hi,
I try to build hello.cpp using both llvmg++ and GNU g++,
the generate llvm bytecode's size is about 960K,
and the size of binary code generated by g++ is only 13K.
Could anyone explain the difference between the two result?
BWT:
I rebuild the cfrontend in RH linux9.0, but when I build the hello.cpp the llvmG++ reports warnings too, it shows:
I try to build hello.cpp using both llvmg++ and GNU g++,
the generate llvm bytecode's size is about 960K,
and the size of binary code generated by g++ is only 13K.
Could anyone explain the difference between the two result?
I can certainly answer this one:
When you link a program with LLVM G++, it statically links in _all_ of
libstdc++ into the resultant executable. This is good from an
optimization standpoint, but obviously results in a larger executable. In
time, we will deal with this, but for now, there isn't a wonderful
solution to this.
Note that you can more directly compare by compiling your program with
'-c', which will not link in libstdc++, or by using 'llvmgcc' to link the
program, which will not link it in either. This should allow you to
compare the sizes of the programs. For another comparison, on my redhat
8.0 system, the native /usr/lib/libstdc++.so.5.0.1 is 4.1MB by itself.
I rebuild the cfrontend in RH linux9.0, but when I build the hello.cpp
the llvmG++ reports warnings too, it shows:
I'll leave this one to John, but the warnings are probably ignorable. 
-Chris
[yue@RH9 Shootout-C++]$ llvmg++ -v hello.cpp -o hello
Reading specs from
/home/yue/cfrontend/install/lib/gcc/i686-pc-linux-gnu/3.4-llvm/specs
Configured with: '../src/configure'
'--prefix=/home/yue/cfrontend/install '--disable-threads '--disable-nls
'--disable-shared '--enable-languages=c,c++ : (reconfigured)
'../src/configure' '--prefix=/home/yue/cfrontend/install
'--disable-threads '--disable-nls '--disable-shared
'--enable-languages=c,c++
Thread model: single
gcc version 3.4-llvm 20030827 (experimental)/home/yue/cfrontend/install/libexec/gcc/i686-pc-linux-gnu/3.4-llvm/cc1plus
-quiet -v -D_GNU_SOURCE hello.cpp -quiet -dumpbase hello.cpp
-mtune=pentiumpro -auxbase hello -version -o /tmp/ccb5CDSP.s
ignoring nonexistent directory
"/home/yue/cfrontend/install/lib/gcc/i686-pc-linux-gnu/3.4-llvm/../../../../i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:/home/yue/cfrontend/install/lib/gcc/i686-pc-linux-gnu/3.4-llvm/../../../../include/c++/3.4-llvm
/home/yue/cfrontend/install/lib/gcc/i686-pc-linux-gnu/3.4-llvm/../../../../include/c++/3.4-llvm/i686-pc-linux-gnu
/home/yue/cfrontend/install/lib/gcc/i686-pc-linux-gnu/3.4-llvm/../../../../include/c++/3.4-llvm/backward
/usr/local/include
/home/yue/cfrontend/install/include
/home/yue/cfrontend/install/lib/gcc/i686-pc-linux-gnu/3.4-llvm/include
/usr/include
End of search list.
GNU C++ version 3.4-llvm 20030827 (experimental) (i686-pc-linux-gnu)
compiled by GNU C version 3.2.2 20030222 (Red Hat Linux 3.2.2-5).
GGC heuristics: --param ggc-min-expand=55 --param ggc-min-heapsize=48067
gccas -o /tmp/ccppFGsT.o /tmp/ccb5CDSP.s
gccld -o hello
-L/home/yue/cfrontend/install/lib/gcc/i686-pc-linux-gnu/3.4-llvm
-L/home/yue/cfrontend/install/lib/gcc/i686-pc-linux-gnu/3.4-llvm/../../..
