Add and make use of llvm::for_each

[aaron.ballman]

Summary

This patch introduces a range-based adapter for std::for_each(), similar to other extensions to <algorithm>. It's intended to be used as a replacement for std::for_each() when the full range is easily available, thus making the code easier to understand. It could also be used as a replacement for range-based for loops, though it may be less of a win there.

It also switches cases within LLVM to use the new facilities.

[aaron.ballman]

Now, with more delicious patch context!

[echristo]

That looks pretty usable for someone as bad at C++ as I am so I'm in favor.

Ultimately I delegate to dblaikie though.

-eric

[dblaikie]

I still feel like for_each might as well change to range-based-for. Some of these examples are admittedly a bit awkward as range-based-for & I doubt there's going to be a big proliferation of for_each from people who don't know range-for is there, so doesn't seem like there's much harm/risk to having this for the few cases it can be handy for. (:

[aaron.ballman]

Thanks for the review! I've commit in r317356.

../llvm/include/llvm/ADT/STLExtras.h

 /// deletes the second elements and then clears the container.
 template<typename Container>
 void DeleteContainerSeconds(Container &C) {
   for (auto &V : C)
     delete V.second;
   C.clear();
 }
 
+/// Provide wrappers to std::for_each which take ranges instead of having to
+/// pass begin/end explicitly.
+template <typename R, typename UnaryPredicate>
+UnaryPredicate for_each(R &&Range, UnaryPredicate P) {
+  return std::for_each(std::begin(Range), std::end(Range), P);
+}
+
 /// Provide wrappers to std::all_of which take ranges instead of having to pass
 /// begin/end explicitly.
 template <typename R, typename UnaryPredicate>
 bool all_of(R &&Range, UnaryPredicate P) {
   return std::all_of(std::begin(Range), std::end(Range), P);
 }
 
 /// Provide wrappers to std::any_of which take ranges instead of having to pass

../llvm/lib/LTO/LTOCodeGenerator.cpp

 
     auto I = ExternalSymbols.find(GV.getName());
     if (I == ExternalSymbols.end())
       return;
 
     GV.setLinkage(I->second);
   };
 
-  std::for_each(MergedModule->begin(), MergedModule->end(), externalize);
-  std::for_each(MergedModule->global_begin(), MergedModule->global_end(),
-                externalize);
-  std::for_each(MergedModule->alias_begin(), MergedModule->alias_end(),
-                externalize);
+  llvm::for_each(MergedModule->functions(), externalize);
+  llvm::for_each(MergedModule->globals(), externalize);
+  llvm::for_each(MergedModule->aliases(), externalize);
 }
 
 void LTOCodeGenerator::verifyMergedModuleOnce() {
   // Only run on the first call.
   if (HasVerifiedInput)
     return;
   HasVerifiedInput = true;
 

../llvm/lib/Target/Hexagon/HexagonVectorLoopCarriedReuse.cpp

 
     findLoopCarriedDeps();
     findValueToReuse();
     if (ReuseCandidate.isDefined()) {
       reuseValue();
       Changed = true;
       Continue = true;
     }
-    std::for_each(Dependences.begin(), Dependences.end(),
-                  std::default_delete<DepChain>());
+    llvm::for_each(Dependences, std::default_delete<DepChain>());
   } while (Continue);
   return Changed;
 }
 
 void HexagonVectorLoopCarriedReuse::findDepChainFromPHI(Instruction *I,
                                                         DepChain &D) {
   PHINode *PN = dyn_cast<PHINode>(I);
   if (!PN) {

../llvm/lib/Transforms/Utils/SplitModule.cpp

         addAllGlobalValueUsers(GVtoClusterMap, F, BA);
       }
     }
 
     if (GV.hasLocalLinkage())
       addAllGlobalValueUsers(GVtoClusterMap, &GV, &GV);
   };
 
-  std::for_each(M->begin(), M->end(), recordGVSet);
-  std::for_each(M->global_begin(), M->global_end(), recordGVSet);
-  std::for_each(M->alias_begin(), M->alias_end(), recordGVSet);
+  llvm::for_each(M->functions(), recordGVSet);
+  llvm::for_each(M->globals(), recordGVSet);
+  llvm::for_each(M->aliases(), recordGVSet);
 
   // Assigned all GVs to merged clusters while balancing number of objects in
   // each.
   auto CompareClusters = [](const std::pair<unsigned, unsigned> &a,
                             const std::pair<unsigned, unsigned> &b) {
     if (a.second || b.second)
       return a.second > b.second;
     else

../llvm/tools/llvm-cxxdump/llvm-cxxdump.cpp

   cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
 
   cl::ParseCommandLineOptions(argc, argv, "LLVM C++ ABI Data Dumper\n");
 
   // Default to stdin if no filename is specified.
   if (opts::InputFilenames.size() == 0)
     opts::InputFilenames.push_back("-");
 
-  std::for_each(opts::InputFilenames.begin(), opts::InputFilenames.end(),
-                dumpInput);
+  llvm::for_each(opts::InputFilenames, dumpInput);
 
   return EXIT_SUCCESS;
 }

../llvm/tools/llvm-mcmarkup/llvm-mcmarkup.cpp

   cl::ParseCommandLineOptions(argc, argv, "llvm MC markup parser\n");
 
   ToolName = argv[0];
 
   // If no input files specified, read from stdin.
   if (InputFilenames.size() == 0)
     InputFilenames.push_back("-");
 
