Implement a demangleable strong ownership symbol mangling.
* The original module symbol mangling scheme turned out to be
undemangleable.
* The hoped-for C++17 compatibility of weak ownership turns out to be
fragile
* C++20 now has better ways of controlling C++17 compatibility
The issue is captured on the ABI list at:
https://github.com/itanium-cxx-abi/cxx-abi/issues/134
GCC implements this new mangling.
The old mangling is unceremoniously dropped. No backwards
compatibility, no deprectated old-mangling flag. It was always
labelled experimental. (Old and new manglings cannot be confused.)
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D122256
The existing module symbol mangling scheme turns out to be
undemangleable. It is also desirable to switch to the
strong-ownership model as the hoped-for C++17 compatibility turns out
to be fragile, and we also now have a better way of controlling that.
The issue is captured on the ABI list at:
https://github.com/itanium-cxx-abi/cxx-abi/issues/134
A document describing the issues and new mangling is at:
https://drive.google.com/file/d/1qQjqptzOFT_lfXH8L6-iD9nCRi34wjft/view
This patch is the code-generation part. I have a demangler too, but
that patch is based on some to-be-landed refactoring of the demangler.
The old mangling is unceremoniously dropped. No backwards
compatibility, no deprectated old-mangling flag. It was always
labelled experimental. (Old and new manglings cannot be confused.)
Reviewed By: ChuanqiXu
Differential Revision: https://reviews.llvm.org/D118352
The following was found by a customer and is accepted by the other primary
C++ compilers, but fails to compile in Clang:
namespace sss {
double foo(int, double);
template <class T>
T foo(T); // note: target of using declaration
} // namespace sss
namespace oad {
void foo();
}
namespace oad {
using ::sss::foo;
}
namespace sss {
using oad::foo; // note: using declaration
}
namespace sss {
double foo(int, double) { return 0; }
template <class T>
T foo(T t) { // error: declaration conflicts with target of using
return t;
}
} // namespace sss
I believe the issue is that MergeFunctionDecl() was calling
checkUsingShadowRedecl() but only considering a FunctionDecl as a
possible shadow and not FunctionTemplateDecl. The changes in this patch
largely mirror how variable declarations were being handled by also
catching FunctionTemplateDecl.
For a default visibility external linkage definition, dso_local is set for ELF
-fno-pic/-fpie and COFF and Mach-O. Since default clang -cc1 for ELF is similar
to -fpic ("PIC Level" is not set), this nuance causes unneeded binary format differences.
To make emitted IR similar, ELF -cc1 -fpic will default to -fno-semantic-interposition,
which sets dso_local for default visibility external linkage definitions.
To make this flip smooth and enable future (dso_local as definition default),
this patch replaces (function) `define ` with `define{{.*}} `,
(variable/constant/alias) `= ` with `={{.*}} `, or inserts appropriate `{{.*}} `.
and the global and private module fragment.
For now, the private module fragment introducer is ignored, but use of
the global module fragment introducer should be properly enforced.
llvm-svn: 358353
The tests that failed on a windows host have been fixed.
Original message:
Start setting dso_local for COFF.
With this there are still some GVs where we don't set dso_local
because setGVProperties is never called. I intend to fix that in
followup commits. This is just the bare minimum to teach
shouldAssumeDSOLocal what it should do for COFF.
llvm-svn: 325940
When declaring an entity in the "purview" of a module, it's never a
redeclaration of an entity in the purview of a default module or in no module
("in the global module"). Don't consider those other declarations as possible
redeclaration targets if they're not visible, and reject any cases where we
pick a prior visible declaration that violates this rule.
This reinstates r315251 and r315256, reverted in r315309 and r315308
respectively, tweaked to avoid triggering a linkage calculation when declaring
implicit special members (this exposed our pre-existing issue with typedef
names for linkage changing the linkage of types whose linkage has already been
computed and cached in more cases). A testcase for that regression has been
added in r315366.
llvm-svn: 315379
When declaring an entity in the "purview" of a module, it's never a
redeclaration of an entity in the purview of a default module or in no module
("in the global module"). Don't consider those other declarations as possible
redeclaration targets if they're not visible, and reject any cases where we
pick a prior visible declaration that violates this rule.
llvm-svn: 315251
This follows the scheme agreed with Nathan Sidwell, which can be found here:
https://gcc.gnu.org/wiki/cxx-modules?action=AttachFile
This will be proposed to the itanium-cxx-abi list once we have some experience
with how well it works; the ABI for this TS should be considered unstable until
it is part of the Itanium C++ ABI.
llvm-svn: 312467
Extend the -fmodule-file option to support the [<name>=]<file> value format.
If the name is omitted, then the old semantics is preserved (the module file
is loaded whether needed or not). If the name is specified, then the mapping
is treated as just another prebuilt module search mechanism, similar to
-fprebuilt-module-path, and the module file is only loaded if actually used
(e.g., via import). With one exception: this mapping also overrides module
file references embedded in other modules (which can be useful if module files
are moved/renamed as often happens during remote compilation).
This override semantics requires some extra work: we now store the module name
in addition to the file name in the serialized AST representation.
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D35020
llvm-svn: 312220
Extend the -fmodule-file option to support the [<name>=]<file> value format.
If the name is omitted, then the old semantics is preserved (the module file
is loaded whether needed or not). If the name is specified, then the mapping
is treated as just another prebuilt module search mechanism, similar to
-fprebuilt-module-path, and the module file is only loaded if actually used
(e.g., via import). With one exception: this mapping also overrides module
file references embedded in other modules (which can be useful if module files
are moved/renamed as often happens during remote compilation).
This override semantics requires some extra work: we now store the module name
in addition to the file name in the serialized AST representation.
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D35020
llvm-svn: 312105
In addition to the formal linkage rules, the Modules TS includes cases where
internal-linkage symbols within a module interface unit can be referenced from
outside the module via exported inline functions / templates. We give such
declarations "module-internal linkage", which is formally internal linkage, but
results in an externally-visible symbol.
llvm-svn: 307434
