variable is initialized by a non-constant expression, and pass in the variable
being declared so that earlier-initialized fields' values can be used.
Rearrange VarDecl init evaluation to make this possible, and in so doing fix a
long-standing issue in our C++ constant expression handling, where we would
mishandle cases like:
extern const int a;
const int n = a;
const int a = 5;
int arr[n];
Here, n is not initialized by a constant expression, so can't be used in an ICE,
even though the initialization expression would be an ICE if it appeared later
in the TU. This requires computing whether the initializer is an ICE eagerly,
and saving that information in PCH files.
llvm-svn: 146856
floating literal value does not fit into the destination type. Such casts have
undefined behavior at translation time; treating them as non-ICE matches the
behavior of modern gcc versions.
llvm-svn: 146842
fails within a call to a constexpr function. Add -fconstexpr-backtrace-limit
argument to driver and frontend, to control the maximum number of notes so
produced (default 10). Fix APValue printing to be able to pretty-print all
APValue types, and move the testing for this functionality from a unittest to
a -verify test now that it's visible in clang's output.
llvm-svn: 146749
whether an expression is a (core) constant expression as a side-effect of
evaluation. This takes us from accepting far too few expressions as ICEs to
accepting slightly too many -- fixes for the remaining cases are coming next.
The diagnostics produced when an expression is found to be non-constant are
currently quite poor (with generic wording but reasonable source locations),
and will be improved in subsequent commits.
llvm-svn: 146289
documentation) with one based on what GCC's __builtin_constant_p is actually
intended to do (discovered by asking a friendly GCC developer).
In particular, an expression which folds to a pointer is now only considered to
be a "constant" by this builtin if it refers to the first character in a string
literal.
This fixes a rather subtle wrong-code issue when building with glibc. Given:
const char cs[4] = "abcd";
int f(const char *p) { return strncmp(p, cs, 4); }
... the macro magic for strncmp produces a (potentially crashing) call to
strlen(cs), because it expands to an expression starting with:
__builtin_constant_p(cs) && strlen(cs) < 4 ? /* ... */
Under the secret true meaning of __builtin_constant_p, this is guaranteed to be
safe!
llvm-svn: 146236
bound to not have side effects(!). Add constant-folding support for expressions
of void type, to ensure that we can still fold ((void)0, 1) as an array bound.
llvm-svn: 146000
evaluator into constant initializer handling / IRGen. The practical consequence
of this is that the bitcast now lives in the constant's definition, rather than
in its uses.
The code in the constant expression evaluator was producing vectors of the wrong
type and size (and possibly of the wrong value for a big-endian int-to-vector
bitcast). We were getting away with this only because we don't yet support
constant-folding of any expressions which inspect vector values.
llvm-svn: 145981
semantics and defaults as the corresponding g++ arguments. The historical g++
argument -ftemplate-depth-N is kept for compatibility, but modern g++ versions
no longer document that option.
Add -cc1 argument -fconstexpr-depth N to implement the corresponding
functionality.
The -ftemplate-depth=N part of this fixes PR9890.
llvm-svn: 145045
or MemberExpr which refers to it. As a side-effect, MemberExprs which refer to
static member functions and static data members are now emitted as constant
expressions.
llvm-svn: 144468
reinstates r144273; a combination of r144333's fix for NoOp rvalue-to-lvalue
casts and some corresponding changes here resolve the regression which that
caused.
This patch also adds support for some additional forms of member function call,
along with additional testing.
llvm-svn: 144369
is currently too inefficient to allow us to use it for array initializers, but
fortunately we usually don't yet need to evaluate such initializers.
llvm-svn: 144260
expression evaluation:
- When folding a non-value-dependent expression, we may try to use the
initializer of a value-dependent variable. If that happens, give up.
- In C++98, actually check that a const, non-volatile DeclRefExpr inside an ICE
is of integral or enumeration type (a reference isn't OK!)
- In C++11, DeclRefExprs for objects of const literal type initialized with
value-dependent expressions are themselves value-dependent.
- So are references initialized with value-dependent expressions (though this
case is missing from the C++11 standard, along with many others).
llvm-svn: 144056
partially undoes the revert in r143491, but does not introduce any new instances
of the underlying issue (which is not yet fixed) in code which does not use
the 'constexpr' keyword.
llvm-svn: 143905
property references to use a new PseudoObjectExpr
expression which pairs a syntactic form of the expression
with a set of semantic expressions implementing it.
This should significantly reduce the complexity required
elsewhere in the compiler to deal with these kinds of
expressions (e.g. IR generation's special l-value kind,
the static analyzer's Message abstraction), at the lower
cost of specifically dealing with the odd AST structure
of these expressions. It should also greatly simplify
efforts to implement similar language features in the
future, most notably Managed C++'s properties and indexed
properties.
Most of the effort here is in dealing with the various
clients of the AST. I've gone ahead and simplified the
ObjC rewriter's use of properties; other clients, like
IR-gen and the static analyzer, have all the old
complexity *and* all the new complexity, at least
temporarily. Many thanks to Ted for writing and advising
on the necessary changes to the static analyzer.
I've xfailed a small diagnostics regression in the static
analyzer at Ted's request.
llvm-svn: 143867
to allow us to implement the C++11 rule that a non-active union member can't be
read, and use it to implement subobject access for string literals.
llvm-svn: 143677
