When a scope's symbol has characteriztics whose specification
expressions depend on other non-constant symbols in the same scope,
f18 rightfully emits an error. However, in the case of usage in
specification expressions involving host association, the program is not
invalid. This can arise, for example, in the case of an internal
function whose result's attributes use host-associated variables.
Differential Revision: https://reviews.llvm.org/D119565
Section 10.2.2.4, paragraph 3 states that a procedure pointer with an explicit
interface must have the same characteristics as its target. Previously, we
interpreted this as disallowing such pointers to point to procedures with
implicit interfaces. But several other compilers allow this.
We make an exception for the case where the explicit interface cannot be
called via an implicit interface.
This change makes us allow this, also
Differential Revision: https://reviews.llvm.org/D119404
The second argument to the ASSOCIATED intrinsic must be a valid pointer
or target. The test for this property only checked the last symbol
in a data-reference, but any symbol in the reference with the
POINTER or TARGET attribute will do.
Differential Revision: https://reviews.llvm.org/D119450
Fortran allows forward references to derived types, including
function results that are typed in a prefix of a FUNCTION statement.
If a type is defined in the body of the function, a reference to
that type from a prefix on the FUNCTION statement must resolve to
the local symbol, even and especially when that type shadows one
from the host scope.
The solution is to defer the processing of that type until the
end of the function's specification part. But the language doesn't
allow for forward references to other names in the prefix, so defer
the processing of the type only when it is not an intrinsic type.
The data structures in name resolution that track this information
for functions needed to become a stack in order to make this work,
since functions can contain interfaces that are functions.
Differential Revision: https://reviews.llvm.org/D119448
arguments even in situations where the arguments are required to compute
the LEN value at runtime.
Add tests.
Differential Revision: https://reviews.llvm.org/D119373
CMPLX was always rewritten as a complex constructor, but the second operand
of a complex constructor cannot be dynamically absent (i.e., a
disassociated pointer, an unallocated allocatable or an absent OPTIONAL
dummy argument), while the second argument of CMPLX can be dynamically
absent.
To avoid having to generate branches in complex constructor lowering
when Y is a pointer, keep the distinction between CMPLX and a complex
constructor when Y is a pointer, an allocatable, or an OPTIONAL entity.
Differential Revision: https://reviews.llvm.org/D118784
Some entries in the specific intrinsic function table have the
wrong argument keyword names -- they should agree with the names
of the arguments on their corresponding generic intrinsic function.
Clean them up.
Differential Revision: https://reviews.llvm.org/D118721
Apply part of a pending patch for GCC 11 warnings, and
rework a piece of code, to dodge warnings on flag from
GCC 11 build bots exposed by a recent patch.
Applying without review to get bots working again; changes
also tested against GCC 9.3.0.
The intrinsic table entry for INDEX mistakenly required
the optional BACK= argument to be scalar, but it's an
elemental intrinsic that can accept a conforming array.
Differential Revision: https://reviews.llvm.org/D117700
Accept any keyword argument names of the form "An" for
values of n >= 3 in calls to the intrinsic functions MAX, MIN,
and their variants, so long as "n" has no leading zero and
all the keywords are distinct. Previously, f18 was needlessly
requiring the names to be contiguous. When synthesizing keywords
to characterize the procedure's interface, don't conflict with
the program's keywords.
Differential Revision: https://reviews.llvm.org/D117701
Consistent with previously documented policy, in which
BOZ literals are accepted in non-standard-conforming circumstances
where they can be converted to an unambiguous known numeric type,
allow BOZ literals to be passed as an actual argument in a reference
to a procedure whose explicit interface has a corresponding dummy
argument with a numeric type to which the BOZ literal may be
converted. Improve error messages associated with BOZ literal
actual arguments, too: don't emit multiple errors.
Differential Revision: https://reviews.llvm.org/D117698
UBOUND, SIZE, and SHAPE folding was still creating expressions that are
invalid on the caller side without the call expression context.
