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Author SHA1 Message Date
Ehsan Behrangi
00cc9be854 8381560: AArch64: Optimize String.equals intrinsic 
This change improves the AArch64 implementation of String.equals by
introducing SIMD-based fast paths using SVE and NEON.

SVE implementation:
- Uses predicated loads and comparisons for short lengths (len < VL)
- Uses a full predicated loop for longer inputs
- Handles the tail via an overlapped compare at (base + len - VL)

NEON implementation:
- Uses an 8-byte pre-read to simplify tail handling and eliminate
  4/2/1-byte scalar branches
- Processes 16-byte chunks using LDP pair loads
- Uses CMP/CCMP to collapse comparisons into a single branch on mismatch

These changes reduce branch pressure and improve throughput for both
short and long strings.

Correctness:
- The implementation preserves existing semantics and matches behavior
  for all lengths

Testing:
- Updated and extended intrinsic tests to cover boundary conditions
  and mismatch positions

Benchmark:
Across evaluated macrobenchmarks (DaCapo and Renaissance), most workloads
spend <0.5% of CPU time in String.equals. DaCapo biojava is a notable
exception (~8–9%). In biojava, most String.equals calls are on very short
strings (1–2 bytes), where SVE shows ~1% end-to-end improvement, while
NEON is largely neutral or shows a small regression (~1%).

Measured using JMH on AArch64 (Arm Neoverse V2 CPU).
Values are relative (%) vs baseline. Negative values indicate regressions.
Mismatch results are reported across first(DF), middle(DM),
and last(DL) difference positions.

SVE results:
Length | L1_EQ  L1_DF  L1_DM  L1_DL | U16_EQ U16_DF U16_DM U16_DL | Avg
-------+----------------------------+-----------------------------+------
0      | 19.63                      | 20.05                      | 19.84
1      | 16.59  17.81  16.57  18.34 | 16.02   0.71   0.42   1.39 | 10.98
2      | 16.44   1.32   0.30  -0.16 | 15.90  -5.17  -4.55  -1.09 |  2.87
3      | 26.58   1.60   1.43  27.07 | 30.34  -8.86  -7.06  14.08 | 10.65
7      | 41.47  -2.94  -3.37  39.82 | 24.02  -8.82  -6.27  20.48 | 13.05
8      | 19.08  -1.16  -3.50  -0.90 | 22.49  -9.75  17.50  13.13 |  7.11
9      | 20.17  -4.12  -5.17  19.03 |  9.25  -2.24  21.35   3.39 |  7.71
15     | 19.48  -3.83  -4.50  19.01 | 29.26 -10.06  11.76  17.07 |  9.77
16     | 19.04  -3.15  16.41  16.85 | 38.37 -11.12  13.18  27.70 | 14.66
17     |  8.95  -2.40   5.68   6.38 | 16.32  -1.61   7.49  11.44 |  6.53
31     | 28.87  -0.01  19.79  23.37 | 41.43  -7.57  23.85  35.89 | 20.70
32     | 32.58   3.38  12.39  26.90 | 46.01 -10.99  20.53  44.15 | 21.87
33     | 11.62 -15.20   6.04  13.27 | 32.27  -9.38  20.33  32.28 | 11.40
63     | 44.66 -11.59  37.20  42.56 | 55.41 -10.57  43.19  55.90 | 32.10
64     | 53.99  -2.19  27.04  51.79 | 59.36  -8.72  35.41  60.32 | 34.63
65     | 33.79 -14.01  23.95  29.15 | 48.91 -11.58  36.54  50.03 | 24.60
127    | 62.10  -3.79  47.51  62.79 | 58.13  -8.89  60.68  60.90 | 42.43
128    | 67.38  -2.47  38.62  67.09 | 62.83  -0.38  51.72  61.87 | 43.33
129    | 52.02  -1.42  39.17  49.20 | 55.04  -9.52  53.23  52.81 | 36.32
256    | 66.11  -1.38  56.12  64.93 | 70.67  -3.68  53.67  74.54 | 47.62

Average:
         33.03  -2.40  17.46  30.34 | 37.60  -7.27  23.84  33.49 | 20.91

