[LLVMbugs] [Bug 2644] New: miscompile with -loop-rotate -indvars

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=2644

           Summary: miscompile with -loop-rotate -indvars
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Loop Optimizer
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: nlewycky at google.com
                CC: dpatel at apple.com, llvmbugs at cs.uiuc.edu


Created an attachment (id=1896)
 --> (http://llvm.org/bugs/attachment.cgi?id=1896)
testcase; the part that gets miscompiled

I have a miscompile:

$ opt -loop-rotate -indvars c.bc | llc -f -o x2.s
nlewycky at ducttape:~/local$ gcc x.s x2.s -o x -lm
nlewycky at ducttape:~/local$ ./x
Hilbert Slice.  Test case 1 of size 120.
One-Norm(A) ---------- 1.833333e+00.
Segmentation fault

Without the 'opt' phase, the program runs correctly. This is a bugpoint
reduction of sgefa.

I should mention that opt -loop-rotate | opt -indvars appears to produce
different output (it's hard to spot amongst the variable renamings, but it
looks like a GEP is missing or in a different spot).


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