[llvm-bugs] [Bug 47793] New: Miscompilation of single loop with two assignments

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=47793

            Bug ID: 47793
           Summary: Miscompilation of single loop with two assignments
           Product: new-bugs
           Version: unspecified
          Hardware: Macintosh
                OS: MacOS X
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: tuom.larsen at gmail.com
                CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org

Created attachment 24044
  --> https://bugs.llvm.org/attachment.cgi?id=24044&action=edit
Example

The example shows a discrepancy when processing two arrays at once in single
loop and processing each array in a separate loop. It should not matter whether
one array is processed first or both arrays are processed simultaneously but
the later case gives wrong answer. More precise instructions on how to
reproduce the behaviour could be found in the linked example.

It only happens with clang coming with macOS Catalina (sorry, I don't know
which version it is as Apple apparently uses different version numbers as
llvm.org)

Perhaps the single loop gets optimised too aggressively but I'm really guessing
here.

Please find the example below.

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20201011/9188c774/attachment.html>