coroutine noop_coroutine that does nothing. To implement this feature, we implemented
an llvm.coro.noop intrinsic that returns a coroutine handle to a coroutine that
does nothing when resumed or destroyed.
This patch adds a builtin __builtin_coro_noop() that maps to llvm.coro.noop intrinsic.
Related llvm change: https://reviews.llvm.org/D45114
llvm-svn: 328993
Summary:
https://reviews.llvm.org/rL325291 implemented Coroutines TS N4723
section [dcl.fct.def.coroutine]/7, but it performed lookup of allocator
functions within both the global and class scope, whereas the specified
behavior is to perform lookup for custom allocators within just the
class scope.
To fix, add parameters to the `Sema::FindAllocationFunctions` function
such that it can be used to lookup allocators in global scope,
class scope, or both (instead of just being able to look up in just global
scope or in both global and class scope). Then, use those parameters
from within the coroutine Sema.
This incorrect behavior had the unfortunate side-effect of causing the
bug https://bugs.llvm.org/show_bug.cgi?id=36578 (or at least the reports
of that bug in C++ programs). That bug would occur for any C++ user with
a coroutine frame that took a single pointer argument, since it would
then find the global placement form `operator new`, described in the
C++ standard 18.6.1.3.1. This patch prevents Clang from generating code
that triggers the LLVM assert described in that bug report.
Test Plan: `check-clang`
Reviewers: GorNishanov, eric_niebler, lewissbaker
Reviewed By: GorNishanov
Subscribers: EricWF, cfe-commits
Differential Revision: https://reviews.llvm.org/D44552
llvm-svn: 328949
Summary:
Previously we tried too hard to uphold the fiction that destructor
variants work like they do on Itanium throughout the ABI-neutral parts
of clang. This lead to MS C++ ABI incompatiblities and other bugs. Now,
-mconstructor-aliases will no longer control this ABI detail, and clang
-cc1's LLVM IR output will be this much closer to the clang driver's.
Based on a patch by Zahira Ammarguellat:
https://reviews.llvm.org/D39063
I've tried to move the logic that Zahira added into MicrosoftCXXABI.cpp.
There is only one ABI-specific detail sticking out, and that is in
CodeGenModule::getAddrOfCXXStructor, where we collapse complete dtors to
base dtors in the MS ABI.
This fixes PR32990.
Reviewers: erichkeane, zahiraam, majnemer, rjmccall
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D44505
llvm-svn: 327732
The tests that failed on a windows host have been fixed.
Original message:
Start setting dso_local for COFF.
With this there are still some GVs where we don't set dso_local
because setGVProperties is never called. I intend to fix that in
followup commits. This is just the bare minimum to teach
shouldAssumeDSOLocal what it should do for COFF.
llvm-svn: 325940
With this there are still some GVs where we don't set dso_local
because setGVProperties is never called. I intend to fix that in
followup commits. This is just the bare minimum to teach
shouldAssumeDSOLocal what it should do for COFF.
llvm-svn: 325915
Summary:
Depends on https://reviews.llvm.org/D42605.
An implementation of the behavior described in `[dcl.fct.def.coroutine]/7`:
when a promise type overloads `operator new` using a "placement new"
that takes the same argument types as the coroutine function, that
overload is used when allocating the coroutine frame.
Simply passing references to the coroutine function parameters directly
to `operator new` results in invariant violations in LLVM's coroutine
splitting pass, so this implementation modifies Clang codegen to
produce allocator-specific alloc/store/loads for each parameter being
forwarded to the allocator.
Test Plan: `check-clang`
Reviewers: rsmith, GorNishanov, eric_niebler
Reviewed By: GorNishanov
Subscribers: lewissbaker, EricWF, cfe-commits
Differential Revision: https://reviews.llvm.org/D42606
llvm-svn: 325291
Summary:
Fix NRVO for Gro variable.