-  std::for_each(InputFilenames.begin(), InputFilenames.end(),
-                parseMCMarkup);
+  llvm::for_each(InputFilenames, parseMCMarkup);
   return 0;
 }

../llvm/tools/llvm-nm/llvm-nm.cpp

 
   if (SegSect.size() != 0 && SegSect.size() != 2)
     error("bad number of arguments (must be two arguments)",
           "for the -s option");
 
   if (NoDyldInfo && (AddDyldInfo || DyldInfoOnly))
     error("-no-dyldinfo can't be used with -add-dyldinfo or -dyldinfo-only");
 
-  std::for_each(InputFilenames.begin(), InputFilenames.end(),
-                dumpSymbolNamesFromFile);
+  llvm::for_each(InputFilenames, dumpSymbolNamesFromFile);
 
   if (HadError)
     return 1;
 }

../llvm/tools/llvm-objdump/llvm-objdump.cpp

       && !(ObjcMetaData && MachOOpt)
       && !(FilterSections.size() != 0 && MachOOpt)
       && !PrintFaultMaps
       && DwarfDumpType == DIDT_Null) {
     cl::PrintHelpMessage();
     return 2;
   }
 
-  std::for_each(InputFilenames.begin(), InputFilenames.end(),
-                DumpInput);
+  llvm::for_each(InputFilenames, DumpInput);
 
   return EXIT_SUCCESS;
 }

../llvm/tools/llvm-pdbutil/llvm-pdbutil.cpp

     }
     if (opts::pretty::ExcludeSystemLibraries) {
       opts::pretty::ExcludeCompilands.push_back(
           "f:\\\\binaries\\\\Intermediate\\\\vctools\\\\crt_bld");
       opts::pretty::ExcludeCompilands.push_back("f:\\\\dd\\\\vctools\\\\crt");
       opts::pretty::ExcludeCompilands.push_back(
           "d:\\\\th.obj.x86fre\\\\minkernel");
     }
-    std::for_each(opts::pretty::InputFilenames.begin(),
-                  opts::pretty::InputFilenames.end(), dumpPretty);
+    llvm::for_each(opts::pretty::InputFilenames, dumpPretty);
   } else if (opts::DumpSubcommand) {
-    std::for_each(opts::dump::InputFilenames.begin(),
-                  opts::dump::InputFilenames.end(), dumpRaw);
+    llvm::for_each(opts::dump::InputFilenames, dumpRaw);
   } else if (opts::BytesSubcommand) {
-    std::for_each(opts::bytes::InputFilenames.begin(),
-                  opts::bytes::InputFilenames.end(), dumpBytes);
+    llvm::for_each(opts::bytes::InputFilenames, dumpBytes);
   } else if (opts::DiffSubcommand) {
     for (StringRef S : opts::diff::RawModiEquivalences) {
       StringRef Left;
       StringRef Right;
       std::tie(Left, Right) = S.split(',');
       uint32_t X, Y;
       if (!to_integer(Left, X) || !to_integer(Right, Y)) {
         errs() << formatv("invalid value {0} specified for modi equivalence\n",

../llvm/tools/llvm-readobj/llvm-readobj.cpp

     opts::Output = opts::GNU;
 
   cl::ParseCommandLineOptions(argc, argv, "LLVM Object Reader\n");
 
   // Default to stdin if no filename is specified.
   if (opts::InputFilenames.size() == 0)
     opts::InputFilenames.push_back("-");
 
-  std::for_each(opts::InputFilenames.begin(), opts::InputFilenames.end(),
-                dumpInput);
+  llvm::for_each(opts::InputFilenames, dumpInput);
 
   if (opts::CodeViewMergedTypes) {
     ScopedPrinter W(outs());
     dumpCodeViewMergedTypes(W, CVTypes.IDTable, CVTypes.TypeTable);
   }
 
   return 0;
 }

../llvm/tools/llvm-size/llvm-size.cpp

       }
     }
   }
 
   if (InputFilenames.size() == 0)
     InputFilenames.push_back("a.out");
 
   MoreThanOneFile = InputFilenames.size() > 1;
-  std::for_each(InputFilenames.begin(), InputFilenames.end(),
-                printFileSectionSizes);
+  llvm::for_each(InputFilenames, printFileSectionSizes);
   if (OutputFormat == berkeley && TotalSizes)
     printBerkelyTotals();
 
   if (HadError)
     return 1;
 }

../llvm/unittests/ADT/STLExtrasTest.cpp

   v.push_back(1);
 
   EXPECT_EQ(3, count(v, 1));
   EXPECT_EQ(2, count(v, 2));
   EXPECT_EQ(1, count(v, 3));
   EXPECT_EQ(1, count(v, 4));
 }
 
+TEST(STLExtrasTest, for_each) {
+  std::vector<int> v{ 0, 1, 2, 3, 4 };
+  int count = 0;
+
+  llvm::for_each(v, [&count](int) { ++count; });
+  EXPECT_EQ(5, count);
+}
+
 TEST(STLExtrasTest, ToVector) {
   std::vector<char> v = {'a', 'b', 'c'};
   auto Enumerated = to_vector<4>(enumerate(v));
   ASSERT_EQ(3u, Enumerated.size());
   for (size_t I = 0; I < v.size(); ++I) {
     EXPECT_EQ(I, Enumerated[I].index());
     EXPECT_EQ(v[I], Enumerated[I].value());
   }