RFR: 8279607: Existing optimization "~x+1" -> "-x" can be generalized to "~x+c" -> "(c-1)-x".

[Zhiqiang Zang]

Hi all,

Existing optimization `~x+1 -> -x` can be generalized to `~x+c -> (c-1)-x`. I included both microbenchmark and jtreg tests.


// Convert (~x+c) into (c-1)-x. Note there isn't a bitwise not
// bytecode, "~x" would typically represented as "x^(-1)", so (~x+c)
// will be (x^(-1))+c.
if (op1 == Op_Xor(bt) &&
    (in2->Opcode() == Op_ConI || in2->Opcode() == Op_ConL) &&
    phase->type(in1->in(2)) == TypeInteger::minus_1(bt)) {
  Node* c_minus_one = phase->makecon(add_ring(phase->type(in(2)), TypeInteger::minus_1(bt)));
  return SubNode::make(c_minus_one, in1->in(1), bt);
}


Thank you for reviewing.

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Commit messages:
 - Merge branch 'master'.
 - fix copyright year.
 - update copyright year to 2022.
 - update copyright year.
 - update benchmark.
 - Merge branch 'master' of https://github.com/openjdk/jdk into addnode-PAddSub1202
 - update microbenchmark.
 - replace normal jtreg test with ir test.
 - icrease the number of iterations in microbenmark tests to reduce errors.
 - add the associated microbenchmark test.
 - ... and 4 more: https://git.openjdk.java.net/jdk/compare/a741b927...ccbb3b9d

Changes: https://git.openjdk.java.net/jdk/pull/6858/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6858&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8279607
  Stats: 312 lines in 4 files changed: 306 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6858.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6858/head:pull/6858

PR: https://git.openjdk.java.net/jdk/pull/6858