Previously, we only marked the GRO declaration as an NRVO variable
when its QualType and the function return's QualType matched exactly
(using operator==). However, this was incorrect for two reasons:
1. We were marking non-class types, such as ints, as being NRVO variables.
2. We failed to handle cases where the canonical types were the same, but the actual `QualType` objects were different. For example, if one was represented by a typedef. (Example: https://godbolt.org/g/3UFgsL)
This patch fixes these bugs by marking the Gro variable as supporting NRVO only
when `BuildReturnStmt` marks the Gro variable as a coroutine candidate.
Reviewers: rsmith, GorNishanov, nicholas
Reviewed By: GorNishanov
Subscribers: majnemer, cfe-commits
Differential Revision: https://reviews.llvm.org/D42343
llvm-svn: 324037
Summary:
Fix NRVO for Gro variable.
Previously, we only marked the GRO declaration as an NRVO variable
when its QualType and the function return's QualType matched exactly
(using operator==). However, this was incorrect for two reasons:
1. We were marking non-class types, such as ints, as being NRVO variables.
2. We failed to handle cases where the canonical types were the same, but the actual `QualType` objects were different. For example, if one was represented by a typedef. (Example: https://godbolt.org/g/3UFgsL)
This patch fixes these bugs by marking the Gro variable as supporting NRVO only
when `BuildReturnStmt` marks the Gro variable as a coroutine candidate.
Reviewers: rsmith, GorNishanov, nicholas
Reviewed By: GorNishanov
Subscribers: majnemer, cfe-commits
Differential Revision: https://reviews.llvm.org/D42343
llvm-svn: 323712
Summary:
Use corutine function arguments to initialize a promise type, but only
if the promise type defines a constructor that takes those arguments.
Otherwise, fall back to the default constructor.
Test Plan: check-clang
Reviewers: rsmith, GorNishanov, eric_niebler
Reviewed By: GorNishanov
Subscribers: toby-allsopp, lewissbaker, EricWF, cfe-commits
Differential Revision: https://reviews.llvm.org/D41820
llvm-svn: 323381
Summary:
We don't want to store cleanup dest slot saved into the coroutine frame (as some of the cleanup code may
access them after coroutine frame destroyed).
This is an alternative to https://reviews.llvm.org/D37093
It is possible to do this for all functions, but, cursory check showed that in -O0, we get slightly longer function (by 1-3 instructions), thus, we are only limiting cleanup.dest.slot elimination to coroutines.
Reviewers: rjmccall, hfinkel, eric_niebler
Reviewed By: eric_niebler
Subscribers: EricWF, cfe-commits
Differential Revision: https://reviews.llvm.org/D39768
llvm-svn: 317981
Summary:
If await_suspend returns a coroutine_handle, as in the example below:
```
coroutine_handle<> await_suspend(coroutine_handle<> h) {
coro.promise().waiter = h;
return coro;
}
```
suspensionExpression processing will resume the coroutine pointed at by that handle.
Related LLVM change rL311751 makes resume calls of this kind `musttail` at any optimization level.
This enables unlimited symmetric control transfer from coroutine to coroutine without blowing up the stack.
Reviewers: GorNishanov
Reviewed By: GorNishanov
Subscribers: rsmith, EricWF, cfe-commits
Differential Revision: https://reviews.llvm.org/D37131
llvm-svn: 311762
Summary:
Previously Clang incorrectly ignored the expression of a void `co_return`. This patch addresses that bug.
I'm not quite sure if I got the code-gen right, but this patch is at least a start.
Reviewers: rsmith, GorNishanov
Reviewed By: rsmith, GorNishanov
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D36070
llvm-svn: 309545
Summary:
The title says it all.
Reviewers: GorNishanov, rsmith
Reviewed By: GorNishanov
Subscribers: rjmccall, cfe-commits
Differential Revision: https://reviews.llvm.org/D34194
llvm-svn: 305496
Summary:
We were not handling correctly rebuilding of parameter and were not creating copies for them.
Now we will always rebuild parameter moves in TreeTransform's TransformCoroutineBodyStmt.