A previous patch intended to deal with this situation (https://reviews.llvm.org/D116933)
but it assumed the return expression would be a descriptor inquiry to
the result symbol, which is not the case if the extent expression is
"scope invariant" inside the called subroutine (e.g., referring to
intent(in) dummy arguments). Simply prevent folding from inlining non
constant extent expression on the caller side.
Folding could be later improved by having ad-hoc folding for UBOUND, SIZE, and
SHAPE on function references where it could try replacing the dummy symbols
by the actual expression, but this is left as a possible later improvement.
Differential Revision: https://reviews.llvm.org/D117686
Fold references to the intrinsic function SCALE().
(Also work around some MSVC headaches somehow exposed by
this patch: disable a bogus MSVC warning that began to appear
in unrelated source files, and avoid the otherwise-necessary
use of the "template" keyword in a call to a template member
function of a class template.)
Differential Revision: https://reviews.llvm.org/D117150
Character substrings weren't being folded correctly;
add tests and rework the implementation so that substrings
of literals and named constant character scalars & arrays
are properly folded for use in constant expressions.
Differential Revision: https://reviews.llvm.org/D117343
We already accept assignments of INTEGER to LOGICAL (& vice versa)
as an extension, but not initialization. Extend initialization
to cover those cases.
(Also fix misspelling in nearby comment as suggested by code reviewer.)
Decouple an inadvertent dependence cycle by moving two
one-line function definitions into a header file.
Differential Revision: https://reviews.llvm.org/D117159
Implements part of the legacy "DEC structures" feature from
VMS Fortran. STRUCTUREs are processed as if they were derived
types with SEQUENCE. DATA-like object entity initialization
is supported as well (e.g., INTEGER FOO/666/) since it was used
for default component initialization in structures. Anonymous
components (named %FILL) are also supported.
These features, and UNION/MAP, were already being parsed.
An omission in the collection of structure field names in the
case of nested structures with entity declarations was fixed
in the parser.
Structures are supported in modules, but this is mostly for
testing purposes. The names of fields in structures accessed
via USE association cannot appear with dot notation in client
code (at least not yet). DEC structures antedate Fortran 90,
so their actual use in applications should not involve modules.
This patch does not implement UNION/MAP, since that feature
would impose difficulties later in lowering them to MLIR types.
In the meantime, if they appear, semantics will issue a
"not yet implemented" error message.
Differential Revision: https://reviews.llvm.org/D117151
The "pad=" argument in the intrinsic function table entry for RESHAPE
has a Rank::Array constraint, and that would be fine if not for RESHAPE
already having an earlier argument that's Rank::Array. It's the only
intrinsic that has multiple Rank::Array arguments. The checking for
the Rank::Array constraint was enforcing that multiple occurrences
of it have the same rank in a call, and that's not appropriate.
Differential Revision: https://reviews.llvm.org/D117149
Currently, something like `print *, size(foo(n,m))` was rewritten
to `print *, size(foo_result_symbol)` when foo result is a non constant
shape array. This cannot be processed by lowering or reprocessed by a
Fortran compiler since the syntax is wrong (`foo_result_symbol` is
unknown on the caller side) and the arguments are lost when they might
be required to compute the result shape.
It is not possible (and probably not desired) to make GetShape fail in
general in such case since returning nullopt seems only expected for
scalars or assumed rank (see GetRank usage in lib/Semantics/check-call.cpp),
and returning a vector with nullopt extent may trigger some checks to
believe they are facing an assumed size (like here in intrinsic argument
checks: 196204c72c/flang/lib/Evaluate/intrinsics.cpp (L1530)).
Hence, I went for a solution that limits the rewrite change to folding
(where the original expression is returned if the shape depends on a non
constant shape from a call).
I added a non default option to GetShapeHelper that prevents the rewrite
of shape inquiry on calls to descriptor inquiries. At first I wanted to
avoid touching GetShapeHelper, but it would require to re-implement all
its logic to determine if the shape comes from a function call or not
(the expression could be `size(1+foo(n,m))`). So added an alternate
entry point to GetShapeHelper seemed the cleanest solution to me.
