Default to -fuse-init-array

Very few ELF platforms still use .ctors/.dtors now.  Linux (glibc: 1999-07),
DragonFlyBSD, FreeBSD (2012-03) and Solaris have supported .init_array
for many years. Some architectures like AArch64/RISC-V default to
.init_array . GNU ld and gold can even convert .ctors to .init_array .

It makes more sense to flip the CC1 default, and only uses
-fno-use-init-array on platforms that don't support .init_array .
For example, OpenBSD did not support DT_INIT_ARRAY before Aug 2016
(https://github.com/openbsd/src/commit/86fa57a2792c6374b0849dd7b818a11e676e60ba)

I may miss some ELF platforms that still use .ctors, but their
maintainers can easily diagnose such problems.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D71393

8 files changed, 27 insertions, 14 deletions

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 38c6acc8551..1ba75562213 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4083,7 +4083,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     // Disable all llvm IR level optimizations.
     CmdArgs.push_back("-disable-llvm-passes");
 
-    // Render target options such as -fuse-init-array on modern ELF platforms.
+    // Render target options.
     TC.addClangTargetOptions(Args, CmdArgs, JA.getOffloadingDeviceKind());
 
     // reject options that shouldn't be supported in bitcode
diff --git a/clang/lib/Driver/ToolChains/Fuchsia.cpp b/clang/lib/Driver/ToolChains/Fuchsia.cpp
index 4c5d4003f14..32cf0369c13 100644
--- a/clang/lib/Driver/ToolChains/Fuchsia.cpp
+++ b/clang/lib/Driver/ToolChains/Fuchsia.cpp
@@ -258,9 +258,9 @@ Fuchsia::GetCXXStdlibType(const ArgList &Args) const {
 void Fuchsia::addClangTargetOptions(const ArgList &DriverArgs,
                                     ArgStringList &CC1Args,
                                     Action::OffloadKind) const {
-  if (DriverArgs.hasFlag(options::OPT_fuse_init_array,
-                         options::OPT_fno_use_init_array, true))
-    CC1Args.push_back("-fuse-init-array");
+  if (!DriverArgs.hasFlag(options::OPT_fuse_init_array,
+                          options::OPT_fno_use_init_array, true))
+    CC1Args.push_back("-fno-use-init-array");
 }
 
 void Fuchsia::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
diff --git a/clang/lib/Driver/ToolChains/Gnu.cpp b/clang/lib/Driver/ToolChains/Gnu.cpp
index 1a729f112bd..0d950852bac 100644
--- a/clang/lib/Driver/ToolChains/Gnu.cpp
+++ b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -2798,7 +2798,7 @@ void Generic_ELF::addClangTargetOptions(const ArgList &DriverArgs,
       getTriple().getArch() == llvm::Triple::riscv32 ||
       getTriple().getArch() == llvm::Triple::riscv64;
 
-  if (DriverArgs.hasFlag(options::OPT_fuse_init_array,
-                         options::OPT_fno_use_init_array, UseInitArrayDefault))
-    CC1Args.push_back("-fuse-init-array");
+  if (!DriverArgs.hasFlag(options::OPT_fuse_init_array,
+                          options::OPT_fno_use_init_array, UseInitArrayDefault))
+    CC1Args.push_back("-fno-use-init-array");
 }
diff --git a/clang/lib/Driver/ToolChains/NetBSD.cpp b/clang/lib/Driver/ToolChains/NetBSD.cpp
index 40514220419..0100a387d6c 100644
--- a/clang/lib/Driver/ToolChains/NetBSD.cpp
+++ b/clang/lib/Driver/ToolChains/NetBSD.cpp
@@ -505,7 +505,7 @@ void NetBSD::addClangTargetOptions(const ArgList &DriverArgs,
     getTriple().getArch() == llvm::Triple::arm ||
     getTriple().getArch() == llvm::Triple::armeb;
 
-  if (DriverArgs.hasFlag(options::OPT_fuse_init_array,
-                         options::OPT_fno_use_init_array, UseInitArrayDefault))
-    CC1Args.push_back("-fuse-init-array");
+  if (!DriverArgs.hasFlag(options::OPT_fuse_init_array,
+                          options::OPT_fno_use_init_array, UseInitArrayDefault))
+    CC1Args.push_back("-fno-use-init-array");
 }
diff --git a/clang/lib/Driver/ToolChains/OpenBSD.cpp b/clang/lib/Driver/ToolChains/OpenBSD.cpp
index e93f5fcc3d8..80343c0394c 100644
--- a/clang/lib/Driver/ToolChains/OpenBSD.cpp
+++ b/clang/lib/Driver/ToolChains/OpenBSD.cpp
@@ -267,3 +267,12 @@ Tool *OpenBSD::buildAssembler() const {
 }
 
 Tool *OpenBSD::buildLinker() const { return new tools::openbsd::Linker(*this); }
+
+void OpenBSD::addClangTargetOptions(const ArgList &DriverArgs,
+                                    ArgStringList &CC1Args,
+                                    Action::OffloadKind) const {
+  // Support for .init_array is still new (Aug 2016).
+  if (!DriverArgs.hasFlag(options::OPT_fuse_init_array,
+                          options::OPT_fno_use_init_array, false))
+    CC1Args.push_back("-fno-use-init-array");
+}
diff --git a/clang/lib/Driver/ToolChains/OpenBSD.h b/clang/lib/Driver/ToolChains/OpenBSD.h
index c92d109b7c1..9f1ee0f6640 100644
--- a/clang/lib/Driver/ToolChains/OpenBSD.h
+++ b/clang/lib/Driver/ToolChains/OpenBSD.h
@@ -75,6 +75,11 @@ public:
 
   SanitizerMask getSupportedSanitizers() const override;
 
+  void
+  addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
+                        llvm::opt::ArgStringList &CC1Args,
+                        Action::OffloadKind DeviceOffloadKind) const override;
+
 protected:
   Tool *buildAssembler() const override;
   Tool *buildLinker() const override;
diff --git a/clang/lib/Driver/ToolChains/RISCVToolchain.cpp b/clang/lib/Driver/ToolChains/RISCVToolchain.cpp
index 25d912428b5..ddc329e3c72 100644
--- a/clang/lib/Driver/ToolChains/RISCVToolchain.cpp
+++ b/clang/lib/Driver/ToolChains/RISCVToolchain.cpp
@@ -76,7 +76,6 @@ void RISCVToolChain::addClangTargetOptions(
     llvm::opt::ArgStringList &CC1Args,
     Action::OffloadKind) const {
   CC1Args.push_back("-nostdsysteminc");
-  CC1Args.push_back("-fuse-init-array");
 }
 
 void RISCVToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
diff --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
index 1bb7c35d0c5..907f86b8233 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -179,9 +179,9 @@ bool WebAssembly::HasNativeLLVMSupport() const { return true; }
 void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
                                         ArgStringList &CC1Args,
                                         Action::OffloadKind) const {
-  if (DriverArgs.hasFlag(clang::driver::options::OPT_fuse_init_array,
-                         options::OPT_fno_use_init_array, true))
-    CC1Args.push_back("-fuse-init-array");
+  if (!DriverArgs.hasFlag(clang::driver::options::OPT_fuse_init_array,
+                          options::OPT_fno_use_init_array, true))
+    CC1Args.push_back("-fno-use-init-array");
 
   // '-pthread' implies atomics, bulk-memory, mutable-globals, and sign-ext
   if (DriverArgs.hasFlag(options::OPT_pthread, options::OPT_no_pthread,