RFR(M) 8138892: C1: Improve counter overflow checking

[Doerr, Martin]

Hi,

C1 currently loads the Method pointer in the fast path even though it is only required in the overflow case. In addition, stupid code gets generated when the frequency is set to 0 which occurs with -Xcomp.

The following webrev optimizes that:
http://cr.openjdk.java.net/~mdoerr/8138892_c1_counter_overflow/webrev.02



It's not tested on aarch64.



Please review this change.  I need a sponsor, please.


Best regards,
  Martin

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