[LazyValueInfo] PR33357 prevent infinite recursion on BinaryOperator
Summary:
It is possible for LVI to encounter instructions that are not in valid
SSA form and reference themselves. One example is the following:
%tmp4 = and i1 %tmp4, undef
Before this patch LVI would recurse until running out of stack memory
and crashed. This patch marks these self-referential instructions as
Overdefined and aborts analysis on the instruction.
Fixes https://bugs.llvm.org/show_bug.cgi?id=33357
Reviewers: craig.topper, anna, efriedma, dberlin, sebpop, kuhar
Reviewed by: dberlin
Subscribers: uabelho, spatel, a.elovikov, fhahn, eli.friedman, mzolotukhin, spop, evandro, davide, llvm-commits
Differential Revision: https://reviews.llvm.org/D34135
llvm-svn: 327432
diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index 65fd007..36e66f7 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1145,9 +1145,17 @@
(!isTrueDest && BO->getOpcode() != BinaryOperator::Or))
return ValueLatticeElement::getOverdefined();
- auto RHS = getValueFromCondition(Val, BO->getOperand(0), isTrueDest, Visited);
- auto LHS = getValueFromCondition(Val, BO->getOperand(1), isTrueDest, Visited);
- return intersect(RHS, LHS);
+ // Prevent infinite recursion if Cond references itself as in this example:
+ // Cond: "%tmp4 = and i1 %tmp4, undef"
+ // BL: "%tmp4 = and i1 %tmp4, undef"
+ // BR: "i1 undef"
+ Value *BL = BO->getOperand(0);
+ Value *BR = BO->getOperand(1);
+ if (BL == Cond || BR == Cond)
+ return ValueLatticeElement::getOverdefined();
+
+ return intersect(getValueFromCondition(Val, BL, isTrueDest, Visited),
+ getValueFromCondition(Val, BR, isTrueDest, Visited));
}
static ValueLatticeElement