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m68k: add more cases, where TST instructions can beoptimized away, because the previous instruction already sets all the required flags

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This commit is contained in:
Karoly Balogh 2024-01-08 15:06:38 +01:00
parent 3c57eb42f9
commit 020ca55e25
1 changed files with 43 additions and 16 deletions
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59
compiler/m68k/aoptcpu.pas
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@ -38,10 +38,12 @@ unit aoptcpu;
function RegLoadedWithNewValue(reg: tregister; hp: tai): boolean; override;
function PeepHoleOptPass1Cpu(var p: tai): boolean; override;
function TryToRemoveTST(var p: tai): boolean;
function TryToOptimizeMove(var p: tai): boolean;
function MaybeRealConstOperSimplify(var p: tai): boolean;
function OptPass1LEA(var p: tai): Boolean;
function OptPass1MOVEM(var p: tai): Boolean;
function OptPass1Bitwise(var p: tai): Boolean;
{ outputs a debug message into the assembler file }
procedure DebugMsg(const s: string; p: tai);
@ -217,6 +219,29 @@ unit aoptcpu;
end;
{$endif DEBUG_AOPTCPU}
function TCpuAsmOptimizer.TryToRemoveTST(var p: tai): boolean;
var
next, next2: tai;
opstr: string[15];
begin
result:=false;
if not((taicpu(p).oper[1]^.typ=top_reg) and isaddressregister(taicpu(p).oper[1]^.reg)) and
GetNextInstruction(p,next) and
MatchInstruction(next,A_TST,[taicpu(p).opsize]) and
MatchOperand(taicpu(p).oper[1]^,taicpu(next).oper[0]^) and
GetNextInstruction(next,next2) and
MatchInstruction(next2,[A_BXX,A_SXX],[S_NO]) and
(taicpu(next2).condition in [C_NE,C_EQ,C_PL,C_MI]) then
begin
opstr:=opname(p);
DebugMsg('Optimizer: '+opstr+', TST, Jxx/Sxx to '+opstr+', Jxx/Sxx',p);
asml.remove(next);
next.free;
result:=true;
end;
end;
function TCpuAsmOptimizer.TryToOptimizeMove(var p: tai): boolean;
var
next, next2: tai;
@ -224,21 +249,11 @@ unit aoptcpu;
begin
result:=false;
if (taicpu(p).opcode=A_MOVE) and
GetNextInstruction(p,next) and
MatchInstruction(next,A_TST,[taicpu(p).opsize]) and
MatchOperand(taicpu(p).oper[1]^,taicpu(next).oper[0]^) and
{ for movea, it won't work }
not((taicpu(p).oper[1]^.typ=top_reg) and isaddressregister(taicpu(p).oper[1]^.reg)) and
GetNextInstruction(next,next2) and
MatchInstruction(next2,[A_BXX,A_SXX],[S_NO]) and
(taicpu(next2).condition in [C_NE,C_EQ,C_PL,C_MI]) then
if (taicpu(p).opcode=A_MOVE) then
begin
DebugMsg('Optimizer: MOVE, TST, Jxx/Sxx to MOVE, Jxx',p);
asml.remove(next);
next.free;
result:=true;
exit;
result:=TryToRemoveTST(p);
if result then
exit;
end;
if GetNextInstruction(p,next) and
(next.typ = ait_instruction) and
@ -426,6 +441,11 @@ unit aoptcpu;
end;
end;
function TCpuAsmOptimizer.OptPass1Bitwise(var p: tai): Boolean;
begin
Result:=TryToRemoveTST(p);
end;
function TCpuAsmOptimizer.PeepHoleOptPass1Cpu(var p: tai): boolean;
var
next: tai;
@ -443,7 +463,10 @@ unit aoptcpu;
A_MOVEM:
result:=OptPass1MOVEM(p);
A_LEA:
Result:=OptPass1LEA(p);
result:=OptPass1LEA(p);
{ Bitwise operations }
A_AND,A_OR,A_EOR:
result:=OptPass1Bitwise(p);
{ Address register sub/add can be replaced with ADDQ/SUBQ or LEA if the value is in the
SmallInt range, which is shorter to encode and faster to execute on most 68k }
A_SUB,A_SUBA,A_ADD,A_ADDA:
@ -473,7 +496,11 @@ unit aoptcpu;
taicpu(p).loadref(0,tmpref);
result:=true;
end;
end;
end
else
result:=TryToRemoveTST(p);
A_SUBQ,A_ADDQ:
result:=TryToRemoveTST(p);
{ MOVEA #0,Ax to SUBA Ax,Ax, because it's shorter }
A_MOVEA:
if (taicpu(p).oper[0]^.typ = top_const) and