SingleColumn: Fix vectorisation of nested else-if bodies

loki/ir/nodes.py

@@ -704,6 +704,16 @@ def __repr__(self):
             return f'Conditional:: {self.name}'
         return 'Conditional::'
 
+    @property
+    def else_bodies(self):
+        """
+        Return all nested node tuples in the ``ELSEIF``/``ELSE`` part
+        of the conditional chain.
+        """
+        if self.has_elseif:
+            return (self.else_body[0].body,) + self.else_body[0].else_bodies
+        return (self.else_body,) if self.else_body else ()
+
 
 @dataclass_strict(frozen=True)
 class _PragmaRegionBase():

loki/ir/tests/test_ir_nodes.py

@@ -151,6 +151,54 @@ def test_conditional(scope, one, i, n, a_i):
     # TODO: Test inline, name, has_elseif
 
 
+def test_multi_conditional(scope, one, i, n, a_i):
+    """
+    Test nested chains of constructors of :any:`Conditional` to form
+    multi-conditional.
+    """
+    multicond = ir.Conditional(
+        condition=sym.Comparison(i, '==', sym.IntLiteral(1)),
+        body=ir.Assignment(lhs=a_i, rhs=sym.Literal(1.0)),
+        else_body=ir.Assignment(lhs=a_i, rhs=sym.Literal(42.0))
+    )
+    for idx in range(2, 4):
+        multicond = ir.Conditional(
+            condition=sym.Comparison(i, '==', sym.IntLiteral(idx)),
+            body=ir.Assignment(lhs=a_i, rhs=sym.Literal(float(idx))),
+            else_body=multicond, has_elseif=True
+        )
+
+    # Check that we can recover all bodies from a nested else-if construct
+    else_bodies = multicond.else_bodies
+    assert len(else_bodies) == 3
+    assert all(isinstance(b, tuple) for b in else_bodies)
+    assert isinstance(else_bodies[0][0], ir.Assignment)
+    assert else_bodies[0][0].lhs == 'a(i)' and else_bodies[0][0].rhs == '2.0'
+    assert isinstance(else_bodies[1][0], ir.Assignment)
+    assert else_bodies[1][0].lhs == 'a(i)' and else_bodies[1][0].rhs == '1.0'
+    assert isinstance(else_bodies[2][0], ir.Assignment)
+    assert else_bodies[2][0].lhs == 'a(i)' and else_bodies[2][0].rhs == '42.0'
+
+    # Not try without the final else
+    multicond = ir.Conditional(
+        condition=sym.Comparison(i, '==', sym.IntLiteral(1)),
+        body=ir.Assignment(lhs=a_i, rhs=sym.Literal(1.0)),
+    )
+    for idx in range(2, 4):
+        multicond = ir.Conditional(
+            condition=sym.Comparison(i, '==', sym.IntLiteral(idx)),
+            body=ir.Assignment(lhs=a_i, rhs=sym.Literal(float(idx))),
+            else_body=multicond, has_elseif=True
+        )
+    else_bodies = multicond.else_bodies
+    assert len(else_bodies) == 2
+    assert all(isinstance(b, tuple) for b in else_bodies)
+    assert isinstance(else_bodies[0][0], ir.Assignment)
+    assert else_bodies[0][0].lhs == 'a(i)' and else_bodies[0][0].rhs == '2.0'
+    assert isinstance(else_bodies[1][0], ir.Assignment)
+    assert else_bodies[1][0].lhs == 'a(i)' and else_bodies[1][0].rhs == '1.0'
+
+
 def test_section(scope, one, i, n, a_n, a_i):
     """
     Test constructors and behaviour of :any:`Section` nodes.

loki/transformations/single_column/tests/test_scc_vector.py

@@ -573,20 +573,30 @@ def test_scc_devector_section_special_case(frontend, horizontal, vertical, block
     """
 
     fcode_kernel = """
-    subroutine some_kernel(start, end, nlon, flag0, flag1)
+    subroutine some_kernel(start, end, nlon, flag0, flag1, flag2)
        implicit none
 
        integer, intent(in) :: nlon, start, end
-       logical, intent(in) :: flag0, flag1
+       logical, intent(in) :: flag0, flag1, flag2
        real, dimension(nlon) :: work
 
        integer :: jl
 
-       if(flag0)then
+       if (flag0) then
          call some_other_kernel()
-       elseif(flag1)then
+       elseif (flag1) then
+         do jl=start,end
+            work(jl) = 1.
+         enddo
+       elseif (flag2) then
          do jl=start,end
             work(jl) = 1.
+            work(jl) = 2.
+         enddo
+       else
+         do jl=start,end
+            work(jl) = 41.
+            work(jl) = 42.
          enddo
        endif
 
@@ -595,7 +605,7 @@ def test_scc_devector_section_special_case(frontend, horizontal, vertical, block
 
     routine = Subroutine.from_source(fcode_kernel, frontend=frontend)
 
-    # check whether pipeline can be applied and works as expected
+    # check whether pipeline can be applied and works as expected
     scc_pipeline = SCCVectorPipeline(
         horizontal=horizontal, vertical=vertical, block_dim=blocking,
         directive='openacc', trim_vector_sections=trim_vector_sections
@@ -611,3 +621,11 @@ def test_scc_devector_section_special_case(frontend, horizontal, vertical, block
         assert isinstance(conditional.else_body[0].body[0], ir.Comment)
         assert isinstance(conditional.else_body[0].body[1], ir.Loop)
         assert conditional.else_body[0].body[1].pragma[0].content.lower() == 'loop vector'
+
+        # Check that all else-bodies have been wrapped
+        else_bodies = conditional.else_bodies
+        assert(len(else_bodies) == 3)
+        for body in else_bodies:
+            assert isinstance(body[0], ir.Comment)
+            assert isinstance(body[1], ir.Loop)
+            assert body[1].pragma[0].content.lower() == 'loop vector'

loki/transformations/single_column/vector.py

@@ -137,15 +137,11 @@ def extract_vector_sections(cls, section, horizontal):
                 subsec_body = cls.extract_vector_sections(separator.body, horizontal)
                 if subsec_body:
                     subsections += subsec_body
-                # we need to prevent that the whole 'else_body' is wrapped in a section,
-                # as 'Conditional's rely on the fact that the first element of the 'else_body'
+                # we need to prevent that all (possibly nested) 'else_bodies' are completely wrapped as a section,
+                # as 'Conditional's rely on the fact that the first element of each 'else_body'
                 # (if 'has_elseif') is a Conditional itself
-                if separator.has_elseif and separator.else_body:
-                    subsec_else = cls.extract_vector_sections(separator.else_body[0].body, horizontal)
-                else:
-                    subsec_else = cls.extract_vector_sections(separator.else_body, horizontal)
-                if subsec_else:
-                    subsections += subsec_else
+                for ebody in separator.else_bodies:
+                    subsections += cls.extract_vector_sections(ebody, horizontal)
 
             if isinstance(separator, ir.MultiConditional):
                 for body in separator.bodies: