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cmd/compile: internal compiler error: panic during prove while compiling: unexpected induction with too many parents [1.21 backport] #63984

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gopherbot opened this issue Nov 7, 2023 · 2 comments
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cmd/compile: internal compiler error: panic during prove while compiling: unexpected induction with too many parents [1.21 backport] #63984

gopherbot opened this issue Nov 7, 2023 · 2 comments
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CherryPickApproved Used during the release process for point releases compiler/runtime Issues related to the Go compiler and/or runtime. FrozenDueToAge
Milestone
Go1.21.5

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@gopherbot
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@randall77 requested issue #63955 to be considered for backport to the next 1.21 minor release.

@gopherbot please open backport issues.

I agree that if this could cause a miscompilation we should backport.
It does seem exceedingly rare though.
@gopherbot gopherbot added the CherryPickCandidate Used during the release process for point releases label Nov 7, 2023
@gopherbot gopherbot mentioned this issue Nov 7, 2023
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@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Nov 7, 2023
@gopherbot gopherbot modified the milestones: Go1.21.4, Go1.21.5 Nov 7, 2023
@gopherbot
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Change https://go.dev/cl/540535 mentions this issue: cmd/compile: fix findIndVar so it does not match disjointed loop headers

@heschi heschi added the CherryPickApproved Used during the release process for point releases label Nov 15, 2023
@gopherbot gopherbot removed the CherryPickCandidate Used during the release process for point releases label Nov 15, 2023
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Closed by merging f7a79cb to release-branch.go1.21.

gopherbot pushed a commit that referenced this issue Nov 28, 2023
@Jorropo @gopherbot
[release-branch.go1.21] cmd/compile: fix findIndVar so it does not ma…
f7a79cb 
…tch disjointed loop headers

Fix #63984

parseIndVar, prove and maybe more are on the assumption that the loop header
is a single block. This can be wrong, ensure we don't match theses cases we
don't know how to handle.

In the future we could update them so that they know how to handle such cases
but theses cases seems rare so I don't think the value would be really high.
We could also run a loop canonicalization pass first which could handle this.

The repro case looks weird because I massaged it so it would crash with the
previous compiler.

Change-Id: I4aa8afae9e90a17fa1085832250fc1139c97faa6
Reviewed-on: https://go-review.googlesource.com/c/go/+/539977
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
(cherry picked from commit 8b4e125)
Reviewed-on: https://go-review.googlesource.com/c/go/+/540535
Reviewed-by: Jorropo <jorropo.pgm@gmail.com>
Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
@golang golang locked and limited conversation to collaborators Nov 27, 2024
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