After 04f30795f1, -Wreturn-type has an effect on functions that
contain @try/@catch statements. CheckFallThrough() was missing
a case for ObjCAtTryStmts, leading to a false positive.
(What about the other two places in CheckFallThrough() that handle
CXXTryStmt but not ObjCAtTryStmts?
- I think the last use of CXXTryStmt is dead in practice: 04c6851cd made it so
that calls never add edges to try bodies, and the CFG block for a try
statement is always an empty block containing just the try element itself as
terminator (the try body itself is part of the normal flow of the function
and not connected to the block for the try statement itself. The try statment
cfg block is only connected to the catch bodies, and only reachable from
throw expressions within the try body.)
- The first use of CXXTryStmt might be important. It looks similar to
the code that adds all cfg blocks for try statements as roots of
the reachability graph for the reachability warnings, but I can't
find a way to trigger it. So I'm omitting it for now. The CXXTryStmt
code path seems to only be hit by try statements that are function
bodies without a surrounding compound statements
(`f() try { ... } catch ...`), and those don't exist for ObjC
@try statements.
)
Fixes PR52473.
Differential Revfision: https://reviews.llvm.org/D114660
CFGBuilder::addStmt() implicitly passes AddStmtChoice::AlwaysAdd
to Visit() already, so this should have no behavior change.
Differential Revision: https://reviews.llvm.org/D111570
The Linux kernel has a macro called IS_ENABLED(), which evaluates to a
constant 1 or 0 based on Kconfig selections, allowing C code to be
unconditionally enabled or disabled at build time. For example:
int foo(struct *a, int b) {
switch (b) {
case 1:
if (a->flag || !IS_ENABLED(CONFIG_64BIT))
return 1;
__attribute__((fallthrough));
case 2:
return 2;
default:
return 3;
}
}
There is an unreachable warning about the fallthrough annotation in the
first case because !IS_ENABLED(CONFIG_64BIT) can be evaluated to 1,
which looks like
return 1;
__attribute__((fallthrough));
to clang.
This type of warning is pointless for the Linux kernel because it does
this trick all over the place due to the sheer number of configuration
options that it has.
Add -Wunreachable-code-fallthrough, enabled under -Wunreachable-code, so
that projects that want to warn on unreachable code get this warning but
projects that do not care about unreachable code can still use
-Wimplicit-fallthrough without having to make changes to their code
base.
Fixes PR51094.
Reviewed By: aaron.ballman, nickdesaulniers
Differential Revision: https://reviews.llvm.org/D107933
This patch introduces a very simple inter-procedural analysis
between blocks and enclosing functions.
We always analyze blocks first (analysis is done as part of semantic
analysis that goes side-by-side with the parsing process), and at the
moment of reporting we don't know how that block will be actually
used.
This patch introduces new logic delaying reports of the "never called"
warnings on blocks. If we are not sure that the block will be called
exactly once, we shouldn't warn our users about that. Double calls,
however, don't require such delays. While analyzing the enclosing
function, we can actually decide what we should do with those
warnings.
Additionally, as a side effect, we can be more confident about blocks
in such context and can treat them not as escapes, but as direct
calls.
rdar://74090107
Differential Revision: https://reviews.llvm.org/D98688
This commit introduces a new attribute `called_once`.
It can be applied to function-like parameters to signify that
this parameter should be called exactly once. This concept
is particularly widespread in asynchronous programs.
Additionally, this commit introduce a new group of dataflow
analysis-based warnings to check this property. It identifies
and reports the following situations:
* parameter is called twice
* parameter is never called
* parameter is not called on one of the paths
Current implementation can also automatically infer `called_once`
attribute for completion handler paramaters that should follow the
same principle by convention. This behavior is OFF by default and
can be turned on by using `-Wcompletion-handler`.
Differential Revision: https://reviews.llvm.org/D92039
rdar://72812043
In CUDA/HIP a function may become implicit host device function by
pragma or constexpr. A host device function is checked in both
host and device compilation. However it may be emitted only
on host or device side, therefore the diagnostics should be
deferred until it is known to be emitted.
Currently clang is only able to defer certain diagnostics. This causes
false alarms and limits the usefulness of host device functions.
