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Synth: tolerate undef rbp merge on leaf blocks

master
Théophile Bastian 3 years ago
parent
commit
c74ec873eb
  1. 110
      DwarfSynth/Simplest.ml

110
DwarfSynth/Simplest.ml

@ -732,6 +732,38 @@ let cleanup_fde (fde_changes: reg_changes_fde) : reg_changes_fde = @@ -732,6 +732,38 @@ let cleanup_fde (fde_changes: reg_changes_fde) : reg_changes_fde =
match AddrMap.fold fold_one fde_changes (AddrMap.empty, None, false) with
| out, _, _ -> out
type merge_type =
Valid_merge
| Invalid_merge
| Valid_with_rbp_erasing of reg_pos
let valid_merge_boilerplate regs_1 regs_2 valid_rbp_merge =
let r1_cfa, r1_rbp = regs_1 in
let r2_cfa, r2_rbp = regs_2 in
(match r1_cfa = r2_cfa with
| true -> valid_rbp_merge r1_rbp r2_rbp r1_cfa
| false -> Invalid_merge)
let symmetric_valid_merge regs_1 regs_2 =
let valid_rbp_merge r1 r2 cfa = (match r1, r2 with
| x, y when x = y -> Valid_merge
| RbpUndef, RbpCfaOffset _ -> Valid_with_rbp_erasing (cfa, r1)
| RbpCfaOffset _, RbpUndef -> Valid_with_rbp_erasing (cfa, r2)
| _ -> Invalid_merge)
in
valid_merge_boilerplate regs_1 regs_2 valid_rbp_merge
let valid_merge previous_regs cur_regs =
let valid_rbp_merge old cur cfa = (match old, cur with
| x, y when x = y -> Valid_merge
| RbpUndef, RbpCfaOffset _ -> Valid_merge
| RbpCfaOffset _, RbpUndef -> Valid_with_rbp_erasing (cfa, cur)
| _ -> Invalid_merge)
in
valid_merge_boilerplate previous_regs cur_regs valid_rbp_merge
let process_sub sub next_instr_graph : subroutine_cfa_data =
(** Extracts the `cfa_changes_fde` of a subroutine *)
@ -746,17 +778,6 @@ let process_sub sub next_instr_graph : subroutine_cfa_data = @@ -746,17 +778,6 @@ let process_sub sub next_instr_graph : subroutine_cfa_data =
let entry_blk = get_entry_blk cfg (first_bap_addr) in
let rbp_pop_set = find_rbp_pop_set cfg entry_blk in
let valid_merge previous_regs cur_regs =
let valid_rbp_merge old cur =
(old = cur) || (match old, cur with
| RbpUndef, RbpCfaOffset _ -> true
| _ -> false)
in
let prev_cfa, prev_rbp = previous_regs in
let cur_cfa, cur_rbp = cur_regs in
(prev_cfa = cur_cfa) && valid_rbp_merge prev_rbp cur_rbp
in
let rec dfs_process
allow_rbp
@ -768,14 +789,21 @@ let process_sub sub next_instr_graph : subroutine_cfa_data = @@ -768,14 +789,21 @@ let process_sub sub next_instr_graph : subroutine_cfa_data =
let cur_blk = CFG.Node.label node in
let tid = BStd.Term.tid @@ cur_blk in
match (TIdMap.find_opt tid sub_changes) with
| None ->
(* Not yet visited: compute the changes *)
let compute_block_and_update entry_offset sub_changes =
let cur_blk_changes, end_reg =
process_blk next_instr_graph rbp_pop_set
allow_rbp entry_offset cur_blk in
let n_sub_changes =
TIdMap.add tid (cur_blk_changes, entry_offset) sub_changes in
n_sub_changes, end_reg
in
match (TIdMap.find_opt tid sub_changes) with
| None ->
(* Not yet visited: compute the changes *)
let n_sub_changes, end_reg =
compute_block_and_update entry_offset sub_changes in
BStd.Seq.fold (CFG.Node.succs node cfg)
~f:(fun accu child ->
@ -787,16 +815,38 @@ let process_sub sub next_instr_graph : subroutine_cfa_data = @@ -787,16 +815,38 @@ let process_sub sub next_instr_graph : subroutine_cfa_data =
~init:n_sub_changes
| Some (_, former_entry_offset) ->
(* Already visited: check that entry values are matching *)
if not @@ valid_merge former_entry_offset entry_offset then (
if allow_rbp then
Format.eprintf "Found inconsistency (0x%Lx <%a>): %a -- %a@."
(int64_addr_of cur_blk)
BStd.Tid.pp tid
pp_reg_pos entry_offset pp_reg_pos former_entry_offset ;
raise (Inconsistent tid)
let do_fail () =
if allow_rbp then
Format.eprintf "Found inconsistency (0x%Lx <%a>): %a -- %a@."
(int64_addr_of cur_blk)
BStd.Tid.pp tid
pp_reg_pos entry_offset pp_reg_pos former_entry_offset ;
raise (Inconsistent tid)
in
(match valid_merge former_entry_offset entry_offset with
| Valid_merge -> sub_changes
| Invalid_merge -> do_fail ()
| Valid_with_rbp_erasing _ ->
(* Valid only if we manage to set back %rbp to undef in this block and
propagate the changes.
This tends to happen mostly in leaf blocks of a function (just
before a return), so we only handle the case for those blocks, in
which case there is no propagation needed.
The easy way to do this is simply to re-synthesize the block.
*)
let out_degree = CFG.Node.degree ~dir:`Out node cfg in
(match out_degree with
| 0 ->
let n_sub_changes, _ =
compute_block_and_update entry_offset sub_changes in
n_sub_changes
| _ ->
do_fail ()
)
)
else
sub_changes
in
let with_rbp_if_needed initial_offset =
@ -832,16 +882,18 @@ let process_sub sub next_instr_graph : subroutine_cfa_data = @@ -832,16 +882,18 @@ let process_sub sub next_instr_graph : subroutine_cfa_data =
let merged_changes = TIdMap.fold
(fun _ (cfa_changes, _) accu -> AddrMap.union (fun addr v1 v2 ->
if v1 = v2 then
Some v1
else (
match (symmetric_valid_merge v1 v2) with
| Valid_merge -> Some v1
| Invalid_merge ->
Format.eprintf "Inconsistency: 0x%Lx: cannot merge %a - %a@."
addr pp_reg_pos v1 pp_reg_pos v2 ;
Some (CfaLostTrack, RbpUndef))
Some (CfaLostTrack, RbpUndef)
| Valid_with_rbp_erasing valid_merge ->
Some valid_merge
)
cfa_changes accu)
changes_map
AddrMap.empty in
changes_map
AddrMap.empty in
let reg_changes = cleanup_fde merged_changes in

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