[flang][NFC] Add complex operations lowering tests

Just adds some lowering test for complex operations. These were not
added when the lowering landed.

This patch is part of the upstreaming effort from fir-dev branch.

Reviewed By: schweitz

Differential Revision: https://reviews.llvm.org/D120672

flang/test/Lower/complex-operations.f90

@@ -0,0 +1,37 @@
+! RUN: bbc %s -o - | FileCheck %s
+
+! CHECK-LABEL: @_QPadd_test
+subroutine add_test(a,b,c)
+  complex :: a, b, c
+  ! CHECK-NOT: fir.extract_value
+  ! CHECK-NOT: fir.insert_value
+  ! CHECK: fir.addc {{.*}}: !fir.complex
+  a = b + c
+end subroutine add_test
+
+! CHECK-LABEL: @_QPsub_test
+subroutine sub_test(a,b,c)
+  complex :: a, b, c
+  ! CHECK-NOT: fir.extract_value
+  ! CHECK-NOT: fir.insert_value
+  ! CHECK: fir.subc {{.*}}: !fir.complex
+  a = b - c
+end subroutine sub_test
+
+! CHECK-LABEL: @_QPmul_test
+subroutine mul_test(a,b,c)
+  complex :: a, b, c
+  ! CHECK-NOT: fir.extract_value
+  ! CHECK-NOT: fir.insert_value
+  ! CHECK: fir.mulc {{.*}}: !fir.complex
+  a = b * c
+end subroutine mul_test
+
+! CHECK-LABEL: @_QPdiv_test
+subroutine div_test(a,b,c)
+  complex :: a, b, c
+  ! CHECK-NOT: fir.extract_value
+  ! CHECK-NOT: fir.insert_value
+  ! CHECK: fir.divc {{.*}}: !fir.complex
+  a = b / c
+end subroutine div_test