[LLVMbugs] [Bug 4689] New: Regalloc problems due to subregs?

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=4689

           Summary: Regalloc problems due to subregs?
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Backend: X86
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: asl at math.spbu.ru
                CC: evan.cheng at apple.com, gohman at apple.com,
                    llvmbugs at cs.uiuc.edu


Created an attachment (id=3291)
 --> (http://llvm.org/bugs/attachment.cgi?id=3291)
Testcase

Recent changes to support kernel code model uncovered interesting bug (however,
it's not connected with it at all, since medium code model is also broken!)

Consider the testcase attached. The bb in question is for.body170

In medium code model we have in that file:

        movabsq $Xrsvd, %r10d

in kernel -
        movq $Xrsvd, %r9d

which is definitely wrong.

I verified - all stuff are of i64 types during isel and instructions selected
in questions are MOV64ri and MOV64ri32 correspondingly having 64 bit output
reg. I haven't looked more, maybe remat introduces invalid reg or something
like this.

The problem seems to have been unnoticed because only small code model is
widely use.


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