NEON results:
Length | L1_EQ  L1_DF  L1_DM  L1_DL | U16_EQ U16_DF U16_DM U16_DL | Avg
-------+----------------------------+-----------------------------+------
0      |  9.22                      |  8.69                      |  8.95
1      |  3.07   3.59   1.34   5.42 |  6.36  -6.20  -6.71 -10.59 | -0.47
2      |  3.23  -4.79  -5.67  -4.09 |  8.06  -8.43  -9.89  -9.20 | -3.85
3      | 12.80  -4.16  -3.95  11.28 | 11.94 -14.50 -14.41  11.83 |  1.36
7      | 31.00  -7.21 -12.76  33.59 |  4.73 -17.67 -17.38   1.65 |  1.99
8      |  4.43  -7.20  -4.70  -6.73 |  2.71 -18.05  -3.17  -4.05 | -4.59
9      | -9.33 -19.90 -16.27  -1.80 | 16.65 -23.72   4.26   8.78 | -5.17
15     | -6.96 -16.17 -15.60  -4.01 |  7.46 -24.60  -3.19  77.82 |  1.84
16     |  2.48 -16.38  -2.56  -3.62 |  9.08 -19.29  -5.45  77.93 |  5.27
17     |  4.88 -18.85  -0.18  19.35 | 18.43 -19.80  -8.37  84.96 | 10.05
31     |  6.92 -21.13  -4.62  60.71 | 24.42 -21.81   9.48 188.59 | 30.32
32     |  7.75 -24.20  -5.29  68.23 | 25.33 -20.57   4.17 183.65 | 29.88
33     | 20.23 -20.42 -11.33  98.60 | 23.76 -24.76   5.97 188.57 | 35.08
63     | 30.25 -22.30  14.29 152.37 | 25.02 -28.37  21.43 419.68 | 76.55
64     | 28.99 -22.91   9.03 185.51 | 38.20 -22.82  19.76 446.60 | 85.29
65     | 16.13 -21.77   1.45 211.38 | 27.94 -24.79  17.50 446.80 | 84.33
127    | 33.69 -28.94  28.75 429.23 | 41.75 -24.86  37.35 832.68 |168.71
128    | 26.28 -29.03  24.13 432.87 | 43.48 -18.53  26.44 810.20 |164.48
129    | 27.73 -20.30  20.84 439.01 | 44.09 -22.35  30.09 827.38 |168.31
256    | 53.30 -20.27  26.09 841.37 | 56.66 -21.07  47.41 1604.98|323.56

Average:
         15.30 -16.97   2.26 156.24 | 22.24 -20.12   8.17 325.70 | 59.10

