[LLVMdev] reg_iterator Caveats
evan.cheng at apple.com
Mon Mar 31 17:35:44 PDT 2008
On Mar 31, 2008, at 4:55 PM, Chris Lattner wrote:
> On Mon, 31 Mar 2008, Evan Cheng wrote:
>>> I just discovered that def_itterator (and presumably, reg_iterator)
>>> include implicit defs, for example at function calls for caller-save
>>> registers. Guh. I'm not sure if it should or not, but it's
>>> necessary information in some cases. Is this expected behavior,
>>> or an
> reg iterators will return everything that is in the function. If the
> implicit operands haven't been added to the machieninstrs yet, then
> won't be returned.
>> MachineRegisterInfo tracks virtual register only.
> It works for vregs and pregs today.
Ok! Fooled me with this comment:
/// MachineRegisterInfo - Keep track of information for each virtual
/// including its register class.
>> I also wish it would track physical register defs and uses as well.
>> can be used to simplify a lot of code (in livevariable, etc.). Chris,
>> do you think that's feasible?
> Really really feasible :)
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