[OpenMP] Add diagnostic for 'factor' width mismatch in 'unroll partial'

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -11700,6 +11700,8 @@ 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 requires a value that can be represented by a 64-bit">;
+def err_omp_unroll_factor_width_mismatch : Error<
+ "unroll factor has width %0 but the iteration variable %1 is only %2 bits wide">;
 def err_omp_not_integral : Error<
  "expression must have integral or unscoped enumeration "
  "type, not %0">;

clang/lib/Sema/SemaOpenMP.cpp

@@ -14980,6 +14980,21 @@ StmtResult SemaOpenMP::ActOnOpenMPUnrollDirective(ArrayRef<OMPClause *> Clauses,
  SourceLocation FactorLoc;
  if (Expr *FactorVal = PartialClause->getFactor();
  FactorVal && !FactorVal->containsErrors()) {
+ if (!VerifyPositiveIntegerConstantInClause(FactorVal, OMPC_partial,
+ /*StrictlyPositive=*/true,
+ /*SuppressExprDiags=*/false)
+ .isUsable())
+ return StmtError();
+ // Check that the iterator variable’s type can hold the factor’s bit-width
+ unsigned FactorValWidth =
+ FactorVal->getIntegerConstantExpr(Context)->getActiveBits();
+ unsigned IteratorVWidth = Context.getTypeSize(OrigVar->getType());
+ if (FactorValWidth > IteratorVWidth) {
+ Diag(FactorVal->getExprLoc(), diag::err_omp_unroll_factor_width_mismatch)
+ << FactorValWidth << OrigVar->getType() << IteratorVWidth;
+ return StmtError();
+ }
+
  Factor = FactorVal->getIntegerConstantExpr(Context)->getZExtValue();
  FactorLoc = FactorVal->getExprLoc();
  } else {

clang/test/OpenMP/unroll_messages.cpp

@@ -58,8 +58,25 @@ void func(int n) {
  // expected-error@+1 {{argument to 'partial' clause must be a strictly positive integer value}} 
  #pragma omp unroll partial(0)
  for (int i = 0; i < n; ++i) {}
-
- // expected-error@+1 {{directive '#pragma omp unroll' cannot contain more than one 'partial' clause}} 
+
+ // expected-error@+1 {{unroll factor has width 36 but the iteration variable 'int' is only 32 bits wide}}
+ #pragma omp unroll partial(0xFFFFFFFFF)
+ for (int i = 0; i < 10; i++) {}
+
+ // expected-error@+2 {{integer literal is too large to be represented in any integer type}}
+ // expected-error@+1 {{argument to 'partial' clause must be a strictly positive integer value}}
+ #pragma omp unroll partial(0x10000000000000000)
+ for (int i = 0; i < 10; i++) {}
+
+ // expected-error@+1 {{unroll factor has width 12 but the iteration variable 'char' is only 8 bits wide}}
+ #pragma omp unroll partial(0xFFF)
+ for (char i = 0; i < 10; i++) {}
+
+ // expected-error@+1 {{unroll factor has width 20 but the iteration variable 'short' is only 16 bits wide}}
+ #pragma omp unroll partial(0xFFFFF)
+ for (short i = 0; i < 10; i++) {}
+
+ // expected-error@+1 {{directive '#pragma omp unroll' cannot contain more than one 'partial' clause}}
  #pragma omp unroll partial partial
  for (int i = 0; i < n; ++i) {}