[LLVMdev] Instruction as Value in PHI

Ryan Taylor ryta1203 at gmail.com
Thu Sep 20 15:18:01 PDT 2012

Curious, is there a pass/mechanism that exists to promote an instruction
that is a value of a PHI?

For example, if one of the incoming values is a sub(x, y) from BB2, does
there exist something to promote this instruction back to BB2 (such that
tmp = sub(x,y)) and the PHI replaces the sub instr with tmp?

Or is the above the natural state that is then optimized into using sub, is
there a call that does this that I can turn off?

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