Daniel Jacobowitz wrote:
> _mcount was doing awful things to its caller's stack frame.
Maybe I'm missing something, but both the old and the new code
add 8 byte more to sp than they subtracted before. How is this
supposed to work?
[snip]
> I think this is close enough; it only adds
> one instruction. Is this OK?
Why do you save and restore $6, $7, seemingly without using them?
> Do I need a "nop" after the subu?
It works here since it is expanded in an
addiu $29,$29,-40
which is executed in one cycle. The usual suspects for hazards
to be NOPed are load/store insns and branches.
[snip]
> + "sw $31,20($29);" \
> "move $5,$31;" \
> "jal __mcount;" \
> "move $4,$1;" \
^
Some stylistic issue: In ".set noreorder" assembly it helps to
indent the insns in a branch delay slot by one blank to avoid
confusion about their non-sequential nature.
Thiemo
