Profiling a basic internal real input read benchmark shows some
hot spots in the code used to prepare input for decimal-to-binary
conversion, which is of course where the time should be spent.
The library that implements decimal to/from binary conversions has
been optimized, but not the code in the Fortran runtime that calls it,
and there are some obvious light changes worth making here.

Move some member functions from *.cpp files into the class definitions
of Descriptor and IoStatementState to enable inlining and specialization.

Make GetNextInputBytes() the new basic input API within the
runtime, replacing GetCurrentChar() -- which is rewritten in terms of
GetNextInputBytes -- so that input routines can have the
ability to acquire more than one input character at a time
and amortize overhead.

These changes speed up the time to read 1M random reals
using internal I/O from a character array from 1.29s to 0.54s
on my machine, which on par with Intel Fortran and much faster than
GNU Fortran.

Differential Revision: https://reviews.llvm.org/D113697

Move the closure of the subset of flang/runtime/*.h header files that
are referenced by source files outside flang/runtime (apart from unit tests)
into a new directory (flang/include/flang/Runtime) so that relative
include paths into ../runtime need not be used.

flang/runtime/pgmath.h.inc is moved to flang/include/flang/Evaluate;
it's not used by the runtime.

Differential Revision: https://reviews.llvm.org/D109107

We should only need to spell the language out in .h files.

Differential Revision: https://reviews.llvm.org/D109138

Add a isFixedRecordLength flag member to Connection to
disambiguate the state of "record has known variable length"
from "record has fixed length".  Code that sets and tests this
flag will appear in later patches.  Rearrange data members to
reduce storage requirements, since Connection might indirectly
end up on a program stack frame.  Add a utility member function
BeginRecord(); use it in internal I/O processing.

Reviewed By: tskeith, sscalpone

Differential Revision: https://reviews.llvm.org/D83098

Original-commit: flang-compiler/f18@9fe84f45d7fd685051004678d6b5775dcc4c6f8f
Reviewed-on: https://github.com/flang-compiler/f18/pull/1094

Scan FORMAT strings locally to avoid C++ binary runtime dependence when computing deepest parenthesis nesting

Remove a dependency on ostream from runtime

Remove remaining direct external references from runtime to C++ library binaries

Remove runtime dependences on lib/common

SetPos() and SetRec()

Instantiate templates for input

Begin input; rearrange locking, deal with CLOSE races

View()

Update error message in test to agree with compiler change

First cut at real input

More robust I/O runtime error handling

Debugging of REAL input

Add iostat.{h,cpp}

Rename runtime/numeric-* to runtime/edit-*

Move templates around, templatize integer output editing

Move LOGICAL and CHARACTER output from io-api.cpp to edit-output.cpp

Change pointer argument to reference

More list-directed input

Complex list-directed input

Use enum class Direction rather than bool for templates

Catch up with changes to master

Undo reformatting of Lower code

Use record number instead of subscripts for internal unit

Unformatted sequential backspace

Testing and debugging

Dodge bogus GCC warning

Add <cstddef> for std::size_t to fix CI build

Address review comments

Original-commit: flang-compiler/f18@50406b349609efdde76e48bf2caa039d031dd1c4
Reviewed-on: https://github.com/flang-compiler/f18/pull/1053

Use internal units for internal I/O state

Replace use of virtual functions

reference_wrapper

Internal formatted output to array descriptor

Delete dead code

Begin list-directed internal output

Refactorings and renamings for clarity

List-directed external I/O (character)

COMPLEX list-directed output

Control list items

First cut at unformatted I/O

More OPEN statement work; rename class to ExternalFileUnit

Complete OPEN (exc. for POSITION=), add CLOSE()

OPEN(POSITION=)

Flush buffers on crash and for terminal output; clean up

Documentation

Fix backquote in documentation

Fix typo in comment

Begin implementation of input

Refactor binary floating-point properties to a new header, simplify numeric output editing

Dodge spurious GCC 7.2 build warning

Address review comments

Original-commit: flang-compiler/f18@9c4bba11cf2329575ea9ee446f69e9caa797135c
Reviewed-on: https://github.com/flang-compiler/f18/pull/982