Bug fixes (was: "Recursion, need more stack space.")_(re)
Tue, 17 Jun 1997 00:43:29 +0100 (WET DST)
On Sun, 5 May 2097, PredatorZeta wrote:
> Peter Gerwinski wrote:
>
> > Or else: Loading the memory reference into a register and
> > pushing that *might* be faster than a direct push (don't know).
>
> Just little clarifying.....:))
> No. Surely not on 80x86 machines. Look this (is for Pentium):
>
> 1 push (mem) take 2 cycles NOT pairable
>
> 2 a) mov (mem), reg take 1 cycle pairable
> AGI Stall (1 cycle+cut off pairing
> system)
> b) push reg take 1 cycle pairable
>
> TOTAL: 3 cycles
>
> Well, is 2 (not pairable) versus 2 1/2 (not pairable) cycles.....
> However, with a manual re-ordering it could take only 1 cycle...8-))
>
The GCC 2.7.2.x backend used by GPC knows nothing about pentium
optimzations or instruction scheduling. However, I happen to have a
Cygnus-CDK based GPC around that _does_ know pentium optimizations and it
still produces the same assembly. So, I guess more work is needed here
(by the GCC crew), although this compiler produces significantly faster
code already :-)
JanJaap
---
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Jan-Jaap van der Heijden (janjaap@Wit381304.student.utwente.nl)
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