From: Eric Christopher <echristo@gmail.com>
Date: Fri, 20 Feb 2015 19:54:07 +0000 (+0000)
Subject: Fix an asan use-after-free bug introduced by the asm printer
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d53224014d4290c083cbb311e350b7e09526f335;p=oota-llvm.git

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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230050 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/PowerPC/PPCAsmPrinter.cpp b/lib/Target/PowerPC/PPCAsmPrinter.cpp
index c31d024003f..480b790a99b 100644
--- a/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -1303,7 +1303,17 @@ static MCSymbol *GetAnonSym(MCSymbol *Sym, MCContext &Ctx) {
 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());