r316713 - Use -fuse-init-array if no gcc installation is found.

[Nico Weber via cfe-commits]

Author: nico
Date: Thu Oct 26 16:26:29 2017
New Revision: 316713

URL: http://llvm.org/viewvc/llvm-project?rev=316713&view=rev
Log:
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

Modified:
    cfe/trunk/docs/ReleaseNotes.rst
    cfe/trunk/lib/Driver/ToolChains/Gnu.cpp
    cfe/trunk/test/Driver/constructors.c

Modified: cfe/trunk/docs/ReleaseNotes.rst
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/docs/ReleaseNotes.rst?rev=316713&r1=316712&r2=316713&view=diff
==============================================================================
--- cfe/trunk/docs/ReleaseNotes.rst (original)
+++ cfe/trunk/docs/ReleaseNotes.rst Thu Oct 26 16:26:29 2017
@@ -105,6 +105,10 @@ Non-comprehensive list of changes in thi
   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
 ------------------
 

Modified: cfe/trunk/lib/Driver/ToolChains/Gnu.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains/Gnu.cpp?rev=316713&r1=316712&r2=316713&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/ToolChains/Gnu.cpp (original)
+++ cfe/trunk/lib/Driver/ToolChains/Gnu.cpp Thu Oct 26 16:26:29 2017
@@ -2366,7 +2366,8 @@ void Generic_ELF::addClangTargetOptions(
       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()) ||

Modified: cfe/trunk/test/Driver/constructors.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/constructors.c?rev=316713&r1=316712&r2=316713&view=diff
==============================================================================
--- cfe/trunk/test/Driver/constructors.c (original)
+++ cfe/trunk/test/Driver/constructors.c Thu Oct 26 16:26:29 2017
@@ -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