656 lines
17 KiB
C
656 lines
17 KiB
C
/* Convert symbols from GDB to GCC
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Copyright (C) 2014-2020 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "compile-internal.h"
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#include "compile-c.h"
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#include "symtab.h"
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#include "parser-defs.h"
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#include "block.h"
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#include "objfiles.h"
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#include "compile.h"
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#include "value.h"
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#include "exceptions.h"
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#include "gdbtypes.h"
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#include "dwarf2loc.h"
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/* Compute the name of the pointer representing a local symbol's
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address. */
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gdb::unique_xmalloc_ptr<char>
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c_symbol_substitution_name (struct symbol *sym)
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{
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return gdb::unique_xmalloc_ptr<char>
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(concat ("__", sym->natural_name (), "_ptr", (char *) NULL));
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}
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/* Convert a given symbol, SYM, to the compiler's representation.
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CONTEXT is the compiler instance. IS_GLOBAL is true if the
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symbol came from the global scope. IS_LOCAL is true if the symbol
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came from a local scope. (Note that the two are not strictly
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inverses because the symbol might have come from the static
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scope.) */
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static void
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convert_one_symbol (compile_c_instance *context,
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struct block_symbol sym,
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int is_global,
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int is_local)
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{
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gcc_type sym_type;
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const char *filename = symbol_symtab (sym.symbol)->filename;
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unsigned short line = SYMBOL_LINE (sym.symbol);
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context->error_symbol_once (sym.symbol);
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if (SYMBOL_CLASS (sym.symbol) == LOC_LABEL)
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sym_type = 0;
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else
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sym_type = context->convert_type (SYMBOL_TYPE (sym.symbol));
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if (SYMBOL_DOMAIN (sym.symbol) == STRUCT_DOMAIN)
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{
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/* Binding a tag, so we don't need to build a decl. */
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context->plugin ().tagbind (sym.symbol->natural_name (),
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sym_type, filename, line);
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}
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else
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{
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gcc_decl decl;
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enum gcc_c_symbol_kind kind;
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CORE_ADDR addr = 0;
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gdb::unique_xmalloc_ptr<char> symbol_name;
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switch (SYMBOL_CLASS (sym.symbol))
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{
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case LOC_TYPEDEF:
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kind = GCC_C_SYMBOL_TYPEDEF;
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break;
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case LOC_LABEL:
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kind = GCC_C_SYMBOL_LABEL;
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addr = SYMBOL_VALUE_ADDRESS (sym.symbol);
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break;
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case LOC_BLOCK:
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kind = GCC_C_SYMBOL_FUNCTION;
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addr = BLOCK_ENTRY_PC (SYMBOL_BLOCK_VALUE (sym.symbol));
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if (is_global && TYPE_GNU_IFUNC (SYMBOL_TYPE (sym.symbol)))
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addr = gnu_ifunc_resolve_addr (target_gdbarch (), addr);
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break;
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case LOC_CONST:
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if (TYPE_CODE (SYMBOL_TYPE (sym.symbol)) == TYPE_CODE_ENUM)
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{
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/* Already handled by convert_enum. */
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return;
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}
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context->plugin ().build_constant
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(sym_type, sym.symbol->natural_name (),
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SYMBOL_VALUE (sym.symbol),
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filename, line);
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return;
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case LOC_CONST_BYTES:
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error (_("Unsupported LOC_CONST_BYTES for symbol \"%s\"."),
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sym.symbol->print_name ());
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case LOC_UNDEF:
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internal_error (__FILE__, __LINE__, _("LOC_UNDEF found for \"%s\"."),
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sym.symbol->print_name ());
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case LOC_COMMON_BLOCK:
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error (_("Fortran common block is unsupported for compilation "
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"evaluaton of symbol \"%s\"."),
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sym.symbol->print_name ());
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case LOC_OPTIMIZED_OUT:
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error (_("Symbol \"%s\" cannot be used for compilation evaluation "
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"as it is optimized out."),
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sym.symbol->print_name ());
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case LOC_COMPUTED:
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if (is_local)
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goto substitution;
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/* Probably TLS here. */
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warning (_("Symbol \"%s\" is thread-local and currently can only "
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"be referenced from the current thread in "
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"compiled code."),
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sym.symbol->print_name ());
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/* FALLTHROUGH */
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case LOC_UNRESOLVED:
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/* 'symbol_name' cannot be used here as that one is used only for
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local variables from compile_dwarf_expr_to_c.
