[v10.x] deps: V8: backport f27ac28 #28061
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Original commit message:
[turbofan] Pin pure unreachable values to effect chain (in rep selection)
Currently, if we lower to a pure computation that is unreachable because
of some runtime check, we just rename it with DeadValue. This is
problematic if the pure computation gets later eliminated - that allows
the DeadValue node float above the check that makes it dead. As we
conservatively lower DeadValues to debug-break (i.e., crash), we
might induce crash where we should not.
With this CL, whenever we lower an impossible effectful node (i.e., with
Type::None) to a pure node in simplified lowering, we insert an
Unreachable node there (pinned to the effect chain) and mark the
impossible node dead (and make it depend on the Unreachable node).
Bug: chromium:910838
Change-Id: I218991c79b9e283a9dd5beb4d3f0c4664be76cb2
Reviewed-on: https://chromium-review.googlesource.com/c/1365274
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58066}
Refs: v8/v8@f27ac28
BethGriggs
approved these changes
Jun 5, 2019
BethGriggs
pushed a commit
that referenced
this pull request
Jun 6, 2019
Original commit message:
[turbofan] Pin pure unreachable values to effect chain (in rep selection)
Currently, if we lower to a pure computation that is unreachable because
of some runtime check, we just rename it with DeadValue. This is
problematic if the pure computation gets later eliminated - that allows
the DeadValue node float above the check that makes it dead. As we
conservatively lower DeadValues to debug-break (i.e., crash), we
might induce crash where we should not.
With this CL, whenever we lower an impossible effectful node (i.e., with
Type::None) to a pure node in simplified lowering, we insert an
Unreachable node there (pinned to the effect chain) and mark the
impossible node dead (and make it depend on the Unreachable node).
Bug: chromium:910838
Change-Id: I218991c79b9e283a9dd5beb4d3f0c4664be76cb2
Reviewed-on: https://chromium-review.googlesource.com/c/1365274
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58066}
Refs: v8/v8@f27ac28
PR-URL: #28061
Fixes: #27107
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
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Fixes: #27107
Original commit message:
Refs: v8/v8@f27ac28