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{
Copyright (c) 2019 by Dmtiry Boyarintsev
Calling conventions for the WebAssembly
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 cpupara;
{$i fpcdefs.inc}
interface
uses
globtype,
cclasses,
aasmtai,aasmdata,
cpubase,cpuinfo,
symconst,symbase,symsym,symtype,symdef,paramgr,parabase,cgbase,cgutils;
type
{ tcpuparamanager }
tcpuparamanager=class(TParaManager)
function get_saved_registers_int(calloption: tproccalloption): tcpuregisterarray;override;
function keep_para_array_range(varspez: tvarspez; def: tdef; calloption: tproccalloption): boolean; override;
function push_addr_param(varspez:tvarspez;def : tdef;calloption : tproccalloption) : boolean;override;
function push_size(varspez: tvarspez; def: tdef; calloption: tproccalloption): longint;override;
function create_paraloc_info(p : TAbstractProcDef; side: tcallercallee):longint;override;
function create_varargs_paraloc_info(p : tabstractprocdef; side: tcallercallee; varargspara:tvarargsparalist):longint;override;
function get_funcretloc(p : tabstractprocdef; side: tcallercallee; forcetempdef: tdef): tcgpara;override;
{ true if the location in paraloc can be reused as localloc }
function param_use_paraloc(const cgpara: tcgpara): boolean; override;
function is_stack_paraloc(paraloc: pcgparalocation): boolean;override;
private
procedure create_paraloc_info_intern(p : tabstractprocdef; side: tcallercallee; paras: tparalist;
var parasize:longint);
end;
implementation
uses
cutils,verbose,systems,
defutil,wasmdef,
aasmcpu,
hlcgobj;
function tcpuparamanager.get_saved_registers_int(calloption: tproccalloption): tcpuregisterarray;
const
{ dummy, not used for WebAssembly }
saved_regs: {$ifndef VER3_0}tcpuregisterarray{$else}array [0..0] of tsuperregister{$endif} = (RS_NO);
begin
result:=saved_regs;
end;
function tcpuparamanager.keep_para_array_range(varspez: tvarspez; def: tdef; calloption: tproccalloption): boolean;
begin
{ even though these don't need a high parameter (see push_high_param),
we do have to keep the original parameter's array length because it's
used by the compiler (to determine the size of the array to construct
to pass to an array of const parameter) }
if not is_array_of_const(def) then
result:=inherited
else
result:=true;
end;
{ true if a parameter is too large to copy and only the address is pushed }
function tcpuparamanager.push_addr_param(varspez:tvarspez;def : tdef;calloption : tproccalloption) : boolean;
begin
result:=false;
{ var,out,constref always require address }
if varspez in [vs_var,vs_out,vs_constref] then
begin
result:=true;
exit;
end;
{ Only vs_const, vs_value here }
case def.typ of
variantdef,
formaldef :
result:=true;
recorddef :
begin
{ Delphi stdcall passes records on the stack for call by value }
result:=(varspez=vs_const) or (not (def.size in [1,2,4,8]));
end;
arraydef :
begin
result:=(tarraydef(def).highrange>=tarraydef(def).lowrange) or
is_open_array(def) or
is_array_of_const(def) or
is_array_constructor(def);
end;
objectdef :
result:=is_object(def);
stringdef :
result:= (tstringdef(def).stringtype in [st_shortstring,st_longstring]);
procvardef :
result:=not(calloption in cdecl_pocalls) and not tprocvardef(def).is_addressonly;
setdef :
result:=not is_smallset(def);
else
;
end;
end;
function tcpuparamanager.push_size(varspez: tvarspez; def: tdef; calloption: tproccalloption): longint;
begin
{ all aggregate types are emulated using indirect pointer types }
result:=inherited;
end;
function tcpuparamanager.get_funcretloc(p : tabstractprocdef; side: tcallercallee; forcetempdef: tdef): tcgpara;
var
paraloc : pcgparalocation;
retcgsize : tcgsize;
begin
result.init;
result.alignment:=get_para_align(p.proccalloption);
if not assigned(forcetempdef) then
result.def:=p.returndef
else
begin
result.def:=forcetempdef;
result.temporary:=true;
end;
result.def:=get_para_push_size(result.def);
{ void has no location }
if is_void(result.def) then
begin
paraloc:=result.add_location;
