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sync: prevent (*Map).Range from always escaping #62408

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@mauri870 mauri870 commented Sep 1, 2023 •
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After the change from CL 426074 the Range method on Map always
escape the read variable, leading to an allocation.

Since the compiler doesn't do live-range splitting for local variables we
need to use some hints to only escape in that particular branch.

Fixes #62404

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Message from Ian Lance Taylor:

Patch Set 1: Commit-Queue+1

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@mauri870 mauri870 force-pushed the bugfix/sync-map-range-escape branch from 88c6787 to 508a10e Compare September 1, 2023 18:10
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This PR (HEAD: 508a10e) has been imported to Gerrit for code review.

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@mauri870
sync: prevent (*Map).Range from always escaping
fcbedb4 
After the change from CL 426074 the Range method on Map always escape
the read variable, generating an allocation.

Since the compiler doesn't do live-range splitting for local variables
we need to use some hints to only escape in that particular branch.

Fixes golang#62404
@mauri870 mauri870 force-pushed the bugfix/sync-map-range-escape branch from 508a10e to fcbedb4 Compare September 1, 2023 18:25
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Message from Bryan Mills:

Patch Set 2: Code-Review+2

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This PR (HEAD: fcbedb4) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/go/+/524976.

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Message from Mauri de Souza Meneguzzo:

Patch Set 2:

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Message from Bryan Mills:

Patch Set 3: Auto-Submit+1 Code-Review+2 Commit-Queue+1 Run-TryBot+1

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gopherbot pushed a commit that referenced this pull request Sep 1, 2023
@mauri870 @gopherbot
sync: prevent (*Map).Range from always escaping
7015ed8 
After the change from CL 426074 the Range method on Map always
escape the read variable, leading to an allocation.

Since the compiler doesn't do live-range splitting for local variables we
need to use some hints to only escape in that particular branch.

Fixes #62404

Change-Id: I938a5e593647455fa827e3dd3ed8ea22c7365df1
GitHub-Last-Rev: fcbedb4
GitHub-Pull-Request: #62408
Reviewed-on: https://go-review.googlesource.com/c/go/+/524976
Auto-Submit: Bryan Mills <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Run-TryBot: Bryan Mills <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
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This PR is being closed because golang.org/cl/524976 has been merged.

@gopherbot gopherbot closed this Sep 1, 2023
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sync: map.Range has started allocating as of Go 1.20
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