Fix invalid overflow check in flang

Statically checking for overflow with

if constexpr (sizeof(std::size_t) <= sizeof(std::int64_t)) {
return static_cast<std::int64_t>(length);
}

Fix invalid overflow check in flang

Statically checking for overflow with

if constexpr (sizeof(std::size_t) <= sizeof(std::int64_t)) {
return static_cast<std::int64_t>(length);
}

Doesn't work if `sizeof(std::size_t) == sizeof(std::int64_t)` because std::size_t
is unsigned.

if `length == std::numeric_limits<size_t>` casting it to `int64_t` is going to overflow.

This code would be much simpler if returning a `uint64_t` instead of a signed
value...

Differential Revision: https://reviews.llvm.org/D122705

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[flang] Add runtime support for GET_COMMAND

Implement the GET_COMMAND intrinsic.
Add 2 new parameters (sourceFile and line) so we can create a terminator
for RUNTIME_CHECKs.

Differential Revision:

[flang] Add runtime support for GET_COMMAND

Implement the GET_COMMAND intrinsic.
Add 2 new parameters (sourceFile and line) so we can create a terminator
for RUNTIME_CHECKs.

Differential Revision: https://reviews.llvm.org/D118777

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[flang] Implement GET_ENVIRONMENT_VARIABLE(VALUE)

Implement the second entry point for GET_ENVIRONMENT_VARIABLE. Reuse
existing bits and pieces wherever possible.

This patch also increases CFI_* er

[flang] Implement GET_ENVIRONMENT_VARIABLE(VALUE)

Implement the second entry point for GET_ENVIRONMENT_VARIABLE. Reuse
existing bits and pieces wherever possible.

This patch also increases CFI_* error codes in order to avoid conflicts.
GET_ENVIRONMENT_VARIABLE is required to return a status of 1 if an
environment variable does not exist and 2 if environment variables are
not supported. However, if we add status codes for that they will
conflict with CFI_ERROR_BASE_ADDR_NULL and CFI_ERROR_BASE_ADDR_NOT_NULL,
which are also 1 and 2 at the moment. We therefore move all CFI error
codes up (an arbitrary) 10 spots to make room. Hopefully this isn't
a problem, since we weren't matching the CFI error codes that gfortran
uses anyway. It may still be an issue if any other runtime functions
will need to return a status of 1 or 2, but we should probably deal with
that when/if it occurs.

Differential Revision: https://reviews.llvm.org/D112698

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[flang] runtime: Read environment variables directly

Add support for reading environment variables directly, via std::getenv.
This needs to allocate a C-style string to pass into std::getenv. If the

[flang] runtime: Read environment variables directly

Add support for reading environment variables directly, via std::getenv.
This needs to allocate a C-style string to pass into std::getenv. If the
memory allocation for that fails, we terminate.

This also changes the interface for EnvVariableLength to receive the
source file and line so we can crash gracefully.

Note that we are now completely ignoring the envp pointer passed into
ProgramStart, since that could go stale if the environment is modified
during execution.

Differential Revision: https://reviews.llvm.org/D111785

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[flang] Implement GET_ENVIRONMENT_VARIABLE(LENGTH)

Search for the environment variable in the envp string passed to
ProgramStart. This doesn't work if the main program isn't Fortran.

Differential R

[flang] Implement GET_ENVIRONMENT_VARIABLE(LENGTH)

Search for the environment variable in the envp string passed to
ProgramStart. This doesn't work if the main program isn't Fortran.

Differential Revision: https://reviews.llvm.org/D111394

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Reland "[flang] GET_COMMAND_ARGUMENT runtime implementation"

Recommit https://reviews.llvm.org/D109813 and
https://reviews.llvm.org/D109814.

This implements the second and final entry point for GET

Reland "[flang] GET_COMMAND_ARGUMENT runtime implementation"

Recommit https://reviews.llvm.org/D109813 and
https://reviews.llvm.org/D109814.

This implements the second and final entry point for GET_COMMAND_ARGUMENT,
handling the VALUE, STATUS and ERRMSG parameters.

It has a small fix in that we're now using memcpy instead of strncpy
(which was a bad idea to begin with, since we're not actually interested
in a string copy).

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Revert "[flang] GET_COMMAND_ARGUMENT(VALUE) runtime implementation"

This reverts commit 0446f1299f6be9fd35bc5f458c78b34dca3105f6 and
df6302311f88d0fbc666b6277d029aa371039945.

There's a warning on f

Revert "[flang] GET_COMMAND_ARGUMENT(VALUE) runtime implementation"

This reverts commit 0446f1299f6be9fd35bc5f458c78b34dca3105f6 and
df6302311f88d0fbc666b6277d029aa371039945.

There's a warning on flang-aarch64-latest-gcc related to strncpy using
the result of strlen as a bound. I'll recommit with a fix.

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[flang] GET_COMMAND_ARGUMENT(ERRMSG) runtime implementation

Implement the final part of GET_COMMAND_ARGUMENT, i.e. the handling of
ERRMSG. This uses some of the infrastructure in stat.h and gets rid

[flang] GET_COMMAND_ARGUMENT(ERRMSG) runtime implementation

Implement the final part of GET_COMMAND_ARGUMENT, i.e. the handling of
ERRMSG. This uses some of the infrastructure in stat.h and gets rid of
the magic numbers that we were using for return codes.

Differential Revision: https://reviews.llvm.org/D109814

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[flang] GET_COMMAND_ARGUMENT(VALUE) runtime implementation

Partial implementation for the second entry point for
GET_COMMAND_ARGUMENT. It handles the VALUE and STATUS arguments, and
doesn't touch ER

[flang] GET_COMMAND_ARGUMENT(VALUE) runtime implementation

Partial implementation for the second entry point for
GET_COMMAND_ARGUMENT. It handles the VALUE and STATUS arguments, and
doesn't touch ERRMSG.

Differential Revision: https://reviews.llvm.org/D109813

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[flang] GET_COMMAND_ARGUMENT(LENGTH) runtime implementation

Implement the ArgumentLength entry point of GET_COMMAND_ARGUMENT. Also
introduce a fixture for the tests.

Note that this also changes the

[flang] GET_COMMAND_ARGUMENT(LENGTH) runtime implementation

Implement the ArgumentLength entry point of GET_COMMAND_ARGUMENT. Also
introduce a fixture for the tests.

Note that this also changes the interface for ArgumentLength from
returning a 4-byte integer to returning an 8-byte integer.

Differential Revision: https://reviews.llvm.org/D109227

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[flang] Move runtime API headers to flang/include/flang/Runtime

Move the closure of the subset of flang/runtime/*.h header files that
are referenced by source files outside flang/runtime (apart from

[flang] Move runtime API headers to flang/include/flang/Runtime

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

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[flang] COMMAND_ARGUMENT_COUNT runtime implementation

Grab whatever ProgramStart has stored in executionEnvironment.argc and
subtract 1 (based on the assumption that ProgramStart is called with
a C-

[flang] COMMAND_ARGUMENT_COUNT runtime implementation

Grab whatever ProgramStart has stored in executionEnvironment.argc and
subtract 1 (based on the assumption that ProgramStart is called with
a C-style argc that counts the command name as an argument).

Spoiler alert: The tests will evolve into fixtures when we implement
GET_COMMAND_ARGUMENT etc.

Differential Revision: https://reviews.llvm.org/D109048

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