Commit Graph

4384 Commits

Author SHA1 Message Date
Peter Klausler
53f775bbc0 [flang][runtime] Support B/O/Z editing of CHARACTER
This is a common extension, though semantics differ across
compilers.  I've chosen to interpret the CHARACTER data
as if it were an arbitrary-precision integer value and
format or read it as such.  This matches Intel's compilers
and nvfortran.  (GNU Fortran can't handle lengths > 1 and XLF
seems to get the enddianness wrong.)

This patch generalizes the previous implementations of
B/O/Z input and output so that they'll work for arbitrary data
in memory, and then uses them for all B/O/Z input/output,
including (now) CHARACTER.

Differential Revision: https://reviews.llvm.org/D124547
2022-04-28 12:44:31 -07:00
Chris Lattner
5dedf911de [AsmParser] Rework logic around "region argument parsing"
The asm parser had a notional distinction between parsing an
operand (like "%foo" or "%4#3") and parsing a region argument
(which isn't supposed to allow a result number like #3).

Unfortunately the implementation has two problems:

1) It didn't actually check for the result number and reject
   it.  parseRegionArgument and parseOperand were identical.
2) It had a lot of machinery built up around it that paralleled
   operand parsing.  This also was functionally identical, but
   also had some subtle differences (e.g. the parseOptional
   stuff had a different result type).

I thought about just removing all of this, but decided that the
missing error checking was important, so I reimplemented it with
a `allowResultNumber` flag on parseOperand.  This keeps the
codepaths unified and adds the missing error checks.

Differential Revision: https://reviews.llvm.org/D124470
2022-04-28 11:12:44 -07:00
Peter Klausler
36771bbad1 [flang][runtime] Correct emission & reading of unterminated final records
When the last operation on a foramtted sequential or stream file (prior
to an implied or explicit ENDFILE) is a non-advancing WRITE, ensure
that any partial record data is emitted to the file without a line
terminator.  Further, when that last record is read with a non-advancing
READ, ensure that it won't raise an end-of-record condition after its
data, but instead will signal an end-of-file.

Differential Revision: https://reviews.llvm.org/D124546
2022-04-28 09:22:07 -07:00
Kiran Chandramohan
b5b3e50f65 [Flang] Initial lowering of the Fortran Do loop
This patch adds code to lower simple Fortran Do loops with loop control.
Lowering is performed by the the `genFIR` function when called with a
`Fortran::parser::DoConstruct`. `genFIR` function calls `genFIRIncrementLoopBegin`
then calls functions to lower the body of the loop and finally calls
the function `genFIRIncrementLoopEnd`. `genFIRIncrementLoopBegin` is
responsible for creating the FIR `do_loop` as well as storing the value of
the loop index to the loop variable. `genFIRIncrementLoopEnd` returns
the incremented value of the loop index and also stores the index value
outside the loop. This is important since the loop variable can be used
outside the loop. Information about a loop is collected in a structure
`IncrementLoopInfo`.

Note 1: Future patches will bring in lowering for unstructured,
infinite, while loops
Note 2: This patch is part of upstreaming code from the fir-dev branch of
https://github.com/flang-compiler/f18-llvm-project.

Reviewed By: awarzynski

Differential Revision: https://reviews.llvm.org/D124277

Co-authored-by: Eric Schweitz <eschweitz@nvidia.com>
Co-authored-by: Jean Perier <jperier@nvidia.com>
Co-authored-by: Val Donaldson <vdonaldson@nvidia.com>
Co-authored-by: Peter Klausler <pklausler@nvidia.com>
Co-authored-by: Valentin Clement <clementval@gmail.com>
2022-04-28 13:03:16 +00:00
Andrzej Warzynski
dcb2ddd6c9 [flang][driver] Fix spelling (nfc)
Merely making sure that we use consistent spelling.
2022-04-28 10:37:27 +00:00
Mike Kashkarov
35cc2ec4ed [flang] Support FINDLOC/MAXLOC/MINLOC with scalar mask
Previously MASK= elements were accessed in assumption that mask is an array of
input argument rank (and in combination with explicit DIM= argument we had
out-of-bounds access), but for MAXLOC/MINLOC/FINDLOC mask should be be
conformable and could be scalar.

