Set the parent pointer of cloned DBG_VALUE instructions correctly.

Fixes PR20523.

When spilling variables onto the stack, spillVirtReg() is setting the
parent pointer of the cloned DBG_VALUE intrinsic for the stack location
to the parent pointer of the original intrinsic. MachineInstr parent
pointers should however always point to the parent basic block.

MBB is shadowing the MBB member variable. The instruction still ends up
being inserted into the right basic block, because it's inserted after MI
which serves as the iterator.

I failed at constructing a reliable testcase for this, see
http://llvm.org/bugs/show_bug.cgi?id=20523 for a large testcases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217260 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/RegAllocFast.cpp b/lib/CodeGen/RegAllocFast.cpp
index 4727f2437f7d3ee10b4a50cefe06e18b8b48744e..6e7e2c7e8ca02eda30fd6d47bf7876f565e9ae2b 100644 (file)
--- a/lib/CodeGen/RegAllocFast.cpp
+++ b/lib/CodeGen/RegAllocFast.cpp
@@ -309,10 +309,10 @@ void RAFast::spillVirtReg(MachineBasicBlock::iterator MI,
         DL = (--EI)->getDebugLoc();
       } else
         DL = MI->getDebugLoc();
-      MachineBasicBlock *MBB = DBG->getParent();
       MachineInstr *NewDV =
           BuildMI(*MBB, MI, DL, TII->get(TargetOpcode::DBG_VALUE))
               .addFrameIndex(FI).addImm(Offset).addMetadata(MDPtr);
+      assert(NewDV->getParent() == MBB && "dangling parent pointer");
       (void)NewDV;
       DEBUG(dbgs() << "Inserting debug info due to spill:" << "\n" << *NewDV);
     }