/tmp/ccppFGsT.o -lstdc++ -lm -lc -lcrtend
WARNING: Found global types that are not compatible:
[16 x sbyte]* %_ZN9__gnu_cxx10messages_cE
"struct.std::messages<char>"* %_ZN9__gnu_cxx10messages_cE
WARNING: Found global types that are not compatible:
[16 x sbyte]* %_ZN9__gnu_cxx10messages_wE
"struct.std::messages<char>"* %_ZN9__gnu_cxx10messages_wE
WARNING: Found global types that are not compatible:
[12 x sbyte]* %_ZN9__gnu_cxx10numpunct_cE
"struct.std::numpunct<char>"* %_ZN9__gnu_cxx10numpunct_cE
WARNING: Found global types that are not compatible:
[12 x sbyte]* %_ZN9__gnu_cxx10numpunct_wE
"struct.std::numpunct<wchar_t>"* %_ZN9__gnu_cxx10numpunct_wE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx10time_get_cE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx10time_get_cE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx10time_get_wE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx10time_get_wE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx10time_put_cE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx10time_put_cE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx10time_put_wE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx10time_put_wE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx11money_get_cE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx11money_get_cE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx11money_get_wE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx11money_get_wE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx11money_put_cE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx11money_put_cE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx11money_put_wE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx11money_put_wE
WARNING: Found global types that are not compatible:
[20 x sbyte]* %_ZN9__gnu_cxx11timepunct_cE
"struct.std::__timepunct<char>"* %_ZN9__gnu_cxx11timepunct_cE
WARNING: Found global types that are not compatible:
[20 x sbyte]* %_ZN9__gnu_cxx11timepunct_wE
"struct.std::__timepunct<wchar_t>"* %_ZN9__gnu_cxx11timepunct_wE
WARNING: Found global types that are not compatible:
[36 x sbyte]* %_ZN9__gnu_cxx12buf_cin_syncE"struct.__gnu_cxx::stdio_sync_filebuf<char,std::char_traits<char> >"*
%_ZN9__gnu_cxx12buf_cin_syncE
WARNING: Found global types that are not compatible:
[36 x sbyte]* %_ZN9__gnu_cxx13buf_cerr_syncE"struct.__gnu_cxx::stdio_sync_filebuf<char,std::char_traits<char> >"*
%_ZN9__gnu_cxx13buf_cerr_syncE
WARNING: Found global types that are not compatible:
[36 x sbyte]* %_ZN9__gnu_cxx13buf_cout_syncE"struct.__gnu_cxx::stdio_sync_filebuf<char,std::char_traits<char> >"*
%_ZN9__gnu_cxx13buf_cout_syncE
WARNING: Found global types that are not compatible:
[36 x sbyte]* %_ZN9__gnu_cxx13buf_wcin_syncE"struct.__gnu_cxx::stdio_sync_filebuf<wchar_t,std::char_traits<wchar_t>
>"* %_ZN9__gnu_cxx13buf_wcin_syncE
WARNING: Found global types that are not compatible:
[20 x sbyte]* %_ZN9__gnu_cxx13c_locale_implE
"struct.std::locale::_Impl"* %_ZN9__gnu_cxx13c_locale_implE
WARNING: Found global types that are not compatible:
[12 x sbyte]* %_ZN9__gnu_cxx13moneypunct_cfE
"struct.std::moneypunct<char, false>"*
%_ZN9__gnu_cxx13moneypunct_cfE
WARNING: Found global types that are not compatible:
[12 x sbyte]* %_ZN9__gnu_cxx13moneypunct_ctE
"struct.std::moneypunct<char, false>"*
%_ZN9__gnu_cxx13moneypunct_ctE
WARNING: Found global types that are not compatible:
[12 x sbyte]* %_ZN9__gnu_cxx13moneypunct_wfE
"struct.std::moneypunct<wchar_t, false>"*
%_ZN9__gnu_cxx13moneypunct_wfE
WARNING: Found global types that are not compatible:
[12 x sbyte]* %_ZN9__gnu_cxx13moneypunct_wtE
"struct.std::moneypunct<wchar_t, false>"*
%_ZN9__gnu_cxx13moneypunct_wtE
WARNING: Found global types that are not compatible:
