[LLVMbugs] [Bug 15041] New: Test PAQ8p hangs in vectorized loop on powerpc64-unknown-linux-gnu

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http://llvm.org/bugs/show_bug.cgi?id=15041

             Bug #: 15041
           Summary: Test PAQ8p hangs in vectorized loop on
                    powerpc64-unknown-linux-gnu
           Product: libraries
           Version: trunk
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Loop Optimizer
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: wschmidt at linux.vnet.ibm.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


The benchmark in projects/test-suite/MultiSource/Benchmarks/PAQ8p has been
failing recently, at least for 64-bit PowerPC.  Debug shows that the Clang++
version of the program hangs in _ZN5Mixer6updateEv in a large vectorized loop. 
(Aside: G++ does not choose to vectorize this loop, for whatever reason.)

The source loop is:

  void update() {
    for (int i=0; i<ncxt; ++i) {
      int err=((y<<12)-pr[i])*7;
      assert(err>=-32768 && err<32768);
      if (err) train(&tx[0], &wx[cxt[i]*N], nx, err);
    }
    nx=base=ncxt=0;
  }

The loop is converted into three versions:  for.body.i, vector.body.i, and
vector.body.  I'm not sure which of the two vector versions is hanging.

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