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

chore: cherry-pick 8c725f7b5bbf from v8 #26409

merged 3 commits into from Nov 10, 2020


Copy link

@nornagon nornagon commented Nov 9, 2020

Merged: [codegen] Skip invalid optimization in tail calls

Preparing for tail call is usually done by emitting the gap moves and
then moving the stack pointer to its new position. An optimization
consists in moving the stack pointer first and transforming some of the
moves into pushes. In the attached case it looks like this (arm):

138 add sp, sp, #40
13c str r6, [sp, #-4]!
140 str r6, [sp, #-4]!
144 str r6, [sp, #-4]!
148 str r6, [sp, #-4]!
14c str r6, [sp, #-4]!
160 vldr d1, [sp - 4*3]

The last line is a gap reload, but because the stack pointer was already
moved, the slot is now below the stack pointer. This is invalid and
triggers this DCHECK:

Fatal error in ../../v8/src/codegen/arm/, line 402
Debug check failed: 0 <= offset (0 vs. -12).

A comment already explains that we skip the optimization if the gap
contains stack moves to prevent this, but the code only checks for
non-FP slots. This is fixed by replacing "source.IsStackSlot()" with

108 vldr d1, [sp + 4*2]
118 str r0, [sp, #+36]
11c str r0, [sp, #+32]
120 str r0, [sp, #+28]
124 str r0, [sp, #+24]
128 str r0, [sp, #+20]
134 add sp, sp, #20


(cherry picked from commit 7506e063d0d7fb00e4b9c06735c91e1953296867)

Change-Id: I66ed6187755af956e245207e940c83ea0697a5e6
Bug: chromium:1137608
No-Try: true
No-Presubmit: true
No-Tree-Checks: true
Reviewed-by: Thibaud Michaud
Commit-Queue: Thibaud Michaud
Cr-Commit-Position: refs/branch-heads/8.6@{#42}
Cr-Branched-From: a64aed2333abf49e494d2a5ce24bbd14fff19f60-refs/heads/8.6.395@{#1}
Cr-Branched-From: a626bc036236c9bf92ac7b87dc40c9e538b087e3-refs/heads/master@{#69472}

Notes: Security: backported fix for chromium:1137608.

@nornagon nornagon requested a review from a team as a code owner November 9, 2020 22:29
@nornagon nornagon added 9-x-y backport-check-skip Skip trop's backport validity checking labels Nov 9, 2020
@electron-cation electron-cation bot added new-pr 🌱 PR opened in the last 24 hours and removed new-pr 🌱 PR opened in the last 24 hours labels Nov 9, 2020
@nornagon nornagon merged commit badae80 into 9-x-y Nov 10, 2020
Copy link

release-clerk bot commented Nov 10, 2020

Release Notes Persisted

Security: backported fix for chromium:1137608.

This was referenced Mar 15, 2021
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
9-x-y backport-check-skip Skip trop's backport validity checking
None yet

Successfully merging this pull request may close these issues.

None yet

3 participants