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Global variables can be accessed by GCC only by their address, not
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by their name. */
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{
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struct value *val;
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struct frame_info *frame = NULL;
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if (symbol_read_needs_frame (sym.symbol))
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{
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frame = get_selected_frame (NULL);
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if (frame == NULL)
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error (_("Symbol \"%s\" cannot be used because "
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"there is no selected frame"),
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sym.symbol->print_name ());
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}
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val = read_var_value (sym.symbol, sym.block, frame);
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if (VALUE_LVAL (val) != lval_memory)
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error (_("Symbol \"%s\" cannot be used for compilation "
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"evaluation as its address has not been found."),
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sym.symbol->print_name ());
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kind = GCC_C_SYMBOL_VARIABLE;
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addr = value_address (val);
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}
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break;
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case LOC_REGISTER:
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case LOC_ARG:
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case LOC_REF_ARG:
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case LOC_REGPARM_ADDR:
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case LOC_LOCAL:
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substitution:
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kind = GCC_C_SYMBOL_VARIABLE;
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symbol_name = c_symbol_substitution_name (sym.symbol);
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break;
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case LOC_STATIC:
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kind = GCC_C_SYMBOL_VARIABLE;
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addr = SYMBOL_VALUE_ADDRESS (sym.symbol);
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break;
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case LOC_FINAL_VALUE:
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default:
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gdb_assert_not_reached ("Unreachable case in convert_one_symbol.");
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}
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/* Don't emit local variable decls for a raw expression. */
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if (context->scope () != COMPILE_I_RAW_SCOPE
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|| symbol_name == NULL)
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{
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decl = context->plugin ().build_decl
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(sym.symbol->natural_name (),
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kind,
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sym_type,
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symbol_name.get (), addr,
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filename, line);
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context->plugin ().bind (decl, is_global);
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}
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}
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}
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/* Convert a full symbol to its gcc form. CONTEXT is the compiler to
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use, IDENTIFIER is the name of the symbol, SYM is the symbol
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itself, and DOMAIN is the domain which was searched. */
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static void
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convert_symbol_sym (compile_c_instance *context, const char *identifier,
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struct block_symbol sym, domain_enum domain)
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{
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const struct block *static_block;
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int is_local_symbol;
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/* If we found a symbol and it is not in the static or global
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scope, then we should first convert any static or global scope
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symbol of the same name. This lets this unusual case work:
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int x; // Global.
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int func(void)
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{
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int x;
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// At this spot, evaluate "extern int x; x"
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}
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*/
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static_block = block_static_block (sym.block);
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/* STATIC_BLOCK is NULL if FOUND_BLOCK is the global block. */
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is_local_symbol = (sym.block != static_block && static_block != NULL);
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if (is_local_symbol)
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{
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struct block_symbol global_sym;
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global_sym = lookup_symbol (identifier, NULL, domain, NULL);
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/* If the outer symbol is in the static block, we ignore it, as
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it cannot be referenced. */
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if (global_sym.symbol != NULL
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&& global_sym.block != block_static_block (global_sym.block))
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{
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if (compile_debug)
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fprintf_unfiltered (gdb_stdlog,
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"gcc_convert_symbol \"%s\": global symbol\n",
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identifier);
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convert_one_symbol (context, global_sym, 1, 0);
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}
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}
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if (compile_debug)
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fprintf_unfiltered (gdb_stdlog,
