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* Elaborating removal of branches with delay slots: ignore reg. deallocations that are inserted by RA between branch and its delay slot instruction.

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* Also skip possible ait_marker's between branch and its immediately following target (which was preventing certain optimizations of "exit" statements on all targets because procedure's exit label is always preceded by location marker).

git-svn-id: trunk@25855 -
This commit is contained in:
sergei 2013-10-26 17:45:01 +00:00
parent 85c8be531a
commit 40239e8bcc
1 changed files with 29 additions and 16 deletions
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45
compiler/aoptobj.pas
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@ -330,6 +330,10 @@ Unit AoptObj;
function getlabelwithsym(sym: tasmlabel): tai;
{ Removes an instruction following hp1 (possibly with reg.deallocations in between),
if its opcode is A_NOP. }
procedure RemoveDelaySlot(hp1: tai);
{ peephole optimizer }
procedure PrePeepHoleOpts;
procedure PeepHoleOptPass1;
@ -1180,6 +1184,24 @@ Unit AoptObj;
end;
procedure TAOptObj.RemoveDelaySlot(hp1:tai);
var
hp2: tai;
begin
hp2:=tai(hp1.next);
while assigned(hp2) and (hp2.typ in SkipInstr) do
hp2:=tai(hp2.next);
if assigned(hp2) and (hp2.typ=ait_instruction) and
(taicpu(hp2).opcode=A_NOP) then
begin
asml.remove(hp2);
hp2.free;
end;
{ Anything except A_NOP must be left in place: these instructions
execute before branch, so code stays correct if branch is removed. }
end;
function TAOptObj.GetFinalDestination(hp: taicpu; level: longint): boolean;
{traces sucessive jumps to their final destination and sets it, e.g.
je l1 je l3
@ -1327,6 +1349,10 @@ Unit AoptObj;
no-line-info-start/end etc }
if hp1.typ<>ait_marker then
begin
{$if defined(SPARC) or defined(MIPS) }
if (hp1.typ=ait_instruction) and (taicpu(hp1).is_jmp) then
RemoveDelaySlot(hp1);
{$endif SPARC or MIPS }
asml.remove(hp1);
hp1.free;
end
@ -1338,15 +1364,14 @@ Unit AoptObj;
{ remove jumps to a label coming right after them }
if GetNextInstruction(p, hp1) then
begin
SkipEntryExitMarker(hp1,hp1);
if FindLabel(tasmlabel(JumpTargetOp(taicpu(p))^.ref^.symbol), hp1) and
{ TODO: FIXME removing the first instruction fails}
(p<>blockstart) then
begin
tasmlabel(JumpTargetOp(taicpu(p))^.ref^.symbol).decrefs;
{$if defined(SPARC) or defined(MIPS)}
hp2:=tai(p.next);
asml.remove(hp2);
hp2.free;
RemoveDelaySlot(p);
{$endif SPARC or MIPS}
hp2:=tai(hp1.next);
asml.remove(p);
@ -1378,19 +1403,7 @@ Unit AoptObj;
taicpu(p).oper[0]^.ref^.symbol.increfs;
}
{$if defined(SPARC) or defined(MIPS)}
{ Remove delay slot. Initially is is placed immediately after
branch, but RA can insert regallocs in between. }
hp2:=tai(hp1.next);
while assigned(hp2) and (hp2.typ in SkipInstr) do
hp2:=tai(hp2.next);
if assigned(hp2) and (hp2.typ=ait_instruction) and
(taicpu(hp2).opcode=A_NOP) then
begin
asml.remove(hp2);
hp2.free;
end
else
InternalError(2013070301);
RemoveDelaySlot(hp1);
{$endif SPARC or MIPS}
asml.remove(hp1);
hp1.free;