[clang] [clang][OpenMP] Add error for large expr in SIMD collapse (PR #138592)

[Amr Hesham via cfe-commits]

https://github.com/AmrDeveloper created https://github.com/llvm/llvm-project/pull/138592

Report error when OpenMP SIMD collapse clause has an expression that can't be represented in 64-bit

Issue #138445

>From 3f484ebd84597ce803b6c9c82650ab7bf88449dd Mon Sep 17 00:00:00 2001
From: AmrDeveloper <amr96 at programmer.net>
Date: Mon, 5 May 2025 23:01:02 +0200
Subject: [PATCH] [clang][OpenMP] Add error for large expr in SIMD collapse

---
 clang/docs/ReleaseNotes.rst                      | 2 ++
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 2 ++
 clang/lib/Sema/SemaOpenMP.cpp                    | 7 +++++++
 clang/test/OpenMP/simd_collapse_messages.cpp     | 2 ++
 4 files changed, 13 insertions(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 203958dab7430..93c296360aebe 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -503,6 +503,8 @@ Improvements to Clang's diagnostics
 - ``-Wreserved-identifier`` now fires on reserved parameter names in a function
   declaration which is not a definition.
 
+- An error is now emitted when OpenMP SIMD ``collapse`` clause has expression larger than 64 bit.
+
 Improvements to Clang's time-trace
 ----------------------------------
 
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index e5a7cdc14a737..b0cbcf8d8a131 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -11519,6 +11519,8 @@ def note_omp_collapse_ordered_expr : Note<
   "as specified in %select{'collapse'|'ordered'|'collapse' and 'ordered'}0 clause%select{||s}0">;
 def err_omp_negative_expression_in_clause : Error<
   "argument to '%0' clause must be a %select{non-negative|strictly positive}1 integer value">;
+def err_omp_large_expression_in_clause : Error<
+  "argument to '%0' clause cannot have more than 64 bits size">;
 def err_omp_not_integral : Error<
   "expression must have integral or unscoped enumeration "
   "type, not %0">;
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 835dba22a858d..52cb5b1fb5d71 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -15901,6 +15901,13 @@ ExprResult SemaOpenMP::VerifyPositiveIntegerConstantInClause(
         << E->getSourceRange();
     return ExprError();
   }
+
+  if (!Result.isRepresentableByInt64()) {
+    Diag(E->getExprLoc(), diag::err_omp_large_expression_in_clause)
+        << getOpenMPClauseNameForDiag(CKind) << E->getSourceRange();
+    return ExprError();
+  }
+
   if (CKind == OMPC_collapse && DSAStack->getAssociatedLoops() == 1)
     DSAStack->setAssociatedLoops(Result.getExtValue());
   else if (CKind == OMPC_ordered)
diff --git a/clang/test/OpenMP/simd_collapse_messages.cpp b/clang/test/OpenMP/simd_collapse_messages.cpp
index 1ce3bef3535ce..3ae0a818284e9 100644
--- a/clang/test/OpenMP/simd_collapse_messages.cpp
+++ b/clang/test/OpenMP/simd_collapse_messages.cpp
@@ -43,6 +43,8 @@ T tmain(T argc, S **argv) {
   for (int i = ST; i < N; i++) argv[0][i] = argv[0][i] - argv[0][i-ST];
   #pragma omp simd collapse (S) // expected-error {{'S' does not refer to a value}}
   for (int i = ST; i < N; i++) argv[0][i] = argv[0][i] - argv[0][i-ST];
+  #pragma omp simd collapse (0xFFFFFFFFFFFFFFFF) // expected-error {{argument to 'collapse' clause cannot have more than 64 bits size}}
+  for (int i = ST; i < N; i++) argv[0][i] = argv[0][i] - argv[0][i-ST];
 #if __cplusplus <= 199711L
   // expected-error at +4 2 {{integral constant expression}} expected-note at +4 0+{{constant expression}}
 #else