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  1. JDK
  2. JDK-8308340

C2: Idealize Fma nodes

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    • Enhancement
    • Resolution: Fixed
    • P4
    • 22
    • 21
    • hotspot
    • b11
    • generic
    • generic

    Description

      Some platforms, like aarch64, ppc, and riscv, support match rules to fuse `match(Set dst (FmaF src3 (Binary (NegF src1) src2)));`. Since `Fma` is partially communitive, we need to generate partially symmetric rules like:
      ```
        match(Set dst (FmaF src3 (Binary (NegF src1) src2)));
        match(Set dst (FmaF src3 (Binary src1 (NegF src2))));
      ```

      If we could idealize these fma nodes in gvn phase, making them canonical, duplicate rules can be removed. Suppose it could help reduce code size.

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              fgao Fei Gao
              fgao Fei Gao
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