When a REAL or COMPLEX literal appears without an explicit kind suffix
or a kind-determining exponent letter, and the conversion of that
literal from decimal to binary is inexact, emit a warning if that
constant is later implicitly widened to a more precise kind, since it
will have a different value than was probably intended.
Values that convert exactly from decimal to default real, e.g. 1.0 and
0.125, do not elicit this warning.
There are many contexts in which Fortran implicitly converts constants.
This patch covers name constant values, variable and component
initialization, constants in expressions, structure constructor
components, and array constructors.
For example, "real(8) :: tenth = 0.1" is a common Fortran bug that's
hard to find, and is one that often trips up even experienced Fortran
programmers. Unlike C and C++, the literal constant 0.1 is *not* double
precision by default, and it does not have the same value as 0.1d0 or
0.1_8 do when it is converted from decimal to real(4) and then to
real(8).
Bring the typed expression representation of a coindexed reference up to
F'2023, which removed some restrictions that had allowed the current
representation to suffice for older revisions of the language. This new
representation is somewhat more simple -- it uses a DataRef as its base,
so any subscripts in a part-ref can be represented as an ArrayRef there.
Update the code that creates the CoarrayRef, and add more checking to
it, as well as actually capturing any STAT=, TEAM=, & TEAM_NUMBER=
specifiers that might appear. Enforce the constraint that the part-ref
must have subscripts if it is an array. (And update a pile of
copied-and-pasted test code that lacked such subscripts.)
… discontiguity
For dummy assumed-shape/-rank device arrays, test the associated actual
argument for stride-1 contiguity, and report an error when the actual
argument is known to not be stride-1 contiguous and nonempty, or a
warning when when the actual argument is not known to be empty or
stride-1 contiguous.
Nearly, but not all, other compilers have a blanket prohibition against
the use of an INTENT(OUT) dummy argument in a specification expression.
Some compilers, however, permit an INTENT(OUT) dummy argument to appear
in a specification expression in a BLOCK construct or inner procedure
via host association.
The argument some have put forth to accept this usage comes from a
reading of 10.1.11 (specification expressions) in Fortran 2023 that, if
followed consistently, would also require host-associated OPTIONAL dummy
argument to be allowed. That would be dangerous for reasons that should
be obvious.
However, I can agree that a non-OPTIONAL dummy argument can't be assumed
to remain undefined on entry to a BLOCK construct or inner procedure, so
we can accept host-associated INTENT(OUT) in specification expressions
with a portability warning.
The optional second argument to IEEE_SUPPORT_FLAG (and related functions
from the intrinsic IEEE_ARITHMETIC module) is needed only for its type,
not its value. Restrictions on local objects as arguments to function
references in specification expressions shouldn't apply to it.
Define a new attribute for dummy data object characteristics to
distinguish such arguments, set it for the appropriate intrinsic
function references, and test it during specification expression
validation.
We currently don't consider an integer division to be a constant
expression unless its divisor is known and nonzero. This produces a
weird result in the linked test; do better.
Fixes https://github.com/llvm/llvm-project/issues/130534.
Refine handling of NULL(...) in semantics to properly distinguish
NULL(), NULL(objectPointer), NULL(procPointer), and NULL(allocatable)
from each other in relevant contexts.
Add IsNullAllocatable() and IsNullPointerOrAllocatable() utility
functions. IsNullAllocatable() is true only for NULL(allocatable); it is
false for a bare NULL(), which can be detected independently with
IsBareNullPointer().
IsNullPointer() now returns false for NULL(allocatable).
ALLOCATED(NULL(allocatable)) now works, and folds to .FALSE.
These utilities were modified to accept const pointer arguments rather
than const references; I usually prefer this style when the result
should clearly be false for a null argument (in the C sense), and it
helped me find all of their use sites in the code.
IsSymplyContiguous was visiting expressions and returning false on
expressions like `x(::2) + y`, which triggered an assert in lowering
when preparing arguments for copy-in/out.
Update it to return false for everything that is not a variable, except
when provided a flag to treat PARAMETER bases as variables. This flags
is required for internal usages in lowering where lowering needs to now
if the read-only memory is being addressed contiguously or not.
Update call lowering to always copy parameter array section into
contiguous writable memory when passing them. The rational here is that
copy-out generated in nested calls using the dummy arguments will cause
a segfault.