Add new regression tests with scalar mask for verification.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D124408
2022-04-28 18:59:04 +09:00
Mike Kashkarov
92e22c97e9 [flang] Fix UBOUND() constant folding for parentheses expr
Similarly to LBOUND((x)) in https://reviews.llvm.org/D123838 - fix UBOUND((x))
folding for constant arrays to return shape instead of recurse scan.

Depends on D123520

Reviewed By: jeanPerier

Differential Revision: https://reviews.llvm.org/D123944
2022-04-28 18:56:54 +09:00
Peixin-Qiao
b6b8d34554 [flang] Add lowering stubs for OpenMP/OpenACC declarative constructs
This patch provides the basic infrastructure for lowering declarative
constructs for OpenMP and OpenACC.

This is part of the upstreaming effort from the fir-dev branch in [1].
[1] https://github.com/flang-compiler/f18-llvm-project

Reviewed By: kiranchandramohan, shraiysh, clementval

Differential Revision: https://reviews.llvm.org/D124225
2022-04-28 09:40:30 +08:00
Peter Steinfeld
9df99d8ac2 [flang] Fix MAXLOC/MINLOC when MASK is scalar .FALSE.
When passing a scalar .FALSE. as the MASK argument to MAXLOC, we were getting
bad memory references.  We were falling into the code intended when the MASK
argument was missing.

I fixed this by checking for a scalar MASK with a .FALSE. value and
setting the result to all zeroes in that case.  I also added tests for
MAXLOC and MINLOC with scalar values of .TRUE. and .FALSE. for the MASK
argument.

I also special cased situations where the MASK argument is a scalar with
a .TRUE. value and passed along a nullptr in such cases.

Along the way, I eliminated the unused "chars" argument from the constructor
for ExtremumLocAccumulator.

Differential Revision: https://reviews.llvm.org/D124484
2022-04-27 14:50:00 -07:00
Peter Klausler
84c6dc96ac [flang] Downgrade a fatal error to a warning
A non-CHARACTER expression in a CASE statement is allowed to have
a distinct kind (not type) from the expression in its SELECT CASE.
If a value in a CASE statement is out of range for the SELECT CASE
type, emit a warning, but it should not be a fatal error.

Differential Revision: https://reviews.llvm.org/D124544
2022-04-27 12:31:58 -07:00
Peter Klausler
787ee99d4f [flang] Allow for host association in ConvertTo(Object|Proc)Entity
Name resolution fails with a bogus "is not a variable" error message
when a host-associated object appears in a NAMELIST group.  The root
cause is that ConvertToObjectEntity() returns false for host-associated
objects.  Fix that, and also apply a similar fix to ConvertToProcEntity()
nearby.

Differential Revision: https://reviews.llvm.org/D124541
2022-04-27 12:30:03 -07:00
Mike Kashkarov
d8b4ea486a [flang] Fix UBOUND() folding for constant arrays
Similarly to LBOUND in https://reviews.llvm.org/D123237, fix UBOUND() folding
for constant arrays (for both w/ and w/o DIM=): convert
GetConstantArrayLboundHelper into common helper class for both lower/upper
bounds.

Reviewed By: jeanPerier

Differential Revision: https://reviews.llvm.org/D123520
2022-04-28 01:17:47 +09:00
Kiran Chandramohan
acd75440c6 [Flang] Lower the FailImage Statement
Lowering of FailImage statement generates a runtime call and the
unreachable operation. The unreachable operation cannot terminate
a structured operation like the IF operation, hence  mark as
unstructured.

Note: This patch is part of upstreaming code from the fir-dev branch of
https://github.com/flang-compiler/f18-llvm-project.

Reviewed By: clementval

Differential Revision: https://reviews.llvm.org/D124520

Co-authored-by: Eric Schweitz <eschweitz@nvidia.com>
2022-04-27 12:20:25 +00:00
Andrzej Warzynski
d902dd011c [flang][driver] NFC: Make code more in line with LLVM style
This patch basically implements [1] in ExecuteCompilerInvocation.cpp. It
also:
  * replaces `CreateFrontendBaseAction` with `CreateFrontendAction`
    (only one method is needed ATM, this change removes the extra
    indirection)
  * removes `InvalidAction` from the `ActionKind` enum (I don't think it
    adds much and keeping it would mean adding a new void case in
    `CreateFrontendAction`)
  * sets the default frontend action in FrontendOptions.h to
    `ParseSyntaxOnly` (note that this is still overridden independently
    in `ParseFrontendArg` in CompilerInvocation.cpp)

No new functionality is added, hence no tests.

