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* Early during register allocation, spill registers which interfere with all usable real registers.

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It is pointless to keep them for further processing. Also it may
  cause endless spilling.
  This can happen when compiling for very constrained CPUs such as
  i8086 where indexed memory access instructions allow only
  few registers as arguments and additionally the calling convention
  provides no general purpose volatile registers.

git-svn-id: trunk@46199 -
This commit is contained in:
yury 2020-08-03 16:46:25 +00:00
parent 601e05f17f
commit ff820247c3
1 changed files with 17 additions and 0 deletions
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17
compiler/rgobj.pas
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@ -629,6 +629,23 @@ unit rgobj;
{ Don't do the real allocation when -sr is passed }
if (cs_no_regalloc in current_settings.globalswitches) then
exit;
{ Spill registers which interfere with all usable real registers.
It is pointless to keep them for further processing. Also it may
cause endless spilling.
This can happen when compiling for very constrained CPUs such as
i8086 where indexed memory access instructions allow only
few registers as arguments and additionally the calling convention
provides no general purpose volatile registers.
}
for i:=first_imaginary to maxreg-1 do
if reginfo[i].real_reg_interferences>=usable_registers_cnt then
spillednodes.add(i);
if spillednodes.length<>0 then
begin
spill_registers(list,headertai);
spillednodes.clear;
end;
{Do register allocation.}
spillingcounter:=0;
repeat