[llvm] r183459 - CodeGenSchedule: smallvector.push_back(smallvector[0]) is dangerous

[Arnold Schwaighofer]

Author: arnolds
Date: Thu Jun  6 18:23:14 2013
New Revision: 183459

URL: http://llvm.org/viewvc/llvm-project?rev=183459&view=rev
Log:
CodeGenSchedule: smallvector.push_back(smallvector[0]) is dangerous

The element passed to push_back is not copied before the vector reallocates.
The client needs to copy the element first before passing it to push_back.

No test case, will be tested by follow-up swift scheduler model change (it
segfaults without this change).

Modified:
    llvm/trunk/utils/TableGen/CodeGenSchedule.cpp

Modified: llvm/trunk/utils/TableGen/CodeGenSchedule.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/CodeGenSchedule.cpp?rev=183459&r1=183458&r2=183459&view=diff
==============================================================================
--- llvm/trunk/utils/TableGen/CodeGenSchedule.cpp (original)
+++ llvm/trunk/utils/TableGen/CodeGenSchedule.cpp Thu Jun  6 18:23:14 2013
@@ -1172,7 +1172,9 @@ pushVariant(const TransVariant &VInfo, b
     unsigned OperIdx = RWSequences.size()-1;
     // Make N-1 copies of this transition's last sequence.
     for (unsigned i = 1, e = SelectedRWs.size(); i != e; ++i) {
-      RWSequences.push_back(RWSequences[OperIdx]);
+      // Create a temporary copy the vector could reallocate.
+      SmallVector<unsigned, 4> Tmp = RWSequences[OperIdx];
+      RWSequences.push_back(Tmp);
     }
     // Push each of the N elements of the SelectedRWs onto a copy of the last
     // sequence (split the current operand into N operands).