{ Copyright (c) 1998-2002 by Florian Klaempfl Generate x86_64 assembler for in set/case nodes This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. **************************************************************************** } unit nx64set; {$i fpcdefs.inc} interface uses constexp, globtype, nset,nx86set; type tx8664casenode = class(tx86casenode) procedure optimizevalues(var max_linear_list:int64;var max_dist:qword);override; procedure genjumptable(hp : pcaselabel;min_,max_ : int64);override; end; implementation uses systems,cpuinfo, verbose,globals, defutil,cutils, aasmbase,aasmtai,aasmdata,aasmcpu, cgbase, cpubase,procinfo, cga,cgutils,cgobj,cgx86; {***************************************************************************** TX8664CASENODE *****************************************************************************} procedure tx8664casenode.optimizevalues(var max_linear_list:int64;var max_dist:qword); begin inc(max_linear_list,9); end; { Always generate position-independent jump table, it is twice less in size at a price of two extra instructions (which shouldn't cause more slowdown than pipeline trashing) } procedure tx8664casenode.genjumptable(hp : pcaselabel; min_,max_ : int64); var last: TConstExprInt; tablelabel: TAsmLabel; basereg,indexreg,jumpreg: TRegister; href: TReference; jtlist: TAsmList; opcgsize: tcgsize; sectype: TAsmSectiontype; jtitemconsttype: taiconst_type; AlmostExhaustive: Boolean; lv, hv: TConstExprInt; ExhaustiveLimit, Range, x, oldmin : aint; const ExhaustiveLimitBase = 32; procedure genitem(t : pcaselabel); var i : TConstExprInt; begin if assigned(t^.less) then genitem(t^.less); { fill possible hole } i:=last+1; while i<=t^._low-1 do begin jtlist.concat(Tai_const.Create_rel_sym(jtitemconsttype,tablelabel,elselabel)); i:=i+1; end; i:=t^._low; while i<=t^._high do begin jtlist.concat(Tai_const.Create_rel_sym(jtitemconsttype,tablelabel,blocklabel(t^.blockid))); i:=i+1; end; last:=t^._high; if assigned(t^.greater) then genitem(t^.greater); end; begin lv:=0; hv:=0; if not(target_info.system in systems_darwin) then jtitemconsttype:=aitconst_32bit else { see https://gmplib.org/list-archives/gmp-bugs/2012-December/002836.html } jtitemconsttype:=aitconst_darwin_dwarf_delta32; jtlist := current_asmdata.CurrAsmList; last:=min_; opcgsize:=def_cgsize(opsize); AlmostExhaustive := False; oldmin := min_; if not(jumptable_no_range) then begin getrange(left.resultdef,lv,hv); Range := aint(max_)-aint(min_); if (cs_opt_size in current_settings.optimizerswitches) then { Limit size of jump tables for small enumerations so they have to be at least two-thirds full before being considered for the "almost exhaustive" treatment } ExhaustiveLimit := min(ExhaustiveLimitBase, TrueCount shl 1) else ExhaustiveLimit := ExhaustiveLimitBase; { If true, then this indicates that almost every possible value of x is covered by a label. As such, it's more cost-efficient to remove the initial range check and instead insert the remaining values into the jump table, pointing at elselabel. [Kit] } if ((hv - lv) - Range <= ExhaustiveLimit) then begin oldmin := min_; min_ := lv.svalue; AlmostExhaustive := True; end else begin { a <= x <= b <-> unsigned(x-a) <= (b-a) } cg.a_op_const_reg(jtlist,OP_SUB,opcgsize,aint(min_),hregister); { case expr greater than max_ => goto elselabel } cg.a_cmp_const_reg_label(jtlist,opcgsize,OC_A,Range,hregister,elselabel); min_:=0; { do not sign extend when we load the index register, as we applied an offset above } opcgsize:=tcgsize2unsigned[opcgsize]; end; end; { local label in order to avoid using GOT } current_asmdata.getlabel(tablelabel,alt_data); indexreg:=cg.makeregsize(jtlist,hregister,OS_ADDR); cg.a_load_reg_reg(jtlist,opcgsize,OS_ADDR,hregister,indexreg); { load table address } reference_reset_symbol(href,tablelabel,0,4,[]); basereg:=cg.getaddressregister(jtlist); cg.a_loadaddr_ref_reg(jtlist,href,basereg); { load table slot, 32-bit sign extended } reference_reset_base(href,basereg,-aint(min_)*4,ctempposinvalid,4,[]); href.index:=indexreg; href.scalefactor:=4; jumpreg:=cg.getaddressregister(jtlist); cg.a_load_ref_reg(jtlist,OS_S32,OS_ADDR,href,jumpreg); { add table address } reference_reset_base(href,basereg,0,ctempposinvalid,sizeof(pint),[]); href.index:=jumpreg; href.scalefactor:=1; cg.a_loadaddr_ref_reg(jtlist,href,jumpreg); { and finally jump } emit_reg(A_JMP,S_NO,jumpreg); { generate jump table } if not(target_info.system in systems_darwin) then sectype:=sec_rodata else { on Mac OS X, dead code stripping ("smart linking") happens based on global symbols: every global/static symbol (symbols that do not start with "L") marks the start of a new "subsection" that is discarded by the linker if there are no references to this symbol. This means that if you put the jump table in the rodata section, it will become part of the block of data associated with the previous non-L-label in the rodata section and stay or be thrown away depending on whether that block of data is referenced. Therefore, jump tables must be added in the code section and since aktlocaldata is inserted right after the routine, it will become part of the same subsection that contains the routine's code } sectype:=sec_code; jtlist := current_procinfo.aktlocaldata; new_section(jtlist,sectype,current_procinfo.procdef.mangledname,4); jtlist.concat(Tai_label.Create(tablelabel)); if AlmostExhaustive then begin { Fill the table with the values below _min } x := lv.svalue; while x < oldmin do begin jtlist.concat(Tai_const.Create_rel_sym(jtitemconsttype,tablelabel,elselabel)); Inc(x); end; genitem(hp); { Fill the table with the values above _max } { Subtracting one from hv and not adding 1 to max_ averts the risk of an overflow } x := max_; hv := hv - 1; while x <= hv.svalue do begin jtlist.concat(Tai_const.Create_rel_sym(jtitemconsttype,tablelabel,elselabel)); Inc(x); end; end else genitem(hp); end; begin ccasenode:=tx8664casenode; end.