Whenever LLVM_ENABLE_ABI_BREAKING_CHECKS is enabled, which
is usually the case for example when asserts are enabled,
Error's destructor does some additional checking to make sure
that that it does not represent an error condition and that it
was checked.
However, this is -- by definition -- not the likely codepath.
Some profiling shows that at least with some compilers, simply
calling assertIsChecked -- in a release build with full
optimizations -- can account for up to 15% of the entire
runtime of the program, even though this function should almost
literally be a no-op.
The problem is that the assertIsChecked function can be considered
too big to inline depending on the compiler's inliner. Since it's
unlikely to ever need to failure path though, we can move it out
of line and force it to not be inlined, so that the fast path
can be inlined.
In my test (using lld to link clang with CMAKE_BUILD_TYPE=Release
and LLVM_ENABLE_ASSERTIONS=ON), this reduces link time from 27
seconds to 23.5 seconds, which is a solid 15% gain.
llvm-svn: 317824
This reverts commit 4e4ee1c507e2707bb3c208e1e1b6551c3015cbf5.
This is failing due to some code that isn't built on MSVC
so I didn't catch. Not immediately obvious how to fix this
at first glance, so I'm reverting for now.
llvm-svn: 315536
There's a lot of misuse of Twine scattered around LLVM. This
ranges in severity from benign (returning a Twine from a function
by value that is just a string literal) to pretty sketchy (storing
a Twine by value in a class). While there are some uses for
copying Twines, most of the very compelling ones are confined
to the Twine class implementation itself, and other uses are
either dubious or easily worked around.
This patch makes Twine's copy constructor private, and fixes up
all callsites.
Differential Revision: https://reviews.llvm.org/D38767
llvm-svn: 315530
cantFail is the moral equivalent of an assertion that the wrapped call must
return a success value. This patch allows clients to include an associated
error message (the same way they would for an assertion for llvm_unreachable).
If the error message is not specified it will default to: "Failure value
returned from cantFail wrapped call".
llvm-svn: 312066
handleExpected is similar to handleErrors, but takes an Expected<T> as its first
input value and a fallback functor as its second, followed by an arbitary list
of error handlers (equivalent to the handler list of handleErrors). If the first
input value is a success value then it is returned from handleErrors
unmodified. Otherwise the contained error(s) are passed to handleErrors, along
with the handlers. If handleErrors returns success (indicating that all errors
have been handled) then handleExpected runs the fallback functor and returns its
result. If handleErrors returns a failure value then the failure value is
returned and the fallback functor is never run.
This simplifies the process of re-trying operations that return Expected values.
Without this utility such retry logic is cumbersome as the internal Error must
be explicitly extracted from the Expected value, inspected to see if its
handleable and then consumed:
enum FooStrategy { Aggressive, Conservative };
Expected<Foo> tryFoo(FooStrategy S);
Expected<Foo> Result;
(void)!!Result; // "Check" Result so that it can be safely overwritten.
if (auto ValOrErr = tryFoo(Aggressive))
Result = std::move(ValOrErr);
else {
auto Err = ValOrErr.takeError();
if (Err.isA<HandleableError>()) {
consumeError(std::move(Err));
Result = tryFoo(Conservative);
} else
return std::move(Err);
}
with handleExpected, this can be re-written as:
auto Result =
handleExpected(
tryFoo(Aggressive),
[]() { return tryFoo(Conservative); },
[](HandleableError&) { /* discard to handle */ });
llvm-svn: 311870
This just switches handleAllErrors from using custom assertions that all errors
have been handled to using cantFail. This change involves moving some of the
class and function definitions around though.
llvm-svn: 311631
I did this a long time ago with a janky python script, but now
clang-format has built-in support for this. I fed clang-format every
line with a #include and let it re-sort things according to the precise
LLVM rules for include ordering baked into clang-format these days.
I've reverted a number of files where the results of sorting includes
isn't healthy. Either places where we have legacy code relying on
particular include ordering (where possible, I'll fix these separately)
or where we have particular formatting around #include lines that
I didn't want to disturb in this patch.
This patch is *entirely* mechanical. If you get merge conflicts or
anything, just ignore the changes in this patch and run clang-format
over your #include lines in the files.
Sorry for any noise here, but it is important to keep these things
stable. I was seeing an increasing number of patches with irrelevant
re-ordering of #include lines because clang-format was used. This patch
at least isolates that churn, makes it easy to skip when resolving
conflicts, and gets us to a clean baseline (again).
llvm-svn: 304787
This patch allows Error and Expected types to be passed to and returned from
RPC functions.
Serializers and deserializers for custom error types (types deriving from the
ErrorInfo class template) can be registered with the SerializationTraits for
a given channel type (see registerStringError in RPCSerialization.h for an
example), allowing a given custom type to be sent/received. Unregistered types
will be serialized/deserialized as StringErrors using the custom type's log
message as the error string.
llvm-svn: 300167
fallible functions.
Some fallible functions (those returning Error or Expected<T>) may only fail
for a subset of their inputs. For example, a "safe" square root function will
succeed for all finite positive inputs:
Expected<double> safeSqrt(double d) {
if (d < 0 && !isnan(d) && !isinf(d))
return make_error<...>("Cannot sqrt -ve values, nans or infs");
return sqrt(d);
}
At a safe callsite for such a function, checking the error return value is
redundant:
if (auto ValOrErr = safeSqrt(42.0)) {
// use *ValOrErr.
