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+ routine to optimize opcodes with constants

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This commit is contained in:
carl 2002-08-14 19:26:02 +00:00
parent b117e6ad01
commit e5895885fe
1 changed files with 69 additions and 2 deletions
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71
compiler/cgobj.pas
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@ -249,6 +249,17 @@ unit cgobj;
procedure g_flags2reg(list: taasmoutput; size: TCgSize; const f: tresflags; reg: TRegister); virtual; abstract;
procedure g_flags2ref(list: taasmoutput; size: TCgSize; const f: tresflags; const ref:TReference); virtual;
{
This routine tries to optimize the const_reg opcode, and should be
called at the start of a_op_const_reg. It returns the actual opcode
to emit, and the constant value to emit. If this routine returns
FALSE, no instruction should be emitted (.eg : imul reg by 1 )
@param(op The opcode to emit, returns the opcode which must be emitted)
@param(a The constant which should be emitted, returns the constant which must
be amitted)
}
function optimize_const_reg(var op: topcg; var a : aword): boolean;virtual;
{#
This routine is used in exception management nodes. It should
@ -438,7 +449,7 @@ unit cgobj;
uses
globals,globtype,options,systems,cgbase,
verbose,defbase,tgobj,symdef,paramgr,
rgobj;
rgobj,cutils;
const
max_scratch_regs = high(scratch_regs) - low(scratch_regs) + 1;
@ -726,6 +737,59 @@ unit cgobj;
end;
function tcg.optimize_const_reg(var op: topcg; var a : aword): boolean;
var
powerval : longint;
begin
optimize_const_reg := true;
case op of
{ or with zero returns same result }
OP_OR : if a = 0 then optimize_const_reg := false;
{ and with max returns same result }
OP_AND : if (a = high(a)) then optimize_const_reg := false;
{ division by 1 returns result }
OP_DIV :
begin
if a = 1 then
optimize_const_reg := false
else if ispowerof2(int64(a), powerval) then
begin
a := powerval;
op:= OP_SHR;
end;
exit;
end;
OP_IDIV:
begin
if a = 1 then
optimize_const_reg := false
else if ispowerof2(int64(a), powerval) then
begin
a := powerval;
op:= OP_SAR;
end;
exit;
end;
OP_MUL,OP_IMUL:
begin
if a = 1 then
optimize_const_reg := false
else if ispowerof2(int64(a), powerval) then
begin
a := powerval;
op:= OP_SHL;
end;
exit;
end;
OP_SAR,OP_SHL,OP_SHR:
begin
if a = 1 then
optimize_const_reg := false;
exit;
end;
end;
end;
procedure tcg.a_loadfpu_loc_reg(list: taasmoutput; const loc: tlocation; const reg: tregister);
begin
@ -1470,7 +1534,10 @@ finalization
end.
{
$Log$
Revision 1.47 2002-08-11 14:32:26 peter
Revision 1.48 2002-08-14 19:26:02 carl
+ routine to optimize opcodes with constants
Revision 1.47 2002/08/11 14:32:26 peter
* renamed current_library to objectlibrary
Revision 1.46 2002/08/11 13:24:11 peter