Audit all SILPasses to ensure that new instructions are never created

without a valid SILDebugScope. An assertion in IRGenSIL prevents future
optimizations from regressing in this regard.
Introducing SILBuilderWithScope and SILBuilderwithPostprocess to ease the
transition.

This patch is large, but mostly mechanical.
<rdar://problem/18494573> Swift: Debugger is not stopping at the set breakpoint

Swift SVN r22978

lib/SIL/SILBuilder.cpp

@@ -285,4 +285,39 @@ SILValue SILBuilder::emitObjCToThickMetatype(SILLocation Loc, SILValue Op,
   return createObjCToThickMetatype(Loc, Op, Ty);
 }
 
+#ifndef NDEBUG
+/// Determine whether an instruction may not have a SILDebugScope.
+bool swift::maybeScopeless(SILInstruction &I) {
+  // This list is supposed to get ever shorter as we are tightening
+  // the requirements for the optimizer.
+  switch (I.getLoc().getKind()) {
+  case SILLocation::CleanupKind:
+  case SILLocation::ImplicitReturnKind:
+  case SILLocation::ArtificialUnreachableKind:
+  case SILLocation::SILFileKind:
+    return true;
+  default: break;
+  }
+  if (!I.getLoc().isNull() || I.getLoc().isAutoGenerated())
+    return true;
 
+  switch (I.getKind()) {
+  case ValueKind::BranchInst:
+  case ValueKind::CondBranchInst:
+  case ValueKind::DebugValueAddrInst:
+  case ValueKind::DebugValueInst:
+  case ValueKind::GlobalAddrInst:
+  case ValueKind::ReleaseValueInst:
+  case ValueKind::RetainValueInst:
+  case ValueKind::StrongReleaseInst:
+  case ValueKind::StrongRetainInst:
+  case ValueKind::TupleInst:
+  case ValueKind::UnreachableInst:
+    return true;
+  default: break;
+  }
+
+  auto *Fn = I.getParent()->getParent();
+  return Fn->isTransparent() || Fn->isBare();
+}
+#endif