Use rbp only on the subs where we need it
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29ab916c55
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6c18d9f537
1 changed files with 48 additions and 14 deletions
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@ -344,13 +344,14 @@ let is_single_free_reg expr =
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)
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let process_def (local_state: block_local_state) def (cur_reg: reg_pos)
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allow_rbp
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: (reg_pos option * block_local_state) =
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let lose_track = Some CfaLostTrack in
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let cur_cfa, cur_rbp = cur_reg in
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let out_cfa =
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(match cur_cfa, Regs.X86_64.of_var (BStd.Def.lhs def) with
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| RspOffset(cur_offset), Some reg when reg = Regs.X86_64.rsp ->
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(match cur_cfa, Regs.X86_64.of_var (BStd.Def.lhs def), allow_rbp with
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| RspOffset(cur_offset), Some reg, _ when reg = Regs.X86_64.rsp ->
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let exp = BStd.Def.rhs def in
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(match is_single_free_reg exp with
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| Some (bil_var, dw_var) when dw_var = Regs.X86_64.rsp ->
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@ -362,7 +363,7 @@ let process_def (local_state: block_local_state) def (cur_reg: reg_pos)
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)
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| _ -> lose_track
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)
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| RspOffset(cur_offset), Some reg when reg = Regs.X86_64.rbp ->
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| RspOffset(cur_offset), Some reg, true when reg = Regs.X86_64.rbp ->
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(* We have CFA=rsp+k and a line %rbp <- [expr].
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Might be a %rbp <- %rsp *)
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let exp = BStd.Def.rhs def in
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@ -383,7 +384,7 @@ let process_def (local_state: block_local_state) def (cur_reg: reg_pos)
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)
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| _ -> None
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)
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| RbpOffset(cur_offset), Some reg when reg = Regs.X86_64.rbp ->
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| RbpOffset(cur_offset), Some reg, true when reg = Regs.X86_64.rbp ->
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(* Assume we are overwriting %rbp with something — we must revert to
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some rsp-based indexing *)
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(* FIXME don't assume the rsp offset will always be 8, find a smart way
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@ -392,6 +393,7 @@ let process_def (local_state: block_local_state) def (cur_reg: reg_pos)
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value is read from the stack.
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*)
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Some (RspOffset(Int64.of_int 16))
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| RbpOffset _, _, false -> assert false
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| _ -> None
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) in
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@ -518,7 +520,7 @@ let process_jmp jmp (cur_reg: reg_pos)
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| _ -> None
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let process_blk
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next_instr_graph rbp_pop_set (block_init: reg_pos) blk
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next_instr_graph rbp_pop_set allow_rbp (block_init: reg_pos) blk
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: (reg_changes_fde * reg_pos) =
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(** Extracts the registers (CFA+RBP) changes of a block. *)
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@ -539,7 +541,8 @@ let process_blk
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let fold_elt (accu, cur_reg, cur_local_state) elt = match elt with
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| `Def(def) ->
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let new_offset, new_state = process_def cur_local_state def cur_reg in
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let new_offset, new_state =
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process_def cur_local_state def cur_reg allow_rbp in
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apply_offset
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(opt_addr_of def) (accu, cur_reg, new_state) new_offset
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| `Jmp(jmp) ->
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@ -655,6 +658,7 @@ let process_sub sub next_instr_graph : subroutine_cfa_data =
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let rbp_pop_set = find_rbp_pop_set cfg entry_blk in
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let rec dfs_process
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allow_rbp
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(sub_changes: (reg_changes_fde * reg_pos) TIdMap.t)
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node
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(entry_offset: reg_pos) =
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@ -667,26 +671,56 @@ let process_sub sub next_instr_graph : subroutine_cfa_data =
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| None ->
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(* Not yet visited: compute the changes *)
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let cur_blk_changes, end_reg =
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process_blk next_instr_graph rbp_pop_set entry_offset cur_blk in
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process_blk next_instr_graph rbp_pop_set
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allow_rbp entry_offset cur_blk in
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let n_sub_changes =
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TIdMap.add tid (cur_blk_changes, entry_offset) sub_changes in
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BStd.Seq.fold (CFG.Node.succs node cfg)
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~f:(fun accu child -> dfs_process accu child end_reg)
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~f:(fun accu child -> dfs_process allow_rbp accu child end_reg)
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~init:n_sub_changes
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| Some (_, former_entry_offset) ->
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(* Already visited: check that entry values are matching *)
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if entry_offset <> former_entry_offset then
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( Format.eprintf "Found inconsistency (0x%Lx): %a -- %a@."
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if entry_offset <> former_entry_offset then (
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if allow_rbp then
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Format.eprintf "Found inconsistency (0x%Lx): %a -- %a@."
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(int64_addr_of cur_blk)
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pp_reg_pos entry_offset pp_reg_pos former_entry_offset
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;
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raise (Inconsistent tid) )
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pp_reg_pos entry_offset pp_reg_pos former_entry_offset ;
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raise (Inconsistent tid)
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)
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else
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sub_changes
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in
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let with_rbp_if_needed initial_offset =
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(* Tries first without allowing CFA=rbp+k, then allowing it if the first
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result was either inconsistent or lost track *)
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let not_losing_track synth_result =
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let lost_track = TIdMap.exists
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(fun _ (_, (cfa_pos, _)) -> match cfa_pos with
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| CfaLostTrack -> true
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| _ -> false) synth_result
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in
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(match lost_track with
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| true -> None
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| false -> Some synth_result)
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in
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let without_rbp =
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(try
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dfs_process false TIdMap.empty entry_blk initial_offset
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|> not_losing_track
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with Inconsistent _ -> None
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)
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in
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(match without_rbp with
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| Some correct_res -> correct_res
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| None ->
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dfs_process true TIdMap.empty entry_blk initial_offset)
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in
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let initial_offset = (RspOffset initial_cfa_rsp_offset, RbpUndef) in
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let changes_map = dfs_process TIdMap.empty entry_blk initial_offset in
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(* Try first without rbp, then with rbp upon failure *)
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let changes_map = with_rbp_if_needed initial_offset in
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let merged_changes = TIdMap.fold
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(fun _ (cfa_changes, _) accu -> AddrMap.union (fun _ v1 v2 ->
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