Add a -fuse-init-array option to cc1 and map to the UseInitArray target

option. On the driver, check if we are using libraries from gcc 4.7 or newer
and if so pass -fuse-init-array to the frontend.
The crtbegin*.o files in gcc 4.7 no longer call the constructors listed in
.ctors, so we have to use .init_array.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158694 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Driver/CC1Options.td

@@ -196,6 +196,8 @@ def mrelocation_model : Separate<"-mrelocation-model">,
   HelpText<"The relocation model to use">;
 def munwind_tables : Flag<"-munwind-tables">,
   HelpText<"Generate unwinding tables for all functions">;
+def fuse_init_array : Flag<"-fuse-init-array">,
+  HelpText<"Use .init_array instead of .ctors">;
 def mconstructor_aliases : Flag<"-mconstructor-aliases">,
   HelpText<"Emit complete constructors and destructors as aliases when possible">;
 def mlink_bitcode_file : Separate<"-mlink-bitcode-file">,

include/clang/Driver/ToolChain.h

@@ -230,6 +230,10 @@ public:
   virtual void AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                          ArgStringList &CC1Args) const;
 
+  // addClangTargetOptions - Add options that need to be passed to cc1 for
+  // this target.
+  virtual void addClangTargetOptions(ArgStringList &CC1Args) const;
+
   // GetRuntimeLibType - Determine the runtime library type to use with the
   // given compilation arguments.
   virtual RuntimeLibType GetRuntimeLibType(const ArgList &Args) const;

include/clang/Frontend/CodeGenOptions.h

@@ -118,6 +118,8 @@ public:
 
   unsigned StackRealignment  : 1; ///< Control whether to permit stack
                                   ///< realignment.
+  unsigned UseInitArray      : 1; ///< Control whether to use .init_array or
+                                  ///< .ctors.
   unsigned StackAlignment;        ///< Overrides default stack alignment,
                                   ///< if not 0.
 
@@ -228,6 +230,7 @@ public:
     StackRealignment = 0;
     StackAlignment = 0;
     BoundsChecking = 0;
+    UseInitArray = 0;
 
     DebugInfo = NoDebugInfo;
     Inlining = NoInlining;

lib/CodeGen/BackendUtil.cpp

@@ -338,6 +338,9 @@ bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
     Options.NoFramePointerElimNonLeaf = true;
   }
 
+  if (CodeGenOpts.UseInitArray)
+    Options.UseInitArray = true;
+
   // Set float ABI type.
   if (CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp")
     Options.FloatABIType = llvm::FloatABI::Soft;

lib/Driver/ToolChain.cpp

@@ -189,6 +189,9 @@ void ToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
   // Each toolchain should provide the appropriate include flags.
 }
 
+void ToolChain::addClangTargetOptions(ArgStringList &CC1Args) const {
+}
+
 ToolChain::RuntimeLibType ToolChain::GetRuntimeLibType(
   const ArgList &Args) const
 {

lib/Driver/ToolChains.cpp

@@ -2116,6 +2116,12 @@ Tool &Linux::SelectTool(const Compilation &C, const JobAction &JA,
   return *T;
 }
 
+void Linux::addClangTargetOptions(ArgStringList &CC1Args) const {
+  const Generic_GCC::GCCVersion &V = GCCInstallation.getVersion();
+  if (V >= Generic_GCC::GCCVersion::Parse("4.7.0"))
+    CC1Args.push_back("-fuse-init-array");
+}
+
 void Linux::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                       ArgStringList &CC1Args) const {
   const Driver &D = getDriver();
@@ -2258,7 +2264,7 @@ void Linux::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
   // equivalent to '/usr/include/c++/X.Y' in almost all cases.
   StringRef LibDir = GCCInstallation.getParentLibPath();
   StringRef InstallDir = GCCInstallation.getInstallPath();
-  StringRef Version = GCCInstallation.getVersion();
+  StringRef Version = GCCInstallation.getVersion().Text;
   if (!addLibStdCXXIncludePaths(LibDir + "/../include/c++/" + Version,
                                 (GCCInstallation.getTriple().str() +
                                  GCCInstallation.getMultiarchSuffix()),

lib/Driver/ToolChains.h

@@ -99,7 +99,7 @@ protected:
     StringRef getParentLibPath() const { return GCCParentLibPath; }
 
     /// \brief Get the detected GCC version string.
-    StringRef getVersion() const { return Version.Text; }
+    const GCCVersion &getVersion() const { return Version; }
 
   private:
     static void CollectLibDirsAndTriples(
@@ -538,6 +538,7 @@ public:
 
   virtual void AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                          ArgStringList &CC1Args) const;
+  virtual void addClangTargetOptions(ArgStringList &CC1Args) const;
   virtual void AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                                             ArgStringList &CC1Args) const;
 

lib/Driver/Tools.cpp

@@ -1814,6 +1814,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                    AsynchronousUnwindTables))
     CmdArgs.push_back("-munwind-tables");
 
+  getToolChain().addClangTargetOptions(CmdArgs);
+
   if (Arg *A = Args.getLastArg(options::OPT_flimited_precision_EQ)) {
     CmdArgs.push_back("-mlimit-float-precision");
     CmdArgs.push_back(A->getValue(Args));

lib/Frontend/CompilerInvocation.cpp

@@ -1229,6 +1229,7 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.TrapFuncName = Args.getLastArgValue(OPT_ftrap_function_EQ);
   Opts.BoundsChecking = Args.getLastArgIntValue(OPT_fbounds_checking_EQ, 0,
                                                 Diags);
+  Opts.UseInitArray = Args.hasArg(OPT_fuse_init_array);
 
   Opts.FunctionSections = Args.hasArg(OPT_ffunction_sections);
   Opts.DataSections = Args.hasArg(OPT_fdata_sections);

test/Driver/constructors.c

@@ -0,0 +1,14 @@
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1       \
+// RUN:     -target i386-unknown-linux \
+// RUN:     --sysroot=%S/Inputs/fake_install_tree \
+// RUN:   | FileCheck --check-prefix=CHECK-GCC-4-7 %s
+
+// CHECK-GCC-4-7: -fuse-init-array
+
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1       \
+// RUN:     -target i386-unknown-linux \
+// RUN:     --sysroot=%S/Inputs/basic_linux_tree \
+// RUN:   | FileCheck --check-prefix=CHECK-GCC-4-6 %s
+
+
+// CHECK-GCC-4-6-NOT:  -fuse-init-array