[clang] 6cbcfb9 - [OpenACC] Fix Sema 'reduction' to allow arrays

[via cfe-commits]

Author: erichkeane
Date: 2025-07-25T10:26:10-07:00
New Revision: 6cbcfb9a7cb79658c315732b1d7d86ce8a52bc45

URL: https://github.com/llvm/llvm-project/commit/6cbcfb9a7cb79658c315732b1d7d86ce8a52bc45
DIFF: https://github.com/llvm/llvm-project/commit/6cbcfb9a7cb79658c315732b1d7d86ce8a52bc45.diff

LOG: [OpenACC] Fix Sema 'reduction' to allow arrays

Due to a mis-reading of the OpenACC spec, we weren't accepting arrays as
a valid value to a reduction variable.  This patch corrects that.

Added: 
    

Modified: 
    clang/include/clang/Basic/DiagnosticSemaKinds.td
    clang/lib/Sema/SemaOpenACCClause.cpp
    clang/test/SemaOpenACC/compute-construct-reduction-clause.c
    clang/test/SemaOpenACC/compute-construct-reduction-clause.cpp
    clang/test/SemaOpenACC/loop-construct-reduction-clause.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 4a213212f185f..4b2ebe662a8a7 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -13318,8 +13318,9 @@ def err_acc_reduction_num_gangs_conflict
             "appear on a '%2' construct "
             "with a '%3' clause%select{ with more than 1 argument|}0">;
 def err_acc_reduction_type
-    : Error<"OpenACC 'reduction' variable must be of scalar type, sub-array, or a "
-            "composite of scalar types;%select{| sub-array base}1 type is %0">;
+    : Error<"OpenACC 'reduction' variable must be of scalar type, aggregate, "
+            "sub-array, or a composite of scalar types;%select{| sub-array "
+            "base}1 type is %0">;
 def err_acc_reduction_composite_type
     : Error<"OpenACC 'reduction' variable must be a composite of scalar types; "
             "%1 %select{is not a class or struct|is incomplete|is not an "

diff  --git a/clang/lib/Sema/SemaOpenACCClause.cpp b/clang/lib/Sema/SemaOpenACCClause.cpp
index 3f90fe8ff8438..469dba8f0710c 100644
--- a/clang/lib/Sema/SemaOpenACCClause.cpp
+++ b/clang/lib/Sema/SemaOpenACCClause.cpp
@@ -1919,6 +1919,14 @@ ExprResult SemaOpenACC::CheckReductionVar(OpenACCDirectiveKind DirectiveKind,
           << EltTy << /*Sub array base type*/ 1;
       return ExprError();
     }
+  } else if (VarExpr->getType()->isArrayType()) {
+    // Arrays are considered an 'aggregate variable' explicitly, so are OK, no
+    // additional checking required.
+    //
+    // Glossary: Aggregate variables – a variable of any non-scalar datatype,
+    // including array or composite variables.
+    //
+    // The next branch (record decl) checks for composite variables.
   } else if (auto *RD = VarExpr->getType()->getAsRecordDecl()) {
     if (!RD->isStruct() && !RD->isClass()) {
       Diag(VarExpr->getExprLoc(), diag::err_acc_reduction_composite_type)

diff  --git a/clang/test/SemaOpenACC/compute-construct-reduction-clause.c b/clang/test/SemaOpenACC/compute-construct-reduction-clause.c
index 6a77f07720d5d..995b6d3d95eb0 100644
--- a/clang/test/SemaOpenACC/compute-construct-reduction-clause.c
+++ b/clang/test/SemaOpenACC/compute-construct-reduction-clause.c
@@ -68,7 +68,6 @@ void uses(unsigned Parm) {
 #pragma acc parallel reduction(&: ChC)
   while (1);
 
-  // expected-error at +1{{OpenACC 'reduction' variable must be of scalar type, sub-array, or a composite of scalar types; type is 'int[5]'}}
 #pragma acc parallel reduction(&: Array)
   while (1);
 
@@ -76,7 +75,7 @@ void uses(unsigned Parm) {
   while (1);
 
   struct CompositeHasComposite ChCArray[5];
-  // expected-error at +1{{OpenACC 'reduction' variable must be of scalar type, sub-array, or a composite of scalar types; sub-array base type is 'struct CompositeHasComposite'}}
+  // expected-error at +1{{OpenACC 'reduction' variable must be of scalar type, aggregate, sub-array, or a composite of scalar types; sub-array base type is 'struct CompositeHasComposite'}}
 #pragma acc parallel reduction(&: CoS, Array[I], ChCArray[0:I])
   while (1);
 

diff  --git a/clang/test/SemaOpenACC/compute-construct-reduction-clause.cpp b/clang/test/SemaOpenACC/compute-construct-reduction-clause.cpp
index 3e972b0f36846..b40268c9b597d 100644
--- a/clang/test/SemaOpenACC/compute-construct-reduction-clause.cpp
+++ b/clang/test/SemaOpenACC/compute-construct-reduction-clause.cpp
@@ -70,7 +70,6 @@ void uses(unsigned Parm) {
   // expected-note@#COS_FIELD{{invalid field is here}}
 #pragma acc parallel reduction(&: ChC)
   while (1);
-  // expected-error at +1{{OpenACC 'reduction' variable must be of scalar type, sub-array, or a composite of scalar types; type is 'int[5]'}}
 #pragma acc parallel reduction(&: Array)
   while (1);
 
@@ -140,10 +139,8 @@ void TemplUses(T Parm, U CoS, V ChC) {
   // expected-note@#COS_FIELD{{invalid field is here}}
 #pragma acc parallel reduction(&: ChC)
   while (1);
-  // expected-error at +1{{OpenACC 'reduction' variable must be of scalar type, sub-array, or a composite of scalar types; type is 'int[5]'}}
 #pragma acc parallel reduction(&: Array)
   while (1);
-  // expected-error at +1{{OpenACC 'reduction' variable must be of scalar type, sub-array, or a composite of scalar types; type is 'int[5]'}}
 #pragma acc parallel reduction(&: NonDepArray)
   while (1);
 

diff  --git a/clang/test/SemaOpenACC/loop-construct-reduction-clause.cpp b/clang/test/SemaOpenACC/loop-construct-reduction-clause.cpp
index bbcfffbc49256..00bcd744b9e79 100644
--- a/clang/test/SemaOpenACC/loop-construct-reduction-clause.cpp
+++ b/clang/test/SemaOpenACC/loop-construct-reduction-clause.cpp
@@ -36,7 +36,6 @@ void uses() {
 
 #pragma acc serial
   {
-  // expected-error at +1{{OpenACC 'reduction' variable must be of scalar type, sub-array, or a composite of scalar types; type is 'int[5]'}}
 #pragma acc loop reduction(+:Array)
     for(int i = 0; i < 5; ++i){}
   }
@@ -172,7 +171,6 @@ void templ_uses() {
 
 #pragma acc serial
   {
-  // expected-error at +1{{OpenACC 'reduction' variable must be of scalar type, sub-array, or a composite of scalar types; type is 'int[5]'}}
 #pragma acc loop reduction(+:Array)
     for(int i = 0; i < 5; ++i){}
   }