[Flang][OpenMP] Push context when parsing DECLARE VARIANT

[Stylie777]

Basic parsing and semantics support for Declare Variant was added in #130578. However, this did not include variant of Pre and Post within OmpAttributeVisitor. This meant that when a function in the class tried to get the context using GetContext, Flang would crash as the context was empty. To ensure this is possible, such as when resolving names as part of the uniform clause in the simd directive, the context is now pushed within OmpAttributeVisitor when parsing a DECLARE VARIANT directive.

Fixes #145222

[llvmbot]

@llvm/pr-subscribers-flang-openmp
@llvm/pr-subscribers-flang-parser

@llvm/pr-subscribers-flang-semantics

Author: Jack Styles (Stylie777)

Changes

Basic parsing and semantics support for Declare Variant was added in #130578. However, this did not include variant of Pre and Post within OmpAttributeVisitor. This meant that when a function in the class tried to get the context using GetContext, Flang would crash as the context was empty. To ensure this is possible, such as when resolving names as part of the uniform clause in the simd directive, the context is now pushed within OmpAttributeVisitor when parsing a DECLARE VARIANT directive.

Fixes #145222

---

Full diff: https://github.com/llvm/llvm-project/pull/147075.diff

2 Files Affected:

• (modified) flang/lib/Semantics/resolve-directives.cpp (+6)
• (modified) flang/test/Parser/OpenMP/declare-variant.f90 (+27)

diff --git a/flang/lib/Semantics/resolve-directives.cpp b/flang/lib/Semantics/resolve-directives.cpp
index 8d741734601a7..0d11b4a21ca3d 100644
--- a/flang/lib/Semantics/resolve-directives.cpp
+++ b/flang/lib/Semantics/resolve-directives.cpp
@@ -495,6 +495,12 @@ class OmpAttributeVisitor : DirectiveAttributeVisitor<llvm::omp::Directive> {
   bool Pre(const parser::OpenMPAllocatorsConstruct &);
   void Post(const parser::OpenMPAllocatorsConstruct &);
 
+  bool Pre(const parser::OmpDeclareVariantDirective &x) {
+    PushContext(x.source, llvm::omp::Directive::OMPD_declare_variant);
+    return true;
+  }
+  void Post (const parser::OmpDeclareVariantDirective &) { PopContext(); };
+
   void Post(const parser::OmpObjectList &x) {
     // The objects from OMP clauses should have already been resolved,
     // except common blocks (the ResolveNamesVisitor does not visit
diff --git a/flang/test/Parser/OpenMP/declare-variant.f90 b/flang/test/Parser/OpenMP/declare-variant.f90
index 1b97733ea9525..3366b143e62e6 100644
--- a/flang/test/Parser/OpenMP/declare-variant.f90
+++ b/flang/test/Parser/OpenMP/declare-variant.f90
@@ -102,3 +102,30 @@ subroutine vsub(v1, v2)
     type(c_ptr), value :: v1, v2
   end
 end subroutine
+
+subroutine f
+  real :: x, y
+  y = 2
+  !omp simd
+  call f2(x, y)
+  !omp end simd 
+contains
+  subroutine f1 (x, y)
+    real :: x, y
+  end
+
+  subroutine f2 (x, y)
+    real :: x, y
+    !$omp declare variant (f1) match (construct={simd(uniform(y))})
+  end
+end subroutine
+!CHECK: !$OMP DECLARE VARIANT (f1) MATCH(CONSTRUCT={SIMD(UNIFORM(y))})
+!PARSE-TREE: | | | | DeclarationConstruct -> SpecificationConstruct -> OpenMPDeclarativeConstruct -> OmpDeclareVariantDirective
+!PARSE-TREE-NEXT: | | | | | Verbatim
+!PARSE-TREE-NEXT: | | | | | Name = 'f1'
+!PARSE-TREE-NEXT: | | | | | OmpClauseList -> OmpClause -> Match -> OmpMatchClause -> OmpContextSelectorSpecification -> OmpTraitSetSelector
+!PARSE-TREE-NEXT: | | | | | | OmpTraitSetSelectorName -> Value = Construct
+!PARSE-TREE-NEXT: | | | | | | OmpTraitSelector
+!PARSE-TREE-NEXT: | | | | | | | OmpTraitSelectorName -> Value = Simd
+!PARSE-TREE-NEXT: | | | | | | | Properties
+!PARSE-TREE-NEXT: | | | | | | | | OmpTraitProperty -> OmpClause -> Uniform -> Name = 'y'

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[kiranchandramohan]

LGTM. Thanks for the fix.

In future some name resolution will have to happen from !$omp declare variant (f1) to the subroutine f1.