• isharipo's avatar
    cmd/internal/obj: change Prog.From3 to RestArgs ([]Addr) · 8c67f210
    isharipo authored
    This change makes it easier to express instructions
    with arbitrary number of operands.
    
    Rationale: previous approach with operand "hiding" does
    not scale well, AVX and especially AVX512 have many
    instructions with 3+ operands.
    
    x86 asm backend is updated to handle up to 6 explicit operands.
    It also fixes issue with 4-th immediate operand type checks.
    All `ytab` tables are updated accordingly.
    
    Changes to non-x86 backends only include these patterns:
    `p.From3 = X` => `p.SetFrom3(X)`
    `p.From3.X = Y` => `p.GetFrom3().X = Y`
    
    Over time, other backends can adapt Prog.RestArgs
    and reduce the amount of workarounds.
    
    -- Performance --
    
    x/benchmark/build:
    
    $ benchstat upstream.bench patched.bench
    name      old time/op                 new time/op                 delta
    Build-48                  21.7s ± 2%                  21.8s ± 2%   ~     (p=0.218 n=10+10)
    
    name      old binary-size             new binary-size             delta
    Build-48                  10.3M ± 0%                  10.3M ± 0%   ~     (all equal)
    
    name      old build-time/op           new build-time/op           delta
    Build-48                  21.7s ± 2%                  21.8s ± 2%   ~     (p=0.218 n=10+10)
    
    name      old build-peak-RSS-bytes    new build-peak-RSS-bytes    delta
    Build-48                  145MB ± 5%                  148MB ± 5%   ~     (p=0.218 n=10+10)
    
    name      old build-user+sys-time/op  new build-user+sys-time/op  delta
    Build-48                  21.0s ± 2%                  21.2s ± 2%   ~     (p=0.075 n=10+10)
    
    Microbenchmark shows a slight slowdown.
    
    name        old time/op  new time/op  delta
    AMD64asm-4  49.5ms ± 1%  49.9ms ± 1%  +0.67%  (p=0.001 n=23+15)
    
    func BenchmarkAMD64asm(b *testing.B) {
      for i := 0; i < b.N; i++ {
        TestAMD64EndToEnd(nil)
        TestAMD64Encoder(nil)
      }
    }
    
    Change-Id: I4f1d37b5c2c966da3f2127705ccac9bff0038183
    Reviewed-on: https://go-review.googlesource.com/63490
    Run-TryBot: Iskander Sharipov <iskander.sharipov@intel.com>
    TryBot-Result: Gobot Gobot <gobot@golang.org>
    Reviewed-by: 's avatarMatthew Dempsky <mdempsky@google.com>
    8c67f210
ytab.go 1.01 KB