This patch lets clang defer all overloading resolution diagnostics for host device functions.
An option -fgpu-defer-diag is added to control this behavior. By default
it is off.
It is NFC for other languages.
Differential Revision: https://reviews.llvm.org/D84364
Other warning messages for negative capabilities also mention their
kind, and the double space was ugly.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D84603
`OS << ND->getDeclName();` is equivalent to `OS << ND->getNameAsString();`
without the extra temporary string.
This is not quite a NFC since two uses of `getNameAsString` in a
diagnostic are replaced, which results in the named entity being
quoted with additional "'"s (ie: 'var' instead of var).
Summary:
When getting a warning that we release a capability that isn't held it's
sometimes not clear why. So just like we do for double locking, we add a
note on the previous release operation, which marks the point since when
the capability isn't held any longer.
We can find this previous release operation by looking up the
corresponding negative capability.
Reviewers: aaron.ballman, delesley
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D81352
Summary:
Add a new warning -Wuninitialized-const-reference as a subgroup of -Wuninitialized to address a bug filed here: https://bugs.llvm.org/show_bug.cgi?id=45624
This warning is controlled by -Wuninitialized and can be disabled by -Wno-uninitialized-const-reference.
The warning is diagnosed when passing uninitialized variables as const reference parameters to a function.
Differential Revision: https://reviews.llvm.org/D79895
Taking a value and the bitwise-or it with a non-zero constant will always
result in a non-zero value. In a boolean context, this is always true.
if (x | 0x4) {} // always true, intended '&'
This patch creates a new warning group -Wtautological-bitwise-compare for this
warning. It also moves in the existing tautological bitwise comparisons into
this group. A few other changes were needed to the CFGBuilder so that all bool
contexts would be checked. The warnings in -Wtautological-bitwise-compare will
be off by default due to using the CFG.
Fixes: https://bugs.llvm.org/show_bug.cgi?id=42666
Differential Revision: https://reviews.llvm.org/D66046
llvm-svn: 375318
function scope.
This removes one of the last few cases where we build expressions in the
wrong function scope context. No functionality change intended.
llvm-svn: 362178
Turn it into a variant class instead. This conversion does indeed save some code
but there's a plan to add support for more kinds of terminators that aren't
necessarily based on statements, and with those in mind it becomes more and more
confusing to have CFGTerminators implicitly convertible to a Stmt *.
Differential Revision: https://reviews.llvm.org/D61814
llvm-svn: 361586
where either the modification or the other access is unreachable.
This reverts r359984 (which reverted r359962). The bug in clang-tidy's
test suite exposed by the original commit was fixed in r360009.
llvm-svn: 360010
recursively captured.
Under ARC, a block variable is zero-initialized when it is recursively
captured by the block literal initializer.
rdar://problem/11022762
llvm-svn: 359049
Summary:
Similar to D56967, we add the existing diag::note_locked_here to tell
the user where we saw the locking that isn't matched correctly.
Reviewers: aaron.ballman, delesley
Reviewed By: aaron.ballman
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D59455
llvm-svn: 356427
Summary:
When this was rewritten in D43737, the logic changed to better explore infinite loops. The check for a reachable exit block was deleted which accidentally introduced false positives in case the exit node was unreachable.
We were testing for cases like this, but @steven_wu provided an additional test case that I've included in the regression tests for this patch.
Reviewers: steven_wu, rtrieu
Reviewed By: steven_wu, rtrieu
Subscribers: cfe-commits, steven_wu
Tags: #clang
Differential Revision: https://reviews.llvm.org/D58122
llvm-svn: 353984
Summary:
We use the existing diag::note_locked_here to tell the user where we saw
the first locking.
Reviewers: aaron.ballman, delesley
Reviewed By: aaron.ballman
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D56967
llvm-svn: 352549
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Summary:
This fixes ASTContext's parent map for nodes in such classes (e.g. operator()).
https://bugs.llvm.org/show_bug.cgi?id=39949
This also changes the observed shape of the AST for implicit RAVs.
- this includes AST MatchFinder: cxxRecordDecl() now matches lambda classes,
functionDecl() matches the call operator, and the parent chain is body -> call
operator -> lambda class -> lambdaexpr rather than body -> lambdaexpr.
