From: Nico Weber <nicolasweber@gmx.de>
Date: Thu, 26 Oct 2017 23:26:29 +0000 (+0000)
Subject: Use -fuse-init-array if no gcc installation is found.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d724af7fa85aee225bfe4876b602151cc83f5dd0;p=clang

Use -fuse-init-array if no gcc installation is found.

clang currently uses .init_array instead of .ctors on Linux if it detects gcc
4.7+. Make it so that it also uses .init_array if no gcc installation is found
at all – if there's no old gcc, there's nothing we need to be compatible with.

icecc for example runs clang in a very small chroot, so before this change
clang would use .ctors if run under icecc. And lld currently silently mislinks
inputs with .ctors sections, so before this clang + icecc + lld would produce
broken binaries. (But this seems like a good change independent of that lld
bug.)

https://reviews.llvm.org/D39317


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@316713 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index 30afc52ad2..4c8099121e 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -105,6 +105,10 @@ Non-comprehensive list of changes in this release
   Users should generally expect this to be regularly raised to match the most
   recently released version of the Visual C++ compiler.
 
+- clang now defaults to ``.init_array`` if no gcc installation can be found.
+  If a gcc installation is found, it still prefers ``.ctors`` if the found
+  gcc is older than 4.7.0.
+
 New Compiler Flags
 ------------------
 
diff --git a/lib/Driver/ToolChains/Gnu.cpp b/lib/Driver/ToolChains/Gnu.cpp
index 08d4aa51f2..08282ff003 100644
--- a/lib/Driver/ToolChains/Gnu.cpp
+++ b/lib/Driver/ToolChains/Gnu.cpp
@@ -2366,7 +2366,8 @@ void Generic_ELF::addClangTargetOptions(const ArgList &DriverArgs,
       getTriple().getArch() == llvm::Triple::aarch64 ||
       getTriple().getArch() == llvm::Triple::aarch64_be ||
       (getTriple().getOS() == llvm::Triple::Linux &&
-       (!V.isOlderThan(4, 7, 0) || getTriple().isAndroid())) ||
+       ((!GCCInstallation.isValid() || !V.isOlderThan(4, 7, 0)) ||
+        getTriple().isAndroid())) ||
       getTriple().getOS() == llvm::Triple::NaCl ||
       (getTriple().getVendor() == llvm::Triple::MipsTechnologies &&
        !getTriple().hasEnvironment()) ||
diff --git a/test/Driver/constructors.c b/test/Driver/constructors.c
index 39a199a3c6..884fbe8466 100644
--- a/test/Driver/constructors.c
+++ b/test/Driver/constructors.c
@@ -6,6 +6,12 @@
 //
 // RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1       \
 // RUN:     -target i386-unknown-linux \
+// RUN:     --sysroot=%S/Inputs/resource_dir \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=CHECK-INIT-ARRAY %s
+//
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1       \
+// RUN:     -target i386-unknown-linux \
 // RUN:     --sysroot=%S/Inputs/fake_install_tree \
 // RUN:     --gcc-toolchain="" \
 // RUN:   | FileCheck --check-prefix=CHECK-INIT-ARRAY %s