[36 x sbyte]* %_ZN9__gnu_cxx14buf_wcerr_syncE"struct.__gnu_cxx::stdio_sync_filebuf<wchar_t,std::char_traits<wchar_t>
>"* %_ZN9__gnu_cxx14buf_wcerr_syncE
WARNING: Found global types that are not compatible:
[36 x sbyte]* %_ZN9__gnu_cxx14buf_wcout_syncE"struct.__gnu_cxx::stdio_sync_filebuf<wchar_t,std::char_traits<wchar_t>
>"* %_ZN9__gnu_cxx14buf_wcout_syncE
WARNING: Found global types that are not compatible:
[92 x sbyte]* %_ZN9__gnu_cxx16numpunct_cache_cE
"struct.std::__numpunct_cache<char>"*
%_ZN9__gnu_cxx16numpunct_cache_cE
WARNING: Found global types that are not compatible:
[292 x sbyte]* %_ZN9__gnu_cxx16numpunct_cache_wE
"struct.std::__numpunct_cache<wchar_t>"*
%_ZN9__gnu_cxx16numpunct_cache_wE
WARNING: Found global types that are not compatible:
[200 x sbyte]* %_ZN9__gnu_cxx17timepunct_cache_cE
"struct.std::__timepunct_cache<char>"*
%_ZN9__gnu_cxx17timepunct_cache_cE
WARNING: Found global types that are not compatible:
[200 x sbyte]* %_ZN9__gnu_cxx17timepunct_cache_wE
"struct.std::__timepunct_cache<wchar_t>"*
%_ZN9__gnu_cxx17timepunct_cache_wE
WARNING: Found global types that are not compatible:
[44 x sbyte]* %_ZN9__gnu_cxx19moneypunct_cache_cfE
"struct.std::__moneypunct_cache<char>"*
%_ZN9__gnu_cxx19moneypunct_cache_cfE
WARNING: Found global types that are not compatible:
[44 x sbyte]* %_ZN9__gnu_cxx19moneypunct_cache_ctE
"struct.std::__moneypunct_cache<char>"*
%_ZN9__gnu_cxx19moneypunct_cache_ctE
WARNING: Found global types that are not compatible:
[52 x sbyte]* %_ZN9__gnu_cxx19moneypunct_cache_wfE
"struct.std::__moneypunct_cache<wchar_t>"*
%_ZN9__gnu_cxx19moneypunct_cache_wfE
WARNING: Found global types that are not compatible:
[52 x sbyte]* %_ZN9__gnu_cxx19moneypunct_cache_wtE
"struct.std::__moneypunct_cache<wchar_t>"*
%_ZN9__gnu_cxx19moneypunct_cache_wtE
WARNING: Found global types that are not compatible:
[96 x sbyte]* %_ZN9__gnu_cxx7buf_cinE
"struct.__gnu_cxx::stdio_filebuf<char,std::char_traits<char>
>"* %_ZN9__gnu_cxx7buf_cinE
WARNING: Found global types that are not compatible:
[28 x sbyte]* %_ZN9__gnu_cxx7ctype_cE
"struct.std::ctype<char>"* %_ZN9__gnu_cxx7ctype_cE
WARNING: Found global types that are not compatible:
[12 x sbyte]* %_ZN9__gnu_cxx7ctype_wE
"struct.std::codecvt<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx7ctype_wE
WARNING: Found global types that are not compatible:
[96 x sbyte]* %_ZN9__gnu_cxx8buf_cerrE
"struct.__gnu_cxx::stdio_filebuf<char,std::char_traits<char>
>"* %_ZN9__gnu_cxx8buf_cerrE
WARNING: Found global types that are not compatible:
[96 x sbyte]* %_ZN9__gnu_cxx8buf_coutE
"struct.__gnu_cxx::stdio_filebuf<char,std::char_traits<char>
>"* %_ZN9__gnu_cxx8buf_coutE
WARNING: Found global types that are not compatible:
[96 x sbyte]* %_ZN9__gnu_cxx8buf_wcinE"struct.__gnu_cxx::stdio_filebuf<wchar_t,std::char_traits<wchar_t> >"*
%_ZN9__gnu_cxx8buf_wcinE
WARNING: Found global types that are not compatible:
[4 x sbyte]* %_ZN9__gnu_cxx8c_localeE
"struct.std::locale"* %_ZN9__gnu_cxx8c_localeE
WARNING: Found global types that are not compatible:
[12 x [4 x sbyte]]* %_ZN9__gnu_cxx8name_vecE
[12 x sbyte*]* %_ZN9__gnu_cxx8name_vecE
WARNING: Found global types that are not compatible:
[96 x sbyte]* %_ZN9__gnu_cxx9buf_wcerrE"struct.__gnu_cxx::stdio_filebuf<wchar_t,std::char_traits<wchar_t> >"*
%_ZN9__gnu_cxx9buf_wcerrE
WARNING: Found global types that are not compatible:
[96 x sbyte]* %_ZN9__gnu_cxx9buf_wcoutE"struct.__gnu_cxx::stdio_filebuf<wchar_t,std::char_traits<wchar_t> >"*
%_ZN9__gnu_cxx9buf_wcoutE
WARNING: Found global types that are not compatible:
[28 x [4 x sbyte]]* %_ZN9__gnu_cxx9cache_vecE
[28 x "struct.std::locale::facet"*]* %_ZN9__gnu_cxx9cache_vecE
WARNING: Found global types that are not compatible:
