Re: [PATCH] MIPS: Handle removal of 'h' constraint in GCC 4.4

[Richard Sandiford <rdsandiford@googlemail.com>]

"Maciej W. Rozycki" <macro@linux-mips.org> writes:
> On Wed, 17 Dec 2008, David Daney wrote:
>
>> This is an incomplete proof of concept that I applied to be able to
>> build a 64 bit kernel with GCC-4.4.  It doesn't handle the 32 bit case
>> or the R4000_WAR case.
>
>  The R4000_WAR case can use the same C code -- GCC will adjust code 
> generated as necessary according to the -mfix-r4000 flag.  For the 32-bit 
> case I think the conclusion was the only way to get it working is to use 
> MFHI explicitly in the asm.

No, the same sort of cast, multiply and shift should work for 32-bit
code too.  I.e.:

                usecs = ((uint64_t)usecs * lpj) >> 32;

It should work for both -mfix-r4000 and -mno-fix-r4000.

Richard