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

1 files changed, 9 insertions, 0 deletions

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");
+}