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VM: ByteData access hits unaligned write on ARM #22151

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fsc8000 opened this issue Jan 26, 2015 · 4 comments
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VM: ByteData access hits unaligned write on ARM #22151

fsc8000 opened this issue Jan 26, 2015 · 4 comments
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@rmacnak-google
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area-vm Use area-vm for VM related issues, including code coverage, FFI, and the AOT and JIT backends. customer-flutter type-bug Incorrect behavior (everything from a crash to more subtle misbehavior)

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@fsc8000
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fsc8000 commented Jan 26, 2015

I attached a regression test:

$ out/ReleaseSIMARM/dart offset.dart
Simulator hit unaligned write at 0xf68916e5, pc=0xf640fd00

0xf640fd00 e5801008 str r1, [r0, #+8]
sim>

Attachment:
offset.dart (242 Bytes)
@mraleph
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mraleph commented Jan 26, 2015

It's the same on MIPS and ARM64 fwiw.

We need to provide slow path access for platforms like ARM,MIPS.

I think I will take on this, because I am looking into refactoring the way we implemented views anyways.

Set owner to @mraleph.
Added Accepted label.

@iposva-google
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cc @johnmccutchan.

@mraleph
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mraleph commented Jan 26, 2015

Apparently our ARM bots are running in the mode that permits unaligned memory access for str/ldr. Can be detected by checking if "CP15 Register c1 has a U bit set".

We need to decide whether we want to always go slow case on platforms like ARM and MIPS or we could rely on this register to detect if we are running in the mode where unaligned accesses can be generated.

cc @zanderso.

@fsc8000 fsc8000 added Type-Defect area-vm Use area-vm for VM related issues, including code coverage, FFI, and the AOT and JIT backends. labels Jan 26, 2015
@rmacnak-google rmacnak-google mentioned this issue Aug 4, 2015
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@mraleph mraleph assigned zanderso and unassigned mraleph Aug 5, 2015
@fsc8000 fsc8000 mentioned this issue Aug 18, 2015
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@kevmoo kevmoo added type-bug Incorrect behavior (everything from a crash to more subtle misbehavior) and removed accepted labels Feb 29, 2016
rmacnak-google added a commit that referenced this issue Jun 19, 2017
@rmacnak-google
[arm, arm64] Implemented unaligned scalar float access.
72e1775 
[arm64] Fix unaligned (u)int64 stores.

Fix unaligned access test to use host endianness.

Issue #22151

R=zra@google.com

Review-Url: https://codereview.chromium.org/2940883008 .
@rmacnak-google
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26245de
d5580f3
72e1775
dddd96c

This was referenced Sep 25, 2017
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area-vm Use area-vm for VM related issues, including code coverage, FFI, and the AOT and JIT backends. customer-flutter type-bug Incorrect behavior (everything from a crash to more subtle misbehavior)
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@kevmoo @mraleph @fsc8000 @iposva-google @zanderso @rmacnak-google @eseidelGoogle