Differential Revision: https://reviews.llvm.org/D116933
Rather than represent the mixed real/complex subexpression x*(a,b)
as (x*a,x*b), use (x,0)*(a,b) to avoid a potential code duplication
in current lowering code. Same for mixed division, and for mixed
integer*complex and integer/complex cases.
Differential Review: https://reviews.llvm.org/D115732
Array constructors with implied DO loops that oversee structure
constructors were being prematurely folded into invalid constants
containing symbolic references to the ac-implied-do indices,
because they are indeed "constant expressions" as that term is
used in the Fortran standard and implemented as IsConstantExpr().
What's actually needed in structure constructor folding is a
test for actual constant values, which is what results from
folding them later with repetition in the context of folding
an ac-implied-do.
Differential Revision: https://reviews.llvm.org/D115470
Some kinds of Fortran arrays are declared with the same syntax,
and it is impossible to tell from a shape (:, :) or (*) whether
the object is assumed shape, deferred shape, assumed size, implied
shape, or whatever without recourse to more information about the
symbol in question. This patch softens the names of some predicate
functions (IsAssumedShape to CanBeAssumedShape) and makes others
more reflective of the syntax they represent (isAssumed to isStar)
in an attempt to encourage coders to seek and find definitive
predicate functions whose names deliver what they seem to mean.
Address TODO comments in IsSimplyContiguous() by using the
updated IsAssumedShape() predicate.
Differential Revision: https://reviews.llvm.org/D114829
A quick fix last week to the shared library build caused
the predicate IsCoarray(const Symbol &) to be moved from
Semantics to Evaluate. This patch completes that move in
a way that properly combines the existing IsCoarray() tests
for expressions and other object with the test for a symbol.
Differential Revision: https://reviews.llvm.org/D114806
Max(), MIN(), and their specific variants are defined with an unlimited
number of dummy arguments named A1=, A2=, &c. whose names are almost never
used in practice but should be allowed for and properly checked for the
usual errors when they do appear. The intrinsic table's entries otherwise
have fixed numbers of dummy argument definitions, so add some special
case handling in a few spots for MAX/MIN/&c. checking and procedure
characteristics construction.
Differential Revision: https://reviews.llvm.org/D114750
An earlier fix to evaluate::IsSaved() needed to preserve its
treatment of named constants in modules and main programs -- i.e.
they would appear to be saved -- until a correction was added
to the lowering code. This TODO can now be resolved.
Differential Revision: https://reviews.llvm.org/D114756
The current code was relying on the fact that allocatables are deferred
shape and that isAssumedShape() should therefore return true for them.
This is not true, because the current parsing/semantic analysis always
builds a semantics::ArraySpec for `x(:)` that returns true to both
isDeferredShape()/isAssumedShape(), whether x is allocatable/pointer or
not.
It proved tricky to change this behavior, so this is a simple fix for
IsSymplyContiguous where it currently matters, but we most likely want
to investigate more and fix the isDeferredShape()/isAssumedShape() in
a second time.
Differential Revision: https://reviews.llvm.org/D114599
The predicate IsCoarray() needs to be in libFortranEvaluate so that
IsSaved() can call it without breaking the shared library build.
Pushed without pre-commit review as I'm moving code around and
the fix to the shared build is confirmed.
This legacy option (available in other Fortran compilers with various
spellings) implies the SAVE attribute for local variables on subprograms
that are not explicitly RECURSIVE. The SAVE attribute essentially implies
static rather than stack storage. This was the default setting in Fortran
until surprisingly recently, so explicit SAVE statements & attributes
could be and often were omitted from older codes. Note that initialized
objects already have an implied SAVE attribute, and objects in COMMON
effectively do too, as data overlays are extinct; and since objects that are
expected to survive from one invocation of a procedure to the next in static
storage should probably be explicit initialized in the first place, so the
use cases for this option are somewhat rare, and all of them could be
handled with explicit SAVE statements or attributes.
