[LLVMdev] Cost in loop-strength-reduce pass

[alexey ivannikov]

Hello. May somebody explain how cost in loop strength reduction is
calculated?
E.q. I received two different costs with 3 regs and with 1reg and imms. Why
second combination in preffered?

(Some from debug log)
New best at 3 regs, with addrec cost 3.
 Regs: {20000,+,-1}<nw><%for.body> {@x,+,4}<nsw><%for.body>
{@y,+,4}<nsw><%for.body>
New best at 3 regs, with addrec cost 1, plus 16 imm cost.
 Regs: {0,+,-1}<nw><%for.body> @x @y
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