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"gcc_convert_symbol \"%s\": local symbol\n",
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identifier);
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convert_one_symbol (context, sym, 0, is_local_symbol);
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}
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/* Convert a minimal symbol to its gcc form. CONTEXT is the compiler
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to use and BMSYM is the minimal symbol to convert. */
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static void
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convert_symbol_bmsym (compile_c_instance *context,
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struct bound_minimal_symbol bmsym)
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{
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struct minimal_symbol *msym = bmsym.minsym;
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struct objfile *objfile = bmsym.objfile;
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struct type *type;
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enum gcc_c_symbol_kind kind;
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gcc_type sym_type;
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gcc_decl decl;
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CORE_ADDR addr;
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addr = MSYMBOL_VALUE_ADDRESS (objfile, msym);
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/* Conversion copied from write_exp_msymbol. */
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switch (MSYMBOL_TYPE (msym))
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{
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case mst_text:
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case mst_file_text:
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case mst_solib_trampoline:
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type = objfile_type (objfile)->nodebug_text_symbol;
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kind = GCC_C_SYMBOL_FUNCTION;
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break;
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case mst_text_gnu_ifunc:
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type = objfile_type (objfile)->nodebug_text_gnu_ifunc_symbol;
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kind = GCC_C_SYMBOL_FUNCTION;
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addr = gnu_ifunc_resolve_addr (target_gdbarch (), addr);
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break;
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case mst_data:
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case mst_file_data:
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case mst_bss:
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case mst_file_bss:
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type = objfile_type (objfile)->nodebug_data_symbol;
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kind = GCC_C_SYMBOL_VARIABLE;
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break;
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case mst_slot_got_plt:
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type = objfile_type (objfile)->nodebug_got_plt_symbol;
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kind = GCC_C_SYMBOL_FUNCTION;
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break;
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default:
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type = objfile_type (objfile)->nodebug_unknown_symbol;
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kind = GCC_C_SYMBOL_VARIABLE;
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break;
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}
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sym_type = context->convert_type (type);
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decl = context->plugin ().build_decl (msym->natural_name (),
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kind, sym_type, NULL, addr,
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NULL, 0);
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context->plugin ().bind (decl, 1 /* is_global */);
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}
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/* See compile-internal.h. */
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void
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gcc_convert_symbol (void *datum,
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struct gcc_c_context *gcc_context,
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enum gcc_c_oracle_request request,
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const char *identifier)
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{
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compile_c_instance *context
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= static_cast<compile_c_instance *> (datum);
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domain_enum domain;
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int found = 0;
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switch (request)
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{
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case GCC_C_ORACLE_SYMBOL:
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domain = VAR_DOMAIN;
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break;
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case GCC_C_ORACLE_TAG:
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domain = STRUCT_DOMAIN;
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break;
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case GCC_C_ORACLE_LABEL:
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domain = LABEL_DOMAIN;
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break;
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default:
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gdb_assert_not_reached ("Unrecognized oracle request.");
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}
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/* We can't allow exceptions to escape out of this callback. Safest
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is to simply emit a gcc error. */
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try
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{
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struct block_symbol sym;
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sym = lookup_symbol (identifier, context->block (), domain, NULL);
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if (sym.symbol != NULL)
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{
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convert_symbol_sym (context, identifier, sym, domain);
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found = 1;
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}
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else if (domain == VAR_DOMAIN)
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{
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struct bound_minimal_symbol bmsym;
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bmsym = lookup_minimal_symbol (identifier, NULL, NULL);
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if (bmsym.minsym != NULL)
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{