Observations:
- SVE shows consistent improvements across all tested lengths, with gains
  increasing as input size grows
- NEON improves equal-string performance across all lengths
- NEON shows regressions for short mismatched inputs due to the loss
  of the scalar tbz-based early-exit sequence, which efficiently
  detects mismatches at small sizes and at early positions
- The scalar implementation relies on a branchy 4/2/1 tbz ladder,
  which is efficient for early mismatches but suboptimal for equal
  strings
- The NEON implementation replaces this with a branchless SIMD
  approach and performs upfront comparisons of the first and last
  8 bytes, improving throughput and late-mismatch detection
 2026-06-05 12:22:15 +01:00
Daniel Gredler
975e209244 8380794: AttributedString performance 
Reviewed-by: jlu, naoto
 2026-05-11 23:24:19 +00:00
Galder Zamarreño
af9ed6c022 8382881: Swap min/max values and avoid equals min/max values in MinMaxVector 
Reviewed-by: roland
 2026-05-07 09:20:45 +00:00
Paul Hübner
8de6298ed5 8379630: Add JMH benchmark to measure the overhead of using captured call state 
Reviewed-by: pminborg, jvernee, liach
 2026-05-07 07:57:44 +00:00
Quan Anh Mai
41a5c032f5 8382700: C2: Delay inlining instead of giving up when hit NodeCountInliningCutoff 
Co-authored-by: Vladimir Ivanov <vlivanov@openjdk.org>
Co-authored-by: Maurizio Cimadamore <mcimadamore@openjdk.org>
Co-authored-by: Ioannis Tsakpinis <iotsakp@gmail.com>
Reviewed-by: kvn, vlivanov
 2026-04-30 18:17:38 +00:00
John Engebretson
13c92d0d4d 8371656: HashMap.putAll() optimizations 
Reviewed-by: smarks
 2026-04-28 21:38:55 +00:00
Daniel Gredler
f46a698113 8381015: CharsetEncoder.canEncode(CharSequence) is slow for UTF-8, UTF-16, UTF-32 
Reviewed-by: naoto, vyazici
 2026-03-31 21:46:05 +00:00
Brian Burkhalter
40d65f1063 8379583: (fs) Files.copy use of posix_fadvise is problematic on Linux 
Reviewed-by: alanb
 2026-03-26 18:38:04 +00:00
Eirik Bjørsnøs
0379c0b005 8379557: Further optimize URL.toExternalForm 
Reviewed-by: vyazici
 2026-03-18 14:36:58 +00:00
Patrick Strawderman
08c8520b39 8378698: Optimize Base64.Encoder#encodeToString 
Reviewed-by: liach, rriggs
 2026-03-04 20:04:30 +00:00
Liam Miller-Cushon
0fbf58d8ff 8372353: API to compute the byte length of a String encoded in a given Charset 
Reviewed-by: rriggs, naoto, vyazici
 2026-03-04 17:33:32 +00:00
Mohamed Issa
161aa5d528 8371955: Support AVX10 floating point comparison instructions 
Reviewed-by: epeter, sviswanathan, sparasa
 2026-02-09 19:14:46 +00:00
Alan Bateman
ac6e8d481a 8376568: Change Thread::getStackTrace to use handshake op for all cases 
Reviewed-by: pchilanomate, sspitsyn
 2026-02-05 13:46:23 +00:00
Daniel Gredler
992a8ef46b 8376226: CharsetEncoder.canEncode(CharSequence) is much slower than necessary 
Reviewed-by: alanb, naoto
 2026-01-27 13:20:26 +00:00
Hai-May Chao
21dc41f744 8314323: Implement JEP 527: TLS 1.3 Hybrid Key Exchange 
Co-authored-by: Jamil Nimeh <jnimeh@openjdk.org>
Co-authored-by: Weijun Wang <weijun@openjdk.org>
Reviewed-by: wetmore, mullan
 2026-01-20 16:16:38 +00:00
Liam Miller-Cushon
d433ce5236 8369564: Provide a MemorySegment API to read strings with known lengths 
Co-authored-by: Per Minborg <pminborg@openjdk.org>
Reviewed-by: jvernee, mcimadamore
 2026-01-12 15:22:42 +00:00
Jeremy Wood
2a965dffdd 8374377: PNGImageDecoder Slow For 8-bit PNGs 
Reviewed-by: jdv, prr
 2026-01-09 09:56:39 +00:00
Jonas Norlinder
c834e4c641 8373647: Avoid fstat when opening file for write with RandomAccessFile or FileOutputStream 
Reviewed-by: redestad, alanb
 2026-01-08 16:46:28 +00:00
Sergey Bylokhov
c6246d58f7 8374383: Update the copyright year to 2025 in the remaining files under test/ where it was missed 
Reviewed-by: jpai
 2025-12-31 10:04:45 +00:00
Sergey Bylokhov
5c694eab0f 8374363: Update copyright year to 2025 for test/micro in files where it was missed 
Reviewed-by: phh
 2025-12-27 04:45:56 +00:00
Mark Powers
817e3dfde9 8350711: [JMH] test Signatures.RSASSAPSS failed for 2 threads config 
Reviewed-by: hchao, valeriep
 2025-12-16 18:38:11 +00:00
Justin Lu
81e3757688 8373566: Performance regression with java.text.MessageFormat subformat patterns 
Reviewed-by: liach, rriggs, naoto
 2025-12-16 18:11:37 +00:00
Hamlin Li
6700baa505 8357551: RISC-V: support CMoveF/D vectorization 
Reviewed-by: fyang, luhenry
 2025-12-08 13:38:22 +00:00
Xueming Shen
b97ed667db 8365675: Add String Unicode Case-Folding Support 
Reviewed-by: rriggs, naoto, ihse
 2025-12-02 19:47:18 +00:00
Per Minborg
1ce2a44e9f 8371571: Consolidate and enhance bulk memory segment ops benchmarks 
Reviewed-by: jvernee
 2025-11-26 15:11:10 +00:00
Galder Zamarreño
a7bb99ed00 8372119: Missing copyright header in MinMaxVector 
Reviewed-by: chagedorn, thartmann
 2025-11-24 09:24:19 +00:00
John Engebretson
aeea849756 8371164: ArrayList.addAll() optimizations 
Reviewed-by: smarks, ogillespie
 2025-11-18 23:37:06 +00:00
Per Minborg
f946449997 8366178: Implement JEP 526: Lazy Constants (Second Preview) 
8371882: Improve documentation for JEP 526: Lazy Constants

