Fix clang -Wimplicit-fallthrough warnings across llvm, NFC

This patch should not introduce any behavior changes. It consists of
mostly one of two changes:
1. Replacing fall through comments with the LLVM_FALLTHROUGH macro
2. Inserting 'break' before falling through into a case block consisting
   of only 'break'.

We were already using this warning with GCC, but its warning behaves
slightly differently. In this patch, the following differences are
relevant:
1. GCC recognizes comments that say "fall through" as annotations, clang
   doesn't
2. GCC doesn't warn on "case N: foo(); default: break;", clang does
3. GCC doesn't warn when the case contains a switch, but falls through
   the outer case.

I will enable the warning separately in a follow-up patch so that it can
be cleanly reverted if necessary.

Reviewers: alexfh, rsmith, lattner, rtrieu, EricWF, bollu

Differential Revision: https://reviews.llvm.org/D53950

llvm-svn: 345882

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/Analysis/ReachableCode.cpp b/clang/lib/Analysis/ReachableCode.cpp
index 0d4b78b..87f4f70 100644
--- a/clang/lib/Analysis/ReachableCode.cpp
+++ b/clang/lib/Analysis/ReachableCode.cpp
@@ -219,7 +219,7 @@ static bool isConfigurationValue(const Stmt *S,
       return isConfigurationValue(cast<DeclRefExpr>(S)->getDecl(), PP);
     case Stmt::ObjCBoolLiteralExprClass:
       IgnoreYES_NO = true;
-      // Fallthrough.
+      LLVM_FALLTHROUGH;
     case Stmt::CXXBoolLiteralExprClass:
     case Stmt::IntegerLiteralClass: {
       const Expr *E = cast<Expr>(S);