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convert_symbol_bmsym (context, bmsym);
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found = 1;
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}
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}
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}
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catch (const gdb_exception &e)
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{
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context->plugin ().error (e.what ());
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}
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if (compile_debug && !found)
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fprintf_unfiltered (gdb_stdlog,
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"gcc_convert_symbol \"%s\": lookup_symbol failed\n",
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identifier);
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return;
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}
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/* See compile-internal.h. */
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gcc_address
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gcc_symbol_address (void *datum, struct gcc_c_context *gcc_context,
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const char *identifier)
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{
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compile_c_instance *context
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= static_cast<compile_c_instance *> (datum);
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gcc_address result = 0;
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int found = 0;
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/* We can't allow exceptions to escape out of this callback. Safest
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is to simply emit a gcc error. */
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try
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{
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struct symbol *sym;
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/* We only need global functions here. */
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sym = lookup_symbol (identifier, NULL, VAR_DOMAIN, NULL).symbol;
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if (sym != NULL && SYMBOL_CLASS (sym) == LOC_BLOCK)
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{
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if (compile_debug)
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fprintf_unfiltered (gdb_stdlog,
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"gcc_symbol_address \"%s\": full symbol\n",
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identifier);
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result = BLOCK_ENTRY_PC (SYMBOL_BLOCK_VALUE (sym));
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if (TYPE_GNU_IFUNC (SYMBOL_TYPE (sym)))
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result = gnu_ifunc_resolve_addr (target_gdbarch (), result);
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found = 1;
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}
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else
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{
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struct bound_minimal_symbol msym;
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msym = lookup_bound_minimal_symbol (identifier);
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if (msym.minsym != NULL)
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{
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if (compile_debug)
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fprintf_unfiltered (gdb_stdlog,
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"gcc_symbol_address \"%s\": minimal "
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"symbol\n",
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identifier);
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result = BMSYMBOL_VALUE_ADDRESS (msym);
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if (MSYMBOL_TYPE (msym.minsym) == mst_text_gnu_ifunc)
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result = gnu_ifunc_resolve_addr (target_gdbarch (), result);
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found = 1;
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}
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}
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}
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catch (const gdb_exception_error &e)
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{
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context->plugin ().error (e.what ());
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}
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if (compile_debug && !found)
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fprintf_unfiltered (gdb_stdlog,
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"gcc_symbol_address \"%s\": failed\n",
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identifier);
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return result;
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}
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/* A hash function for symbol names. */
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static hashval_t
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hash_symname (const void *a)
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{
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const struct symbol *sym = (const struct symbol *) a;
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return htab_hash_string (sym->natural_name ());
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}
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/* A comparison function for hash tables that just looks at symbol
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names. */
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static int
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eq_symname (const void *a, const void *b)
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{
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const struct symbol *syma = (const struct symbol *) a;
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const struct symbol *symb = (const struct symbol *) b;
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return strcmp (syma->natural_name (), symb->natural_name ()) == 0;
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}
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/* If a symbol with the same name as SYM is already in HASHTAB, return
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1. Otherwise, add SYM to HASHTAB and return 0. */
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static int
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symbol_seen (htab_t hashtab, struct symbol *sym)
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{
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void **slot;
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slot = htab_find_slot (hashtab, sym, INSERT);
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if (*slot != NULL)
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return 1;
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*slot = sym;
