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Fix PR14568: Avoid the DFA packetizer from making an invalid read

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beyond array bounds.

No test case since I cannot reproduce an ICE with this bug. According
to Carlos -- the bug reporter -- a segfault occurs only when LLVM is
compiled with a specific version of GCC.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169783 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Anshuman Dasgupta 2012-12-10 22:45:57 +00:00
parent 617d18385f
commit 079e0819bc
1 changed files with 10 additions and 1 deletions
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11
utils/TableGen/DFAPacketizerEmitter.cpp
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@ -279,6 +279,7 @@ DFAPacketizerEmitter::DFAPacketizerEmitter(RecordKeeper &R):
//
//
void DFA::writeTableAndAPI(raw_ostream &OS, const std::string &TargetName) {
static const std::string SentinelEntry = "{-1, -1}";
DFA::StateSet::iterator SI = states.begin();
// This table provides a map to the beginning of the transitions for State s
// in DFAStateInputTable.
@ -305,12 +306,17 @@ void DFA::writeTableAndAPI(raw_ostream &OS, const std::string &TargetName) {
// If there are no valid transitions from this stage, we need a sentinel
// transition.
if (ValidTransitions == StateEntry[i]) {
OS << "{-1, -1},";
OS << SentinelEntry << ",";
++ValidTransitions;
}
OS << "\n";
}
// Print out a sentinel entry at the end of the StateInputTable. This is
// needed to iterate over StateInputTable in DFAPacketizer::ReadTable()
OS << SentinelEntry << "\n";
OS << "};\n\n";
OS << "const unsigned int " << TargetName << "DFAStateEntryTable[] = {\n";
@ -319,6 +325,9 @@ void DFA::writeTableAndAPI(raw_ostream &OS, const std::string &TargetName) {
for (unsigned i = 0; i < states.size(); ++i)
OS << StateEntry[i] << ", ";
// Print out the index to the sentinel entry in StateInputTable
OS << ValidTransitions << ", ";
OS << "\n};\n";
OS << "} // namespace\n";