title: Assembler Messages: no such instruction when Compiling C++
body: <p>I am attempting to compile a C++ code using gcc/5.3 on Scientific Linux release 6.7. I keep getting the following errors whenever I run my Makefile though:</p>
  
  <pre><code>/tmp/ccjZqIED.s: Assembler messages:
  /tmp/ccjZqIED.s:768: Error: no such instruction: `shlx %rax,%rdx,%rdx'
  /tmp/ccjZqIED.s:1067: Error: no such instruction: `shlx %rax,%rdx,%rdx'
  /tmp/ccjZqIED.s: Assembler messages:
  /tmp/ccjZqIED.s:6229: Error: no such instruction: `mulx %r10,%rcx,%rbx'
  /tmp/ccjZqIED.s:6248: Error: no such instruction: `mulx %r13,%rcx,%rbx'
  /tmp/ccjZqIED.s:7109: Error: no such instruction: `mulx %r10,%rcx,%rbx'
  /tmp/ccjZqIED.s:7128: Error: no such instruction: `mulx %r13,%rcx,%rbx'
  </code></pre>
  
  <p>I've attmpted to follow the advice from this question with no change to my output:
  <a href="https://stackoverflow.com/questions/17126593/compile-errors-with-assembler-messages">Compile errors with Assembler messages</a></p>
  
  <p>My compiler options are currently:</p>
  
  <pre><code>CXXFLAGS        = -g -Wall -O0 -pg -std=c++11
  </code></pre>
  
  <p>Does anyone have any idea what could be causing this?</p>