illegal instruction in stdc++ - linux

Question

program:
#include <stdio.h>
#include <sstream>
int main()
{
std::stringstream ss;
ss << "hello world " << 1234 << "\n";
std::string str = ss.str();
printf(str.c_str());
return 0;
}
makefile:
CC=/usr/local/gcc-4.6.2/bin/g++
CFLAGS=-g -c -W -m32 -Wa,-mtune=pentiumiii
LINKFLAGS=-m32 -static-libgcc -static-libstdc++ -Wl,-rpath,./runtime,--dynamic-linker,./runtime/ld-linux.so.2
all:test
test: list_test.o
$(CC) $(LINKFLAGS) list_test.o -o test
list_test.o: list_test.cpp
$(CC) $(CFLAGS) list_test.cpp
clean:
rm *.o ./test -f
I build it in 64-bit linux. there is an illegal instruction when it run in 32-bit linux with pentinum(R) III cpu.
the illegal instruction is as follow:
(gdb) disas 0x0804f77a 0x0804f77b
Dump of assembler code from 0x804f77a to 0x804f77b:
0x0804f77a <std::basic_stringbuf<char, std::char_traits<char>, std::allocator<char> >::_M_sync(std::basic_stringbuf<char, std::char_traits<char>, std::allocator<char> >::char_type*, std::basic_stringbuf<char, std::char_traits<char>, std::allocator<char> >::__size_type, std::basic_stringbuf<char, std::char_traits<char>, std::allocator<char> >::__size_type)+138>: movq %xmm0,0xc(%esp)
End of assembler dump.
How to resolve this problem?

Answer 1

The instruction movq %xmm0,0xc(%esp) is part of the Streaming SIMD Extensions (SSE) instruction set. The Pentium III in theory supports SSE, but the processor you're trying to run it in apparently doesn't. You can disable the generation of SSE instructions on GCC with the -mno-sse compiler option. You can also try -march=pentium3 to generate code compatible with Pentium III and above.
Also, your printf call has a bug—you should (almost) never pass a non-constant string as the format argument (the first argument). If that string happens to contain any % signs in it, that will lead to undefined behavior. At best, this will crash, and at worst, you could have a silent security vulnerability. The fix is to do this:
printf("%s", str.c_str());
Or better yet, avoid the potential problems with the printf family of functions entirely, since you're using C++:
std::cout << str; // Optionally also do `<< std::flush'

Answer 2

It looks like a SSE instruction, which is apparently not supported by the processor. (Pentium 3 is supposed to support SSE though).
You can try compiling your code with -mno-sse and see if it helps.