Am 19.08.16 um 14:49 schrieb Jonas Maebe:
Michael Ring wrote on Sat, 13 Aug 2016:
I am trying to bring interrupt handling routine size down (and speed
up) for mipsel-embedded target.
I need to use inline assembler routines like this one
procedure TSystemCore.setCoreTimerComp(value : longWord); assembler;
nostackframe;
asm
mtc0 $a1,$11,0
end ['a1'];
Mentioning changed registers at the end of a pure assembler routine
has no effect. The compiler normally prints a warning about this. The
set of changed registers by a routine always only depends on its
calling convention. On most platforms we only support the official
ABI's calling convention, which is also the default.
I also tried also something like this:
procedure TSystemCore.setCoreTimerComp(value : longWord);
begin
asm
mtc0 $a1,$11,0
end ['a1'];
end;
with same result, all registers are saved. intead of only a few.
inside of the interrupt handler, but as soon as I include the call to
this procedure the number of registers that get saved explodes. When
I only need to modify some peripheral I usually get away with only
$v0 and $v1 registers getting saved, but with asm routine included
all registers get saved.
If the ABI default calling convention states that a routine may change
all registers, that is to be expected.
Same is true if I put the asm block directly inside of the interrupt
handler.
In that case, the list of changed registers should be taken into
account. OTOH, using an inline assembler blocks disables the use the
use of register variables for that routine by the compiler, but that
should result in less registers getting saved rather than more.
Do you remember where this is coded or for what I should search in the
fpc sourcecode? Then I can try to find out what is going on in the mips
case.
Thank you,
Michael
Jonas
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