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Optimize FoldShiftLdrStr in ARM Peephole optimizer

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The optimizer now juggles around the base and index register if that opens
up the possibility of folding the shift into the instruction.

This can only be done in the case of addressmode=AM_OFFSET, in case of
[AM_POSTINDEXED, AM_PREINDEXED] we can not move the base register, as this
would cause havoc and destruction.

git-svn-id: trunk@24645 -
This commit is contained in:
masta 2013-05-30 16:13:58 +00:00
parent e57174a14f
commit 073cab8d86
1 changed files with 20 additions and 3 deletions

23
compiler/arm/aoptcpu.pas
View File

@ -1150,18 +1150,35 @@ Implementation
{Only LDR, LDRB, STR, STRB can handle scaled register indexing}
MatchInstruction(hp1, [A_LDR, A_STR], [taicpu(p).condition],
[PF_None, PF_B]) and
(taicpu(hp1).oper[1]^.ref^.index = taicpu(p).oper[0]^.reg) and
(taicpu(hp1).oper[1]^.ref^.base <> taicpu(p).oper[0]^.reg) and
(
{If this is address by offset, one of the two registers can be used}
((taicpu(hp1).oper[1]^.ref^.addressmode=AM_OFFSET) and
(
(taicpu(hp1).oper[1]^.ref^.index = taicpu(p).oper[0]^.reg) xor
(taicpu(hp1).oper[1]^.ref^.base = taicpu(p).oper[0]^.reg)
)
) or
{For post and preindexed only the index register can be used}
((taicpu(hp1).oper[1]^.ref^.addressmode in [AM_POSTINDEXED, AM_PREINDEXED]) and
(
(taicpu(hp1).oper[1]^.ref^.index = taicpu(p).oper[0]^.reg) and
(taicpu(hp1).oper[1]^.ref^.base <> taicpu(p).oper[0]^.reg)
)
)
) and
{ Only fold if there isn't another shifterop already. }
(taicpu(hp1).oper[1]^.ref^.shiftmode = SM_None) and
not(RegModifiedBetween(taicpu(p).oper[1]^.reg,p,hp1)) and
(assigned(FindRegDealloc(taicpu(p).oper[0]^.reg,tai(hp1.Next))) or
regLoadedWithNewValue(taicpu(p).oper[0]^.reg, hp1)) then
begin
DebugMsg('Peephole FoldShiftLdrStr done', hp1);
{ If the register we want to do the shift for resides in base, we need to swap that}
if (taicpu(hp1).oper[1]^.ref^.base = taicpu(p).oper[0]^.reg) then
taicpu(hp1).oper[1]^.ref^.base := taicpu(hp1).oper[1]^.ref^.index;
taicpu(hp1).oper[1]^.ref^.index := taicpu(p).oper[1]^.reg;
taicpu(hp1).oper[1]^.ref^.shiftmode := taicpu(p).oper[2]^.shifterop^.shiftmode;
taicpu(hp1).oper[1]^.ref^.shiftimm := taicpu(p).oper[2]^.shifterop^.shiftimm;
DebugMsg('Peephole FoldShiftLdrStr done', hp1);
asml.remove(p);
p.free;
p:=hp1;