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, 4 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 0b9a0a45c57..7b024a015cd 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -680,7 +680,7 @@ public:
       case LangOptions::SOB_Undefined:
         if (!CGF.SanOpts.has(SanitizerKind::SignedIntegerOverflow))
           return Builder.CreateNSWMul(Ops.LHS, Ops.RHS, "mul");
-        // Fall through.
+        LLVM_FALLTHROUGH;
       case LangOptions::SOB_Trapping:
         if (CanElideOverflowCheck(CGF.getContext(), Ops))
           return Builder.CreateNSWMul(Ops.LHS, Ops.RHS, "mul");
@@ -2305,7 +2305,7 @@ llvm::Value *ScalarExprEmitter::EmitIncDecConsiderOverflowBehavior(
   case LangOptions::SOB_Undefined:
     if (!CGF.SanOpts.has(SanitizerKind::SignedIntegerOverflow))
       return Builder.CreateNSWAdd(InVal, Amount, Name);
-    // Fall through.
+    LLVM_FALLTHROUGH;
   case LangOptions::SOB_Trapping:
     if (!E->canOverflow())
       return Builder.CreateNSWAdd(InVal, Amount, Name);
@@ -3311,7 +3311,7 @@ Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &op) {
     case LangOptions::SOB_Undefined:
       if (!CGF.SanOpts.has(SanitizerKind::SignedIntegerOverflow))
         return Builder.CreateNSWAdd(op.LHS, op.RHS, "add");
-      // Fall through.
+      LLVM_FALLTHROUGH;
     case LangOptions::SOB_Trapping:
       if (CanElideOverflowCheck(CGF.getContext(), op))
         return Builder.CreateNSWAdd(op.LHS, op.RHS, "add");
@@ -3346,7 +3346,7 @@ Value *ScalarExprEmitter::EmitSub(const BinOpInfo &op) {
       case LangOptions::SOB_Undefined:
         if (!CGF.SanOpts.has(SanitizerKind::SignedIntegerOverflow))
           return Builder.CreateNSWSub(op.LHS, op.RHS, "sub");
-        // Fall through.
+        LLVM_FALLTHROUGH;
       case LangOptions::SOB_Trapping:
         if (CanElideOverflowCheck(CGF.getContext(), op))
           return Builder.CreateNSWSub(op.LHS, op.RHS, "sub");