https://llvm.org/bugs/show_bug.cgi?id=31758
Bug ID: 31758
Summary: [NewGVN] Crash while looking up domtree node
Product: libraries
Version: trunk
Hardware: PC
OS: Windows NT
Status: NEW
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: dav...@freebsd.org
CC: dber...@dberlin.org, llvm-bugs@lists.llvm.org
Blocks: 30995
Classification: Unclassified
We mark a block unreachable so DT->getNode() returns nullptr. Maybe there's a
different/more correct way to fix this. Tried to bootstrap/test suite.
Testcase reduced from one of our internal codebases (game7).
%struct.dipsy = type {}
%struct.fluttershy = type { %struct.dipsy* }
%struct.patatino = type {}
define void @tinkywinky() {
bb:
br label %bb90
bb90: ; preds = %bb90, %bb
%tmp = getelementptr inbounds %struct.fluttershy, %struct.fluttershy* undef,
i64 0, i32 0
%tmp91 = bitcast %struct.dipsy** %tmp to %struct.patatino**
%tmp92 = load %struct.patatino*, %struct.patatino** %tmp91, align 8
%tmp99 = getelementptr inbounds %struct.patatino, %struct.patatino* %tmp92
%tmp134 = getelementptr inbounds %struct.fluttershy, %struct.fluttershy*
undef, i64 0, i32 0
%tmp135 = bitcast %struct.dipsy** %tmp134 to %struct.patatino**
%tmp136 = load %struct.patatino*, %struct.patatino** %tmp135, align 8
br label %bb90
bb138: ; preds = %bb138
%tmp139 = getelementptr inbounds %struct.patatino, %struct.patatino* %tmp136
br label %bb138
}
Proposed patch:
fluttershy@SONY-PC C:\Users\fluttershy\work\llvm
> git diff
diff --git a/lib/Transforms/Scalar/NewGVN.cpp
b/lib/Transforms/Scalar/NewGVN.cpp
index d4e41e1..cc87c79 100644
--- a/lib/Transforms/Scalar/NewGVN.cpp
+++ b/lib/Transforms/Scalar/NewGVN.cpp
@@ -1939,8 +1939,14 @@ void NewGVN::convertDenseToDFSOrdered(
VD.LocalNum = InstrDFS.lookup(I);
}
DomTreeNode *DomNode = DT->getNode(IBlock);
- VD.DFSIn = DomNode->getDFSNumIn();
- VD.DFSOut = DomNode->getDFSNumOut();
+ if (DomNode) {
+ VD.DFSIn = DomNode->getDFSNumIn();
+ VD.DFSOut = DomNode->getDFSNumOut();
+ }
+ else {
+ VD.DFSIn = 0;
+ VD.DFSOut = 0;
+ }
VD.U = &U;
DFSOrderedSet.emplace_back(VD);
}
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