mirror of
https://github.com/Mercury-Language/mercury.git
synced 2026-04-15 17:33:38 +00:00
106 lines
4.2 KiB
Mathematica
106 lines
4.2 KiB
Mathematica
%-----------------------------------------------------------------------------%
|
|
% vim: ft=mercury ts=4 sw=4 et
|
|
%-----------------------------------------------------------------------------%
|
|
% Copyright (C) 2001-2003, 2005-2007, 2010-2011 The University of Melbourne.
|
|
% Copyright (C) 2014-2015, 2018 The Mercury team.
|
|
% This file may only be copied under the terms of the GNU General
|
|
% Public License - see the file COPYING in the Mercury distribution.
|
|
%-----------------------------------------------------------------------------%
|
|
%
|
|
% File: wrap_blocks.m
|
|
% Author: zs.
|
|
%
|
|
% The optimizations in use_local_vars.m insert into instruction sequences
|
|
% references to temporary variables whose values need be preserved only within
|
|
% an extended basic block. The wrap_blocks pass looks for references to
|
|
% temporaries and introduces block instructions whenever it sees them. These
|
|
% block instructions go from the first reference to a temporary to the end of
|
|
% its extended basic block.
|
|
%
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- module ll_backend.wrap_blocks.
|
|
:- interface.
|
|
|
|
:- import_module ll_backend.llds.
|
|
|
|
:- import_module list.
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- pred wrap_blocks(list(instruction)::in, list(instruction)::out) is det.
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- implementation.
|
|
|
|
:- import_module ll_backend.opt_util.
|
|
|
|
:- import_module bool.
|
|
:- import_module int.
|
|
:- import_module require.
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
wrap_blocks(Instrs0, Instrs) :-
|
|
wrap_instrs(Instrs0, 0, 0, [], Instrs).
|
|
|
|
% R is the number of the highest numbered tempr variable seen so far;
|
|
% R = 0 means we haven't seen any temp variables. Similarly, F is the
|
|
% highest numbered tempf variable seen so far. RevSofar is a
|
|
% reversed list of instructions starting with the first instruction
|
|
% in this block that accesses a temp variable. Invariant: RevSofar
|
|
% is always empty if R = 0 and F = 0.
|
|
%
|
|
:- pred wrap_instrs(list(instruction)::in, int::in, int::in,
|
|
list(instruction)::in, list(instruction)::out) is det.
|
|
|
|
wrap_instrs([], R, F, RevSofar, []) :-
|
|
(
|
|
RevSofar = [_ | _],
|
|
unexpected($pred, "procedure ends with fallthrough")
|
|
;
|
|
RevSofar = [],
|
|
( if ( R > 0 ; F > 0 ) then
|
|
unexpected($pred, "procedure ends without closing block")
|
|
else
|
|
true
|
|
)
|
|
).
|
|
wrap_instrs([Instr0 | Instrs0], R0, F0, RevSofar, Instrs) :-
|
|
Instr0 = llds_instr(Uinstr0, _Comment0),
|
|
opt_util.count_temps_instr(Uinstr0, R0, R1, F0, F1),
|
|
( if ( R1 > 0 ; F1 > 0) then
|
|
% We must close the block before a label, since you can jump
|
|
% to a label from other blocks.
|
|
%
|
|
% Call instructions cannot fall through, but they cannot refer
|
|
% to the temp variables declared by the block either, so we
|
|
% close the block either just before or just after the call
|
|
% instruction. We close the block before the call instruction,
|
|
% because including it in the block causes the test case
|
|
% debugger/all_solutions to fail.
|
|
|
|
( if ( Uinstr0 = label(_) ; Uinstr0 = llcall(_, _, _, _, _, _) ) then
|
|
list.reverse(RevSofar, BlockInstrs),
|
|
wrap_instrs(Instrs0, 0, 0, [], Instrs1),
|
|
BlockInstr = llds_instr(block(R1, F1, BlockInstrs), ""),
|
|
Instrs = [BlockInstr, Instr0 | Instrs1]
|
|
else if opt_util.can_instr_fall_through(Uinstr0) = no then
|
|
list.reverse([Instr0 | RevSofar], BlockInstrs),
|
|
wrap_instrs(Instrs0, 0, 0, [], Instrs1),
|
|
BlockInstr = llds_instr(block(R1, F1, BlockInstrs), ""),
|
|
Instrs = [BlockInstr | Instrs1]
|
|
else
|
|
wrap_instrs(Instrs0, R1, F1, [Instr0 | RevSofar], Instrs)
|
|
)
|
|
else
|
|
wrap_instrs(Instrs0, 0, 0, [], Instrs1),
|
|
Instrs = [Instr0 | Instrs1]
|
|
).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
:- end_module ll_backend.wrap_blocks.
|
|
%-----------------------------------------------------------------------------%
|