} else
llvm_unreachable("safeSqrt should always succeed for +ve values");
The cantFail function wraps this check and extracts the contained value,
simplifying control flow:
double Result = cantFail(safeSqrt(42.0));
This function should be used with care: it is a programmatic error to wrap a
call with cantFail if it can in fact fail. For debug builds this will
result in llvm_unreachable being called. For release builds the behavior is
undefined.
Use of this function is likely to be rare in library code, but more common
for tool and unit-test code where inputs and mock functions may be known to be
safe.
llvm-svn: 296384
This macro is supposed to be the one controlling the compatibility
of ABI breaks induced when enabling or disabling assertions in LLVM.
The macro is enabled by default in assertions build, so this commit
won't disable the tests.
Differential Revision: https://reviews.llvm.org/D26700
llvm-svn: 288087
The macro LLVM_ENABLE_ABI_BREAKING_CHECKS is moved to a new header
abi-breaking.h, from llvm-config.h. Only headers that are using the
macro are including this new header.
LLVM will define a symbol, either EnableABIBreakingChecks or
DisableABIBreakingChecks depending on the configuration setting for
LLVM_ABI_BREAKING_CHECKS.
The abi-breaking.h header will add weak references to these symbols in
every clients that includes this header. This should ensure that
a mismatch triggers a link failure (or a load time failure for DSO).
On MSVC, the pragma "detect_mismatch" is used instead.
Differential Revision: https://reviews.llvm.org/D26876
llvm-svn: 288082
This is forcing to use Error::success(), which is in a wide majority
of cases a lot more readable.
Differential Revision: https://reviews.llvm.org/D26481
llvm-svn: 286561
This fixes a mismatch between the declared error_type and the type used with
the placement new that initializes the field.
Patch by Yichao Yu.
llvm-svn: 285970
(1) Switches to raw pointer and bitmasking operations for Error payload.
(2) Always includes the 'unchecked' bitfield in Expected<T>, even in -Asserts.
(3) Always propagates checked bit status in move-ops for both classes, even in
-Asserts.
This should allow debug programs to link against release libraries without
encountering spurious 'unchecked error' terminations.
Error checks still aren't verified in release mode so this doesn't introduce
any new control flow, but it does require new bit-masking ops in release mode
to preserve the flag values during move ops. I expect the overhead to be
minimal, but if we discover any corner cases where it matters we could fix
this by making flag propagation conditional on a new build option.
llvm-svn: 285426
This reverts commit r280016, and the followups of r280017, r280027,
r280051, r280058, and r280059.
MSVC's implementation of std::promise does not get along with
llvm::Error. It uses its promised value too much like a normal value
type.
llvm-svn: 280100
only) for Expected<T> so that it can interoperate with MSVC's std::future
implementation.
MSVC 2013's std::future implementation requires the wrapped type to be default
constructible.
Hopefully this will fix the bot breakage in
http://lab.llvm.org:8011/builders/clang-x86-win2008-selfhost/builds/9937 .
llvm-svn: 280058
This allows ErrorAsOutParameter to work better with "optional" errors. For
example, consider a function where for certain input values it is known that
the function can't fail. This can now be written as:
Result foo(Arg X, Error *Err) {
ErrorAsOutParameter EAO(Err);
if (<Error Condition>) {
if (Err)
*Err = <report error>;
else
llvm_unreachable("Unexpected failure!");
}
}
Rather than having to construct an ErrorAsOutParameter under every conditional
where Err is known to be non-null.
llvm-svn: 276430
See http://reviews.llvm.org/D22079
Changes the Archive::child_begin and Archive::children to require a reference
to an Error. If iterator increment fails (because the archive header is
damaged) the iterator will be set to 'end()', and the error stored in the
given Error&. The Error value should be checked by the user immediately after
the loop. E.g.:
Error Err;
for (auto &C : A->children(Err)) {
// Do something with archive child C.
}
// Check the error immediately after the loop.
if (Err)
return Err;
Failure to check the Error will result in an abort() when the Error goes out of
scope (as guaranteed by the Error class).
llvm-svn: 275316
When concatenating two error lists the ErrorList::join method (which is called
by joinErrors) was failing to set the checked bit on the second error, leading
to a 'failure to check error' assertion.
llvm-svn: 274249
This comment was included in Peter Collingbourne's original version of
StringError (see http://reviews.llvm.org/D20550), where it made sense. It was
accidentally copied over with the rest of the class, but no longer applies.
llvm-svn: 270956
StringError can be used to represent Errors that aren't recoverable based on
the error type, but that have a useful error message that can be reported to
the user or logged.
llvm-svn: 270948
toString() consumes an Error and returns a string representation of its
contents. This commit also adds a message() method to ErrorInfoBase for
convenience.
Differential Revision: http://reviews.llvm.org/D19883
llvm-svn: 268465
destruction.
This makes the Expected<T> class behave like Error, even when in success mode.
Expected<T> values must be checked to see whether they contain an error prior
to being dereferenced, assigned to, or destructed.
llvm-svn: 265446
This helper method creates a pre-checked Error suitable for use as an out
parameter in a constructor. This avoids the need to have the constructor
check a known-good error before assigning to it.
llvm-svn: 264467
This is a temporary crutch to enable code that currently uses std::error_code
to be incrementally moved over to Error. Requiring all Error instances be
convertible enables clients to call errorToErrorCode on any error (not just
ECErrors created by conversion *from* an error_code).
This patch also moves code for Error from ErrorHandling.cpp into a new
Error.cpp file.
llvm-svn: 264221
