From b249d2c2c01775fb015b38b272389b8693e414f6 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Fri, 24 Apr 2020 13:40:31 -0600 Subject: Prefer existing data when evaluating DWARF expression When evaluating a DWARF expression, the dynamic type resolution code will pass in a buffer of bytes via the property_addr_info. However, the DWARF expression evaluator will then proceed to read memory from the inferior, even when the request could be filled from this buffer. This, in turn, is a problem in some cases; and specifically when trying to handle the Ada scenario of extracting a variable-length value from a packed array. Here, the ordinary DWARF expression cannot be directly evaluated, because the data may appear at some arbitrary bit offset. So, it is unpacked into a staging area and then the expression is evaluated -- using an address of 0. This patch fixes the problem by arranging for the DWARF evaluator, in this case, to prefer passed-in memory when possible. The type of the buffer in the property_addr_info is changed to an array_view so that bounds checking can be done. gdb/ChangeLog 2020-04-24 Tom Tromey * ada-lang.c (ada_discrete_type_high_bound, ada_discrete_type_low) (ada_value_primitive_packed_val): Update. * ada-valprint.c (ada_value_print_1): Update. * dwarf2/loc.c (evaluate_for_locexpr_baton): New struct. (dwarf2_locexpr_baton_eval): Take a property_addr_info rather than just an address. Use evaluate_for_locexpr_baton. (dwarf2_evaluate_property): Update. * dwarf2/loc.h (struct property_addr_info) : Now an array_view. * findvar.c (default_read_var_value): Update. * gdbtypes.c (compute_variant_fields_inner) (resolve_dynamic_type_internal): Update. (resolve_dynamic_type): Change type of valaddr parameter. * gdbtypes.h (resolve_dynamic_type): Update. * valarith.c (value_subscripted_rvalue): Update. * value.c (value_from_contents_and_address): Update. --- gdb/valarith.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'gdb/valarith.c') diff --git a/gdb/valarith.c b/gdb/valarith.c index 07cb501..504264b 100644 --- a/gdb/valarith.c +++ b/gdb/valarith.c @@ -220,7 +220,7 @@ value_subscripted_rvalue (struct value *array, LONGEST index, LONGEST lowerbound CORE_ADDR address; address = value_address (array) + elt_offs; - elt_type = resolve_dynamic_type (elt_type, NULL, address); + elt_type = resolve_dynamic_type (elt_type, {}, address); } return value_from_component (array, elt_type, elt_offs); -- cgit v1.1