[1] https://llvm.org/docs/CodingStandards.html#don-t-use-default-labels-in-fully-covered-switches-over-enumerations

Differential Revision: https://reviews.llvm.org/D124245
2022-04-27 09:20:07 +00:00
Eric Schweitz
8dc8e59eba Upstream test for wide character literals.
Reviewed By: vdonaldson

Differential Revision: https://reviews.llvm.org/D124488
2022-04-26 18:25:13 -07:00
Eric Schweitz
44e58509be [NFC] More synching of sources for upstreaming.
Reviewed By: clementval

Differential Revision: https://reviews.llvm.org/D124476
2022-04-26 14:54:43 -07:00
Peter Klausler
f4bb211a3b [flang] Fix crash from PDT component init in module file
Semantics now needs to preserve the parse trees from module files,
in case they contain parameterized derived type definitions with
component initializers that may require re-analysis during PDT
instantiation.  Save them in the SemanticsContext.

Differential Revision: https://reviews.llvm.org/D124467
2022-04-26 10:49:05 -07:00
Peter Klausler
e1836123a7 [flang] Get ppc64le build bot back up
A recent change assumed that the native C++ "long double" maps to
a Fortran data type; but this turns out to not be true for ppc64le,
which uses "double-double" for "long double".

This is a quick patch to get the ppc64le flang build bot back up.
A better fix that either uses HostTypeExists<> or replaces "long double"
with "ieee128_t" (or some other solution) is expected to follow soon.

Differential Revision: https://reviews.llvm.org/D124423
2022-04-26 09:40:03 -07:00
Eric Schweitz
1f31795cb3 [NFC] Cleanup code to get back in synch for upstreaming.
Differential Revision: https://reviews.llvm.org/D124410
2022-04-25 15:57:04 -07:00
Peter Klausler
2c272a4e8f [flang][runtime] Fix total MAXLOC/MINLOC for non-integer data
A template argument was hard-coded as the Integer type category
rather than properly forwarding the type category of the data for
type-specific instantiations of total (no DIM=) MAXLOC and MINLOC.
This broke total MAXLOC and MINLOC reductions for real and character
data.

Differential Revision: https://reviews.llvm.org/D124303
2022-04-25 12:42:20 -07:00
Peter Klausler
f65e76d16d [flang] Add semantic checks for intrinsic function REDUCE()
Support REDUCE's special semantic requirements in intrinsic
procedure semantics.

Differential Revision: https://reviews.llvm.org/D124296
2022-04-25 12:37:53 -07:00
Peter Klausler
b8f5cf9d2c [flang] Accept "INFINITY" as real input
Both "INF" and "INFINITY" are standard.

Differential Revision: https://reviews.llvm.org/D124401
2022-04-25 12:12:10 -07:00
Peter Klausler
6bcdde2334 [flang][runtime] Fix KIND=16 real/complex component I/O
Don't treat KIND=16 as 80-bit extended floating-point any more on x86.

Differential Revision: https://reviews.llvm.org/D124400
2022-04-25 11:18:21 -07:00
Peter Klausler
72904a990c [flang] Avoid global name conflict when BIND(C,NAME=) is used
At the top level of program units in a source file, two subprograms
are allowed to have the same name if at least one of them has a
distinct interoperable binding name.  F18's symbol table requires
(most) symbols in a scope to have distinct names, though.  Solve
by using compiler-created names for the symbols of global scope
subprograms that have interoperable binding names.

Differential Revision: https://reviews.llvm.org/D124295
2022-04-25 09:25:44 -07:00
Peter Klausler
149d3e4365 [flang] Disambiguate F(X)=Y case where F is a function returning a pointer
F(X)=Y may be initially parsed as a statement function definition; an
existing pass will detect statement functions that should be rewritten
into assignment statemets with array element references as their
left-hand side variables.  However, F() may also be a reference to a
function that returns a data pointer, and f18 did not handle this
case correctly.

