Class hierarchy of GIMPLE statements

The following diagram shows the C++ inheritance hierarchy of statement kinds, along with their relationships to GSS_ values (layouts) and GIMPLE_ values (codes):

gimple
  |    layout: GSS_BASE
  |    used for 4 codes: GIMPLE_ERROR_MARK
  |                      GIMPLE_NOP
  |                      GIMPLE_OMP_SECTIONS_SWITCH
  |                      GIMPLE_PREDICT
  |
  + gimple_statement_with_ops_base
  |   |    (no GSS layout)
  |   |
  |   + gimple_statement_with_ops
  |   |   |    layout: GSS_WITH_OPS
  |   |   |
  |   |   + gcond
  |   |   |     code: GIMPLE_COND
  |   |   |
  |   |   + gdebug
  |   |   |     code: GIMPLE_DEBUG
  |   |   |
  |   |   + ggoto
  |   |   |     code: GIMPLE_GOTO
  |   |   |
  |   |   + glabel
  |   |   |     code: GIMPLE_LABEL
  |   |   |
  |   |   + gswitch
  |   |         code: GIMPLE_SWITCH
  |   |
  |   + gimple_statement_with_memory_ops_base
  |       |    layout: GSS_WITH_MEM_OPS_BASE
  |       |
  |       + gimple_statement_with_memory_ops
  |       |   |    layout: GSS_WITH_MEM_OPS
  |       |   |
  |       |   + gassign
  |       |   |    code GIMPLE_ASSIGN
  |       |   |
  |       |   + greturn
  |       |        code GIMPLE_RETURN
  |       |
  |       + gcall
  |       |        layout: GSS_CALL, code: GIMPLE_CALL
  |       |
  |       + gasm
  |       |        layout: GSS_ASM, code: GIMPLE_ASM
  |       |
  |       + gtransaction
  |                layout: GSS_TRANSACTION, code: GIMPLE_TRANSACTION
  |
  + gimple_statement_omp
  |   |    layout: GSS_OMP.  Used for code GIMPLE_OMP_SECTION
  |   |
  |   + gomp_critical
  |   |        layout: GSS_OMP_CRITICAL, code: GIMPLE_OMP_CRITICAL
  |   |
  |   + gomp_for
  |   |        layout: GSS_OMP_FOR, code: GIMPLE_OMP_FOR
  |   |
  |   + gomp_parallel_layout
  |   |   |    layout: GSS_OMP_PARALLEL_LAYOUT
  |   |   |
  |   |   + gimple_statement_omp_taskreg
  |   |   |   |
  |   |   |   + gomp_parallel
  |   |   |   |        code: GIMPLE_OMP_PARALLEL
  |   |   |   |
  |   |   |   + gomp_task
  |   |   |            code: GIMPLE_OMP_TASK
  |   |   |
  |   |   + gimple_statement_omp_target
  |   |            code: GIMPLE_OMP_TARGET
  |   |
  |   + gomp_sections
  |   |        layout: GSS_OMP_SECTIONS, code: GIMPLE_OMP_SECTIONS
  |   |
  |   + gimple_statement_omp_single_layout
  |       |    layout: GSS_OMP_SINGLE_LAYOUT
  |       |
  |       + gomp_single
  |       |        code: GIMPLE_OMP_SINGLE
  |       |
  |       + gomp_teams
  |                code: GIMPLE_OMP_TEAMS
  |
  + gbind
  |        layout: GSS_BIND, code: GIMPLE_BIND
  |
  + gcatch
  |        layout: GSS_CATCH, code: GIMPLE_CATCH
  |
  + geh_filter
  |        layout: GSS_EH_FILTER, code: GIMPLE_EH_FILTER
  |
  + geh_else
  |        layout: GSS_EH_ELSE, code: GIMPLE_EH_ELSE
  |
  + geh_mnt
  |        layout: GSS_EH_MNT, code: GIMPLE_EH_MUST_NOT_THROW
  |
  + gphi
  |        layout: GSS_PHI, code: GIMPLE_PHI
  |
  + gimple_statement_eh_ctrl
  |   |    layout: GSS_EH_CTRL
  |   |
  |   + gresx
  |   |        code: GIMPLE_RESX
  |   |
  |   + geh_dispatch
  |            code: GIMPLE_EH_DISPATCH
  |
  + gtry
  |        layout: GSS_TRY, code: GIMPLE_TRY
  |
  + gimple_statement_wce
  |        layout: GSS_WCE, code: GIMPLE_WITH_CLEANUP_EXPR
  |
  + gomp_continue
  |        layout: GSS_OMP_CONTINUE, code: GIMPLE_OMP_CONTINUE
  |
  + gomp_atomic_load
  |        layout: GSS_OMP_ATOMIC_LOAD, code: GIMPLE_OMP_ATOMIC_LOAD
  |
  + gimple_statement_omp_atomic_store_layout
      |    layout: GSS_OMP_ATOMIC_STORE_LAYOUT,
      |    code: GIMPLE_OMP_ATOMIC_STORE
      |
      + gomp_atomic_store
      |        code: GIMPLE_OMP_ATOMIC_STORE
      |
      + gomp_return
               code: GIMPLE_OMP_RETURN