[LLVMdev] global type legalization?
Jakob Stoklund Olesen
stoklund at 2pi.dk
Wed Aug 18 11:31:12 PDT 2010
On Aug 18, 2010, at 11:22 AM, Chris Lattner wrote:
> On Aug 18, 2010, at 11:13 AM, Jakob Stoklund Olesen wrote:
>> On Aug 18, 2010, at 9:56 AM, Chris Lattner wrote:
>>> Some things to consider: When the input to the zext is spilled, the reload can be folded into the zext on almost all targets, making the zext free. When the zext *isn't* folded into a load, what you're really looking for is a code placement pass which tries to put the zexts in non-redundant (and non-partially redundant) places.
>> That makes sense to me, but note that this is not currently implemented. All our RISC-like targets only support folding of COPY to load/store through the target-independent mechanisms.
>> It should be fairly simple to add a foldMemoryOperandImpl override to ARM that folds load+zext into a zextload.
> Really? I'm pretty sure that ppc folded load into [sz]ext (with custom code). If ARM isn't doing this, it should - it is a clear win.
It is entirely possible I broke it when I added the COPY instruction.
I deleted the RISC target hooks for foldMemoryOperandImpl, thinking that COPY folding was all they needed.
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