[llvm-dev] Custom Instruction Cost Model to LLVM RISC-V Backend (original) (raw)
Bandhav Veluri via llvm-dev llvm-dev at lists.llvm.org
Mon May 25 19:54:52 PDT 2020
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Hi,
I’m working on a RISC-V architecture that has instruction costs different from those in the default cost model. Is there an out-of-source way to provide llc with custom cost model? Or, does this need a change in LLVM backend?
Also, the cost model is not totally static. For example, loads from 0x1000-0x1ffc take 1 cycle, whereas loads from address > 0x80000000, take 10-100 cycles. Is it possible to model these costs in the scheduler? Requiring programmer to define custom pointer types to mark pointers, to one or the other address space, is okay. Is there a way to model different costs for different pointer types?
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