[OpenMP 5.2] New syntax for 'uses_allocators' clause #157025

ravurvi20 · 2025-09-05T06:06:39Z

This patch updates the parsing changes to handle the new syntax of the uses_allocators clause as defined in OpenMP 5.2(Section 6.8).

// Case 1: Allocator without traits
// < 5.2 → error
// ≥ 5.2 → OK, empty traits set
#pragma omp target teams uses_allocators(cgroup_alloc)

// Case 2: Allocator with traits
// Old syntax (< 5.2):
#pragma omp target teams uses_allocators(cgroup_alloc(cgroup_traits))
// New syntax (≥ 5.2):
#pragma omp target teams uses_allocators(traits(cgroup_traits) : cgroup_alloc)

// Case 3: Multiple allocators
// Old syntax (< 5.2), comma-separated:
#pragma omp target teams uses_allocators(cgroup_alloc(cgroup_traits), aligned_alloc(aligned_traits))
// New syntax (≥ 5.2), semicolon-separated:
#pragma omp target teams uses_allocators(traits(cgroup_traits) : cgroup_alloc; traits(aligned_traits) : aligned_alloc)

llvmbot · 2025-09-05T06:07:12Z

@llvm/pr-subscribers-clang

Author: Urvi Rav (ravurvi20)

Changes

This patch updates the parsing changes to handle the new syntax of the uses_allocators clause as defined in OpenMP 5.2(Section 6.8).

// Case 1: Allocator without traits
// &lt; 5.2 → error
// ≥ 5.2 → OK, empty traits set
#pragma omp target teams uses_allocators(cgroup_alloc)

// Case 2: Allocator with traits
// Old syntax (&lt; 5.2):
#pragma omp target teams uses_allocators(cgroup_alloc(cgroup_traits))
// New syntax (≥ 5.2):
#pragma omp target teams uses_allocators(traits(cgroup_traits) : cgroup_alloc)

// Case 3: Multiple allocators
// Old syntax (&lt; 5.2), comma-separated:
#pragma omp target teams uses_allocators(cgroup_alloc(cgroup_traits), aligned_alloc(aligned_traits))
// New syntax (≥ 5.2), semicolon-separated:
#pragma omp target teams uses_allocators(traits(cgroup_traits) : cgroup_alloc; traits(aligned_traits) : aligned_alloc)

Full diff: https://github.com/llvm/llvm-project/pull/157025.diff

4 Files Affected:

(modified) clang/include/clang/Basic/DiagnosticParseKinds.td (+5)
(modified) clang/lib/Parse/ParseOpenMP.cpp (+71)
(modified) clang/lib/Sema/SemaOpenMP.cpp (+2)
(modified) clang/test/OpenMP/target_uses_allocators_messages.cpp (+23-4)

diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index bc7a6e231d93c..44c3d07bf6027 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -1497,6 +1497,11 @@ def err_omp_multiple_step_or_linear_modifier : Error<
   "multiple %select{'step size'|'linear modifier'}0 found in linear clause">;
 def err_omp_deprecate_old_syntax: Error<
   "old syntax '%0' on '%1' clause was deprecated, use new syntax '%2'">;
+def warn_omp_deprecate_old_syntax: Warning<
+  "old syntax '%0' on '%1' clause was deprecated, use new syntax '%2'">, 
+  InGroup<Deprecated>;
+def err_omp_allocator_comma_separator :
+  Error<"',' not allowed as separator in 'uses_allocators' clause, use ';' instead">;
 def warn_omp_future_directive_spelling: Warning<
   "directive spelling '%0' is introduced in a later OpenMP version">,
   InGroup<OpenMPFuture>;
diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index 5db2f2e2ccf86..92abc7084bed0 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -2959,6 +2959,69 @@ OMPClause *Parser::ParseOpenMPUsesAllocatorClause(OpenMPDirectiveKind DKind) {
     return nullptr;
   SmallVector<SemaOpenMP::UsesAllocatorsData, 4> Data;
   do {
+    // Parse 'traits(expr) : Allocator' for >=5.2
+    if (getLangOpts().OpenMP >= 52 &&
+        Tok.is(tok::identifier) &&
+        Tok.getIdentifierInfo()->getName() == "traits") {
+
+      SemaOpenMP::UsesAllocatorsData &D = Data.emplace_back();
+
+      ConsumeToken();
+
+      // Parse '(' <expr> ')'
+      BalancedDelimiterTracker TraitParens(*this, tok::l_paren, tok::annot_pragma_openmp_end);
+      TraitParens.consumeOpen();
+      ExprResult AllocatorTraits =
+          getLangOpts().CPlusPlus ? ParseCXXIdExpression() : ParseExpression();
+      TraitParens.consumeClose();
+
+      if (AllocatorTraits.isInvalid()) {
+        SkipUntil({tok::comma, tok::semi, tok::r_paren, tok::annot_pragma_openmp_end},
+                  StopBeforeMatch);
+        break;
+      }
+
+      // Expect ':'
+      if (Tok.isNot(tok::colon)) {
+        Diag(Tok, diag::err_expected) << tok::colon;
+        SkipUntil({tok::comma, tok::semi, tok::r_paren, tok::annot_pragma_openmp_end},
+                  StopBeforeMatch);
+        continue;
+      }
+      ConsumeToken();
+
+      CXXScopeSpec SS;
+      Token Replacement;
+      ExprResult AllocatorExpr =
+          getLangOpts().CPlusPlus
+              ? ParseCXXIdExpression()
+              : tryParseCXXIdExpression(SS, /*isAddressOfOperand=*/false, Replacement);
+
+      if (AllocatorExpr.isInvalid()) {
+        SkipUntil({tok::comma, tok::semi, tok::r_paren, tok::annot_pragma_openmp_end},
+                  StopBeforeMatch);
+        break;
+      }
+
+      D.Allocator = AllocatorExpr.get();
+      D.AllocatorTraits = AllocatorTraits.get();
+      D.LParenLoc = TraitParens.getOpenLocation();
+      D.RParenLoc = TraitParens.getCloseLocation();
+
+      // Separator handling(;)
+      if (Tok.is(tok::comma)) {
+        // In 5.2, comma is invalid
+        Diag(Tok.getLocation(), diag::err_omp_allocator_comma_separator)
+            << FixItHint::CreateReplacement(Tok.getLocation(), ";");
+        ConsumeAnyToken();
+      } else if (Tok.is(tok::semi)) {
+        ConsumeAnyToken(); // valid separator
+      }
+
+      continue;
+    }
+
+    // Parse 'Allocator(expr)' for <5.2
     CXXScopeSpec SS;
     Token Replacement;
     ExprResult Allocator =
@@ -2988,6 +3051,14 @@ OMPClause *Parser::ParseOpenMPUsesAllocatorClause(OpenMPDirectiveKind DKind) {
       D.AllocatorTraits = AllocatorTraits.get();
       D.LParenLoc = T.getOpenLocation();
       D.RParenLoc = T.getCloseLocation();
+
+      // Deprecation diagnostic in >= 5.2
+      if (getLangOpts().OpenMP >= 52) {
+        Diag(Loc, diag::warn_omp_deprecate_old_syntax)
+            << "allocator(expr)"      // %0: old form
+            << "uses_allocators"      // %1: clause name
+            << "traits(expr): alloc"; // %2: suggested new form
+      }
     }
     if (Tok.isNot(tok::comma) && Tok.isNot(tok::r_paren))
       Diag(Tok, diag::err_omp_expected_punc) << "uses_allocators" << 0;
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index a1dd5b090c59b..7db5226da4cb5 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -24083,11 +24083,13 @@ OMPClause *SemaOpenMP::ActOnOpenMPUsesAllocatorClause(
       // OpenMP [2.12.5, target Construct]
       // Non-predefined allocators appearing in a uses_allocators clause must
       // have traits specified.
+      if (getLangOpts().OpenMP < 52) {
       if (!IsPredefinedAllocator && !D.AllocatorTraits) {
         Diag(D.Allocator->getExprLoc(),
              diag::err_omp_nonpredefined_allocator_without_traits);
         continue;
       }
+    }
       // No allocator traits - just convert it to rvalue.
       if (!D.AllocatorTraits)
         AllocatorExpr = SemaRef.DefaultLvalueConversion(AllocatorExpr).get();
diff --git a/clang/test/OpenMP/target_uses_allocators_messages.cpp b/clang/test/OpenMP/target_uses_allocators_messages.cpp
index b145c4d9501cf..45906bc92999e 100644
--- a/clang/test/OpenMP/target_uses_allocators_messages.cpp
+++ b/clang/test/OpenMP/target_uses_allocators_messages.cpp
@@ -2,6 +2,10 @@
 
