[LLVMbugs] [Bug 2466] New: CodeGenPrepare merges critical edges which are immediately split again by OptimizeBlock

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=2466

           Summary: CodeGenPrepare merges critical edges which are
                    immediately split again by OptimizeBlock
           Product: new-bugs
           Version: unspecified
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: baldrick at free.fr
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=1751)
 --> (http://llvm.org/bugs/attachment.cgi?id=1751)
testcase .bc

On the attached testcase I noticed that EliminateMostlyEmptyBlocks
was eliminating many blocks which later somehow popped up again.
It turns out that it was eliminating all the critical edges, which
were all restored right after by OptimizeBlock.  This seems like a
waste of time and effort: presumably EliminateMostlyEmptyBlocks
should detect this case and leave critical edges alone.


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