CBE output doesn't compile with GCC 4.2.X

[llvmbot]

Bugzilla Link	1583
Resolution	FIXED
Resolved on	Aug 03, 2007 18:53
Version	1.0
OS	Linux
Reporter	LLVM Bugzilla Contributor

Extended Description

In testing llvm/llvm-project#1518 , I noticed that a lot of CBE tests in the test-suite are failing. I've updated my compilation environmen tto use GCC 4.2.1. The output is fine when compiled with gcc but the test-suite uses g++ to compile them and it fails with, for example:

g++ Output/ackermann.cbe.c -o Output/ackermann.cbe Output/ackermann.cbe.c:267: error: ‘::main’ must return ‘int’ Output/ackermann.cbe.c:288: error: redefinition of ‘l_struct_2E_std_3A3A_ctype_base _ZSt8ioinit’ Output/ackermann.cbe.c:281: error: ‘l_struct_2E_std_3A3A_ctype_base _ZSt8ioinit’ previously declared here Output/ackermann.cbe.c:289: error: redefinition of ‘unsigned char _2E_str [7]’ Output/ackermann.cbe.c:282: error: ‘unsigned char _2E_str [7]’ previously declared here Output/ackermann.cbe.c:290: error: redefinition of ‘unsigned char _2E_str1 [4]’ Output/ackermann.cbe.c:283: error: ‘unsigned char _2E_str1 [4]’ previously declared here Output/ackermann.cbe.c:378: error: ‘::main’ must return ‘int’

I'm not sure why the makefiles compile with g++ instead of gcc. It probably shouldn't.

[llvmbot]

Resolved with r40797. The makefiles just needed to compile .cbe.c and .s files appropriately with the right libraries for the llvm-gcc compiler in use.

[llvmbot]

The issue is entirely with the CBE output. I believe it is correct for GCC 4.2 to be making the redefinition of statics illegal. The CBE has depended on lax reporting of static redefinitions in the past, but it should not do this. I believe this was done to solve the initializer reference problem.

The CBE generates things like:

static char foo; static char foo = "";

The first foo being a declaration and the second being a definition. However, GCC 4.2 is taking them both as definitions and issuing a redefinition error.

[llvmbot]

Actually, its not that weird. The original source in this case is a C++ program which uses the stdc++ library. Simply adding -lstdc++ to the link line allows it to link properly.

[llvmbot]

Interestingly enough, if you change the makefiles to link with gcc instead of g++ then you get:

gcc -L/proj/llvm/#1146 /installed/lib/gcc/i686-pc-linux-gnu/4.0.1 -L/proj/llvm/#1146 /installed/lib Output/ackermann.cbe.c \ -fno-strict-aliasing -O2 -fno-inline -o Output/ackermann.cbe Output/ackermann.cbe.c:275: warning: conflicting types for built-in function ‘malloc’ Output/ackermann.cbe.c: In function ‘main’: Output/ackermann.cbe.c:378: warning: return type of ‘main’ is not ‘int’ /tmp/ccqUd2lQ.o: In function main': ackermann.cbe.c:(.text+0xd5): undefined reference tostd::cout' ackermann.cbe.c:(.text+0xda): undefined reference to std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)' ackermann.cbe.c:(.text+0xe6): undefined reference tostd::basic_ostream<char, std::char_traits >::operator<<(int)' ackermann.cbe.c:(.text+0xf6): undefined reference to std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)' ackermann.cbe.c:(.text+0x102): undefined reference tostd::basic_ostream<char, std::char_traits >::operator<<(int)' ackermann.cbe.c:(.text+0x10a): undefined reference to std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)' ackermann.cbe.c:(.text+0x112): undefined reference tostd::basic_ostream<char, std::char_traits >::operator<<(std::basic_ostream<char, std::char_traits >& (*)(std::basic_ostream<char, std::char_traits >&))' /tmp/ccqUd2lQ.o: In function global destructors keyed to _Z3Ackii': ackermann.cbe.c:(.text+0x19e): undefined reference tostd::ios_base::Init::~Init()' /tmp/ccqUd2lQ.o: In function global constructors keyed to _Z3Ackii': ackermann.cbe.c:(.text+0x1be): undefined reference tostd::ios_base::Init::Init()' collect2: ld returned 1 exit status

which is very weird for a C program.