[LLVMdev] How does extra copy added by spill code get eliminated?

Thomson lilotom at gmail.com
Mon Dec 29 22:01:42 PST 2014


The spill code like "trivial spiller" in LLVM creates a new virtual
register and an extra load/store instruction based on the new virtual
register for each def/use of the original register which is replaced. Since
the newly created vreg doesn't need physical register, where doesn't it get
eliminated? I checked RegisterCoalescer but didn't get the exact function
for such purpose.

Thanks
Thomson
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