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* x86: New reference support methods to detect modification

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J. Gareth "Curious Kit" Moreton 2024-04-18 02:09:44 +01:00 committed by FPK
parent d0c7838eec
commit e187d49590
1 changed files with 77 additions and 0 deletions
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77
compiler/x86/aoptx86.pas
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@ -91,6 +91,11 @@ unit aoptx86;
}
function GetNextInstructionUsingRegTrackingUse(Current: tai; out Next: tai; reg: TRegister): Boolean;
function RegModifiedByInstruction(Reg: TRegister; p1: tai): boolean; override;
{ returns true if any of the registers in ref are modified by any
instruction between p1 and p2, or if those instructions write to the
reference }
function RefModifiedBetween(Ref: TReference; RefSize: ASizeInt; p1, p2: tai): Boolean;
private
function SkipSimpleInstructions(var hp1: tai): Boolean;
@ -246,6 +251,9 @@ unit aoptx86;
function RefsEqual(const r1, r2: treference): boolean;
{ Like RefsEqual, but doesn't compare the offsets }
function RefsAlmostEqual(const r1, r2: treference): boolean;
{ Note that Result is set to True if the references COULD overlap but the
compiler cannot be sure (e.g. "(%reg1)" and "4(%reg2)" with a range of 4
might still overlap because %reg2 could be equal to %reg1-4 }
@ -481,6 +489,18 @@ unit aoptx86;
end;
function RefsAlmostEqual(const r1, r2: treference): boolean;
begin
RefsAlmostEqual :=
(r1.symbol=r2.symbol) and (r1.refaddr = r2.refaddr) and
(r1.relsymbol = r2.relsymbol) and
(r1.segment = r2.segment) and (r1.base = r2.base) and
(r1.index = r2.index) and (r1.scalefactor = r2.scalefactor) and
{ Don't compare the offsets }
(r1.volatility + r2.volatility = []);
end;
function RefsMightOverlap(const r1, r2: treference; const Range: asizeint): boolean;
begin
if (r1.symbol<>r2.symbol) then
@ -1316,6 +1336,63 @@ unit aoptx86;
end;
function TX86AsmOptimizer.RefModifiedBetween(Ref: TReference; RefSize: ASizeInt; p1, p2: tai): Boolean;
const
WriteOps: array[0..3] of set of TInsChange =
([CH_RWOP1,CH_WOP1,CH_MOP1],
[Ch_RWOP2,Ch_WOP2,Ch_MOP2],
[Ch_RWOP3,Ch_WOP3,Ch_MOP3],
[Ch_RWOP4,Ch_WOP4,Ch_MOP4]);
var
X: Integer;
CurrentP1Size: asizeint;
begin
Result := (
(Ref.base <> NR_NO) and
{$ifdef x86_64}
(Ref.base <> NR_RIP) and
{$endif x86_64}
RegModifiedBetween(Ref.base, p1, p2)
) or
(
(Ref.index <> NR_NO) and
(Ref.index <> Ref.base) and
RegModifiedBetween(Ref.index, p1, p2)
);
{ Now check to see if the memory itself is written to }
if not Result then
begin
while assigned(p1) and assigned(p2) and GetNextInstruction(p1,p1) and (p1<>p2) do
if p1.typ = ait_instruction then
begin
CurrentP1Size := topsize2memsize[taicpu(p1).opsize] shr 3; { Convert to bytes }
with insprop[taicpu(p1).opcode] do
for X := 0 to taicpu(p1).ops - 1 do
if (taicpu(p1).oper[X]^.typ = top_ref) and
RefsAlmostEqual(Ref, taicpu(p1).oper[X]^.ref^) and
{ Catch any potential overlaps }
(
(RefSize = 0) or
((taicpu(p1).oper[X]^.ref^.offset - Ref.offset) < RefSize)
) and
(
(CurrentP1Size = 0) or
((Ref.offset - taicpu(p1).oper[X]^.ref^.offset) < CurrentP1Size)
) and
{ Reference is used, but does the instruction write to it? }
(
(Ch_All in Ch) or
((WriteOps[X] * Ch) <> [])
) then
begin
Result := True;
Break;
end;
end;
end;
end;
{$ifdef DEBUG_AOPTCPU}
procedure TX86AsmOptimizer.DebugMsg(const s: string;p : tai);
begin