kamlesh kumar via llvm-dev
2019-Dec-10 11:10 UTC
[llvm-dev] X86 does not follow -fuse-init-array
Hi Devs,
consider below testcases,
$cat test.cc
class B {
public:
B(int t) {
j=t;
}
int j;
};
B b(1);
=============$clang test.cc -target -i386 -c -fuse-init-array
$llvm-objdump -h test.o |grep ctors
7 .ctors 00000004 00000000 DATA
8 .rel.ctors 00000008 00000000
As you can see it ignores the -fuse-init-array options.It happens for
x86,Other target like aarch64 is doing fine.
like to community thoughts on this, before going after fix?
./kamlesh
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Reid Kleckner via llvm-dev
2019-Dec-10 19:48 UTC
[llvm-dev] X86 does not follow -fuse-init-array
I bet if you use `-target i386-linux` it will work. You passed `-target -i386`, which is a triple with no OS, so Clang is doing something arbitrary. Grepping Clang sources shows that this flag is handled in an OS-specific manner: $ git grep -i fuse_init_array ../clang/lib/Driver/ ../clang/lib/Driver/ToolChains/Fuchsia.cpp: if (DriverArgs.hasFlag(options::OPT_fuse_init_array, ../clang/lib/Driver/ToolChains/Gnu.cpp: if (DriverArgs.hasFlag(options::OPT_fuse_init_array, ../clang/lib/Driver/ToolChains/NetBSD.cpp: if (DriverArgs.hasFlag(options::OPT_fuse_init_array, ../clang/lib/Driver/ToolChains/WebAssembly.cpp: if (DriverArgs.hasFlag(clang::driver::options::OPT_fuse_init_array, The Gnu.cpp file most likely handles the case of Linux. This logic looks like it is ripe for refactoring. Patches very welcome. =( On Tue, Dec 10, 2019 at 3:11 AM kamlesh kumar via llvm-dev < llvm-dev at lists.llvm.org> wrote:> Hi Devs, > > consider below testcases, > $cat test.cc > class B { > public: > B(int t) { > j=t; > } > int j; > }; > B b(1); > =============> $clang test.cc -target -i386 -c -fuse-init-array > $llvm-objdump -h test.o |grep ctors > 7 .ctors 00000004 00000000 DATA > 8 .rel.ctors 00000008 00000000 > > As you can see it ignores the -fuse-init-array options.It happens for > x86,Other target like aarch64 is doing fine. > > like to community thoughts on this, before going after fix? > > ./kamlesh > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20191210/0d3d3996/attachment.html>
Fangrui Song via llvm-dev
2019-Dec-12 05:32 UTC
[llvm-dev] X86 does not follow -fuse-init-array
On 2019-12-10, Reid Kleckner via llvm-dev wrote:>I bet if you use `-target i386-linux` it will work. You passed `-target -i386`, >which is a triple with no OS, so Clang is doing something arbitrary. Grepping >Clang sources shows that this flag is handled in an OS-specific manner: > >$ git grep -i fuse_init_array ../clang/lib/Driver/ >../clang/lib/Driver/ToolChains/Fuchsia.cpp: if (DriverArgs.hasFlag >(options::OPT_fuse_init_array, >../clang/lib/Driver/ToolChains/Gnu.cpp: if (DriverArgs.hasFlag >(options::OPT_fuse_init_array, >../clang/lib/Driver/ToolChains/NetBSD.cpp: if (DriverArgs.hasFlag >(options::OPT_fuse_init_array, >../clang/lib/Driver/ToolChains/WebAssembly.cpp: if (DriverArgs.hasFlag >(clang::driver::options::OPT_fuse_init_array, > >The Gnu.cpp file most likely handles the case of Linux. > >This logic looks like it is ripe for refactoring. Patches very welcome. =(We should probably make -fuse-init-array the CC1 default and the default for Driver/ToolChains/Gnu.cpp. Very few platforms actually use .ctors/.dtors nowadays. (This caused a bug this year which was fixed by https://reviews.llvm.org/D62509) If my suggestion does not sound too stupid, I can create a patch.