The right fix is to rewrite the parse tree for F(X)=Y into an assignment
to a function reference result.  The cases that are actually assignments
to array elements -- including all of the cases previously handled --
will have their left-hand sides converted to array element references
later by another existing rewriting step.

Differential Revision: https://reviews.llvm.org/D124299
2022-04-25 09:25:09 -07:00
Andrzej Warzynski
97a32d3e43 [flang][driver] Add support for generating executables
This patch adds 2 missing items required for `flang-new` to be able to
generate executables:

1. The Fortran_main runtime library, which implements the main entry
   point into Fortran's `PROGRAM` in Flang,

2. Extra linker flags to include Fortran runtime libraries (e.g.
   Fortran_main).

Fortran_main is the bridge between object files generated by Flang and
the C runtime that takes care of program set-up at system-level. For
every Fortran `PROGRAM`, Flang generates the `_QQmain` function.
Fortran_main implements the C `main` function that simply calls
`_QQmain`.

Additionally, "<driver-path>/../lib" directory is added to the list of
search directories for libraries. This is where the required runtime
libraries are currently located. Note that this the case for the build
directory. We haven't considered installation directories/targets yet.

With this change, you can generate an executable that will print `hello,
world!` as follows:

```bash
$ cat hello.f95
PROGRAM HELLO
  write(*, *) "hello, world!"
END PROGRAM HELLO
$ flang-new -flang-experimental-exec hello.f95
./a.out
hello, world!
```

NOTE 1: Fortran_main has to be a static library at all times. It invokes
`_QQmain`, which is the main entry point generated by Flang for the
given input file (you can check this with `flang-new -S hello.f95 -o - |
grep "Qmain"`). This means that Fortran_main has an unresolved
dependency at build time. The linker will allow this for a static
library. However, if Fortran_main was a shared object, then the linker
will produce an error: `undefined symbol: `_QQmain`.

NOTE 2: When Fortran runtime libraries are generated as shared libraries
(excluding Fortran_main, which is always static), you will need to
tell the dynamic linker (by e.g. tweaking LD_LIBRARY_PATH) where to look
for them when invoking the executables. For example:
```bash
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:<flang-build-dir>/lib/ ./a.out
```

NOTE 3: This feature is considered experimental and currently guarded
with a flag: `-flang-experimental-exec`.

Differential Revision: https://reviews.llvm.org/D122008

[1] https://github.com/flang-compiler/f18-llvm-project

CREDITS: Fortran_main was originally written by Eric Schweitz, Jean
Perier, Peter Klausler and Steve Scalpone in the fir-dev` branch in [1].

Co-authored-by: Eric Schweitz <eschweitz@nvidia.com>
Co-authored-by: Peter Klausler <pklausler@nvidia.com>
Co-authored-by: Jean Perier <jperier@nvidia.com>
Co-authored-by: Steve Scalpone <sscalpone@nvidia.com
2022-04-25 12:00:23 +00:00
Jean Perier
fca52e8218 [flang] fix LBOUND lowering with KIND and no DIM arguments
The lowering code was mistakenly assuming that the second argument
in the signature provided by semantics is the DIM argument. This
caused calls with a KIND argument but no DIM to be lowered as if the
KIND argument was DIM.

Differential Revision: https://reviews.llvm.org/D124243
2022-04-25 09:20:51 +02:00
Valentin Clement (バレンタイン クレメン)
6243b90ead
[flang] Do not create arith.extui with same from/to type
In some case the lowering of `ichar` is generating an `arith.extui` operation
with the same from/to type. This operation do not accept from/to types to be
the same. If the from/to types are identical, we do not generate the extra
operation.

Reviewed By: jeanPerier

Differential Revision: https://reviews.llvm.org/D124107
2022-04-24 20:37:48 +02:00
Eric Schweitz
de8a65f787 [NFC] Sync code for upstreaming.
Remove redundant code.

Differential Revision: https://reviews.llvm.org/D124310
2022-04-23 06:10:20 -07:00
River Riddle
eda6f907d2 [mlir][NFC] Shift a bunch of dialect includes from the .h to the .cpp
Now that dialect constructors are generated in the .cpp file, we can
drop all of the dependent dialect includes from the .h file.

