title: Eigen - maxCoeff causes compiler to crash
body: <p>I am using library Eigen for some high performance computing with matrices and I wanted to get maximal element from an matrix <code>centers</code> defined as <code>Eigen::MatrixXi centers(A.rows(), 1);</code> (where A is also an matrix). For this reason I called </p>
  
  <pre><code>std::cout &lt;&lt; centers.maxCoeff();
  </code></pre>
  
  <p>but when I tried to compile it with clang++ (version 3.5), when makefile was doing</p>
  
  <pre><code>clang++ -shared -fPIC build/snf.bc -o snf.so
  </code></pre>
  
  <p>the compiler gave me this error message:</p>
  
  <pre><code>clang++ -shared -fPIC build/snf.bc -o snf.so
  fatal error: error in backend: Cannot select: 0x4815390: v4i32 = X86ISD::SMAX 0x4812860, 0x4979e70 [ORD=20] [ID=23]
    0x4812860: v4i32 = bitcast 0x4a2be70 [ORD=17] [ID=22]
      0x4a2be70: v2i64,ch = load 0x4812660, 0x4812960, 0x496fb30&lt;LD16[%1]&gt; [ORD=17] [ID=21]
        0x4812960: i64 = FrameIndex&lt;0&gt; [ID=6]
        0x496fb30: i64 = undef [ID=3]
    0x4979e70: v4i32 = bitcast 0x4a2c270 [ORD=19] [ID=16]
      0x4a2c270: v2i64,ch = load 0x4a2c170, 0x4812c60, 0x496fb30&lt;LD16[%7]&gt; [ORD=13] [ID=14] dbg:/usr/include/eigen3/Eigen/src/Core/arch/SSE/PacketMath.h:194:10
        0x4812c60: i64,ch = CopyFromReg 0x2d19a10, 0x4813060 [ORD=8] [ID=11]
          0x4813060: i64 = Register %vreg3 [ID=4]
        0x496fb30: i64 = undef [ID=3]
  In function: _ZN5Eigen8internal4pmaxIDv2_xEET_RKS3_S5_
  clang: error: clang frontend command failed with exit code 70 (use -v to see invocation)
  Ubuntu clang version 3.5-1ubuntu1 (trunk) (based on LLVM 3.5)
  Target: x86_64-pc-linux-gnu
  Thread model: posix
  </code></pre>
  
  <p>Please can you give me any suggestions what might be the problem? I never got internal compiler error before.</p>