This implicit SAVE attribute must not apply to automatic (in the Fortran sense)
local objects, whose sizes cannot be known at compilation time. To get the
semantics of IsSaved() right, the IsAutomatic() predicate was moved into
Evaluate/tools.cpp to allow for dynamic linking of the compiler. The
redundant predicate IsAutomatic() was noticed, removed, and its uses replaced.
GNU Fortran's spelling of the option (-fno-automatic) was added to
the clang-based driver and used for basic sanity testing.
Differential Revision: https://reviews.llvm.org/D114209
Fortran defines LEN(X) = 0 after CHARACTER(LEN=-1)::X so
apply MAX(0, ...) to character length expressions.
Differential Revision: https://reviews.llvm.org/D114030
Previous code was returning true for `x(:)` where x is a pointer without
the contiguous attribute.
In case the array ref is a whole array section, check the base for contiguity
to solve the issue.
Differential Revision: https://reviews.llvm.org/D114084
Section 10.2.2.4, paragraph 3 states that, for procedure pointer assignment:
If the pointer object has an explicit interface, its characteristics shall be
the same as the pointer target ...
Thus, it's illegal for a procedure pointer with an explicit interface to be
associated with a procedure whose interface is implicit. However, there's no
prohibition that disallows a procedure pointer with an implicit interface from
being associated with a procedure whose interface is explicit.
We were incorrectly emitting an error message for this latter case.
We were also not covering the case of procedures with explicit
interfaces where calling them requires the use of a descriptor. Such
procedures cannot be associated with procedure pointers with implicit
interfaces.
Differential Revision: https://reviews.llvm.org/D113706
Fortran defines an ENTRY point name as being pure if its enclosing
subprogram scope defines a pure procedure.
Differential Revision: https://reviews.llvm.org/D113711
The ORDER= argument to the transformational intrinsic function RESHAPE
was being misinterpreted in an inverted way that could be detected only
with 3-d or higher rank array. Fix in both folding and the runtime, and
extend tests.
Differential Revision: https://reviews.llvm.org/D113699
If the procedure pointer has an explicit interface, its characteristics must
equal the characteristics of its target, except that the target may be pure or
elemental also when the pointer is not (cf. F2018 10.2.2.4(3)). In the semantics
check for assignment of procedure pointers, the attributes of the procedures
were not checked correctly due to a typo. This caused some illegal
pointer-target-combinations to pass without raising an error. Fix this, and
expand the test case to improve the coverage of procedure pointer assignment
checks.
Reviewed By: PeteSteinfeld
Differential Revision: https://reviews.llvm.org/D113368
When an array's shape involves references to symbols that are not
invariant in a scope -- the classic example being a dummy array
with an explicit shape involving other dummy arguments -- the
compiler was creating shape expressions that referenced those
symbols. This might be valid if those symbols are somehow
captured and copied at each entry point to a subprogram, and
the copies referenced in the shapes instead, but that's not
the case.
This patch introduces a new expression predicate IsScopeInvariantExpr(),
which defines a class of expressions that contains constant expressions
(in the sense that the standard uses that term) as well as references
to items that may be safely accessed in a context-free way throughout
their scopes. This includes dummy arguments that are INTENT(IN)
and not VALUE, descriptor inquiries into descriptors that cannot
change, and bare LEN type parameters within the definitions of
derived types. The new predicate is then used in shape analysis
to winnow out results that would have otherwise been contextual.
Differential Revision: https://reviews.llvm.org/D113309
The tests for folding these intrinsics neglected to name the
logical scalars with a leading "test_", so test failures caused
by recent work to implement a combined constant folding facility
for these intrinsics wasn't catching some bugs. This patch fixes
the tests and the bugs.
Differential Revision: https://reviews.llvm.org/D112741
An erroneous entry in the intrinsics table causes semantics to
crash on a call to system_clock if the optional "count_max="
argument appears and "count=" does not.