Differential Revision: https://reviews.llvm.org/D124298
2022-04-23 01:09:29 -07:00
Peter Klausler
aac6e25f7d [flang][runtime] Signal record read overrun when PAD='NO'
When PAD='NO' and ADVANCE='YES', we currently signal an input
error when a formatted read tries to go past the end of a record
only when a fixed RECL= is in effect.  Other compilers will signal
an error without RECL= too, and that seems like a precedent we
should follow.

Differential Revision: https://reviews.llvm.org/D124301
2022-04-22 16:52:05 -07:00
Peter Klausler
c02abb68cd [flang][runtime] Enforce some limits on kP scale factors
Ew.d and Dw.d output edit descriptors should respect limitations from
the standard on the value of a kP scale factor with respect to the
digit count (d), at least for values of k other than zero.

Differential Revision: https://reviews.llvm.org/D124300
2022-04-22 16:51:36 -07:00
Peter Klausler
f1dbf8e4ad [flang][runtime] Fix edge-case FP input bugs
Blanks are allowed in more places than I allowed for, and
"NAN(foobar)" is allowed to have any parenthesis-balanced
characters in parentheses.

Update: Fix up old sanity test, then avoid usage of "limit" when null.

Differential Revision: https://reviews.llvm.org/D124294
2022-04-22 16:12:04 -07:00
Peter Klausler
839f0abdaa [flang][runtime] Accept "." as REAL input
".", possibly followed by an exponent, is a valid REAL input value (meaning zero).

Differential Revision: https://reviews.llvm.org/D124279
2022-04-22 12:38:07 -07:00
Peter Klausler
cbbc662900 [flang][runtime] Ignore leading spaces even in BZ mode
When editing numeric input, always skip leading spaces, even if
BZ mode (or BLANK='ZERO') is in effect; otherwise, a sign character
preceded by blanks will not be recognized.

Differential Revision: https://reviews.llvm.org/D124278
2022-04-22 12:27:19 -07:00
Peter Klausler
bf8f9b35c1 [flang] Fix regression from generic fix
A recent change that corrected the name resolution of a generic interface
when the same name was visible in scope incorrectly prevented a local
generic from shadowing an outer name that is not a generic, subprogram,
or derived type -- e.g., a simple variable -- leading to an inappropriate
error message.

Differential Revision: https://reviews.llvm.org/D124276
2022-04-22 12:26:44 -07:00
Eric Schweitz
67609cdf09 [NFC] Cosmetic changes to OpenACC.cpp.
Differential Revision: https://reviews.llvm.org/D124272
2022-04-22 10:20:33 -07:00
Andrzej Warzynski
2186a4aea0 [flang] Make the plugin API independent of the driver internals
This patch adds a few new member methods in the `PluginParseTreeAction`
frontend action base class. With these new methods, the plugin API
becomes independent of the driver internals. In particular, plugin
writers no longer require the `CompilerInstance.h` header file to access
various driver data structures (instead, they can use newly added
hooks).

This change is desirable as `CompilerInstance.h` includes various
headers from Clang (both explicitly and implicitly). Some of these
header files are generated at build time (through TableGen) and
including them creates a dependency on some of Clang's build targets.
However, plugins in Flang should not depend on Clang build targets.

Note that plugins might still work fine most of the time, even without
this change and without adding Clang build targets as dependency in
plugin's CMake definition. Indeed, these Clang build targets are often
generated early in the build process. However, that's not guaranteed and
we did notice that on occasions plugins would fail to build.

Differential Revision: https://reviews.llvm.org/D120999
2022-04-22 09:18:04 +00:00
Jean Perier
6c81b4a01e [flang] Fold transformational bessels when host runtime has bessels
Transformational bessel intrinsic functions require the same math runtime
as elemental bessel intrinsics.

Currently elemental bessels could be folded if f18 was linked with pgmath
(cmake -DLIBPGMATH_DIR option). `j0`, `y0`, ... C libm functions were not
used because they are not standard C functions: they are Posix
extensions.

This patch enable:
- Using the Posix bessel host runtime functions when available.
- folding the transformational bessel using the elemental version.

