Hi Brian, Daniel, and Andrew, You demystify the deferentiated implementations of ABIs over 64-bit AMD Opteron vs. 32-bit P4/P5 architectures; and the corresponding interpretations of "sizeof" from the GNU/GCC compiler. I understand them mostly now. I will write a parser in Perl to sift out from C/C++ code the ambiguous "typedef", which result in different sizes in 64-bit vs. 32-bit ELF binaries. I will unify the usage of the C/C++ data types and modifiers from the following lists, which have the same sizes for both 64-bit and 32-bit. size of int 4 size of float 4 size of double 8 size of char 1 size of bool 1 size of char 1 size of unsigned char 1 size of signed char 1 size of unsigned int 4 size of signed int 4 size of short int 2 size of unsigned short int 2 size of signed short int 2 Daniel's class template way is practical; I will refer it in future projects. Tom Andrew Haley-5 wrote: > > tom peng writes: > > > Thanks for correcting my typo on "signed long int 4 8". > > > > The problem I have here is about simulating a hardware model in C/C++. > The > > hardware model development was based on 32-bit CPU originally. We had > > presumed "signed long int" as 32-bit/4 byte length -- as specified in > C/C++ > > code "typedef signed long int int32". > > > > It is apparent that this "int32" in 64-bit ELF executable is of length > 8 > > bytes, not what we expect. It "might" cause the hw simulation > inconsistency > > when running in 64 vs. 32 ELF format. > > > > I hope to get a generic picture about the size difference of C/C++ data > type > > and their modifiers in 32/64 ELF format compiled by GCC. > > > > Are those 32-bit / 64-bit difference stipulated in C/C++ standard or > ruled > > by the GNU/GCC compiler? > > Neither of those. They are defined by the ABI, at > http://refspecs.freestandards.org/elf/x86_64-abi-0.95.pdf Page 12. > > GCC, as the system compiler, must conform to this specification. It > isn't something that we compiler writers get to decide for ourseleves. > > Andrew. > > -- View this message in context: http://www.nabble.com/Size-of-C-C%2B%2B-data-type-from-GNU-GCC-g%2B%2B-compiled-ELF-64-bit-LSB-executable%2C-AMD-x86-64-vs.-ELF-32-bit-LSB-executable%2C-Intel-80386-tf3942845.html#a11193485 Sent from the gcc - Help mailing list archive at Nabble.com.
