From 47138b2f833921f37781884080295d4b576ec920 Mon Sep 17 00:00:00 2001
From: Nico Weber <thakis@chromium.org>
Date: Wed, 25 Mar 2020 13:48:02 -0400
Subject: [PATCH] Suppress a few -Wunreachable-code warnings.

No behavior change. Also fix a comment to say match reality.
---
 lib/DebugInfo/DWARF/DWARFContext.cpp    | 10 +++-----
 lib/TextAPI/MachO/TextStub.cpp          |  6 ++---
 tools/llvm-lipo/llvm-lipo.cpp           |  1 -
 utils/PerfectShuffle/PerfectShuffle.cpp |  4 +--
 utils/TableGen/CodeGenSchedule.cpp      | 34 ++++++++++++-------------
 5 files changed, 23 insertions(+), 32 deletions(-)

diff --git a/lib/DebugInfo/DWARF/DWARFContext.cpp b/lib/DebugInfo/DWARF/DWARFContext.cpp
index 7541bb794c7..908128b0205 100644
--- a/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -1931,14 +1931,10 @@ Error DWARFContext::loadRegisterInfo(const object::ObjectFile &Obj) {
 uint8_t DWARFContext::getCUAddrSize() {
   // In theory, different compile units may have different address byte
   // sizes, but for simplicity we just use the address byte size of the
-  // last compile unit. In practice the address size field is repeated across
+  // first compile unit. In practice the address size field is repeated across
   // various DWARF headers (at least in version 5) to make it easier to dump
   // them independently, not to enable varying the address size.
-  uint8_t Addr = 0;
-  for (const auto &CU : compile_units()) {
-    Addr = CU->getAddressByteSize();
-    break;
-  }
-  return Addr;
+  unit_iterator_range CUs = compile_units();
+  return CUs.empty() ? 0 : (*CUs.begin())->getAddressByteSize();
 }
 
diff --git a/lib/TextAPI/MachO/TextStub.cpp b/lib/TextAPI/MachO/TextStub.cpp
index 5637639b8ef..3c6c5ac2530 100644
--- a/lib/TextAPI/MachO/TextStub.cpp
+++ b/lib/TextAPI/MachO/TextStub.cpp
@@ -450,10 +450,8 @@ template <> struct MappingTraits<const InterfaceFile *> {
       if (File->isInstallAPI())
         Flags |= TBDFlags::InstallAPI;
 
-      for (const auto &Iter : File->umbrellas()) {
-        ParentUmbrella = Iter.second;
-        break;
-      }
+      if (!File->umbrellas().empty())
+        ParentUmbrella = File->umbrellas().begin()->second;
 
       std::set<ArchitectureSet> ArchSet;
       for (const auto &Library : File->allowableClients())
diff --git a/tools/llvm-lipo/llvm-lipo.cpp b/tools/llvm-lipo/llvm-lipo.cpp
index e75327ee53a..8c2740d8c94 100644
--- a/tools/llvm-lipo/llvm-lipo.cpp
+++ b/tools/llvm-lipo/llvm-lipo.cpp
@@ -763,7 +763,6 @@ static void extractSlice(ArrayRef<OwningBinary<Binary>> InputBinaries,
     reportError("input file " +
                 InputBinaries.front().getBinary()->getFileName() +
                 " must be a fat file when the -extract option is specified");
-    exit(EXIT_FAILURE);
   }
 
   SmallVector<std::unique_ptr<MachOObjectFile>, 2> ExtractedObjects;
diff --git a/utils/PerfectShuffle/PerfectShuffle.cpp b/utils/PerfectShuffle/PerfectShuffle.cpp
index 0f2e6729840..d941cd685ec 100644
--- a/utils/PerfectShuffle/PerfectShuffle.cpp
+++ b/utils/PerfectShuffle/PerfectShuffle.cpp
@@ -423,7 +423,7 @@ int main() {
   }
   std::cout << "  0\n};\n";
 
-  if (0) {
+  LLVM_DEBUG({
     // Print out the table.
     for (unsigned i = 0; i != 0x8889; ++i) {
       if (!isValidMask(i)) continue;
@@ -440,7 +440,7 @@ int main() {
         std::cerr << "\n";
       }
     }
-  }
+  })
 }
 
 
diff --git a/utils/TableGen/CodeGenSchedule.cpp b/utils/TableGen/CodeGenSchedule.cpp
index 09cbb234f89..67583c736cd 100644
--- a/utils/TableGen/CodeGenSchedule.cpp
+++ b/utils/TableGen/CodeGenSchedule.cpp
@@ -1082,15 +1082,14 @@ void CodeGenSchedModels::createInstRWClass(Record *InstRWDef) {
           for (Record *RWD : RWDefs) {
             if (RWD->getValueAsDef("SchedModel") == RWModelDef &&
                 RWModelDef->getValueAsBit("FullInstRWOverlapCheck")) {
-              for (Record *Inst : InstDefs) {
-                PrintFatalError
-                    (InstRWDef->getLoc(),
-                     "Overlapping InstRW definition for \"" +
-                     Inst->getName() +
-                     "\" also matches previous \"" +
-                     RWD->getValue("Instrs")->getValue()->getAsString() +
-                     "\".");
-              }
+              assert(!InstDefs.empty()); // Checked at function start.
+              PrintFatalError
+                  (InstRWDef->getLoc(),
+                   "Overlapping InstRW definition for \"" +
+                   InstDefs.front()->getName() +
+                   "\" also matches previous \"" +
+                   RWD->getValue("Instrs")->getValue()->getAsString() +
+                   "\".");
             }
           }
           LLVM_DEBUG(dbgs() << "InstRW: Reuse SC " << OldSCIdx << ":"
@@ -1118,15 +1117,14 @@ void CodeGenSchedModels::createInstRWClass(Record *InstRWDef) {
       Record *RWModelDef = InstRWDef->getValueAsDef("SchedModel");
       for (Record *OldRWDef : SchedClasses[OldSCIdx].InstRWs) {
         if (OldRWDef->getValueAsDef("SchedModel") == RWModelDef) {
-          for (Record *InstDef : InstDefs) {
-            PrintFatalError
-                (InstRWDef->getLoc(),
-                 "Overlapping InstRW definition for \"" +
-                 InstDef->getName() +
-                 "\" also matches previous \"" +
-                 OldRWDef->getValue("Instrs")->getValue()->getAsString() +
-                 "\".");
-          }
+          assert(!InstDefs.empty()); // Checked at function start.
+          PrintFatalError
+              (InstRWDef->getLoc(),
+               "Overlapping InstRW definition for \"" +
+               InstDefs.front()->getName() +
+               "\" also matches previous \"" +
+               OldRWDef->getValue("Instrs")->getValue()->getAsString() +
+               "\".");
         }
         assert(OldRWDef != InstRWDef &&
                "SchedClass has duplicate InstRW def");