[PATCH] D18155: Instcombine: try to avoid wasted work in ConstantFold

[escha via llvm-commits]

escha added a comment.

To try to be more clear, this code appears to:

1. Drop instructions that are dead.
2. If constant, fold the constant. [this step folds ConstExprs as part of its internals, because that's how ConstantFolding works]
3. If not constant-foldable, check to see if any ConstExpr operands are foldable [this is where we duplicate work]
4. Add to the initial instcombine worklist.


Repository:
  rL LLVM

http://reviews.llvm.org/D18155