[LLVMbugs] [Bug 1639] New: GlobalOpt can' t see through PHI nodes when doing SROA on malloc's

bugzilla-daemon at cs.uiuc.edu bugzilla-daemon at cs.uiuc.edu
Wed Sep 5 18:57:08 PDT 2007


http://llvm.org/bugs/show_bug.cgi?id=1639

           Summary: GlobalOpt can't see through PHI nodes when doing SROA on
                    malloc's
           Product: new-bugs
           Version: unspecified
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: resistor at mac.com
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=1102)
 --> (http://llvm.org/bugs/attachment.cgi?id=1102)
gvn-out.bc

GlobalOpt, when it tries to do SROA on malloc's, must ensure that all uses of
the global would trap if the global were null.  This check, however, cannot see
through PHI nodes, which causes a regression on 179.art when using GVN. 
Attached is the example bitcode.  Note that GlobalOpt fails to SROA the global
variable f1_layer because of the instruction %tmp11.rle in init_net().


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