This is the second part loosely extracted from D71179 and cleaned up.
This patch provides semantic analysis support for `omp begin/end declare
variant`, mostly as defined in OpenMP technical report 8 (TR8) [0].
The sema handling makes code generation obsolete as we generate "the
right" calls that can just be handled as usual. This handling also
applies to the existing, albeit problematic, `omp declare variant
support`. As a consequence a lot of unneeded code generation and
complexity is removed.
A major purpose of this patch is to provide proper `math.h`/`cmath`
support for OpenMP target offloading. See PR42061, PR42798, PR42799. The
current code was developed with this feature in mind, see [1].
The logic is as follows:
If we have seen a `#pragma omp begin declare variant match(<SELECTOR>)`
but not the corresponding `end declare variant`, and we find a function
definition we will:
1) Create a function declaration for the definition we were about to generate.
2) Create a function definition but with a mangled name (according to
`<SELECTOR>`).
3) Annotate the declaration with the `OMPDeclareVariantAttr`, the same
one used already for `omp declare variant`, using and the mangled
function definition as specialization for the context defined by
`<SELECTOR>`.
When a call is created we inspect it. If the target has an
`OMPDeclareVariantAttr` attribute we try to specialize the call. To this
end, all variants are checked, the best applicable one is picked and a
new call to the specialization is created. The new call is used instead
of the original one to the base function. To keep the AST printing and
tooling possible we utilize the PseudoObjectExpr. The original call is
the syntactic expression, the specialized call is the semantic
expression.
[0] https://www.openmp.org/wp-content/uploads/openmp-TR8.pdf
[1] https://reviews.llvm.org/D61399#change-496lQkg0mhRN
Reviewers: kiranchandramohan, ABataev, RaviNarayanaswamy, gtbercea, grokos, sdmitriev, JonChesterfield, hfinkel, fghanim, aaron.ballman
Subscribers: bollu, guansong, openmp-commits, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D75779
This patch implements an almost complete handling of OpenMP
contexts/traits such that we can reuse most of the logic in Flang
through the OMPContext.{h,cpp} in llvm/Frontend/OpenMP.
All but construct SIMD specifiers, e.g., inbranch, and the device ISA
selector are define in `llvm/lib/Frontend/OpenMP/OMPKinds.def`. From
these definitions we generate the enum classes `TraitSet`,
`TraitSelector`, and `TraitProperty` as well as conversion and helper
functions in `llvm/lib/Frontend/OpenMP/OMPContext.{h,cpp}`.
The above enum classes are used in the parser, sema, and the AST
attribute. The latter is not a collection of multiple primitive variant
arguments that contain encodings via numbers and strings but instead a
tree that mirrors the `match` clause (see `struct OpenMPTraitInfo`).
The changes to the parser make it more forgiving when wrong syntax is
read and they also resulted in more specialized diagnostics. The tests
are updated and the core issues are detected as before. Here and
elsewhere this patch tries to be generic, thus we do not distinguish
what selector set, selector, or property is parsed except if they do
behave exceptionally, as for example `user={condition(EXPR)}` does.
The sema logic changed in two ways: First, the OMPDeclareVariantAttr
representation changed, as mentioned above, and the sema was adjusted to
work with the new `OpenMPTraitInfo`. Second, the matching and scoring
logic moved into `OMPContext.{h,cpp}`. It is implemented on a flat
representation of the `match` clause that is not tied to clang.
`OpenMPTraitInfo` provides a method to generate this flat structure (see
`struct VariantMatchInfo`) by computing integer score values and boolean
user conditions from the `clang::Expr` we keep for them.
The OpenMP context is now an explicit object (see `struct OMPContext`).
This is in anticipation of construct traits that need to be tracked. The
OpenMP context, as well as the `VariantMatchInfo`, are basically made up
of a set of active or respectively required traits, e.g., 'host', and an
ordered container of constructs which allows duplication. Matching and
scoring is kept as generic as possible to allow easy extension in the
future.
---
Test changes:
The messages checked in `OpenMP/declare_variant_messages.{c,cpp}` have
been auto generated to match the new warnings and notes of the parser.
The "subset" checks were reversed causing the wrong version to be
picked. The tests have been adjusted to correct this.
We do not print scores if the user did not provide one.
We print spaces to make lists in the `match` clause more legible.
Reviewers: kiranchandramohan, ABataev, RaviNarayanaswamy, gtbercea, grokos, sdmitriev, JonChesterfield, hfinkel, fghanim
Subscribers: merge_guards_bot, rampitec, mgorny, hiraditya, aheejin, fedor.sergeev, simoncook, bollu, guansong, dexonsmith, jfb, s.egerton, llvm-commits, cfe-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71830
If the context selector score was not specified, its value must be set
to 0. Simplify the processing of unspecified scores + save memory in
attribute representation.
and of vendors, not or.
If several vendors are provided in the same vendor context trait, the
context shall match only if all vendors are matching, not one of them.
This is per OpenMP 5.0, 2.3.3 Matching and Scoring Context Selectors,
all selectors in the construct, device, and implementation sets of the
context selector appear in the corresponding trait set of the OpenMP
context.
llvm-svn: 374107
selector.
According to OpenMP 5.0, 2.3.2 Context Selectors, Restrictions, each
trait-selector-name can only be specified once. Added check for this
restriction.
llvm-svn: 374093
According to OpenMP 5.0, 2.3.2 Context Selectors, Restrictions, each
trait-set-selector-name can only be specified once. Added check to
implement this restriction.
llvm-svn: 374072
C linkage.
After some discussion with OpenMP developers, it was decided that the
functions with the different C linkage can be used in declare variant
directive.
llvm-svn: 374057
Context selectors may include optional score clause in format
`score(<expr>):`, where `<expr>` must be a constant integer expression.
Added parsing/sema analysis only.
llvm-svn: 373502
sets.
According to OpenMP 5.0, context selector set might include several
context selectors, separated with commas. Patch fixes this problem.
llvm-svn: 372235
Added attribute for declare variant directive. It will allow to handle
declare variant directive at the codegen and will allow to add extra
checks.
llvm-svn: 372147
Johannes Doerfert