 // RUN: %clang_cc1 -verify -fopenmp-simd %s -Wuninitialized
 
+// RUN: %clang_cc1 -DOMP52 -verify=omp52 -fopenmp -fopenmp-version=52 %s -Wuninitialized
+
+// RUN: %clang_cc1 -DOMP52 -verify=omp52 -fopenmp-simd  -fopenmp-version=52 %s -Wuninitialized
+
 struct omp_alloctrait_t {};
 
 typedef void **omp_allocator_handle_t;
@@ -16,10 +20,15 @@ extern const omp_allocator_handle_t omp_pteam_mem_alloc;
 extern const omp_allocator_handle_t omp_thread_mem_alloc;
 
 int main(int argc, char **argv) {
-  omp_alloctrait_t traits[10];
+  omp_alloctrait_t my_traits[10];
   omp_alloctrait_t *ptraits;
   omp_allocator_handle_t my_alloc = nullptr;
   const omp_allocator_handle_t c_my_alloc = my_alloc;
+  omp_alloctrait_t aligned_traits[10];
+  omp_allocator_handle_t aligned_alloc;
+
+#ifndef OMP52
+
 #pragma omp target uses_allocators // expected-error {{expected '(' after 'uses_allocator'}}
 {}
 #pragma omp target uses_allocators( // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected unqualified-id}}
@@ -34,7 +43,7 @@ int main(int argc, char **argv) {
 {}
 #pragma omp target uses_allocators(omp_default_mem_alloc, omp_large_cap_mem_alloc, omp_const_mem_alloc, omp_high_bw_mem_alloc, omp_low_lat_mem_alloc, omp_cgroup_mem_alloc, omp_pteam_mem_alloc, omp_thread_mem_alloc)
 {}
-#pragma omp target uses_allocators(omp_default_mem_alloc(traits), omp_large_cap_mem_alloc(traits), omp_const_mem_alloc(traits), omp_high_bw_mem_alloc(traits), omp_low_lat_mem_alloc(traits), omp_cgroup_mem_alloc(traits), omp_pteam_mem_alloc(traits), omp_thread_mem_alloc(traits)) // expected-error 8 {{predefined allocator cannot have traits specified}} expected-note-re 8 {{predefined trait '{{omp_default_mem_alloc|omp_large_cap_mem_alloc|omp_const_mem_alloc|omp_high_bw_mem_alloc|omp_low_lat_mem_alloc|omp_cgroup_mem_alloc|omp_pteam_mem_alloc|omp_thread_mem_alloc}}' used here}}
+#pragma omp target uses_allocators(omp_default_mem_alloc(my_traits), omp_large_cap_mem_alloc(my_traits), omp_const_mem_alloc(my_traits), omp_high_bw_mem_alloc(my_traits), omp_low_lat_mem_alloc(my_traits), omp_cgroup_mem_alloc(my_traits), omp_pteam_mem_alloc(my_traits), omp_thread_mem_alloc(my_traits)) // expected-error 8 {{predefined allocator cannot have traits specified}} expected-note-re 8 {{predefined trait '{{omp_default_mem_alloc|omp_large_cap_mem_alloc|omp_const_mem_alloc|omp_high_bw_mem_alloc|omp_low_lat_mem_alloc|omp_cgroup_mem_alloc|omp_pteam_mem_alloc|omp_thread_mem_alloc}}' used here}}
 {}
 #pragma omp target uses_allocators(my_alloc, c_my_alloc) // expected-error {{non-predefined allocator must have traits specified}} expected-error {{expected variable of the 'omp_allocator_handle_t' type, not 'const omp_allocator_handle_t' (aka 'void **const')}}
 {}
@@ -46,10 +55,20 @@ int main(int argc, char **argv) {
 {}
 #pragma omp target uses_allocators(my_alloc(ptraits)) // expected-error {{expected constant sized array of 'omp_alloctrait_t' elements, not 'omp_alloctrait_t *'}}
 {}
-#pragma omp target uses_allocators(my_alloc(traits)) private(my_alloc) // expected-error {{allocators used in 'uses_allocators' clause cannot appear in other data-sharing or data-mapping attribute clauses}} expected-note {{defined as private}}
+#pragma omp target uses_allocators(my_alloc(my_traits)) private(my_alloc) // expected-error {{allocators used in 'uses_allocators' clause cannot appear in other data-sharing or data-mapping attribute clauses}} expected-note {{defined as private}}
+{}
+#pragma omp target map(my_alloc, my_traits) uses_allocators(my_alloc(my_traits)) // expected-error {{allocators used in 'uses_allocators' clause cannot appear in other data-sharing or data-mapping attribute clauses}} expected-note {{used here}}
+{}
+#else
+#pragma omp target teams uses_allocators(traits(my_traits): my_alloc; traits(aligned_traits): aligned_alloc)
+{}
+#pragma omp target teams uses_allocators(my_alloc)
+{}
+#pragma omp target teams uses_allocators(traits(my_traits): my_alloc, traits(aligned_traits): aligned_alloc) // omp52-error {{',' not allowed as separator in 'uses_allocators' clause, use ';' instead}}
 {}
-#pragma omp target map(my_alloc, traits) uses_allocators(my_alloc(traits)) // expected-error {{allocators used in 'uses_allocators' clause cannot appear in other data-sharing or data-mapping attribute clauses}} expected-note {{used here}}
+#pragma omp target teams uses_allocators(my_alloc(my_traits), aligned_alloc(aligned_traits)) // omp52-warning {{old syntax 'allocator(expr)' on 'uses_allocators' clause was deprecated, use new syntax 'traits(expr): alloc'}} //omp52-warning {{old syntax 'allocator(expr)' on 'uses_allocators' clause was deprecated, use new syntax 'traits(expr): alloc'}}
 {}
+#endif
   return 0;
 }