Reviewed-by: jvernee, mcimadamore
 2025-11-18 12:20:23 +00:00
Alan Bateman
26460b6f12 8353835: Implement JEP 500: Prepare to Make Final Mean Final 
Reviewed-by: liach, vlivanov, dholmes, vyazici
 2025-11-18 08:06:18 +00:00
Chen Liang
7aff8e15ba 8371319: java.lang.reflect.Method#equals doesn't short-circuit with same instances 
Reviewed-by: jvernee
 2025-11-14 22:55:28 +00:00
Jorn Vernee
a51a0bf57f 8370344: Arbitrary Java frames on stack during scoped access 
Reviewed-by: pchilanomate, dholmes, liach
 2025-11-04 15:40:40 +00:00
Raffaello Giulietti
deb7edb151 8366017: Extend the set of inputs handled by fast paths in FloatingDecimal 
Reviewed-by: darcy
 2025-11-03 09:48:55 +00:00
Sergey Kuksenko
2158719aab 8370150: Add StrictMath microbenchmarks to cover FDLIBM algorithms 
Reviewed-by: rgiulietti
 2025-10-31 14:00:55 +00:00
Shaojin Wen
5862358965 8370013: Refactor Double.toHexString to eliminate regex and StringBuilder 
Reviewed-by: rgiulietti, darcy
 2025-10-24 00:40:13 +00:00
Chen Liang
43e036ba89 8366424: Missing type profiling in generated Record Object methods 
Reviewed-by: jvernee
 2025-10-21 19:00:51 +00:00
Brian Burkhalter
09e87971e8 8368633: (fs) Path.toRealPath(NOFOLLOW_LINKS) very slow on macOS 
Reviewed-by: alanb
 2025-10-14 17:48:37 +00:00
Jatin Bhateja
449641813a 8365205: C2: Optimize popcount value computation using knownbits 
Reviewed-by: epeter, hgreule, qamai
 2025-10-14 03:35:11 +00:00
Xueming Shen
4ca4485e9a 8365588: defineClass that accepts a ByteBuffer does not work as expected 
Reviewed-by: alanb
 2025-10-13 20:29:06 +00:00
Johannes Graham
a48538dd63 8367324: Avoid redundant parsing when formatting with DigitList 
Reviewed-by: jlu, rgiulietti
 2025-09-25 18:23:13 +00:00
Justin Lu
aeffce7c22 8367271: Add parsing tests to DateFormat JMH benchmark 
Reviewed-by: naoto
 2025-09-12 16:31:03 +00:00
Brian Burkhalter
d023982600 8361209: (bf) Use CharSequence::getChars for StringCharBuffer bulk get methods 
Reviewed-by: rriggs, alanb
 2025-08-12 17:39:14 +00:00
John Jiang
4c9eaddaef 8364597: Replace THL A29 Limited with Tencent 
Reviewed-by: jiefu
 2025-08-08 02:27:30 +00:00
Mohamed Issa
05f8a6fca8 8360559: Optimize Math.sinh for x86 64 bit platforms 
Reviewed-by: sviswanathan, sparasa
 2025-08-04 18:47:57 +00:00
Johannes Graham
d19442399c 8358880: Performance of parsing with DecimalFormat can be improved 
Reviewed-by: jlu, liach, rgiulietti
 2025-07-31 17:50:18 +00:00
Shaojin Wen
e2feff8599 8355177: Speed up StringBuilder::append(char[]) via Unsafe::copyMemory 
Reviewed-by: rriggs, rgiulietti
 2025-07-30 13:16:27 +00:00
Roland Westrelin
f155661151 8342692: C2: long counted loop/long range checks: don't create loop-nest for short running loops 
Co-authored-by: Maurizio Cimadamore <mcimadamore@openjdk.org>
Co-authored-by: Christian Hagedorn <chagedorn@openjdk.org>
Reviewed-by: chagedorn, thartmann
 2025-07-22 08:35:36 +00:00
Andrew Haley
9dd93c6a2c 8361497: Scoped Values: orElse and orElseThrow do not access the cache 
Reviewed-by: alanb
 2025-07-21 17:05:50 +00:00
Brian Burkhalter
6e203384f8 8358533: Improve performance of java.io.Reader.readAllLines 
Reviewed-by: rriggs, sherman
 2025-07-09 16:15:36 +00:00
Andrew Haley
4df9c87345 8360884: Better scoped values 
Reviewed-by: liach, alanb
 2025-07-07 09:16:39 +00:00
Kim Barrett
21f2e9a71c 8344332: (bf) Migrate DirectByteBuffer away from jdk.internal.ref.Cleaner 
Reviewed-by: rriggs, bchristi
 2025-07-04 04:08:42 +00:00