diff options
Diffstat (limited to 'gcc/fortran/trans.cc')
| -rw-r--r-- | gcc/fortran/trans.cc | 42 |
1 files changed, 38 insertions, 4 deletions
diff --git a/gcc/fortran/trans.cc b/gcc/fortran/trans.cc index 333dfa6..f0a5dfb 100644 --- a/gcc/fortran/trans.cc +++ b/gcc/fortran/trans.cc @@ -446,10 +446,14 @@ gfc_build_spanned_array_ref (tree base, tree offset, tree span) } -/* Build an ARRAY_REF with its natural type. */ +/* Build an ARRAY_REF with its natural type. + NON_NEGATIVE_OFFSET indicates if it’s true that OFFSET can’t be negative, + and thus that an ARRAY_REF can safely be generated. If it’s false, we + have to play it safe and use pointer arithmetic. */ tree -gfc_build_array_ref (tree base, tree offset, tree decl, tree vptr) +gfc_build_array_ref (tree base, tree offset, tree decl, + bool non_negative_offset, tree vptr) { tree type = TREE_TYPE (base); tree span = NULL_TREE; @@ -495,10 +499,40 @@ gfc_build_array_ref (tree base, tree offset, tree decl, tree vptr) pointer arithmetic. */ if (span != NULL_TREE) return gfc_build_spanned_array_ref (base, offset, span); - /* Otherwise use a straightforward array reference. */ - else + /* Else use a straightforward array reference if possible. */ + else if (non_negative_offset) return build4_loc (input_location, ARRAY_REF, type, base, offset, NULL_TREE, NULL_TREE); + /* Otherwise use pointer arithmetic. */ + else + { + gcc_assert (TREE_CODE (TREE_TYPE (base)) == ARRAY_TYPE); + tree min = NULL_TREE; + if (TYPE_DOMAIN (TREE_TYPE (base)) + && !integer_zerop (TYPE_MIN_VALUE (TYPE_DOMAIN (TREE_TYPE (base))))) + min = TYPE_MIN_VALUE (TYPE_DOMAIN (TREE_TYPE (base))); + + tree zero_based_index + = min ? fold_build2_loc (input_location, MINUS_EXPR, + gfc_array_index_type, + fold_convert (gfc_array_index_type, offset), + fold_convert (gfc_array_index_type, min)) + : fold_convert (gfc_array_index_type, offset); + + tree elt_size = fold_convert (gfc_array_index_type, + TYPE_SIZE_UNIT (type)); + + tree offset_bytes = fold_build2_loc (input_location, MULT_EXPR, + gfc_array_index_type, + zero_based_index, elt_size); + + tree base_addr = gfc_build_addr_expr (pvoid_type_node, base); + + tree ptr = fold_build_pointer_plus_loc (input_location, base_addr, + offset_bytes); + return build1_loc (input_location, INDIRECT_REF, type, + fold_convert (build_pointer_type (type), ptr)); + } } |