Fix a reassociate crash on sozefx when compiling with dragonegg+gcc-4.7 due to
the optimizers producing a multiply expression with more multiplications than
the original (!).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159426 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/Reassociate.cpp b/lib/Transforms/Scalar/Reassociate.cpp
index fc7db2e..547a51e 100644
--- a/lib/Transforms/Scalar/Reassociate.cpp
+++ b/lib/Transforms/Scalar/Reassociate.cpp
@@ -674,8 +674,6 @@
// Flags are cleared from the operator in ExpressionChanged up to I inclusive.
BinaryOperator *ExpressionChanged = 0;
for (unsigned i = 0; ; ++i) {
- assert(!NodesToRewrite.empty() &&
- "Optimized expressions has more nodes than original!");
BinaryOperator *Op = NodesToRewrite.pop_back_val();
// The last operation (which comes earliest in the IR) is special as both
@@ -753,9 +751,19 @@
}
// Otherwise, grab a spare node from the original expression and use that as
- // the left-hand side.
- assert(!NodesToRewrite.empty() &&
- "Optimized expressions has more nodes than original!");
+ // the left-hand side. If there are no nodes left then the optimizers made
+ // an expression with more nodes than the original! This usually means that
+ // they did something stupid but it might mean that the problem was just too
+ // hard (finding the mimimal number of multiplications needed to realize a
+ // multiplication expression is NP-complete). Whatever the reason, smart or
+ // stupid, create a new node if there are none left.
+ if (NodesToRewrite.empty()) {
+ Constant *Undef = UndefValue::get(I->getType());
+ BinaryOperator *N = BinaryOperator::Create(Instruction::BinaryOps(Opcode),
+ Undef, Undef, "", I);
+ NodesToRewrite.push_back(N);
+ }
+
DEBUG(dbgs() << "RA: " << *Op << '\n');
Op->setOperand(0, NodesToRewrite.back());
DEBUG(dbgs() << "TO: " << *Op << '\n');