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Bug 45346 - AArch64 Windows EH UnwindHelp object not located at fixed offset from FP
Summary: AArch64 Windows EH UnwindHelp object not located at fixed offset from FP
Status: RESOLVED FIXED
Alias: None
Product: libraries
Classification: Unclassified
Component: Backend: AArch64 (show other bugs)
Version: 9.0
Hardware: PC Windows NT
: P normal
Assignee: Unassigned LLVM Bugs
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2020-03-29 09:49 PDT by Daniel Frampton
Modified: 2020-10-13 15:54 PDT (History)
5 users (show)

See Also:
Fixed By Commit(s):

Attachments
Program that will crash if compiled and run on aarch64-pc-windows-msvc (274 bytes, text/plain)
2020-03-29 09:49 PDT, Daniel Frampton 		Details
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Description Daniel Frampton 2020-03-29 09:49:05 PDT 
Created attachment 23289 [details]
Program that will crash if compiled and run on aarch64-pc-windows-msvc

On AArch64 Windows the UnwindHelp object used for EH is allocated as a normal stack object.

If there are aligned objects in the frame, then the object will be subject to alignment.

This means during exception handling the object can not be reliably found, causing incorrect exception handling behavior.

Attaching simple C++ repro.

Bug exists in both LLVM9 and master.
Comment 1 Daniel Frampton 2020-03-29 09:55:03 PDT 
See https://reviews.llvm.org/D77016
Comment 2 Eli Friedman 2020-10-13 15:54:05 PDT 
The fix was merged.