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return 0;
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}
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/* Generate C code to compute the length of a VLA. */
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static void
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generate_vla_size (compile_instance *compiler,
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string_file *stream,
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struct gdbarch *gdbarch,
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unsigned char *registers_used,
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CORE_ADDR pc,
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struct type *type,
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struct symbol *sym)
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{
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type = check_typedef (type);
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if (TYPE_IS_REFERENCE (type))
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type = check_typedef (TYPE_TARGET_TYPE (type));
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switch (TYPE_CODE (type))
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{
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case TYPE_CODE_RANGE:
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{
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if (TYPE_HIGH_BOUND_KIND (type) == PROP_LOCEXPR
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|| TYPE_HIGH_BOUND_KIND (type) == PROP_LOCLIST)
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{
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const struct dynamic_prop *prop = &TYPE_RANGE_DATA (type)->high;
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std::string name = c_get_range_decl_name (prop);
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dwarf2_compile_property_to_c (stream, name.c_str (),
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gdbarch, registers_used,
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prop, pc, sym);
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}
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}
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break;
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case TYPE_CODE_ARRAY:
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generate_vla_size (compiler, stream, gdbarch, registers_used, pc,
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TYPE_INDEX_TYPE (type), sym);
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generate_vla_size (compiler, stream, gdbarch, registers_used, pc,
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TYPE_TARGET_TYPE (type), sym);
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break;
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case TYPE_CODE_UNION:
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case TYPE_CODE_STRUCT:
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{
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int i;
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for (i = 0; i < TYPE_NFIELDS (type); ++i)
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if (!field_is_static (&TYPE_FIELD (type, i)))
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generate_vla_size (compiler, stream, gdbarch, registers_used, pc,
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TYPE_FIELD_TYPE (type, i), sym);
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}
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break;
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}
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}
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/* Generate C code to compute the address of SYM. */
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static void
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generate_c_for_for_one_variable (compile_instance *compiler,
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string_file *stream,
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struct gdbarch *gdbarch,
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unsigned char *registers_used,
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CORE_ADDR pc,
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struct symbol *sym)
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{
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try
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{
|
||
if (is_dynamic_type (SYMBOL_TYPE (sym)))
|
||
{
|
||
/* We need to emit to a temporary buffer in case an error
|
||
occurs in the middle. */
|
||
string_file local_file;
|
||
|
||
generate_vla_size (compiler, &local_file, gdbarch, registers_used, pc,
|
||
SYMBOL_TYPE (sym), sym);
|
||
|
||
stream->write (local_file.c_str (), local_file.size ());
|
||
}
|
||
|
||
if (SYMBOL_COMPUTED_OPS (sym) != NULL)
|
||
{
|
||
gdb::unique_xmalloc_ptr<char> generated_name
|
||
= c_symbol_substitution_name (sym);
|
||
/* We need to emit to a temporary buffer in case an error
|
||
occurs in the middle. */
|
||
string_file local_file;
|
||
|
||
SYMBOL_COMPUTED_OPS (sym)->generate_c_location (sym, &local_file,
|
||
gdbarch,
|
||
registers_used,
|
||
pc,
|
||
generated_name.get ());
|
||
stream->write (local_file.c_str (), local_file.size ());
|
||
}
|
||
else
|
||
{
|
||
switch (SYMBOL_CLASS (sym))
|
||
{
|
||
case LOC_REGISTER:
|
||
case LOC_ARG:
|
||
case LOC_REF_ARG:
|
||
case LOC_REGPARM_ADDR:
|
||
case LOC_LOCAL:
|
||
error (_("Local symbol unhandled when generating C code."));
|
||
|
||
case LOC_COMPUTED:
|
||
gdb_assert_not_reached (_("LOC_COMPUTED variable "
|
||
"missing a method."));
|
||
|
||
default:
|
||
/* Nothing to do for all other cases, as they don't represent
|
||
local variables. */
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
catch (const gdb_exception_error &e)
|
||
{
|
||
compiler->insert_symbol_error (sym, e.what ());
|
||
}
|
||
}
|
||
|
||
/* See compile-c.h. */
|
||
|
||
gdb::unique_xmalloc_ptr<unsigned char>
|
||
generate_c_for_variable_locations (compile_instance *compiler,
|
||
string_file *stream,
|
||
struct gdbarch *gdbarch,
|
||
const struct block *block,
|
||
CORE_ADDR pc)
|
||
{
|
||
const struct block *static_block = block_static_block (block);
|
||
|
||
/* If we're already in the static or global block, there is nothing
|
||
to write. */
|
||
if (static_block == NULL || block == static_block)
|
||
return NULL;
|
||
|
||
gdb::unique_xmalloc_ptr<unsigned char> registers_used
|
||
(XCNEWVEC (unsigned char, gdbarch_num_regs (gdbarch)));
|
||
|
||
/* Ensure that a given name is only entered once. This reflects the
|
||
reality of shadowing. */
|
||
htab_up symhash (htab_create_alloc (1, hash_symname, eq_symname, NULL,
|
||
xcalloc, xfree));
|
||
|
||
while (1)
|
||
{
|
||
struct symbol *sym;
|
||
struct block_iterator iter;
|
||
|
||
/* Iterate over symbols in this block, generating code to
|
||
compute the location of each local variable. */
|
||
for (sym = block_iterator_first (block, &iter);
|
||
sym != NULL;
|
||
sym = block_iterator_next (&iter))
|
||
{
|
||
if (!symbol_seen (symhash.get (), sym))
|
||
generate_c_for_for_one_variable (compiler, stream, gdbarch,
|
||
registers_used.get (), pc, sym);
|
||
}
|
||
|
||
/* If we just finished the outermost block of a function, we're
|
||
done. */
|
||
if (BLOCK_FUNCTION (block) != NULL)
|
||
break;
|
||
block = BLOCK_SUPERBLOCK (block);
|
||
}
|
||
|
||
return registers_used;
|
||
}
|