Re: PPC Compiler Problem?

[Gary Thomas <gdt@linuxppc.org>]

On 01-Dec-99 VALETTE Eric wrote:
> 
>>>>>> "Alois" == Alois Fertl <alois_fertl@muenchen.europe.mcd.mot.com> writes:
> 
> Alois> Given the following lines of C, I'd expect that the 4th argument
> Alois> is placed into register 6 and 7. As the assembler listing tells,
> Alois> register 6 is omitted and the argument goes into r7/r8.
> 
> I indeed checked the "PowerPC Processor ABI Supplement" dated September 95
> (SVR4 PowerPC ABI) and on 3-18 I see :
> 
> For PowerPC, up to eight words are passed in general purpose registers, loaded
> sequentially into general purpose registers r3 through r10.
> 
> It is clear that this breaks the SVR4 ABI... So you can probably open a bug
> report...
> 

If you read carefully, on page 3-18 of the SYSV ABI report, for a long long
argument being placed in register 'gr':
  " if gr is even, set gr to gr+1.  Load the lower addressed word into gr and
    the higher addressed word into gr+1."

Thus, the implementation _is_ correct.  long long arguments always occupy
an odd/even pair of registers.


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Gary Thomas                              |
email: gdt@linuxppc.org                  | "Fine wine is a necessity of
   ... opinions expressed here are mine  |        life for me"
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