yaxunl marked 3 inline comments as done.
yaxunl added inline comments.
================
Comment at: lib/Sema/SemaDecl.cpp:10286
+ // these variables must be a compile time constant.
+ VDecl->getType().getAddressSpace() == LangAS::opencl_constant)
CheckForConstantInitializer(Init, DclT);
----------------
rjmccall wrote:
> yaxunl wrote:
> > rjmccall wrote:
> > > Should this rule apply even in C++ mode? I can't remember if there are
> > > any OpenCL/C++ hybrids.
> > No. This rule (static local variable needs to be initialised with
> > compile-time constant) only applies to C and OpenCL.
> > In C++ static local variable can be initialised with non-compile-time
> > constant, in which case Clang will emit atomic instructions to make sure it
> > is only initialised once.
> >
> > Currently OpenCL 2.2 defines OpenCL C++ but clang does not support it.
> Yes, I understand that C++ generally allows static locals to be lazily
> initialized, and that that rule would (probably) still apply to ordinary
> static locals in OpenCL C++. However, I would expect that OpenCL C++ rule is
> that __constant local variables still need to be statically initialized,
> because there's no plausible way in the OpenCL implementation model to
> actually put lazily-initialized variables in the constant address space.
> Assuming that's correct, then I would recommend reworking this whole chain of
> conditions to:
>
> // Don't check the initializer if the declaration is malformed.
> if (VDecl->isInvalidDecl()) {
> // do nothing
>
> // OpenCL __constant locals must be constant-initialized, even in OpenCL
> C++.
> } else if (VDecl->getType().getAddressSpace() == LangAS::opencl_constant) {
> CheckForConstantInitializer(Init, DclT);
>
> // Otherwise, C++ does not restrict the initializer.
> } else if (getLangOpts().CPlusPlus) {
> // do nothing
>
> // C99 6.7.8p4: All the expressions in an initializer for an object that has
> // static storage duration shall be constant expressions or string literals.
> } else if (VDecl->getStorageClass() == SC_Static) {
> CheckForConstantInitializer(Init, DclT);
>
> // C89 is stricter than C99 for aggregate initializers.
> // C89 6.5.7p3: All the expressions [...] in an initializer list
> // for an object that has aggregate or union type shall be
> // constant expressions.
> } else if (!getLangOpts().C99 && VDecl->getType()->isAggregateType() &&
> isa<InitListExpr>(Init)) {
> Expr *Culprit;
> if (!Init->isConstantInitializer(Context, false, &Culprit)) {
> ...
> }
> }
Agree that even OpenCL C++ is unable to lazy initialise function-scope var in
constant addr space. Will do.
https://reviews.llvm.org/D32977
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
