Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

runtime: hash collisions in arm64 #33960

Closed
randall77 opened this issue Aug 29, 2019 · 1 comment
Closed

runtime: hash collisions in arm64 #33960

randall77 opened this issue Aug 29, 2019 · 1 comment
Labels
FrozenDueToAge

Comments

@randall77
Copy link
Contributor

The arm64 builder is failing on a hash function tests I just checked in. I think the assembly code is using only the low 32 bits of the seed. The test that makes this evident is:

--- FAIL: TestSmhasherSeed (0.13s)
    smhasher_test.go:94: unexpected number of collisions: got=100000 mean=0.000000 stddev=0.000033
FAIL
FAIL	bytes/hash	0.319s

aeshashbody does:

	VMOV	R3, V30.S[0]
	VMOV	R1, V30.S[1] // load length into seed

We should really use VMOVD into V30.D[0] and V30.D[1], I think.

@mengzhuo @cherryyz
@gopherbot
Copy link

Change https://golang.org/cl/192498 mentions this issue: runtime: use all 64 bits of hash seed on arm64

tomocy pushed a commit to tomocy/go that referenced this issue Sep 1, 2019
@randall77 @tomocy
runtime: use all 64 bits of hash seed on arm64
7188337 
Fixes golang#33960

Change-Id: I4f8cf65dcf4140a97e7b368572b31c171c453316
Reviewed-on: https://go-review.googlesource.com/c/go/+/192498
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
t4n6a1ka pushed a commit to t4n6a1ka/go that referenced this issue Sep 5, 2019
@randall77 @t4n6a1ka
runtime: use all 64 bits of hash seed on arm64
e47ac2c 
Fixes golang#33960

Change-Id: I4f8cf65dcf4140a97e7b368572b31c171c453316
Reviewed-on: https://go-review.googlesource.com/c/go/+/192498
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
@golang golang locked and limited conversation to collaborators Aug 29, 2020
Sign up for free to subscribe to this conversation on GitHub. Already have an account? Sign in.
Assignees
No one assigned
Labels
FrozenDueToAge
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
2 participants
@randall77 @gopherbot