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93b527ef78
Mutable addrmaps currently require an obstack. This was probably done to avoid having to call splay_tree_delete, but examination of the code shows that all mutable obstacks have a limited lifetime -- now it's simple to treat them as ordinary C++ objects, in some cases stack-allocating them, and have a destructor to make the needed call. This patch implements this change.
195 lines
7.4 KiB
C++
195 lines
7.4 KiB
C++
/* addrmap.h --- interface to address map data structure.
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Copyright (C) 2007-2022 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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#ifndef ADDRMAP_H
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#define ADDRMAP_H
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#include "splay-tree.h"
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#include "gdbsupport/function-view.h"
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/* An address map is essentially a table mapping CORE_ADDRs onto GDB
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data structures, like blocks, symtabs, partial symtabs, and so on.
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An address map uses memory proportional to the number of
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transitions in the map, where a CORE_ADDR N is mapped to one
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object, and N+1 is mapped to a different object.
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Address maps come in two flavors: fixed, and mutable. Mutable
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address maps consume more memory, but can be changed and extended.
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A fixed address map, once constructed (from a mutable address map),
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can't be edited. */
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/* The type of a function used to iterate over the map.
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OBJ is NULL for unmapped regions. */
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typedef gdb::function_view<int (CORE_ADDR start_addr, void *obj)>
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addrmap_foreach_fn;
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/* The base class for addrmaps. */
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struct addrmap
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{
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virtual ~addrmap () = default;
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/* In the mutable address map MAP, associate the addresses from START
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to END_INCLUSIVE that are currently associated with NULL with OBJ
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instead. Addresses mapped to an object other than NULL are left
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unchanged.
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As the name suggests, END_INCLUSIVE is also mapped to OBJ. This
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convention is unusual, but it allows callers to accurately specify
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ranges that abut the top of the address space, and ranges that
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cover the entire address space.
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This operation seems a bit complicated for a primitive: if it's
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needed, why not just have a simpler primitive operation that sets a
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range to a value, wiping out whatever was there before, and then
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let the caller construct more complicated operations from that,
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along with some others for traversal?
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It turns out this is the mutation operation we want to use all the
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time, at least for now. Our immediate use for address maps is to
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represent lexical blocks whose address ranges are not contiguous.
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We walk the tree of lexical blocks present in the debug info, and
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only create 'struct block' objects after we've traversed all a
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block's children. If a lexical block declares no local variables
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(and isn't the lexical block for a function's body), we omit it
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from GDB's data structures entirely.
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However, this means that we don't decide to create a block (and
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thus record it in the address map) until after we've traversed its
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children. If we do decide to create the block, we do so at a time
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when all its children have already been recorded in the map. So
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this operation --- change only those addresses left unset --- is
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actually the operation we want to use every time.
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It seems simpler to let the code which operates on the
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representation directly deal with the hair of implementing these
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semantics than to provide an interface which allows it to be
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implemented efficiently, but doesn't reveal too much of the
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representation. */
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virtual void set_empty (CORE_ADDR start, CORE_ADDR end_inclusive,
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void *obj) = 0;
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/* Return the object associated with ADDR in MAP. */
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virtual void *find (CORE_ADDR addr) const = 0;
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/* Relocate all the addresses in MAP by OFFSET. (This can be applied
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to either mutable or immutable maps.) */
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virtual void relocate (CORE_ADDR offset) = 0;
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/* Call FN for every address in MAP, following an in-order traversal.
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If FN ever returns a non-zero value, the iteration ceases
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immediately, and the value is returned. Otherwise, this function
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returns 0. */
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virtual int foreach (addrmap_foreach_fn fn) = 0;
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};
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struct addrmap_mutable;
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/* Fixed address maps. */
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struct addrmap_fixed : public addrmap,
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public allocate_on_obstack
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{
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public:
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addrmap_fixed (struct obstack *obstack, addrmap_mutable *mut);
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DISABLE_COPY_AND_ASSIGN (addrmap_fixed);
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void set_empty (CORE_ADDR start, CORE_ADDR end_inclusive,
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void *obj) override;
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void *find (CORE_ADDR addr) const override;
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void relocate (CORE_ADDR offset) override;
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int foreach (addrmap_foreach_fn fn) override;
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private:
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/* A transition: a point in an address map where the value changes.
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The map maps ADDR to VALUE, but if ADDR > 0, it maps ADDR-1 to
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something else. */
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struct addrmap_transition
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{
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CORE_ADDR addr;
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void *value;
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};
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/* The number of transitions in TRANSITIONS. */
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size_t num_transitions;
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/* An array of transitions, sorted by address. For every point in
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the map where either ADDR == 0 or ADDR is mapped to one value and
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ADDR - 1 is mapped to something different, we have an entry here
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containing ADDR and VALUE. (Note that this means we always have
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an entry for address 0). */
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struct addrmap_transition *transitions;
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};
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/* Mutable address maps. */
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struct addrmap_mutable : public addrmap
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{
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public:
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addrmap_mutable ();
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~addrmap_mutable ();
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DISABLE_COPY_AND_ASSIGN (addrmap_mutable);
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void set_empty (CORE_ADDR start, CORE_ADDR end_inclusive,
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void *obj) override;
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void *find (CORE_ADDR addr) const override;
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void relocate (CORE_ADDR offset) override;
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int foreach (addrmap_foreach_fn fn) override;
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private:
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/* A splay tree, with a node for each transition; there is a
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transition at address T if T-1 and T map to different objects.
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Any addresses below the first node map to NULL. (Unlike
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fixed maps, we have no entry at (CORE_ADDR) 0; it doesn't
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simplify enough.)
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The last region is assumed to end at CORE_ADDR_MAX.
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Since we can't know whether CORE_ADDR is larger or smaller than
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splay_tree_key (unsigned long) --- I think both are possible,
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given all combinations of 32- and 64-bit hosts and targets ---
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our keys are pointers to CORE_ADDR values. Since the splay tree
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library doesn't pass any closure pointer to the key free
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function, we can't keep a freelist for keys. Since mutable
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addrmaps are only used temporarily right now, we just leak keys
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from deleted nodes; they'll be freed when the obstack is freed. */
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splay_tree tree;
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/* Various helper methods. */
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splay_tree_key allocate_key (CORE_ADDR addr);
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void force_transition (CORE_ADDR addr);
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splay_tree_node splay_tree_lookup (CORE_ADDR addr) const;
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splay_tree_node splay_tree_predecessor (CORE_ADDR addr) const;
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splay_tree_node splay_tree_successor (CORE_ADDR addr);
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void splay_tree_remove (CORE_ADDR addr);
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void splay_tree_insert (CORE_ADDR key, void *value);
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};
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/* Dump the addrmap to OUTFILE. If PAYLOAD is non-NULL, only dump any
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components that map to PAYLOAD. (If PAYLOAD is NULL, the entire
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map is dumped.) */
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void addrmap_dump (struct addrmap *map, struct ui_file *outfile,
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void *payload);
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#endif /* ADDRMAP_H */
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