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From what I can tell, the truncstore paths all fail instruction selection in the current PTX backend. This is easy to work around for int types >= 16 bits by setting the truncstore action to expand in PTXISelLowering.cpp, but this cannot handle i8 values, since the PTX backend has no register representation for i8s. As a result of all this, it is not possible to store to i8 pointers at all. PTX does support truncating stores, including to i8s. (ld/st and cvt are the only ops which work with i8 types.) Is...

Hi, Dan Someone on the irc suggest me using custom lowering to do the mapping correctly. But I am still trying to figure out how to do that. Regards, chenwj -- Wei-Ren Chen (陳韋任) Computer Systems Lab, Institute of Information Science, Academia Sinica, Taiwan (R.O.C.) Tel:886-2-2788-3799 #1667

...ote: > Hi, Dan > > Someone on the irc suggest me using custom lowering to do the mapping > correctly. But I am still trying to figure out how to do that. > Custom lowering means implementing the SelectionDAG instruction selection in the C++ class instead of the TableGen file. See PTXISelLowering.{h,cpp} for some examples. This just allows arbitrary matching and code generation logic instead of just pattern matching. Though, I have to agree with Dan on assessing whether the selection logic is needed. Do you have an example where the PTX back-end cannot generate code for some piece o...