Folding in the front end was replacing calls to LEN and dropping

arguments even in situations where the arguments are required to compute
the LEN value at runtime.

Add tests.

Differential Revision: https://reviews.llvm.org/D119373

diff --git a/flang/lib/Evaluate/fold-integer.cpp b/flang/lib/Evaluate/fold-integer.cpp
index 2618949..6a110cb 100644 (file)
--- a/flang/lib/Evaluate/fold-integer.cpp
+++ b/flang/lib/Evaluate/fold-integer.cpp
@@ -677,7 +677,11 @@ Expr<Type<TypeCategory::Integer, KIND>> FoldIntrinsicFunction(
       return std::visit(
           [&](auto &kx) {
             if (auto len{kx.LEN()}) {
-              return Fold(context, ConvertToType<T>(*std::move(len)));
+              if (IsScopeInvariantExpr(*len)) {
+                return Fold(context, ConvertToType<T>(*std::move(len)));
+              } else {
+                return Expr<T>{std::move(funcRef)};
+              }
             } else {
               return Expr<T>{std::move(funcRef)};
             }

diff --git a/flang/test/Evaluate/rewrite01.f90 b/flang/test/Evaluate/rewrite01.f90
index f5fc578..1627dc6 100644 (file)
--- a/flang/test/Evaluate/rewrite01.f90
+++ b/flang/test/Evaluate/rewrite01.f90
@@ -76,4 +76,44 @@ subroutine lbound_test(x, n, m)
   !CHECK: PRINT *, 1_4
   print *, lbound(returns_array_3(), dim=1)
 end subroutine
+
+!CHECK: len_test
+subroutine len_test(a,b, c, d, e, n, m)
+  character(*), intent(in) :: a
+  character(*) :: b
+  external b
+  character(10), intent(in) :: c
+  character(10) :: d
+  external d
+  integer, intent(in) :: n, m
+  character(n), intent(in) :: e
+
+  !CHECK: PRINT *, int(a%len,kind=4)
+  print *, len(a)
+  !CHECK: PRINT *, 5_4
+  print *, len(a(1:5))
+  !CHECK: PRINT *, len(b(a))
+  print *, len(b(a))
+  !CHECK: PRINT *, len(b(a)//a)
+  print *, len(b(a) // a)
+  !CHECK: PRINT *, 10_4
+  print *, len(c)
+  !CHECK: PRINT *, len(c(int(i,kind=8):int(j,kind=8)))
+  print *, len(c(i:j))
+  !CHECK: PRINT *, 5_4
+  print *, len(c(1:5))
+  !CHECK: PRINT *, 10_4
+  print *, len(d(c))
+  !CHECK: PRINT *, 20_4
+  print *, len(d(c) // c)
+  !CHECK: PRINT *, 0_4
+  print *, len(a(10:4))
+  !CHECK: PRINT *, int(max(0_8,int(m,kind=8)-int(n,kind=8)+1_8),kind=4)
+  print *, len(a(n:m))
+  !CHECK: PRINT *, len(b(a(int(n,kind=8):int(m,kind=8))))
+  print *, len(b(a(n:m)))
+  !CHECK: PRINT *, int(max(0_8,max(0_8,int(n,kind=8))-4_8+1_8),kind=4)
+  print *, len(e(4:))
+end subroutine len_test
+
 end module