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

5 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp b/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp
index 424be5e4476..ba9f638796e 100644
--- a/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp
@@ -1208,6 +1208,7 @@ void HCE::recordExtender(MachineInstr &MI, unsigned OpNum) {
       case Hexagon::S4_subaddi:       // (__: ## - Rs<<0)
         ED.Expr.Rs = MI.getOperand(OpNum+1);
         ED.Expr.Neg = true;
+        break;
       default:                        // (__: ## + __<<_)
         break;
     }
diff --git a/llvm/lib/Target/Hexagon/HexagonConstPropagation.cpp b/llvm/lib/Target/Hexagon/HexagonConstPropagation.cpp
index 8f22a71dc1f..fa192391313 100644
--- a/llvm/lib/Target/Hexagon/HexagonConstPropagation.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonConstPropagation.cpp
@@ -2463,6 +2463,7 @@ APInt HexagonConstEvaluator::getCmpImm(unsigned Opc, unsigned OpX,
     case Hexagon::A4_cmpheqi:    // s8
     case Hexagon::C4_cmpneqi:   // s8
       Signed = true;
+      break;
     case Hexagon::A4_cmpbeqi:    // u8
       break;
     case Hexagon::C2_cmpgtui:      // u9
diff --git a/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp b/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp
index 9a66aece579..470b05bda4c 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp
@@ -1547,6 +1547,7 @@ bool HexagonDAGToDAGISel::keepsLowBits(const SDValue &Val, unsigned NumBits,
         return true;
       }
     }
+    break;
   }
   default:
     break;
diff --git a/llvm/lib/Target/Hexagon/HexagonMachineScheduler.cpp b/llvm/lib/Target/Hexagon/HexagonMachineScheduler.cpp
index ebfe21bd17d..908ce24136c 100644
--- a/llvm/lib/Target/Hexagon/HexagonMachineScheduler.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonMachineScheduler.cpp
@@ -105,6 +105,7 @@ bool VLIWResourceModel::isResourceAvailable(SUnit *SU, bool IsTop) {
   default:
     if (!ResourcesModel->canReserveResources(*SU->getInstr()))
       return false;
+    break;
   case TargetOpcode::EXTRACT_SUBREG:
   case TargetOpcode::INSERT_SUBREG:
   case TargetOpcode::SUBREG_TO_REG:
diff --git a/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.cpp b/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.cpp
index 93b5bedbb38..722699907ca 100644
--- a/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.cpp
@@ -1568,6 +1568,7 @@ bool HexagonPacketizerList::isLegalToPacketizeTogether(SUnit *SUI, SUnit *SUJ) {
             if (GlueAllocframeStore)
               continue;
           }
+          break;
         default:
           break;
       }