github-actions · 2025-09-05T06:10:21Z

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

alexey-bataev

Update OpenMP.rst and whatsnew docs for clang

alexey-bataev · 2025-09-08T15:56:43Z

clang/include/clang/Basic/DiagnosticParseKinds.td

+def warn_omp_deprecate_old_syntax: Warning<
+  "old syntax '%0' on '%1' clause was deprecated, use new syntax '%2'">, 
+  InGroup<Deprecated>;


Why do we want a warning instead of error?

@alexey-bataev Since the construct is deprecated and not removed, I kept it as a warning for backward compatibility. I can change it to an error if preferred.

The question is: is the old syntax still allowed in 6.0? If not, it should be the error.

looked into the spec (Section B.2, Version 5.2 to 6.0 Differences) which states: All features deprecated in versions 5.0, 5.1 and 5.2 were removed.
Since the old syntax falls under this, it is no longer allowed in 6.0. Based on this, I’ve updated it to emit an error instead of a warning.

ravurvi20 · 2025-09-11T05:26:49Z

ping @alexey-bataev

alexey-bataev · 2025-09-11T16:04:41Z

clang/include/clang/Basic/DiagnosticParseKinds.td

+def warn_omp_deprecate_old_syntax: Warning<
+  "old syntax '%0' on '%1' clause was deprecated, use new syntax '%2'">, 
+  InGroup<Deprecated>;


The question is: is the old syntax still allowed in 6.0? If not, it should be the error.

alexey-bataev · 2025-09-11T16:05:16Z

clang/include/clang/Basic/DiagnosticParseKinds.td

+def err_omp_allocator_comma_separator :
+  Error<"',' not allowed as separator in 'uses_allocators' clause, use ';' instead">;


Can you try to reuse existing message? I think there should be something similar already

I checked through the file to see if there’s an existing message we could reuse, but didn’t find anything relevant (using ; instead of ,) If that’s fine, can we move ahead with this as is?

