[llvm] r230050 - Fix an asan use-after-free bug introduced by the asm printer

[Eric Christopher]

Author: echristo
Date: Fri Feb 20 13:54:07 2015
New Revision: 230050

URL: http://llvm.org/viewvc/llvm-project?rev=230050&view=rev
Log:
Fix an asan use-after-free bug introduced by the asm printer
changes to remove non-Function based subtargets out of the asm
printer. For module level emission we'll need to construct up
an MCSubtargetInfo so that we can encode instructions for
emission.

Modified:
    llvm/trunk/lib/Target/PowerPC/PPCAsmPrinter.cpp

Modified: llvm/trunk/lib/Target/PowerPC/PPCAsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCAsmPrinter.cpp?rev=230050&r1=230049&r2=230050&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCAsmPrinter.cpp (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCAsmPrinter.cpp Fri Feb 20 13:54:07 2015
@@ -1303,7 +1303,17 @@ static MCSymbol *GetAnonSym(MCSymbol *Sy
 void PPCDarwinAsmPrinter::
 EmitFunctionStubs(const MachineModuleInfoMachO::SymbolListTy &Stubs) {
   bool isPPC64 = TM.getDataLayout()->getPointerSizeInBits() == 64;
-  
+
+  // Construct a local MCSubtargetInfo and shadow EmitToStreamer here.
+  // This is because the MachineFunction won't exist (but have not yet been
+  // freed) and since we're at the global level we can use the default
+  // constructed subtarget.
+  std::unique_ptr<MCSubtargetInfo> STI(TM.getTarget().createMCSubtargetInfo(
+      TM.getTargetTriple(), TM.getTargetCPU(), TM.getTargetFeatureString()));
+  auto EmitToStreamer = [&STI] (MCStreamer &S, const MCInst &Inst) {
+    S.EmitInstruction(Inst, *STI);
+  };
+
   const TargetLoweringObjectFileMachO &TLOFMacho = 
     static_cast<const TargetLoweringObjectFileMachO &>(getObjFileLowering());