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* patch by Nico Erfurth: Implement FoldShiftProcess Peephole optimizer for ARM

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This optimizer folds shift/roll operations into following data
instructions.

It will change code like:

mov r0, r0, lsl #16
add r1, r0, r1

into

add r1, r1, r0, lsl #16

Source registers will be reordered when necessary, also SUB/SBC will be
replaced with RSB/RSC and vice versa when reordering is required.

It could be expanded to support more operations like LDR/STR.

git-svn-id: trunk@21507 -
This commit is contained in:
florian 2012-06-06 19:43:36 +00:00
parent 5393efb128
commit 83fb4c289d
1 changed files with 70 additions and 1 deletions
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71
compiler/arm/aoptcpu.pas
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@ -227,6 +227,7 @@ Implementation
hp1,hp2: tai;
i: longint;
TmpUsedRegs: TAllUsedRegs;
tempop: tasmop;
begin
result := false;
case p.typ of
@ -465,6 +466,8 @@ Implementation
add r1, r0, #1
Todo: Make it work for mov+cmp too
CAUTION! If this one is successful p might not be a mov instruction anymore!
}
if (taicpu(p).ops = 2) and
(taicpu(p).oper[1]^.typ = top_reg) and
@ -499,11 +502,77 @@ Implementation
end;
end;
end;
{ This folds shifterops into following instructions
mov r0, r1, lsl #8
add r2, r3, r0
to
add r2, r3, r1, lsl #8
CAUTION! If this one is successful p might not be a mov instruction anymore!
}
if (taicpu(p).opcode = A_MOV) and
(taicpu(p).ops = 3) and
(taicpu(p).oper[1]^.typ = top_reg) and
(taicpu(p).oper[2]^.typ = top_shifterop) and
(taicpu(p).oppostfix = PF_NONE) and
GetNextInstruction(p, hp1) and
(tai(hp1).typ = ait_instruction) and
(taicpu(hp1).ops = 3) and {Currently we can't fold into another shifterop}
(taicpu(hp1).oper[2]^.typ = top_reg) and
(taicpu(hp1).oppostfix = PF_NONE) and
(taicpu(hp1).condition = taicpu(p).condition) and
(taicpu(hp1).opcode in [A_ADD, A_ADC, A_RSB, A_RSC, A_SUB, A_SBC,
A_AND, A_BIC, A_EOR, A_ORR, A_TEQ, A_TST]) and
(
{Only ONE of the two src operands is allowed to match}
MatchOperand(taicpu(p).oper[0]^, taicpu(hp1).oper[1]^) xor
MatchOperand(taicpu(p).oper[0]^, taicpu(hp1).oper[2]^)
) then
begin
CopyUsedRegs(TmpUsedRegs);
if not(RegUsedAfterInstruction(taicpu(p).oper[0]^.reg,hp1,TmpUsedRegs)) or
(MatchOperand(taicpu(p).oper[0]^, taicpu(hp1).oper[0]^)) then
for I:=1 to 2 do
if MatchOperand(taicpu(p).oper[0]^, taicpu(hp1).oper[I]^.reg) then
begin
if I = 1 then
begin
{The SUB operators need to be changed when we swap parameters}
case taicpu(hp1).opcode of
A_SUB: tempop:=A_RSB;
A_SBC: tempop:=A_RSC;
A_RSB: tempop:=A_SUB;
A_RSC: tempop:=A_SBC;
else tempop:=taicpu(hp1).opcode;
end;
hp2:=taicpu.op_reg_reg_reg_shifterop(tempop,
taicpu(hp1).oper[0]^.reg, taicpu(hp1).oper[2]^.reg,
taicpu(p).oper[1]^.reg, taicpu(p).oper[2]^.shifterop^);
end
else
hp2:=taicpu.op_reg_reg_reg_shifterop(taicpu(hp1).opcode,
taicpu(hp1).oper[0]^.reg, taicpu(hp1).oper[1]^.reg,
taicpu(p).oper[1]^.reg, taicpu(p).oper[2]^.shifterop^);
asml.insertbefore(hp2, p);
asml.remove(p);
asml.remove(hp1);
p.free;
hp1.free;
p:=hp2;
GetNextInstruction(p,hp1);
asml.insertbefore(tai_comment.Create(strpnew('Peephole FoldShiftProcess done')), p);
break;
end;
ReleaseUsedRegs(TmpUsedRegs);
end;
{
Often we see shifts and then a superfluous mov to another register
In the future this might be handled in RedundantMovProcess when it uses RegisterTracking
}
if GetNextInstruction(p, hp1) then
if (taicpu(p).opcode = A_MOV) and
GetNextInstruction(p, hp1) then
RemoveSuperfluousMove(p, hp1, 'MovMov2Mov');
end;
A_ADD,