Reviewers: rsmith, GorNishanov
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D33797
llvm-svn: 304620
Summary:
Simple types like int are handled by LLVM Coroutines just fine.
But for non-scalar parameters we need to create copies of those parameters in the coroutine frame and make all uses of those parameters to refer to parameter copies.
Reviewers: rsmith, EricWF, GorNishanov
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D33507
llvm-svn: 303803
Summary:
1. Coroutine cannot be constexpr (added a check in SemaLambda.cpp not to mark coroutine as constexpr)
2. TransformCoroutineBodyStmt should transform ResultDecl and ReturnStmt
Reviewers: rsmith, GorNishanov
Reviewed By: GorNishanov
Subscribers: EricWF, cfe-commits
Differential Revision: https://reviews.llvm.org/D33498
llvm-svn: 303764
Summary:
* Test that coroutine promise destructor is called.
* Test that we call return_void on fallthrough
* Test that we call unhandled exception in a try catch surrounding the body
Reviewers: EricWF, GorNishanov
Reviewed By: GorNishanov
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D33479
llvm-svn: 303748
Summary:
Sema creates a declaration for gro variable as:
auto $gro = $promise.get_return_object();
However, gro variable has to outlive coroutine frame and coroutine promise, but,
it can only be initialized after the coroutine promise was created, thus, we
split its emission in two parts: EmitGroAlloca emits an alloca and sets up
the cleanups. Later when the coroutine promise is available we initialize
the gro and set the flag that the cleanup is now active.
Duplicate of: https://reviews.llvm.org/D31670 (which arc patch refuses to apply for some reason)
Reviewers: GorNishanov, rsmith
Reviewed By: GorNishanov
Subscribers: EricWF, cfe-commits
Differential Revision: https://reviews.llvm.org/D33477
llvm-svn: 303716
Wrap deallocation code with:
if (auto *mem = coro.free()) Deallocate
When backend decides to elide allocations it will replace coro.free with nullptr to suppress deallocation code.
llvm-svn: 303599
SemaCoroutine forms expressions referring to the coroutine frame of the enclosing coroutine using coro.frame builtin.
During codegen, we emit llvm.coro.begin intrinsic that returns the address of the coroutine frame.
When coro.frame is emitted, we replace it with SSA value of coro.begin.
llvm-svn: 303598
Summary:
If unhandled_exception member function is present in the coroutine promise,
wrap the body of the coroutine in:
```
try {
body
} catch(...) { promise.unhandled_exception(); }
```
Reviewers: EricWF, rnk, rsmith
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D31692
llvm-svn: 303583
Summary:
1. build declaration of the gro local variable that keeps the result of get_return_object.
2. build return statement returning the gro variable
3. emit them during CodeGen
4. sema and CodeGen tests updated
Reviewers: EricWF, rsmith
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D31646
llvm-svn: 303573
Summary:
This patch implements [dcl.fct.def.coroutine]p8:
> The unqualified-id get_return_object_on_allocation_failure is looked up in the scope of
> class P by class member access lookup (3.4.5). If a declaration is found, ..., and if a
> global allocation function is selected, the ::operator new(size_t, nothrow_t) form shall be used.
> [...]
> The allocation function used in this case must have a non-throwing noexcept-specification.
Reviewers: GorNishanov, rsmith, majnemer, aaron.ballman
Reviewed By: GorNishanov
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D31562
llvm-svn: 300524
Summary:
Certain implicitly generated coroutine statements, such as the calls to 'return_value()' or `return_void()` or `get_return_object_on_allocation_failure()`, cannot be built until the promise type is no longer dependent. This means they are not built until after the coroutine body statement has been transformed.
This patch fixes an issue where these statements would never be built for coroutine templates.
It also fixes a small issue where diagnostics about `get_return_object_on_allocation_failure()` were incorrectly suppressed.
Reviewers: rsmith, majnemer, GorNishanov, aaron.ballman
Reviewed By: GorNishanov
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D31487
llvm-svn: 300504
Erik Pilkington