[12 x sbyte]* %_ZN9__gnu_cxx9codecvt_cE
"struct.std::codecvt<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx9codecvt_cE
WARNING: Found global types that are not compatible:
[12 x sbyte]* %_ZN9__gnu_cxx9codecvt_wE
"struct.std::codecvt<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx9codecvt_wE
WARNING: Found global types that are not compatible:
[12 x sbyte]* %_ZN9__gnu_cxx9collate_cE
"struct.std::collate<char>"* %_ZN9__gnu_cxx9collate_cE
WARNING: Found global types that are not compatible:
[12 x sbyte]* %_ZN9__gnu_cxx9collate_wE
"struct.std::collate<char>"* %_ZN9__gnu_cxx9collate_wE
WARNING: Found global types that are not compatible:
[28 x [4 x sbyte]]* %_ZN9__gnu_cxx9facet_vecE
[28 x "struct.std::locale::facet"*]* %_ZN9__gnu_cxx9facet_vecE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx9num_get_cE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx9num_get_cE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx9num_get_wE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx9num_get_wE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx9num_put_cE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx9num_put_cE
WARNING: Found global types that are not compatible:
[8 x sbyte]* %_ZN9__gnu_cxx9num_put_wE
"struct.std::__codecvt_abstract_base<char,char,__mbstate_t>"*
%_ZN9__gnu_cxx9num_put_wE
WARNING: Found global types that are not compatible:
[144 x sbyte]* %_ZSt3cin
"struct.std::basic_istream<char,std::char_traits<char> >"*
%_ZSt3cin
WARNING: Found global types that are not compatible:
[140 x sbyte]* %_ZSt4cerr
"struct.std::basic_ostream<char,std::char_traits<char> >"*
%_ZSt4cerr
WARNING: Found global types that are not compatible:
[140 x sbyte]* %_ZSt4clog
"struct.std::basic_ostream<char,std::char_traits<char> >"*
%_ZSt4clog
WARNING: Found global types that are not compatible:
"struct.std::basic_ostream<char,std::char_traits<char> >"*
%_ZSt4cout
[140 x sbyte]* %_ZSt4cout
WARNING: Found global types that are not compatible:
[148 x sbyte]* %_ZSt4wcin
"struct.std::basic_istream<wchar_t,std::char_traits<wchar_t>
>"* %_ZSt4wcin
WARNING: Found global types that are not compatible:
[144 x sbyte]* %_ZSt5wcerr
"struct.std::basic_ostream<wchar_t,std::char_traits<wchar_t>
>"* %_ZSt5wcerr
WARNING: Found global types that are not compatible:
[144 x sbyte]* %_ZSt5wclog
"struct.std::basic_ostream<wchar_t,std::char_traits<wchar_t>
>"* %_ZSt5wclog
WARNING: Found global types that are not compatible:
[144 x sbyte]* %_ZSt5wcout
"struct.std::basic_ostream<wchar_t,std::char_traits<wchar_t>
>"* %_ZSt5wcout
[yue@RH9 Shootout-C++]$
-------------------------------------------yueqiang
2003/12/22_______________________________________________
LLVM Developers mailing list
LLVMdev@cs.uiuc.edu http://llvm.cs.uiuc.edu
http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev
-Chris
yue wrote:
hi,
I try to build hello.cpp using both llvmg++ and GNU g++,
the generate llvm bytecode's size is about 960K,
and the size of binary code generated by g++ is only 13K.Could anyone explain the difference between the two result?
The difference, most likely, is that LLVM only supports static linking with LLVM bytecode libraries (presently; this may change in the future). In the case of a C++ program, libstdc++ is statically linked in by llvmg++, but dynamically linked in by regular g++.
BWT:
I rebuild the cfrontend in RH linux9.0, but when I build the hello.cpp the llvmG++ reports warnings too, it shows:
I'll have to look into the warnings; I don't know off hand why you're getting them.
Would you be able to post your hello.cpp file to llvmdev? Now that I think of it, I don't think I've ever seen it before. Having an exact copy of it might help.
Thanks.
Regards,
John T. Criswell