### 12.2 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