[LLVMbugs] [Bug 4477] New: indvars wrong loop trip count

bugzilla-daemon at cs.uiuc.edu bugzilla-daemon at cs.uiuc.edu
Mon Jun 29 07:14:24 PDT 2009


           Summary: indvars wrong loop trip count
           Product: new-bugs
           Version: unspecified
          Platform: PC
        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=3135)
 --> (http://llvm.org/bugs/attachment.cgi?id=3135)
testcase .ll

On the attached testcase indvars seems to think the trip count is more
than it is.  This can be seen by looking at the loop exit values it

        %.lcssa1 = phi i8 [ 108, %cc70a02__complex_integers__Oadd.153.exit.i ] 
        ; <i8> [#uses=1]
        %.lcssa = phi i8 [ -48, %cc70a02__complex_integers__Oadd.153.exit.i ]  
        ; <i8> [#uses=1]

The correct values are 63 and -28 respectively (these are 9*7 and
-4*7, while indvars has calculated 9*12 and -4*12).  Reduced from Ada
ACATS test cc70a02.

Reproduce using: opt -indvars

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