Previously, iteration through nil objects which resulted from
objc-messages being set to nil were modeled incorrectly.
There are a couple of notes about this patch:
In principle, ExprEngineObjC might be left untouched IFF osx.loops
checker is enabled.
I however think that we should not do something
completely incorrect depending on what checkers are left on.
We should evaluate and potentially remove altogether the isConsumedExpr
performance heuristic, as it seems very fragile.
rdar://22205149
Differential Revision: https://reviews.llvm.org/D44178
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The pattern was born out of the lack of range-based for loops in C++98
and is somewhat obscure. No functionality change intended.
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Previously our edges were completely broken here; now, the final result
is a very simple set of edges in most cases: one up to the "for" keyword
for context, and one into the body of the loop. This matches the behavior
for ObjC for-in loops.
In the AST, however, CXXForRangeStmts are handled very differently from
ObjCForCollectionStmts. Since they are specified in terms of equivalent
statements in the C++ standard, we actually have implicit AST nodes for
all of the semantic statements. This makes evaluation very easy, but
diagnostic locations a bit trickier. Fortunately, the problem can be
generally defined away by marking all of the implicit statements as
part of the top-level for-range statement.
One of the implicit statements in a for-range statement is the declaration
of implicit iterators __begin and __end. The CFG synthesizes two
separate DeclStmts to match each of these decls, but until now these
synthetic DeclStmts weren't in the function's ParentMap. Now, the CFG
keeps track of its synthetic statements, and the AnalysisDeclContext will
make sure to add them to the ParentMap.
<rdar://problem/14038483>
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We based decisions during analysis and during path generation on whether
or not an expression is consumed, so if a top-level expression has
cleanups it's important for us to look through that.
<rdar://problem/14076125>
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Constructs like PseudoObjectExpr, where an expression can appear more than
once in the AST, use OpaqueValueExprs to guard against inadvertent
re-processing of the shared expression during AST traversal. The most
common form of this is to share expressions between the syntactic
"as-written" form of, say, an Objective-C property access 'obj.prop', and
the underlying "semantic" form '[obj prop]'.
However, some constructs can produce OpaqueValueExprs that don't appear in
the syntactic form at all; in these cases the ParentMap wasn't ever traversing
the children of these expressions. This patch fixes that by checking to see
if an OpaqueValueExpr's child has ever been traversed before. There's also a
bit of reset logic when visiting a PseudoObjectExpr to handle the case of
updating the ParentMap, which some external clients depend on.
This still isn't exactly the right fix because we probably want the parent
of the OpaqueValueExpr itself to be its location in the syntactic form if
it's syntactic and the PseudoObjectExpr or BinaryConditionalOperator itself
if it's semantic. Whe I originally wrote the code to do this, I didn't realize
that OpaqueValueExprs themselves are shared in the AST, not just their source
expressions. This patch doesn't change the existing behavior so as not to
break anything inadvertently relying on it; we'll come back to this later.
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Ted and I spent a long time discussing this today and found out that neither
the existing code nor the new code was doing what either of us thought it
was, which is never good. The good news is we found a much simpler way to
fix the motivating test case (an ObjCSubscriptExpr).
This reverts r182083, but pieces of it will come back in subsequent commits.
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This optimizes some spurious edges resulting from PseudoObjectExprs.
This required far more changes than I anticipated. The current
ParentMap does not record any hierarchy information between
a PseudoObjectExpr and its *semantic* expressions that may be
wrapped in OpaqueValueExprs, which are the expressions actually
laid out in the CFG. This means the arrow pruning logic could
not map from an expression to its containing PseudoObjectExprs.
To solve this, this patch adds a variant of ParentMap that
returns the "semantic" parentage of expressions (essentially
as they are viewed by the CFG). This alternate ParentMap is then
used by the arrow reducing logic to identify edges into pseudo
object expressions, and then eliminate them.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@182083 91177308-0d34-0410-b5e6-96231b3b80d8
The Clang ASTs are a DAG, not a pure tree. However, ParentMap has to
choose a single parent for each object. In the main (only?) cases in
which the AST forms a DAG, it protects from multiple traversal by using
OpaqueValueExprs. Previously, ParentMap would just unconditionally look
through all OpaqueValueExprs when building its map.
In order to make this behavior better for the analyzer's diagnostics,
ParentMap was changed to not set a statement's parent if there already
was one in the map. However, ParentMap is supposed to allow updating
existing mappings by calling addStmt once again. This change makes the
"transparency" of OpaqueValueExprs explicit, and disables it when it
is not desired, rather than checking the current contents of the map.
This new code seems like a big change, but it should actually have
essentially the same performance as before. Only OpaqueValueExprs and
their users (PseudoObjectExpr and BinaryConditionalOperator) will
have any different behavior.
There should be no user-visible functionality change, though a test
has been added for the current behavior of BinaryConditionalOperator
source locations and accompanying Xcode arrows (which are not so great...).
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- Replace calling -zone with 'nil'. -zone is obsolete in ARC.
- Allow removing retain/release on a static global var.
- Fix assertion hit when scanning for name references outside a NSAutoreleasePool scope.
- Automatically add bridged casts for results of objc method calls and when calling CFRetain, for example:
NSString *s;
CFStringRef ref = [s string]; -> CFStringRef ref = (__bridge CFStringRef)([s string]);
ref = s.string; -> ref = (__bridge CFStringRef)(s.string);
ref = [NSString new]; -> ref = (__bridge_retained CFStringRef)([NSString new]);
ref = [s newString]; -> ref = (__bridge_retained CFStringRef)([s newString]);
ref = [[NSString alloc] init]; -> ref = (__bridge_retained CFStringRef)([[NSString alloc] init]);
ref = [[s string] retain]; -> ref = (__bridge_retained CFStringRef)([s string]);
ref = CFRetain(s); -> ref = (__bridge_retained CFTypeRef)(s);
ref = [s retain]; -> ref = (__bridge_retained CFStringRef)(s);
- Emit migrator error when trying to cast to CF type the result of autorelease/release:
for
CFStringRef f3() {
return (CFStringRef)[[[NSString alloc] init] autorelease];
}
emits:
t.m:12:10: error: [rewriter] it is not safe to cast to 'CFStringRef' the result of 'autorelease' message; a __bridge cast may result in a pointer to a destroyed object and a __bridge_retained may leak the object
return (CFStringRef)[[[NSString alloc] init] autorelease];
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
t.m:12:3: note: [rewriter] remove the cast and change return type of function to 'NSString *' to have the object automatically autoreleased
return (CFStringRef)[[[NSString alloc] init] autorelease];
^
- Before changing attributes to weak/unsafe_unretained, check if the backing ivar
is set to a +1 object, in which case use 'strong' instead.
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Language-design credit goes to a lot of people, but I particularly want
to single out Blaine Garst and Patrick Beard for their contributions.
Compiler implementation credit goes to Argyrios, Doug, Fariborz, and myself,
in no particular order.
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Stmt::const_child_range, then make a bunch of places use them instead
of the individual iterator accessors.
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value of its subexpressions unless it is a comma (in which case it doesn't
consume the left subexpression).
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should only be an error if that value is consumed. This fix was largely
accomplished by moving 'isConsumedExpr' back to ParentMap.
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- Kill unnecessary #includes in .cpp files. This is an automatic
sweep so some things removed are actually used, but happen to be
included by a previous header. I tried to get rid of the obvious
examples and this was the easiest way to trim the #includes in one
fell swoop.
- We now return to regularly scheduled development.
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Fangrui Song