Add tests for negative array extents where necessary, motivated by a
compiler crash exposed by yet another fuzzer test, and improve overall
error message quality for RESHAPE().
Fixes https://github.com/llvm/llvm-project/issues/122060.
At present, the compiler doesn't analyze substring references for
contiguity. But there are cases where substrings can be known to be
contiguous (scalar base, empty substring, or complete substring) or can
be known to be discontiguous, and references to the intrinsic function
IS_CONTIGUOUS in those cases may appear in constant expressions.
Fixes https://github.com/llvm/llvm-project/issues/115675.
(This is a big patch, but it's nearly an NFC. No test results have
changed and all Fortran tests in the LLVM test suites work as expected.)
Allow a parser::Message for a warning to be marked with the
common::LanguageFeature or common::UsageWarning that controls it. This
will allow a later patch to add hooks whereby a driver will be able to
decorate warning messages with the names of its options that enable each
particular warning, and to add hooks whereby a driver can map those
enumerators by name to command-line options that enable/disable the
language feature and enable/disable the messages.
The default settings in the constructor for LanguageFeatureControl were
moved from its header file into its C++ source file.
Hooks for a driver to use to map the name of a feature or warning to its
enumerator were also added.
To simplify the tagging of warnings with their corresponding language
feature or usage warning, to ensure that they are properly controlled by
ShouldWarn(), and to ensure that warnings never issue at code sites in
module files, two new Warn() member function templates were added to
SemanticsContext and other contextual frameworks. Warn() can't be used
before source locations can be mapped to scopes, but the bulk of
existing code blocks testing ShouldWarn() and FindModuleFile() before
calling Say() were convertible into calls to Warn(). The ones that were
not convertible were extended with explicit calls to
Message::set_languageFeature() and set_usageWarning().
Specification expressions may contain references to dummy arguments,
host objects, module variables, and variables in COMMON blocks, since
they will have values on entry to the scope. A local variable with a
initializer and the SAVE attribute (which will always be implied by an
explicit initialization) will also always work, and is accepted by at
least one other compiler, so accept it with a warning.
When a local character variable with non-constant length has an
initializer, it's an error in a couple of ways (SAVE variable with
unknown size, static initializer that isn't constant due to conversion
to an unknown length). The error that f18 reports is the latter, but the
message contains a formatted representation of the initialization
expression that exposes a non-Fortran %SET_LENGTH() operation. Print the
original expression in the message instead.
Transformational functions from the intrinsic module ISO_C_BINDING are
allowed in specification expressions, so tweak some general checks that
would otherwise trigger error messages about inadmissible targets, dummy
procedures in specification expressions, and pure procedures with impure
dummy procedures.
SIZEOF and C_SIZEOF were broken for assumed-ranks because
`TypeAndShape::MeasureSizeInBytes` behaved as a scalar because the
`TypeAndShape::shape_` member was the same for scalar and assumed-ranks.
The easy fix would have been to add special handling in
`MeasureSizeInBytes` for assumed-ranks using the TypeAndShape
attributes, but I think this solution would leave `TypeAndShape::shape_`
manipulation fragile to future developers. Hence, I went for the
solution that turn shape_ into a `std::optional<Shape>`.
No specification expression in the declaration of the result variable of
an elemental function may depend on the value of a dummy argument. This
ensures that all of the results have the same type when the elemental
function is applied to the elements of an array.
Lower select rank according to [assumed-rank lowering design
doc](https://github.com/llvm/llvm-project/blob/main/flang/docs/AssumedRank.md).
The construct is lowered using fir.box_rank and fir.select_case
operation and, for the non pointer/allocatable case, a
fir.is_assumed_size + conditional branch before the select_case to deal
with the assumed-size case.
The way the CFG logic is generated, apart from the extra conditional
branch for assumed-size, is similar to what is done for SELECT CASE
lowering, hence the sharing of the construct level visitor.
For the CFG parts. The main difference is that we need to keep track of
the selector to cook it and map it inside the cases (hence the new
members of the ConstructContext).
The only TODOs left are to deal with the RANK(*) case for polymorphic
entities and PDTs. I will do the polymorphic case in a distinct patch,
this patch has enough content.
Fortran::evaluate::IsSimplyContiguous change is needed to avoid generating
copy-in/copy-out runtime calls when passing the RANK(*) associating
entity to some implicit interface.