- this appears not to matter for the ASTImporterLookupTable builder
- this doesn't matter for the other RAVs in-tree.
In order to do this, we remove the TraverseLambdaBody hook. The problem is it's
hard/weird to ensure this hook is called when traversing via the implicit class.
There were just two users of this hook in-tree, who use it to skip bodies.
I replaced these with explicitly traversing the captures only. Another approach
would be recording the bodies when the lambda is visited, and then recognizing
them later.
I'd be open to suggestion on how to preserve this hook, instead.
Reviewers: aaron.ballman, JonasToth
Subscribers: cfe-commits, rsmith, jdennett
Differential Revision: https://reviews.llvm.org/D56444
llvm-svn: 351047
It seems the two failing tests can be simply fixed after r348037
Fix 3 cases in Analysis/builtin-functions.cpp
Delete the bad CodeGen/builtin-constant-p.c for now
llvm-svn: 348053
Kept the "indirect_builtin_constant_p" test case in test/SemaCXX/constant-expression-cxx1y.cpp
while we are investigating why the following snippet fails:
extern char extern_var;
struct { int a; } a = {__builtin_constant_p(extern_var)};
llvm-svn: 348039
This was reverted in r347656 due to me thinking it caused a miscompile of
Chromium. Turns out it was the Chromium code that was broken.
llvm-svn: 347756
This caused a miscompile in Chrome (see crbug.com/908372) that's
illustrated by this small reduction:
static bool f(int *a, int *b) {
return !__builtin_constant_p(b - a) || (!(b - a));
}
int arr[] = {1,2,3};
bool g() {
return f(arr, arr + 3);
}
$ clang -O2 -S -emit-llvm a.cc -o -
g() should return true, but after r347417 it became false for some reason.
This also reverts the follow-up commits.
r347417:
> Re-Reinstate 347294 with a fix for the failures.
>
> Don't try to emit a scalar expression for a non-scalar argument to
> __builtin_constant_p().
>
> Third time's a charm!
r347446:
> The result of is.constant() is unsigned.
r347480:
> A __builtin_constant_p() returns 0 with a function type.
r347512:
> isEvaluatable() implies a constant context.
>
> Assume that we're in a constant context if we're asking if the expression can
> be compiled into a constant initializer. This fixes the issue where a
> __builtin_constant_p() in a compound literal was diagnosed as not being
> constant, even though it's always possible to convert the builtin into a
> constant.
r347531:
> A "constexpr" is evaluated in a constant context. Make sure this is reflected
> if a __builtin_constant_p() is a part of a constexpr.
llvm-svn: 347656
Looks like the only reason we use a unique_ptr here is so that we can
conditionally construct a LogicalErrorHandler. It's a small type, and
Optional can do the same thing with 100% fewer heap allocations.
llvm-svn: 338962
As documented here: https://software.intel.com/en-us/node/682969 and
https://software.intel.com/en-us/node/523346. cpu_dispatch multiversioning
is an ICC feature that provides for function multiversioning.
This feature is implemented with two attributes: First, cpu_specific,
which specifies the individual function versions. Second, cpu_dispatch,
which specifies the location of the resolver function and the list of
resolvable functions.
This is valuable since it provides a mechanism where the resolver's TU
can be specified in one location, and the individual implementions
each in their own translation units.
The goal of this patch is to be source-compatible with ICC, so this
implementation diverges from the ICC implementation in a few ways:
1- Linux x86/64 only: This implementation uses ifuncs in order to
properly dispatch functions. This is is a valuable performance benefit
over the ICC implementation. A future patch will be provided to enable
this feature on Windows, but it will obviously more closely fit ICC's
implementation.
2- CPU Identification functions: ICC uses a set of custom functions to identify
the feature list of the host processor. This patch uses the cpu_supports
functionality in order to better align with 'target' multiversioning.
1- cpu_dispatch function def/decl: ICC's cpu_dispatch requires that the function
marked cpu_dispatch be an empty definition. This patch supports that as well,
however declarations are also permitted, since the linker will solve the
issue of multiple emissions.
Differential Revision: https://reviews.llvm.org/D47474
llvm-svn: 337552
Kazu Hirata