forked from OSchip/llvm-project
cd03e96f00
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(). |
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| .. | ||
| CMakeLists.txt | ||
| Fortran-parsers.cpp | ||
| basic-parsers.h | ||
| char-block.cpp | ||
| char-buffer.cpp | ||
| char-set.cpp | ||
| characters.cpp | ||
| debug-parser.cpp | ||
| debug-parser.h | ||
| executable-parsers.cpp | ||
| expr-parsers.cpp | ||
| expr-parsers.h | ||
| instrumented-parser.cpp | ||
| io-parsers.cpp | ||
| message.cpp | ||
| misc-parsers.h | ||
| openacc-parsers.cpp | ||
| openmp-parsers.cpp | ||
| parse-tree.cpp | ||
| parsing.cpp | ||
| preprocessor.cpp | ||
| preprocessor.h | ||
| prescan.cpp | ||
| prescan.h | ||
| program-parsers.cpp | ||
| provenance.cpp | ||
| source.cpp | ||
| stmt-parser.h | ||
| token-parsers.h | ||
| token-sequence.cpp | ||
| token-sequence.h | ||
| tools.cpp | ||
| type-parser-implementation.h | ||
| type-parsers.h | ||
| unparse.cpp | ||
| user-state.cpp | ||