Originally posted by type_r503
How can a compiler support an unreleased, undocumented cpu without the support of the Manufacturer? I guess gcc was just hacked to support a non existent cpu. In order for the compiler to write instructions for a cpu it must know the instructions the cpu uses. Thus if gcc now supports the PPC970 the only LOGICAL conclusion would be that IBM or APPLE(as Apple and IBM are working together) have supplied the code for this. Once again this is very good news!
It is very simple. There is only one place where GCC lists itself as supporting the PowerPC 970 and that is on a comment on one line of one source file. If you read the release notes and the other associated GCC documentation, you will find no mention of support for the PowerPC 970, only newly added support for the POWER4.
The PowerPC 970 is hardly an undocumented processor. It supports a documented ISA--the PowerPC 64-bit ISA. Its architecture details have been documented by IBM. Since the processor has the same number of integer, floating point and load/store units as the POWER4 and both implement the PowerPC 64-bit ISA, it is logical to assume the optimization code will be the same.
People are blowing this way out of all proportion to what it actually means. It means nothing more than GCC now supports the POWER4 architecture with the belief that the same set of optimizations will work for the PowerPC 970 (not a bad assumption).
I expect that Apple and/or IBM will have to do additional work to GCC to get it to support the AltiVec unit. I think the surest sign that people have blown this way out of proportion is that there is
no mention at all for AltiVec support. That fact alone means GCC does not fully support the PowerPC 970.
This is becoming like the G5. People are so convinced that PowerPC 970 based PowerMacs and PowerBooks are coming out in June that anything that mentions the processor is taken as evidence we are only a few short weeks away from release. This tidbit means nothing beyond GCC support for the POWER4.