[PATCH] D14050: [X86][SSE] Shuffle blends with zero

[Elena Demikhovsky via llvm-commits]

delena added a comment.

In more general case it will work if one of V1 or V2 is vector of constants with '0' in the right place. When you calculate computeZeroableShuffleElements() you check this option.

if (Zeroable[i]) {

  You just should know what input to choose. You don't need to rebuild V1 or V2. 
  And you **always **can define mask for the "zeroable" element, no fallthru in this case.

If computeZeroableShuffleElements() was returning not only mask, but also input number (V1 or V2) per zeroable element, you'd just use this information.


Repository:
  rL LLVM

http://reviews.llvm.org/D14050