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ISelDAG: spot chain cycles involving MachineNodes

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Previously, the DAGISel function WalkChainUsers was spotting that it
had entered already-selected territory by whether a node was a
MachineNode (amongst other things). Since it's fairly common practice
to insert MachineNodes during ISelLowering, this was not the correct
check.

Looking around, it seems that other nodes get their NodeId set to -1
upon selection, so this makes sure the same thing happens to all
MachineNodes and uses that characteristic to determine whether we
should stop looking for a loop during selection.

This should fix PR15840.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191165 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tim Northover
2013-09-22 08:21:56 +00:00
parent 7d052f272d
commit 3e84ad28d4
14 changed files with 54 additions and 11 deletions
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10
lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
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@@ -1857,15 +1857,15 @@ WalkChainUsers(const SDNode *ChainedNode,
SDNode *User = *UI;
if (User->getOpcode() == ISD::HANDLENODE) // Root of the graph.
continue;
// If we see an already-selected machine node, then we've gone beyond the
// pattern that we're selecting down into the already selected chunk of the
// DAG.
if (User->isMachineOpcode() ||
User->getOpcode() == ISD::HANDLENODE) // Root of the graph.
continue;
unsigned UserOpcode = User->getOpcode();
if (UserOpcode == ISD::CopyToReg ||
if (User->isMachineOpcode() ||
UserOpcode == ISD::CopyToReg ||
UserOpcode == ISD::CopyFromReg ||
UserOpcode == ISD::INLINEASM ||
UserOpcode == ISD::EH_LABEL ||