[llvm] r298642 - Zero-Initialize PrevInstBB when entering a new MachineFunction.

[Adrian Prantl via llvm-commits]

Author: adrian
Date: Thu Mar 23 15:23:42 2017
New Revision: 298642

URL: http://llvm.org/viewvc/llvm-project?rev=298642&view=rev
Log:
Zero-Initialize PrevInstBB when entering a new MachineFunction.

It is not guaranteed that the memory used for MachineBasicBlocks in
the previous MachineFunction hasn't been freed, so holding on to a
pointer to the last function's isn't correct. Particularly I have
observed the sret.ll testcase failing because the first BasicBlock in
the new function happened to be allocated to the exact same memory as
the previously saved and (deleted) PrevInstBB.

Modified:
    llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp?rev=298642&r1=298641&r2=298642&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp Thu Mar 23 15:23:42 2017
@@ -130,6 +130,7 @@ bool hasDebugInfo(const MachineModuleInf
 
 void DebugHandlerBase::beginFunction(const MachineFunction *MF) {
   assert(Asm);
+  PrevInstBB = nullptr;
 
   if (!hasDebugInfo(MMI, MF)) {
     skippedNonDebugFunction();