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* New "TryRemoveRegAlloc" optimisation utility

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J. Gareth "Curious Kit" Moreton 2023-10-23 01:18:18 +01:00 committed by FPK
parent 4f82fade82
commit 1fafcbc125
1 changed files with 78 additions and 0 deletions
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78
compiler/aoptobj.pas
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@ -426,6 +426,11 @@ Unit AoptObj;
{ Jump/label optimisation entry method }
function DoJumpOptimizations(var p: tai; var stoploop: Boolean): Boolean;
{ Attempts to reconfigure the Regallocs and Regdeallocs before p1 and
after p2 so Reg is no longer allocated between them. Returns True if
the register is no longer allocated at p1 }
function TryRemoveRegAlloc(const Reg: TRegister; p1, p2: tai): Boolean;
{ insert debug comments about which registers are read and written by
each instruction. Useful for debugging the InstructionLoadsFromReg and
other similar functions. }
@ -2566,6 +2571,79 @@ Unit AoptObj;
end;
{ Attempts to reconfigure the Regallocs and Regdeallocs before p1 and
after p2 so Reg is no longer allocated between them. Returns True if the
register is no longer allocated at p1 }
function TAOptObj.TryRemoveRegAlloc(const Reg: TRegister; p1, p2: tai): Boolean;
var
CurrentAlloc: tai;
begin
Result := False;
if RegInInstruction(Reg, p1) then
{ Register is definitely in use }
Exit;
{ Search for the first de/alloc before p1 that relates to Reg }
CurrentAlloc := tai(p1.Previous);
repeat
while Assigned(CurrentAlloc) and
((CurrentAlloc.typ in (SkipInstr - [ait_regAlloc])) or
((CurrentAlloc.typ = ait_label) and
not(Tai_Label(CurrentAlloc).labsym.Is_Used))) do
CurrentAlloc := Tai(CurrentAlloc.Previous);
if Assigned(CurrentAlloc) and
(CurrentAlloc.typ = ait_regalloc) then
begin
if (getregtype(tai_regalloc(CurrentAlloc).Reg) = getregtype(Reg)) and
(getsupreg(tai_regalloc(CurrentAlloc).Reg) = getsupreg(Reg)) then
begin
Break;
end;
CurrentAlloc := Tai(CurrentAlloc.Previous);
end
else
begin
CurrentAlloc := nil;
Break;
end;
until false;
{ Remove any register allocation prior to p1 }
if Assigned(CurrentAlloc) and (CurrentAlloc.typ = ait_regalloc) and
(tai_regalloc(CurrentAlloc).ratype = ra_alloc) then
begin
RemoveInstruction(CurrentAlloc);
Result := True;
end
else if not Assigned(CurrentAlloc) or (CurrentAlloc.typ <> ait_regalloc) or
(tai_regalloc(CurrentAlloc).ratype <> ra_dealloc) then
begin
AsmL.InsertBefore(tai_regalloc.dealloc(Reg, nil), p1);
Result := True;
end;
if (p1 <> p2) and RegInInstruction(Reg, p2) then
begin
{ Reg is in use, so insert allocation before it }
AsmL.InsertBefore(tai_regalloc.alloc(Reg, nil), p2);
Exit;
end;
{ If a deallocation exists, remove it since the register will no longer be allocated by this time }
CurrentAlloc := FindRegDealloc(Reg, tai(p2.Next));
if Assigned(CurrentAlloc) and (CurrentAlloc.typ = ait_regalloc) and
(tai_regalloc(CurrentAlloc).ratype = ra_dealloc) then
begin
RemoveInstruction(CurrentAlloc);
end
else
begin
{ Since no deallocation was found, Register may end up being used afterwards, so add a new alloc to play safe }
AsmL.InsertAfter(tai_regalloc.alloc(Reg, nil), p2);
end;
end;
procedure TAOptObj.PrePeepHoleOpts;
var
p: tai;