Differential Revision: https://reviews.llvm.org/D112738
Check that when a procedure pointer is initialised or assigned with an intrinsic
function, or when its interface is being defined by one, that intrinsic function
is unrestricted specific (listed in Table 16.2 of F'2018).
Mark intrinsics LGE, LGT, LLE, and LLT as restricted specific. Getting their
classifications right helps in designing the tests.
Differential Revision: https://reviews.llvm.org/D112381
The clang-aarch64-full-2stage buildbot is complaining about a
warning with three instances in f18 code (none modified recently).
The warning is for using the | bitwise OR operator on bool operands.
In one instance, the bitwise operator was being used instead of the
logical || operator in order to avoid short-circuting. The fix
requires using some temporary variables. In the other two instances,
the bitwise operator seemed more idiomatic in context, but can be
replaced without harm with the logical operator.
Pushing without review as confidence is high and nobody wants
a buildbot to stay sad for long.
Allocatable dummy arguments can be used to distinguish
two specific procedures in a generic interface when
it is the case that exactly one of them is polymorphic
or exactly one of them is unlimited polymorphic. The
standard requires that an actual argument corresponding
to an (unlimited) polymorphic allocatable dummy argument
must also be an (unlimited) polymorphic allocatable, so an
actual argument that's acceptable to one procedure must
necessarily be a bad match for the other.
Differential Revision: https://reviews.llvm.org/D112237
Negative shift counts are of course valid for ISHFT when
shifting to the right. This patch decouples the folding of
ISHFT from that of SHIFTA/L/R and adds tests.
Differential Revision: https://reviews.llvm.org/D112244
Semantics is rejecting valid programs with NULL() actual arguments
to generic interfaces, including user-defined operators. Subclause
16.9.144(para 6) makes clear that NULL() can be a valid actual
argument to a generic interface so long as it does not produce
ambiguity. This patch handles those cases, revises existing
tests, and adjust an error message about NULL() operands to
appear less like a blanket prohibition.
Differential Revision: https://reviews.llvm.org/D111850
Fold the legacy intrinsic functions LGE, LGT, LLE, & LLT
by rewriting them into character relational expressions and
then folding those. Also fix folding of comparisons of
character values of distinct lengths: the shorter value must
be padded with blanks. (This fix exposed some bad test cases,
which are also fixed.)
Differential Revision: https://reviews.llvm.org/D111843
The Fortran 2018 standard defines the concept of simple contiguity
in subclause 9.5.4 as a characteristic of arrays. So that scalars
may also be used in contexts where simply contiguous arrays are
allowed, f18 treats them as single-element arrays that are trivially
contiguous. This patch documents this semantic extension and
also adds comments to the predicate that implements the concept.
Differential Revision: https://reviews.llvm.org/D111679
An LLVM Flang build bot for Windows recently failed with a
bunch of warning messages. None were from recent changes to
the Fortran compiler; I suspect that a newer (or maybe older)
version of MSVC was being used, or perhaps a different set of
compiler options were temporarily applied to the build, since
the buildbot status went back to green shortly thereafter.
Most of the warnings looked bogus to me, but some are legitimate
concerns and we might as well clean them up. This patch does so.
Differential Revision: https://reviews.llvm.org/D111677
To get proper wrap-around behavior for the various kind parameter
values of the optional COUNT= and COUNT_MAX= dummy arguments to
the intrinsic subroutine SYSTEM_CLOCK, add an extra argument to
the APIs for lowering to pass the integer kind of the actual argument.
Avoid confusion by requiring that both actual arguments have the same
kind when both are present. The results of the runtime functions
remain std::int64_t and lowering should still convert them before
storing to the actual argument variables.
Rework the implementation a bit to accomodate the dynamic
specification of the kind parameter, and to clean up some coding
issues with preprocessing and templates.
Use the kind of the COUNT=/COUNT_MAX= actual arguments to determine
the clock's resolution, where possible, in conformance with other
Fortran implementations.
Differential Revision: https://reviews.llvm.org/D111281
Peter Klausler