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Fast path Uint8List to _OneByteString conversion #41703

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askeksa-google opened this issue Apr 29, 2020 · 0 comments
Closed

Fast path Uint8List to _OneByteString conversion #41703

askeksa-google opened this issue Apr 29, 2020 · 0 comments
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area-vm Use area-vm for VM related issues, including code coverage, FFI, and the AOT and JIT backends. type-performance Issue relates to performance or code size

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The new UTF-8 decoder, when the input is found to contain only ASCII bytes, simply calls String.fromCharCodes on the desired range of the input Uint8List.

String.fromCharCodes performs a lot of type and range checks (which are redundant in this case) before it gets to the actual copying loop. Using a specialized conversion function without all the checks could significantly speed up the conversion of short strings.
@askeksa-google askeksa-google added area-vm Use area-vm for VM related issues, including code coverage, FFI, and the AOT and JIT backends. type-performance Issue relates to performance or code size labels Apr 29, 2020
@askeksa-google askeksa-google self-assigned this Apr 29, 2020
@askeksa-google askeksa-google mentioned this issue May 1, 2020
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dart-bot pushed a commit that referenced this issue Jun 10, 2020
@rmacnak-google
Revert "[vm] MemoryCopy instruction for copying between typed data an…
d1b0713 
…d strings."

This reverts commit 6ecd8a1.

Reason for revert: Breaks ABI

Original change's description:
> [vm] MemoryCopy instruction for copying between typed data and strings.
> 
> Used for copying the bytes from the Uint8List to the _OneByteString in
> String.fromCharCodes and the pure-ASCII case of UTF-8 decoding.
> 
> Issue #42072
> Closes #41703
> 
> Change-Id: I1ae300222877d1c6e64e32c2f40b8fb187a584c0
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149500
> Commit-Queue: Aske Simon Christensen <askesc@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>

TBR=kustermann@google.com,askesc@google.com

Change-Id: I5fc0b58da80dca23c91b57ec2833492e9d0885a8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150802
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
dart-bot pushed a commit that referenced this issue Jun 11, 2020
@askeksa
Reland "[vm] MemoryCopy instruction for copying between typed data an…
e35ca30 
…d strings."

This is a reland of 6ecd8a1

Original change's description:
> [vm] MemoryCopy instruction for copying between typed data and strings.
> 
> Used for copying the bytes from the Uint8List to the _OneByteString in
> String.fromCharCodes and the pure-ASCII case of UTF-8 decoding.
> 
> Issue #42072
> Closes #41703
> 
> Change-Id: I1ae300222877d1c6e64e32c2f40b8fb187a584c0
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149500
> Commit-Queue: Aske Simon Christensen <askesc@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>

Change-Id: Ia231c521e5f2db168cfc6094dfc7322327dedc6d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150925
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Aske Simon Christensen <askesc@google.com>
tekknolagi pushed a commit to tekknolagi/dart-assembler that referenced this issue Nov 3, 2020
@askeksa
[vm] MemoryCopy instruction for copying between typed data and strings.
23186c8 
Used for copying the bytes from the Uint8List to the _OneByteString in
String.fromCharCodes and the pure-ASCII case of UTF-8 decoding.

Issue dart-lang#42072
Closes dart-lang#41703

Change-Id: I1ae300222877d1c6e64e32c2f40b8fb187a584c0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149500
Commit-Queue: Aske Simon Christensen <askesc@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
tekknolagi pushed a commit to tekknolagi/dart-assembler that referenced this issue Nov 3, 2020
@rmacnak-google
Revert "[vm] MemoryCopy instruction for copying between typed data an…
b57855f 
…d strings."

This reverts commit 6ecd8a1.

Reason for revert: Breaks ABI

Original change's description:
> [vm] MemoryCopy instruction for copying between typed data and strings.
> 
> Used for copying the bytes from the Uint8List to the _OneByteString in
> String.fromCharCodes and the pure-ASCII case of UTF-8 decoding.
> 
> Issue dart-lang#42072
> Closes dart-lang#41703
> 
> Change-Id: I1ae300222877d1c6e64e32c2f40b8fb187a584c0
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149500
> Commit-Queue: Aske Simon Christensen <askesc@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>

TBR=kustermann@google.com,askesc@google.com

Change-Id: I5fc0b58da80dca23c91b57ec2833492e9d0885a8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150802
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
tekknolagi pushed a commit to tekknolagi/dart-assembler that referenced this issue Nov 3, 2020
@askeksa
Reland "[vm] MemoryCopy instruction for copying between typed data an…
00afad1 
…d strings."

This is a reland of 6ecd8a1

Original change's description:
> [vm] MemoryCopy instruction for copying between typed data and strings.
> 
> Used for copying the bytes from the Uint8List to the _OneByteString in
> String.fromCharCodes and the pure-ASCII case of UTF-8 decoding.
> 
> Issue dart-lang#42072
> Closes dart-lang#41703
> 
> Change-Id: I1ae300222877d1c6e64e32c2f40b8fb187a584c0
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149500
> Commit-Queue: Aske Simon Christensen <askesc@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>

Change-Id: Ia231c521e5f2db168cfc6094dfc7322327dedc6d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150925
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Aske Simon Christensen <askesc@google.com>
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