diff options
| author | Duncan Sands <baldrick@free.fr> | 2012-06-13 12:15:56 +0000 |
|---|---|---|
| committer | Duncan Sands <baldrick@free.fr> | 2012-06-13 12:15:56 +0000 |
| commit | d34491f6751ae2f8daf3e857c84bcb5b06fba889 (patch) | |
| tree | a9d5f9657a7a63f520da1732d6a2a78e6fd7eadc /lib/Transforms/Scalar/Reassociate.cpp | |
| parent | ee5a094ccf1f04d3fcc92ac4d2fc8a2926cbb232 (diff) | |
It is possible for several constants which aren't individually absorbing to
combine to the absorbing element. Thanks to nbjoerg on IRC for pointing this
out.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158399 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/Scalar/Reassociate.cpp')
| -rw-r--r-- | lib/Transforms/Scalar/Reassociate.cpp | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/Reassociate.cpp b/lib/Transforms/Scalar/Reassociate.cpp index ed7340f7e6..66fa0744b8 100644 --- a/lib/Transforms/Scalar/Reassociate.cpp +++ b/lib/Transforms/Scalar/Reassociate.cpp @@ -629,8 +629,13 @@ static bool LinearizeExprTree(BinaryOperator *I, // Add any constants back into Ops, all globbed together and reduced to having // weight 1 for the convenience of users. Constant *Identity = ConstantExpr::getBinOpIdentity(Opcode, I->getType()); - if (Cst && Cst != Identity) + if (Cst && Cst != Identity) { + // If combining multiple constants resulted in the absorber then the entire + // expression must evaluate to the absorber. + if (Cst == Absorber) + Ops.clear(); Ops.push_back(std::make_pair(Cst, APInt(Bitwidth, 1))); + } // For nilpotent operations or addition there may be no operands, for example // because the expression was "X xor X" or consisted of 2^Bitwidth additions: |