When the characteristics of a procedure depend on a procedure that
hasn't yet been defined, the compiler currently emits an unconditional
error message. This includes the case of a procedure whose
characteristics depend, perhaps indirectly, on itself. However, in the
case where the characteristics of a procedure are needed to resolve a
generic, we should not emit an error for a hitherto undefined procedure
-- either the call will resolve to another specific procedure, in which
case the error is spurious, or it won't, and then an error will issue
anyway.
Fixes https://github.com/llvm/llvm-project/issues/88677.
Address TODOs in the intrinsic module ISO_FORTRAN_ENV, and extend the
implementation of NUMERIC_STORAGE_SIZE so that the calculation of its
value is deferred until it is needed so that the effects of
-fdefault-integer-8 or -fdefault-real-8 are reflected. Emit a warning
when NUMERIC_STORAGE_SIZE is used from the module file and the default
integer and real sizes do not match.
Fixes https://github.com/llvm/llvm-project/issues/87476.
Detect attempts to use non-constant targets, including internal
procedures, as initializers for procedure pointers, including components
of structure components being used as initializers.
Before emitting a warning message, code should check that the usage in
question should be diagnosed by calling ShouldWarn(). A fair number of
sites in the code do not, and can emit portability warnings
unconditionally, which can confuse a user that hasn't asked for them
(-pedantic) and isn't terribly concerned about portability *to* other
compilers.
Add calls to ShouldWarn() or IsEnabled() around messages that need them,
and add -pedantic to tests that now require it to test their portability
messages, and add more expected message lines to those tests when
-pedantic causes other diagnostics to fire.
Pure intrinsic functions are acceptable in constant expressions so long
as their arguments are constant expressions. Allow them to appear in
subscripts in DATA statement variables.
Fixes https://github.com/llvm/llvm-project/issues/65046.
A section of a parameter array may be non-contiguous,
so the current !IsVariable(expr) check is too optimistic
to claim contiguity.
This patch fixes issues with incorrect hlfir.designate op generated
during lowering: the lowering queries IsContiguous to decide whether
to use fir.box<fir.array> or plain fir.ref<fir.array> to represent
the designator result.
Reviewed By: klausler
Differential Revision: https://reviews.llvm.org/D156494
Make __builtin_c_loc() into an intrinsic function and verify the
special semantic requirements on its actual arguments.
Differential Revision: https://reviews.llvm.org/D149988
TYPE(*) arguments fell through in IS_CONTIGUOUS folding
because they are not Expr<SomeType>. Expose entry point for
symbols in IsContiguous and use that.
The added test revealed that IS_CONTIGUOUS was folded to
false for assumed rank arguments. Fix this: the contiguity of
assumed rank without the CONTIGUOUS argument can only be
verified at runtime.
Differential Revision: https://reviews.llvm.org/D148128
Currently, the selector of a construct entity (e.g., ASSOCIATE(x=>a(1:20)))
is inheriting the CONTIGUOUS attribute from its associated variable
even if it has subscripts that make it noncontiguous (a(1:20:2)).
Add construct entities to the dynamic contiguity predicate instead.
Differential Revision: https://reviews.llvm.org/D145114
It's basically impossible to write a switch statement with a case
for every enumerator in an enum class if the cases each have a
return statement and get it to compile without warnings for all
of our build compilers & versions. Rewrite as a sequence of
if statements.
This patch fixes:
flang/lib/Evaluate/check-expression.cpp:509:3: error: default label
in switch which covers all enumeration values
[-Werror,-Wcovered-switch-default]
When a descriptor inquiry or inquiry function's result is
not constant and is known to be impossible to correctly determine
at runtime, raise an error. For example, LEN(X) when X is
a local allocatable variable with deferred length.
Differential Revision: https://reviews.llvm.org/D142759
Implement the visit of component refs in DesignatorBuilder.
The ArrayRef code has to be updated a bit to cope with the
case where the base is an array and the component is also an
array.
Improve the result type of array sections designators (only return
a fir.box if the array section is not contiguous/has dynamic extent).
This required exposing IsContiguous entry point for different
front-end designator nodes (the implementation already existed,
but was internal to check-expression.cpp).
Differential Revision: https://reviews.llvm.org/D141470
Check most of the requiremens of constraint C1577 for statement functions.
The restrictions that prevent recursion are hard errors; the others seem
to be benign legacies and are caught as portability warnings.
