== FoldArrayAccess

@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Fork(3)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public class FoldArrayAccess {

    static final String TEST_STRING_LATIN1 = "Foo";
    static final String TEST_STRING_UTF16  = "Фуу";

    private int idx = 0;

    @Benchmark
    public char string_latin1_const() {
        return TEST_STRING_LATIN1.charAt(0);
    }

    @Benchmark
    public char string_utf16_const() {
        return TEST_STRING_UTF16.charAt(0);
    }

    @Benchmark
    public char string_latin1_field() {
        return TEST_STRING_LATIN1.charAt(idx);
    }

    @Benchmark
    public char string_utf16_field() {
        return TEST_STRING_UTF16.charAt(idx);
    }

}

=== Results

Benchmark                            Mode  Cnt  Score   Error  Units

# Baseline
FoldArrayAccess.string_latin1_const  avgt   15  3.520 ± 0.083  ns/op
FoldArrayAccess.string_latin1_field  avgt   15  3.288 ± 0.030  ns/op
FoldArrayAccess.string_utf16_const   avgt   15  3.512 ± 0.038  ns/op
FoldArrayAccess.string_utf16_field   avgt   15  3.308 ± 0.051  ns/op


# Patched
FoldArrayAccess.string_latin1_const  avgt   15  2.882 ± 0.017  ns/op
FoldArrayAccess.string_latin1_field  avgt   15  3.278 ± 0.014  ns/op
FoldArrayAccess.string_utf16_const   avgt   15  2.877 ± 0.006  ns/op
FoldArrayAccess.string_utf16_field   avgt   15  3.301 ± 0.140  ns/op


=== Generated Code (C2) [Const cases]

Baseline (latin1):

                  [Verified Entry Point]
  7.17%    0.46%    0x00007f777d95e000: sub    $0x18,%rsp
  0.11%    0.09%    0x00007f777d95e007: mov    %rbp,0x10(%rsp)      
  0.04%    0.05%    0x00007f777d95e00c: movabs $0x5e92f3e28,%r10     ;   {oop([B)}
  6.56%    8.16%    0x00007f777d95e016: movzbl 0x10(%r10),%eax       ; <--- array access
                    0x00007f777d95e01b: add    $0x10,%rsp
  0.09%    0.12%    0x00007f777d95e01f: pop    %rbp
 26.67%   38.37%    0x00007f777d95e020: test   %eax,0x105ddfda(%rip) 
           0.04%    0x00007f777d95e026: retq   

Baseline (utf16):

                  [Verified Entry Point]
  7.02%    0.35%    0x00007f1bf195e200: sub    $0x18,%rsp
  0.07%    0.04%    0x00007f1bf195e207: mov    %rbp,0x10(%rsp) 
  0.04%    0.02%    0x00007f1bf195e20c: movabs $0x5e92f3db8,%r10     ;   {oop([B)}
  7.25%    8.36%    0x00007f1bf195e216: movzwl 0x10(%r10),%eax       ; <--- array access
  0.02%             0x00007f1bf195e21b: add    $0x10,%rsp
  0.04%    0.05%    0x00007f1bf195e21f: pop    %rbp
 26.33%   39.03%    0x00007f1bf195e220: test   %eax,0xee6cdda(%rip)
  0.02%             0x00007f1bf195e226: retq   


Patched (latin1):

                  [Verified Entry Point]
  6.88%    7.26%    0x00007fbe7995cf00: sub    $0x18,%rsp
  2.17%    2.40%    0x00007fbe7995cf07: mov    %rbp,0x10(%rsp)
                    0x00007fbe7995cf0c: mov    $0x46,%eax             ; <--- folded
  6.29%    6.01%    0x00007fbe7995cf11: add    $0x10,%rsp
                    0x00007fbe7995cf15: pop    %rbp
 17.05%   22.36%    0x00007fbe7995cf16: test   %eax,0xe4ab0e4(%rip)
                    0x00007fbe7995cf1c: retq   

Patched (utf16):

                  [Verified Entry Point]
  5.75%    7.06%    0x00007ffaed1d2180: sub    $0x18,%rsp
  1.91%    2.54%    0x00007ffaed1d2187: mov    %rbp,0x10(%rsp)     
                    0x00007ffaed1d218c: mov    $0x424,%eax            ; <--- folded
  6.92%    5.87%    0x00007ffaed1d2191: add    $0x10,%rsp
                    0x00007ffaed1d2195: pop    %rbp
 17.63%   22.79%    0x00007ffaed1d2196: test   %eax,0x12496e64(%rip)
                    0x00007ffaed1d219c: retq   



== FoldArrayLength

@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Fork(3)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public class FoldArrayLength {

    static final String TEST_STRING_LATIN1 = "Foo";
    static final String TEST_STRING_UTF16  = "Фуу";

    @Benchmark
    public int string_length_latin1() {
        return TEST_STRING_LATIN1.length();
    }

    @Benchmark
    public int string_length_utf16() {
        return TEST_STRING_UTF16.length();
    }
}


Benchmark                             Mode  Cnt  Score   Error  Units

# Baseline
FoldArrayLength.string_length_latin1  avgt   15  2.885 ± 0.017  ns/op
FoldArrayLength.string_length_utf16   avgt   15  2.882 ± 0.008  ns/op

# Patched
FoldArrayLength.string_length_latin1  avgt   15  2.880 ± 0.011  ns/op
FoldArrayLength.string_length_utf16   avgt   15  2.896 ± 0.034  ns/op