Differential Revision: https://reviews.llvm.org/D124167
2022-04-22 09:37:49 +02:00
Daniil Dudkin
488b9fd103 [flang] Do not ICE on recursive function definition in function result
The following code causes the compiler to ICE in several places due to
lack of support of recursive procedure definitions through the function
result.

  function foo() result(r)
    procedure(foo), pointer :: r
  end function foo
2022-04-21 19:04:17 +09:00
Nimish Mishra
00c511b351 Added lowering support for atomic read and write constructs
This patch adds lowering support for atomic read and write constructs.
Also added is pointer modelling code to allow FIR pointer like types to
be inferred and converted while lowering.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D122725

Co-authored-by: Kiran Chandramohan <kiran.chandramohan@arm.com>
2022-04-21 12:19:13 +05:30
Shraiysh Vaishay
88bb2521b0 [mlir][OpenMP] Add checks and tests for hint clause and fix empty hint
This patch handles empty hint value for critical and atomic constructs.

This also adds checks and tests for hint clause on atomic constructs.

Reviewed By: peixin, kiranchandramohan, NimishMishra

Differential Revision: https://reviews.llvm.org/D123186
2022-04-21 07:31:03 +05:30
V Donaldson
7d61a8419b [flang] Semantics limits on kP scale factors
When known at compile time, Ew.d and Dw.d output edit descriptors
should respect limitations from the standard on the value of a
kP scale factor with respect to the digit count (d), at least for
values of k other than zero.
2022-04-20 14:43:21 -07:00
Mike Kashkarov
39ee23ed5a [flang] Set LBOUND() folding for (x) expression as ones
Set LBOUND() constant folding for parentheses expr. as ones

Array bounds should not propagate throught omitted bounds specifications or
temporary variables - fix constant folding in case of Parentheses<T> expression
by explicitly returning array of ones (or scalar in case of DIM=).

Add set of tests for (x) bounds checks (w/ and w/o 'parameter' arrays)

Reviewed By: jeanPerier

Differential Revision: https://reviews.llvm.org/D123838
2022-04-20 20:06:11 +03:00
Mike Kashkarov
bd5371e4fc [flang] Fix LBOUND() folding for constant arrays
Previously constant folding uses 'dim' without checks which leads to ICE if we
do not have DIM= parameter. And for inputs without DIM= we need to form an
array of rank size with computed bounds instead of single value.

Add additional PackageConstant function to simplify 'if (dim)' handling since we
need to distinguish between scalar initialization in case of DIM= argument and
rank=1 array.

Also add a few more tests with 'parameter' type to verify folding for constant
arrays.

Reviewed By: jeanPerier

Differential Revision: https://reviews.llvm.org/D123237
2022-04-20 20:04:31 +03:00
Jean Perier
3d63d2111c [flang] Do not pass derived type by descriptor when not needed
A missing "!" in the call interface lowering caused all derived type
arguments without length parameters that require and explicit interface
to be passed via fir.box (runtime descriptor).

This was not the intent: there is no point passing a simple derived type
scalars or explicit shapes by descriptor just because they have an attribute
like TARGET. This would actually be problematic with existing code that is
not always 100% compliant: some code implicitly calls procedures with
TARGET dummy attributes (this is not something a compiler can enforce
if the call and procedure definition are not in the same file).

Add a Scope::IsDerivedTypeWithLengthParameter to avoid passing derived
types with only kind parameters by descriptor. There is no point, the
callee knows about the kind parameter values.

Differential Revision: https://reviews.llvm.org/D123990
2022-04-20 10:00:34 +02:00
River Riddle
58ceae9561 [mlir:NFC] Remove the forward declaration of FuncOp in the mlir namespace
FuncOp has been moved to the `func` namespace for a little over a month, the
using directive can be dropped now.
2022-04-18 12:01:55 -07:00
Peter Klausler
b8a929cb2f [flang] Fix regression with recent work on intrinsic/generic interactions
When resolving a procedure reference, do not allow a successful
intrinsic procedure probe result to override an existing
symbol.

Differential Revision: https://reviews.llvm.org/D123905
2022-04-18 11:10:41 -07:00
Peter Klausler
cd03e96f00 [flang] Add & use a better visit() (take 2)
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().
2022-04-16 16:00:48 -07:00
Peter Klausler
1fe7a187ae [flang][runtime] Don't emit empty lines for bad writes
When an error occurs in a formatted sequential output statement
and no output was ever emitted, don't emit a blank record.
This matches the error case behavior of other Fortran compilers.

Differential Revision: https://reviews.llvm.org/D123734
2022-04-15 20:32:32 -07:00