Adds flang/include/flang/Common/log2-visit.h, which defines
a Fortran::common::visit() template function that is a drop-in
replacement for std::visit(). Modifies most use sites in
the front-end and runtime to use common::visit().
The C++ standard mandates that std::visit() have O(1) execution
time, which forces implementations to build dispatch tables.
This new common::visit() is O(log2 N) in the number of alternatives
in a variant<>, but that N tends to be small and so this change
produces a fairly significant improvement in compiler build
memory requirements, a 5-10% improvement in compiler build time,
and a small improvement in compiler execution time.
Building with -DFLANG_USE_STD_VISIT causes common::visit()
to be an alias for std::visit().
Calls to common::visit() with multiple variant arguments
are referred to std::visit(), pending further work.
This change is enabled only for GCC builds with GCC >= 9;
an earlier attempt (D122441) ran into bugs in some versions of
clang and was reverted rather than simply disabled; and it is
not well tested with MSVC. In non-GCC and older GCC builds,
common::visit() is simply an alias for std::visit().
Adds flang/include/flang/Common/visit.h, which defines
a Fortran::common::visit() template function that is a drop-in
replacement for std::visit(). Modifies most use sites in
the front-end and runtime to use common::visit().
The C++ standard mandates that std::visit() have O(1) execution
time, which forces implementations to build dispatch tables.
This new common::visit() is O(log2 N) in the number of alternatives
in a variant<>, but that N tends to be small and so this change
produces a fairly significant improvement in compiler build
memory requirements, a 5-10% improvement in compiler build time,
and a small improvement in compiler execution time.
Building with -DFLANG_USE_STD_VISIT causes common::visit()
to be an alias for std::visit().
Calls to common::visit() with multiple variant arguments
are referred to std::visit(), pending further work.
Differential Revision: https://reviews.llvm.org/D122441
Summary:
This change implements support for image selectors and image selector
specifications as described in section 9.6.
In check-coarray[.h,cpp] I changed the `Leave()` function for
`parser::ImageSelectorSpec` to take a `parser::ImageSelector`, which
contains a list of image selector specifications. This allows us to
detect when the same specification is used more than once. I also added
code to analyze the expressions for the image selector specifications to
expression.cpp and a test for all of the conditions to check at
compile-time.
Note that we do not check at compile-time to see if the value of the
cosubscripts are within the specified cobounds. We also do not check anything
related to selecting a valid team. We also do not check that the denotation of
the `stat-variable` is not dependent on the evaluation of an entity in the
same statement.
Reviewers: klausler, tskeith, DavidTruby
Subscribers: llvm-commits
Tags: #llvm, #flang
Differential Revision: https://reviews.llvm.org/D83336
Rolls up small changes across the frontend to prepare for the large
forthcoming patch (part 4/4) that completes DATA statement processing
via conversion to initializers.
Reviewed By: PeteSteinfeld
Differential Revision: https://reviews.llvm.org/D82137
Peter Klausler