[llvm] r327432 - [LazyValueInfo] PR33357 prevent infinite recursion on BinaryOperator
Brian M. Rzycki via llvm-commits
llvm-commits at lists.llvm.org
Tue Mar 13 11:14:10 PDT 2018
Author: brzycki
Date: Tue Mar 13 11:14:10 2018
New Revision: 327432
URL: http://llvm.org/viewvc/llvm-project?rev=327432&view=rev
Log:
[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
Added:
llvm/trunk/test/Transforms/JumpThreading/PR33357-lvi-recursion.ll
Modified:
llvm/trunk/lib/Analysis/LazyValueInfo.cpp
Modified: llvm/trunk/lib/Analysis/LazyValueInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/LazyValueInfo.cpp?rev=327432&r1=327431&r2=327432&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/LazyValueInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/LazyValueInfo.cpp Tue Mar 13 11:14:10 2018
@@ -1145,9 +1145,17 @@ getValueFromConditionImpl(Value *Val, Va
(!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
Added: llvm/trunk/test/Transforms/JumpThreading/PR33357-lvi-recursion.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/JumpThreading/PR33357-lvi-recursion.ll?rev=327432&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/JumpThreading/PR33357-lvi-recursion.ll (added)
+++ llvm/trunk/test/Transforms/JumpThreading/PR33357-lvi-recursion.ll Tue Mar 13 11:14:10 2018
@@ -0,0 +1,37 @@
+; RUN: opt -S -jump-threading -verify -o - %s | FileCheck %s
+ at a = external global i16, align 1
+
+; CHECK-LABEL: f
+; CHECK: bb6:
+; CHECK: bb2:
+; CHECK: bb3:
+; CHECK-NOT: bb0:
+; CHECK-NOT: bb1:
+; CHECK-NOT: bb4:
+; CHECK-NOT: bb5:
+define void @f(i32 %p1) {
+bb0:
+ %0 = icmp eq i32 %p1, 0
+ br i1 undef, label %bb6, label %bb1
+
+bb1:
+ br label %bb2
+
+bb2:
+ %1 = phi i1 [ %0, %bb1 ], [ %2, %bb4 ]
+ %2 = and i1 %1, undef
+ br i1 %2, label %bb3, label %bb4
+
+bb3:
+ store i16 undef, i16* @a, align 1
+ br label %bb4
+
+bb4:
+ br i1 %0, label %bb2, label %bb5
+
+bb5:
+ unreachable
+
+bb6:
+ ret void
+}
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