diff options
Diffstat (limited to 'lib/Transforms')
| -rw-r--r-- | lib/Transforms/Scalar/PRE.cpp | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/PRE.cpp b/lib/Transforms/Scalar/PRE.cpp index 6227a371eb..3a1239f4e6 100644 --- a/lib/Transforms/Scalar/PRE.cpp +++ b/lib/Transforms/Scalar/PRE.cpp @@ -307,6 +307,17 @@ bool PRE::ProcessExpression(Instruction *Expr) { std::vector<Value*> Values; VN->getEqualNumberNodes(Expr, Values); +#if 0 + // FIXME: This should handle PHI nodes correctly. To do this, we need to + // consider expressions of the following form equivalent to this set of + // expressions: + // + // If an operand is a PHI node, add any occurances of the expression with the + // PHI operand replaced with the PHI node operands. This is only valid if the + // PHI operand occurances exist in blocks post-dominated by the incoming edge + // of the PHI node. +#endif + // We have to be careful to handle expression definitions which dominated by // other expressions. These can be directly eliminated in favor of their // dominating value. Keep track of which blocks contain definitions (the key) |