RFR: 8308340: C2: Idealize Fma nodes

[Fei Gao]

Some platforms, like aarch64, ppc, and riscv, support fusing `Math.fma(-a, b, c)` or `Math.fma(a, -b, c)` by generating partially symmetric match rules like:


  match(Set dst (FmaF src3 (Binary (NegF src1) src2)));
  match(Set dst (FmaF src3 (Binary src1 (NegF src2))));


Since `Fma` is partially communitive, the patch is to convert `Math.fma(-a, b, c)` to `Math.fma(b, -a, c)` in gvn phase, making node patterns canonical. Then we can remove redundant rules.

Also, we should guarantee that C2 generates `Fma` nodes only on platforms supporting `Fma` instructions before matcher, so we can remove all `predicate(UseFMA)` for all `Fma` rules.

After the patch, the code size of libjvm.so on aarch64 platform decreased by 63.4k.

The patch passed all tier 1 - 3 on aarch64 and x86 platforms.

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Commit messages:
 - 8308340: C2: Idealize Fma nodes

Changes: https://git.openjdk.org/jdk/pull/14576/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14576&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308340
  Stats: 581 lines in 18 files changed: 368 ins; 117 del; 96 mod
  Patch: https://git.openjdk.org/jdk/pull/14576.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14576/head:pull/14576

PR: https://git.openjdk.org/jdk/pull/14576