Improve libcore_util_CharsetUtils performance.
Use ScopedFastNativeObjectAccess for @FastNative methods.
Avoid expensive JNI calls by using mirror::ByteArray.
For compressed strings, just copy the ASCII data.
For uncompressed strings, pre-calculate the UTF-8 length
to avoid unnecessary reallocations. Also access 16-bit
characters directly instead of using String::CharAt() to
avoid unnecessary string compression checks that clang++
is unable to optimize away.
The results for StringToBytesBenchmark on blueline little
cores running at fixed frequency 1420800 are approximately
(medians from 3 runs) before after
timeGetBytesAscii EMPTY 1599.86 519.36
timeGetBytesAscii L_16 1849.31 535.59
timeGetBytesAscii L_64 2582.72 646.07
timeGetBytesAscii L_256 5566.70 1132.11
timeGetBytesAscii L_512 9585.88 1649.34
timeGetBytesAscii A_16 1840.06 540.05
timeGetBytesAscii A_64 2550.41 614.85
timeGetBytesAscii A_256 5382.15 919.59
timeGetBytesAscii A_512 9181.93 1226.82
timeGetBytesIso88591 EMPTY 1589.57 515.62
timeGetBytesIso88591 L_16 1835.09 535.58
timeGetBytesIso88591 L_64 2588.90 650.84
timeGetBytesIso88591 L_256 5585.69 1118.37
timeGetBytesIso88591 L_512 9635.12 1625.92
timeGetBytesIso88591 A_16 1827.21 529.83
timeGetBytesIso88591 A_64 2548.83 603.32
timeGetBytesIso88591 A_256 5356.75 916.76
timeGetBytesIso88591 A_512 9172.74 1224.04
timeGetBytesUtf8 EMPTY 1599.00 510.61
timeGetBytesUtf8 L_16 1876.05 632.55
timeGetBytesUtf8 L_64 2781.85 1054.06
timeGetBytesUtf8 L_256 12136.15 3708.94
timeGetBytesUtf8 L_512 21357.30 7811.28
timeGetBytesUtf8 A_16 1888.64 531.15
timeGetBytesUtf8 A_64 2785.70 598.75
timeGetBytesUtf8 A_256 6300.25 906.34
timeGetBytesUtf8 A_512 11074.56 1231.62
Test: run-libcore-tests.sh --mode=host
Bug: 170281727
Change-Id: I03d2420b2e1eefc1fa5232deddba593aebd51941
1 file changed
