From 63e43d3aedb8b1112899c2d0ad74cbbee687e5d6 Mon Sep 17 00:00:00 2001 From: Pierre-Marie de Rodat Date: Thu, 5 Feb 2015 17:00:06 +0100 Subject: DWARF: handle non-local references in nested functions GDB's current behavior when dealing with non-local references in the context of nested fuctions is approximative: - code using valops.c:value_of_variable read the first available stack frame that holds the corresponding variable (whereas there can be multiple candidates for this); - code directly relying on read_var_value will instead read non-local variables in frames where they are not even defined. This change adds the necessary context to symbol reads (to get the block they belong to) and to blocks (the static link property, if any) so that GDB can make the proper decisions when dealing with non-local varibale references. gdb/ChangeLog: * ada-lang.c (ada_read_var_value): Add a var_block argument and pass it to default_read_var_value. * block.c (block_static_link): New accessor. * block.h (block_static_link): Declare it. * buildsym.c (finish_block_internal): Add a static_link argument. If there is a static link, associate it to the new block. (finish_block): Add a static link argument and pass it to finish_block_internal. (end_symtab_get_static_block): Update calls to finish_block and to finish_block_internal. (end_symtab_with_blockvector): Update call to finish_block_internal. * buildsym.h: Forward-declare struct dynamic_prop. (struct context_stack): Add a static_link field. (finish_block): Add a static link argument. * c-exp.y: Remove an obsolete comment (evaluation of variables already start from the selected frame, and now they climb *up* the call stack) and propagate the block information to the produced expression. * d-exp.y: Likewise. * f-exp.y: Likewise. * go-exp.y: Likewise. * jv-exp.y: Likewise. * m2-exp.y: Likewise. * p-exp.y: Likewise. * coffread.c (coff_symtab_read): Update calls to finish_block. * dbxread.c (process_one_symbol): Likewise. * xcoffread.c (read_xcoff_symtab): Likewise. * compile/compile-c-symbols.c (convert_one_symbol): Promote the "sym" parameter to struct block_symbol, update its uses and pass its block to calls to read_var_value. (convert_symbol_sym): Update the calls to convert_one_symbol. * compile/compile-loc2c.c (do_compile_dwarf_expr_to_c): Update call to read_var_value. * dwarf2loc.c (block_op_get_frame_base): New. (dwarf2_block_frame_base_locexpr_funcs): Implement the get_frame_base method. (dwarf2_block_frame_base_loclist_funcs): Likewise. (dwarf2locexpr_baton_eval): Add a frame argument and use it instead of the selected frame in order to evaluate the expression. (dwarf2_evaluate_property): Add a frame argument. Update call to dwarf2_locexpr_baton_eval to provide a frame in available and to handle the absence of address stack. * dwarf2loc.h (dwarf2_evaluate_property): Add a frame argument. * dwarf2read.c (attr_to_dynamic_prop): Add a forward declaration. (read_func_scope): Record any available static link description. Update call to finish_block. (read_lexical_block_scope): Update call to finish_block. * findvar.c (follow_static_link): New. (get_hosting_frame): New. (default_read_var_value): Add a var_block argument. Use get_hosting_frame to handle non-local references. (read_var_value): Add a var_block argument and pass it to the LA_READ_VAR_VALUE method. * gdbtypes.c (resolve_dynamic_range): Update calls to dwarf2_evaluate_property. (resolve_dynamic_type_internal): Likewise. * guile/scm-frame.c (gdbscm_frame_read_var): Update call to read_var_value, passing it the block coming from symbol lookup. * guile/scm-symbol.c (gdbscm_symbol_value): Update call to read_var_value (TODO). * infcmd.c (finish_command_continuation): Update call to read_var_value, passing it the block coming from symbol lookup. * infrun.c (insert_exception_resume_breakpoint): Likewise. * language.h (struct language_defn): Add a var_block argument to the LA_READ_VAR_VALUE method. * objfiles.c (struct static_link_htab_entry): New. (static_link_htab_entry_hash): New. (static_link_htab_entry_eq): New. (objfile_register_static_link): New. (objfile_lookup_static_link): New. (free_objfile): Free the STATIC_LINKS hashed map if needed. * objfiles.h: Include hashtab.h. (struct objfile): Add a static_links field. (objfile_register_static_link): New. (objfile_lookup_static_link): New. * printcmd.c (print_variable_and_value): Update call to read_var_value. * python/py-finishbreakpoint.c (bpfinishpy_init): Likewise. * python/py-frame.c (frapy_read_var): Update call to read_var_value, passing it the block coming from symbol lookup. * python/py-framefilter.c (extract_sym): Add a sym_block parameter and set the pointed value to NULL (TODO). (enumerate_args): Update call to extract_sym. (enumerate_locals): Update calls to extract_sym and to read_var_value. * python/py-symbol.c (sympy_value): Update call to read_var_value (TODO). * stack.c (read_frame_local): Update call to read_var_value. (read_frame_arg): Likewise. (return_command): Likewise. * symtab.h (struct symbol_block_ops): Add a get_frame_base method. (struct symbol): Add a block field. (SYMBOL_BLOCK): New accessor. * valops.c (value_of_variable): Remove frame/block handling and pass the block argument to read_var_value, which does this job now. (value_struct_elt_for_reference): Update calls to read_var_value. (value_of_this): Pass the block found to read_var_value. * value.h (read_var_value): Add a var_block argument. (default_read_var_value): Likewise. gdb/testsuite/ChangeLog: * gdb.base/nested-subp1.exp: New file. * gdb.base/nested-subp1.c: New file. * gdb.base/nested-subp2.exp: New file. * gdb.base/nested-subp2.c: New file. * gdb.base/nested-subp3.exp: New file. * gdb.base/nested-subp3.c: New file. --- gdb/guile/scm-frame.c | 9 +++++++-- gdb/guile/scm-symbol.c | 6 +++++- 2 files changed, 12 insertions(+), 3 deletions(-) (limited to 'gdb/guile') diff --git a/gdb/guile/scm-frame.c b/gdb/guile/scm-frame.c index 64ac0c0..de77c21 100644 --- a/gdb/guile/scm-frame.c +++ b/gdb/guile/scm-frame.c @@ -855,6 +855,7 @@ gdbscm_frame_read_var (SCM self, SCM symbol_scm, SCM rest) SCM block_scm = SCM_UNDEFINED; struct frame_info *frame = NULL; struct symbol *var = NULL; + const struct block *block = NULL; struct value *value = NULL; f_smob = frscm_get_frame_smob_arg_unsafe (self, SCM_ARG1, FUNC_NAME); @@ -909,9 +910,13 @@ gdbscm_frame_read_var (SCM self, SCM symbol_scm, SCM rest) TRY { + struct block_symbol lookup_sym; + if (block == NULL) block = get_frame_block (frame, NULL); - var = lookup_symbol (var_name, block, VAR_DOMAIN, NULL).symbol; + lookup_sym = lookup_symbol (var_name, block, VAR_DOMAIN, NULL); + var = lookup_sym.symbol; + block = lookup_sym.block; } CATCH (ex, RETURN_MASK_ALL) { @@ -940,7 +945,7 @@ gdbscm_frame_read_var (SCM self, SCM symbol_scm, SCM rest) TRY { - value = read_var_value (var, frame); + value = read_var_value (var, block, frame); } CATCH (except, RETURN_MASK_ALL) { diff --git a/gdb/guile/scm-symbol.c b/gdb/guile/scm-symbol.c index 01c9eb1..0970a72 100644 --- a/gdb/guile/scm-symbol.c +++ b/gdb/guile/scm-symbol.c @@ -550,7 +550,11 @@ gdbscm_symbol_value (SCM self, SCM rest) if (symbol_read_needs_frame (symbol) && frame_info == NULL) error (_("Symbol requires a frame to compute its value")); - value = read_var_value (symbol, frame_info); + /* TODO: currently, we have no way to recover the block in which SYMBOL + was found, so we have no block to pass to read_var_value. This will + yield an incorrect value when symbol is not local to FRAME_INFO (this + can happen with nested functions). */ + value = read_var_value (symbol, NULL, frame_info); } CATCH (except, RETURN_MASK_ALL) { -- cgit v1.1