Differential Revision: https://reviews.llvm.org/D139136
Some intrinsic functions can handle NULL() as an actual argument; most
can't. Distinguish the two with a new ArgFlag facility in the intrinsic
procedure table. Also transform some confusing Optionality codes that
were standing in for flags into ArgFlags. Last, return false for a NULL()
pointer from the utility IsActuallyConstant(), ensuring that it can
still deal with a nested NULL() for components in structure constructors.
Differential Revision: https://reviews.llvm.org/D136893
Don't return a hard .FALSE. when folding IS_CONTIGUOUS() unless the
subscript triplets are discontiguous and array section is nonempty,
or if the array section is nonempty and there is a vector subscript.
Differential Revision: https://reviews.llvm.org/D135334
When a component array of a named constant is extracted as
a constant value, ensure that the lower bounds of the array
are properly acquired from the declaration of the component.
Differential Revision: https://reviews.llvm.org/D134499
At present, IS_CONTIGUOUS() can only either fold to .TRUE. or
remain unknown. The underlying analysis, however, is capable
of returning a tri-state result (true, false, or unknown).
Extend and expose it to folding so that IS_CONTIGUOUS() can
fold to .FALSE. as well as to .TRUE. when contiguity is
known.
Differential Revision: https://reviews.llvm.org/D134466
The previous code was rewriting all shape inquires on associate
construct entities to inquires on the associated expression or variable.
This is is incorrect because at the point of inquiry, some statement
between the association and the inquiry may have modified the expression
operands or variable in a way that changes its shapes or bounds.
For instance, in the example below, expression rewrites was previously
replacing `size(x, 1)` by `size(p, 1)` which is invalid if p is a
pointer.
```
associate(x => p + 1)
call call_that_may_modify_p_shape()
print *, size(x, 1)
end associate
```
This change restricts rewrites of shape inquiries on associate construct entity
to use the associated expression shape and bounds if and only if the
shape/bounds are compile time constant. Otherwise, this may be invalid.
Differential Revision: https://reviews.llvm.org/D133857
A NULL() pointer is a valid actual argument for a procedure pointer dummy
argument whose intent is INTENT(IN); it should also be acceptable for a
procedure pointer dummy argument with unspecified intent.
Also make it possible to discern null object pointers from null procedure
pointers, so that an attempt to use one in place of the other in a context
where the distinction matters will still elicit an error.
Differential Revision: https://reviews.llvm.org/D132687
F18 preserves lower bounds of explicit-shape named constant arrays, but
failed to also do so for implicit-shape named constants. Fix.
Differential Revision: https://reviews.llvm.org/D127021
Inquiries into the bounds, size, and length of local variables (and function results)
are acceptable specification expressions. A recent change allowed them for dummy
arguments that are not OPTIONAL or INTENT(OUT), but didn't address other object
entities.
Differential Revision: https://reviews.llvm.org/D125343
The rules in the Fortran standard for specification expressions
are full of special cases and exceptions, and semantics didn't get
them exactly right. It is valid to refer to an INTENT(OUT) dummy
argument in a specification expression in the context of a
specification inquiry function like SIZE(); it is not valid to
reference an OPTIONAL dummy argument outside of the context of
PRESENT. This patch makes the specification expression checker
a little context-sensitive about whether it's examining an actual
argument of a specification inquiry intrinsic function or not.
Differential Revision: https://reviews.llvm.org/D125131
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().
In case a character component PDT length only depends on kind parameters,
fold it while instantiating the PDT. This is especially important if the
component has an initializer because later semantic phases (offset
computation or runtime type info generation) might get confused and
generate offset/type info that will lead to crashes in lowering.
Differential Revision: https://reviews.llvm.org/D122938
Adds flang/include/flang/Common/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.
Differential Revision: https://reviews.llvm.org/D122441
Similarly to LBOUND in https://reviews.llvm.org/D121488, UBOUND must
return zero for an empty dimension, no matter the specification
expression.
Add a GetUBOUND method to be used in expression rewrite that prevents
folding UBOUND to a bound specification expression if the extent is
not a compile time constant.
Fold the case where the extents is known to be zero (and also deal with
this case in LBOUND since we can and should to comply with constant
expression requirements).
Differential Revision: https://reviews.llvm.org/D122242
LBOUND must return 1 for an empty dimension, no matter what
explicit expression might appear in a declaration or arrive in
a descriptor.
Differential Revision: https://reviews.llvm.org/D121488