alexey-bataev · 2025-09-12T16:36:19Z

Also update clang release notes document

ravurvi20 · 2025-09-15T05:40:13Z

Also update clang release notes document

done!!

clang/docs/ReleaseNotes.rst

alexey-bataev · 2025-09-15T16:39:39Z

clang/docs/OpenMPSupport.rst

 | device                       | clause: extended device                                      | :good:`done`             |                                                                       |
 +------------------------------+--------------------------------------------------------------+--------------------------+-----------------------------------------------------------------------+
-| device                       | clause: uses_allocators clause                               | :good:`done`             |                                                                       |
+| device                       | clause: uses_allocators clause                               | :good:`done`             | https://github.com/llvm/llvm-project/pull/157025                      |


Do we need to do anything in codegen? If yes, this should be partial, I think

It's just a parsing change for the new uses_allocator syntax, no codegen required; works the same way, so keeping it as done.

chandraghale · 2025-09-18T08:12:01Z

@ravurvi20 merging this PR, since already approved !!

urvi-rav added 2 commits September 4, 2025 04:47

Implement new syntax for uses_allocators clause

1efc6c0

allocators without traits

03420e3

llvmbot added clang Clang issues not falling into any other category clang:frontend Language frontend issues, e.g. anything involving "Sema" clang:openmp OpenMP related changes to Clang labels Sep 5, 2025

Merge branch 'main' into uses_allocator_syntax

ce8572c

formatting changes

cfe1df3

ravurvi20 force-pushed the uses_allocator_syntax branch from b975a4b to cfe1df3 Compare September 5, 2025 07:15

chandraghale requested a review from alexey-bataev September 8, 2025 15:55

alexey-bataev reviewed Sep 8, 2025

View reviewed changes

Updated OpenMPSupport.rst

51f5f07

ravurvi20 force-pushed the uses_allocator_syntax branch from 04875d1 to 51f5f07 Compare September 9, 2025 08:55

Merge branch 'main' into uses_allocator_syntax

de4fb9a

ravurvi20 requested a review from alexey-bataev September 9, 2025 09:50

alexey-bataev reviewed Sep 11, 2025

View reviewed changes

urvi-rav and others added 2 commits September 12, 2025 02:33

Removed warning

c38139f

Merge branch 'main' into uses_allocator_syntax

e1da8f9

ravurvi20 requested a review from alexey-bataev September 12, 2025 08:26

urvi-rav and others added 2 commits September 15, 2025 00:19

Updated release notes

649ee30

Merge branch 'main' into uses_allocator_syntax

3ecdd11

ravurvi20 added 2 commits September 15, 2025 11:34

Merge branch 'main' into uses_allocator_syntax

99abd4e

Merge branch 'main' into uses_allocator_syntax

e54597e

alexey-bataev reviewed Sep 15, 2025

View reviewed changes

clang/docs/ReleaseNotes.rst Show resolved Hide resolved

alexey-bataev reviewed Sep 15, 2025

View reviewed changes

Merge branch 'main' into uses_allocator_syntax

8a854c2

ravurvi20 requested a review from alexey-bataev September 16, 2025 12:40

Modifited Releasenotes.rst

0f880ba

alexey-bataev approved these changes Sep 16, 2025

View reviewed changes

chandraghale merged commit cac3894 into llvm:main Sep 18, 2025
10 checks passed

		def err_omp_allocator_comma_separator :
		Error<"',' not allowed as separator in 'uses_allocators' clause, use ';' instead">;

[OpenMP 5.2] New syntax for 'uses_allocators' clause #157025

[OpenMP 5.2] New syntax for 'uses_allocators' clause #157025

Uh oh!

Conversation

ravurvi20 commented Sep 5, 2025

Uh oh!

llvmbot commented Sep 5, 2025

Uh oh!

github-actions bot commented Sep 5, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

alexey-bataev left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

ravurvi20 commented Sep 11, 2025

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

alexey-bataev commented Sep 12, 2025

Uh oh!

ravurvi20 commented Sep 15, 2025

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

chandraghale commented Sep 18, 2025

Uh oh!

Uh oh!

Uh oh!

github-actions bot commented Sep 5, 2025 •

edited

Loading