Looking through TOT sources, I don't see anything that would provide
def/use chains (or equivalent information) post register allocation. I
would like to write some peeps to clean up various target-specific
things but for safety I will need such information.
Is such an analysis pass available somewhere that I've missed? If not,
is there a better way to find all uses of a defined value post register
allocation? Writing a def/use chain pass would not be hard but if the
information is already there I'd rather avoid that cost. :)
-Dave
On Jun 15, 2012, at 2:54 PM, dag at cray.com wrote:> Looking through TOT sources, I don't see anything that would provide > def/use chains (or equivalent information) post register allocation. I > would like to write some peeps to clean up various target-specific > things but for safety I will need such information. > > Is such an analysis pass available somewhere that I've missed? If not, > is there a better way to find all uses of a defined value post register > allocation? Writing a def/use chain pass would not be hard but if the > information is already there I'd rather avoid that cost. :)Do the MachineRegisterInfo::def_begin/def_end/use_begin/use_end iterators not work on physical registers? --Owen
On 6/15/2012 6:00 PM, Owen Anderson wrote:> On Jun 15, 2012, at 2:54 PM, dag at cray.com wrote: > >> Looking through TOT sources, I don't see anything that would provide >> def/use chains (or equivalent information) post register allocation. I >> would like to write some peeps to clean up various target-specific >> things but for safety I will need such information. >> >> Is such an analysis pass available somewhere that I've missed? If not, >> is there a better way to find all uses of a defined value post register >> allocation? Writing a def/use chain pass would not be hard but if the >> information is already there I'd rather avoid that cost. :) > Do the MachineRegisterInfo::def_begin/def_end/use_begin/use_end iterators not work on physical registers? >I seem to recall, the last time I used those, that they ended up being a fairly flat list of all definitions and all uses of a physical registers, not all the uses of a particular definition (or vice versa). -- Joshua Cranmer News submodule owner DXR coauthor
Owen Anderson <resistor at mac.com> writes:> On Jun 15, 2012, at 2:54 PM, dag at cray.com wrote: > >> Looking through TOT sources, I don't see anything that would provide >> def/use chains (or equivalent information) post register allocation.> Do the MachineRegisterInfo::def_begin/def_end/use_begin/use_end > iterators not work on physical registers?Sure, they do, but that doesn't tell you anything about how they relate to each other. They simply list every def and use of a register. For SSA form, this is great. But post RA we're not in SSA anymore. -Dave