result.size:=OS_NO;
result.intsize:=0;
paraloc^.size:=OS_NO;
paraloc^.def:=voidtype;
paraloc^.loc:=LOC_VOID;
exit;
end;
{ Constructors return self instead of a boolean }
if (p.proctypeoption=potype_constructor) then
begin
retcgsize:=OS_INT;
result.intsize:=sizeof(pint);
end
//todo: wasm should have the similar
{else if jvmimplicitpointertype(result.def) then
begin
retcgsize:=OS_ADDR;
result.def:=cpointerdef.getreusable_no_free(result.def);
end}
else
begin
retcgsize:=def_cgsize(result.def);
result.intsize:=result.def.size;
end;
result.size:=retcgsize;
paraloc:=result.add_location;
{ all values are returned on the evaluation stack }
paraloc^.loc:=LOC_REFERENCE;
paraloc^.reference.index:=NR_EVAL_STACK_BASE;
paraloc^.reference.offset:=0;
paraloc^.size:=result.size;
paraloc^.def:=result.def;
end;
function tcpuparamanager.param_use_paraloc(const cgpara: tcgpara): boolean;
begin
{ all parameters are copied to the linear stack, so that their address
can be taken }
result:=false;
end;
function tcpuparamanager.is_stack_paraloc(paraloc: pcgparalocation): boolean;
begin
{ all parameters are passed on the evaluation stack }
result:=true;
end;
function tcpuparamanager.create_varargs_paraloc_info(p : tabstractprocdef; side: tcallercallee; varargspara:tvarargsparalist):longint;
var
parasize : longint;
begin
parasize:=0;
{ calculate the registers for the normal parameters }
create_paraloc_info_intern(p,side,p.paras,parasize);
{ append the varargs }
if assigned(varargspara) then
begin
if side=callerside then
create_paraloc_info_intern(p,side,varargspara,parasize)
else
internalerror(2019021924);
end;
create_funcretloc_info(p,side);
result:=parasize;
end;
procedure tcpuparamanager.create_paraloc_info_intern(p : tabstractprocdef; side: tcallercallee;paras:tparalist;
var parasize:longint);
var
paraloc : pcgparalocation;
i : integer;
hp : tparavarsym;
paracgsize : tcgsize;
paraofs : longint;
paradef : tdef;
begin
paraofs:=0;
for i:=0 to paras.count-1 do
begin
hp:=tparavarsym(paras[i]);
if push_copyout_param(hp.varspez,hp.vardef,p.proccalloption) then
begin
{ passed via array reference (instead of creating a new array
type for every single parameter, use java_jlobject) }
paracgsize:=OS_ADDR;
paradef:=ptruinttype;
end
else if push_addr_param(hp.varspez, hp.vardef,p.proccalloption) then
begin
paracgsize:=OS_ADDR;
paradef:=cpointerdef.getreusable_no_free(hp.vardef);
end
else
begin
paracgsize:=def_cgsize(hp.vardef);
if paracgsize=OS_NO then
paracgsize:=OS_ADDR;
paradef:=hp.vardef;
end;
paradef:=get_para_push_size(paradef);
hp.paraloc[side].reset;
hp.paraloc[side].size:=paracgsize;
hp.paraloc[side].def:=paradef;
hp.paraloc[side].alignment:=std_param_align;
hp.paraloc[side].intsize:=tcgsize2size[paracgsize];
paraloc:=hp.paraloc[side].add_location;
{ All parameters are passed on the evaluation stack, pushed from
left to right (including self, if applicable). At the callee side,
they're available as local variables 0..n-1 }
paraloc^.loc:=LOC_REFERENCE;
paraloc^.reference.offset:=paraofs;
paraloc^.size:=paracgsize;
paraloc^.def:=paradef;
case side of
callerside:
begin
paraloc^.loc:=LOC_REFERENCE;
{ we use a fake loc_reference to indicate the stack location;
the offset (set above) will be used by ncal to order the
parameters so they will be pushed in the right order }
paraloc^.reference.index:=NR_EVAL_STACK_BASE;
end;
calleeside:
begin
paraloc^.loc:=LOC_REFERENCE;
paraloc^.reference.index:=NR_STACK_POINTER_REG;
end;
else
;
end;
inc(paraofs);
end;
parasize:=paraofs;
end;
function tcpuparamanager.create_paraloc_info(p : tabstractprocdef; side: tcallercallee):longint;
var
parasize : longint;
begin
parasize:=0;
create_paraloc_info_intern(p,side,p.paras,parasize);
{ Create Function result paraloc }
create_funcretloc_info(p,side);
{ We need to return the size allocated on the stack }
result:=parasize;
end;
initialization
ParaManager:=tcpuparamanager.create;
end.
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