AMDGPU/GlobalISel: Restore insert point when getting aperture

Avoids SSA violations in a future patch.

llvm-svn: 371008
diff --git a/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp b/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
index 96ab522..53a36a0 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
@@ -1326,10 +1326,16 @@
   // Insert the argument copy if it doens't already exist.
   // FIXME: It seems EmitLiveInCopies isn't called anywhere?
   if (!MRI.getVRegDef(LiveIn)) {
+    // FIXME: Should have scoped insert pt
+    MachineBasicBlock &OrigInsBB = B.getMBB();
+    auto OrigInsPt = B.getInsertPt();
+
     MachineBasicBlock &EntryMBB = B.getMF().front();
     EntryMBB.addLiveIn(Arg->getRegister());
     B.setInsertPt(EntryMBB, EntryMBB.begin());
     B.buildCopy(LiveIn, Arg->getRegister());
+
+    B.setInsertPt(OrigInsBB, OrigInsPt);
   }
 
   return true;