Revert some fastcomp changes

Author: brson

lib/Transforms/InstCombine/InstCombineVectorOps.cpp

@@ -1249,17 +1249,7 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
 
   // If the result mask is equal to one of the original shuffle masks,
   // or is a splat, do the replacement.
-  //
-  // XXX EMSCRIPTEN: Add '|| true' so that we always do the replacement.
-  // We're targetting SIMD.js, so there's less of an expectation that a
-  // particular shuffle mask will always map onto a particular instruction on
-  // a particular ISA because we aren't targetting a particular ISA (what the
-  // JS engine does is another story). We may wish to re-evaluate this choice
-  // as we move on to higher-element-count vectors, but especially for now this
-  // is quite desirable.
-  if (isSplat || newMask == LHSMask || newMask == RHSMask || newMask == Mask ||
-      true)
-  {
+  if (isSplat || newMask == LHSMask || newMask == RHSMask || newMask == Mask) {
     SmallVector<Constant*, 16> Elts;
     for (unsigned i = 0, e = newMask.size(); i != e; ++i) {
       if (newMask[i] < 0) {