[LLVMdev] Support for PPC 440/450

Jim Grosbach grosbach at apple.com
Wed Oct 5 14:35:35 PDT 2011

On Oct 5, 2011, at 2:14 PM, Jakob Stoklund Olesen wrote:

> On Oct 5, 2011, at 8:22 AM, Hal Finkel wrote:
>> I've been working on adding support for the PPC 440/450 "embedded" cores
>> to the PowerPC backend. These are used on IBM's Blue Gene L and P
>> supercomputers, but are also used in other environments (like on the
>> Xilinx Virtex-5). Here is my first patch. I'm new to LLVM, and so I
>> apologize if this is the wrong way to do this [the online docs seem to
>> imply that a patch should be sent to a mailing list, although does not
>> specify which one, should it go to the bug tracker instead?].
> llvm-commits is the place to send your patches.
>> I've tried to touch as little of the existing code as possible. There
>> are some other changes which should probably be made, but would require
>> touching the existing PowerPC code.
> This patch looks fine to me, but I am missing some test cases.
> There should at least be a test case just sending some code through this scheduler.
>> For example, the general load/store
>> itinerary should really be split into a general load and general store.
>> Also, on the so-called "Book E" embedded PPC cores, the sync instruction
>> is called msync (same opcode, different name). I'm not sure what the
>> best way of doing a predicate-base asm name is.
> I am not sure how to do that.  X86 has alternative syntaxes, but that is way overkill.

You can put a predicate on an InstAlias or a MnemonicAlias. Just do:

def : MnemonicAlias<"msync", "sync">, Requires<[IsBookE]>;

>> I'm just about done with a patch to add support for the FP2 (aka Double
>> Hummer) v2f64 vector instruction set, but I figured that it would be
>> good to make that a separate patch.
> Definitely.
> /jakob
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