http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59444
Bug ID: 59444 Summary: [4.6.3 32-bit] Character buffers on stack not aligned on a 4-byte boundary. Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: vasiliy.v.buzoverya at intel dot com Created attachment 31408 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31408&action=edit Preprocessed file that triggers the bug. 4.6.3 on Ubuntu 12.04 32-bit. A function has two character buffers on stack(of 5 and 10 bytes in size). The addresses of the buffers won't get aligned on a 4-byte boundary even if the -mpreferred-stack-boundary=2 compilation option is specified. The addresses of the buffers are odd values, e.g. 0xbffff17f and 0xbffff175. Here's a snippet of assembler code: 0x080483e4 <+0>: push %ebp 0x080483e5 <+1>: mov %esp,%ebp 0x080483e7 <+3>: sub $0x20,%esp 0x080483ea <+6>: lea -0x9(%ebp),%eax ... 0x08048403 <+31>: lea -0x13(%ebp),%eax ... Build log: Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/i686-linux-gnu/4.6/lto-wrapper Target: i686-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.6.3-1ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.6 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable-objc-gc --enable-targets=all --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=i686-linux-gnu --host=i686-linux-gnu --target=i686-linux-gnu Thread model: posix gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-O0' '-mpreferred-stack-boundary=2' '-fno-stack-protector' '-mtune=generic' '-march=i686' /usr/lib/gcc/i686-linux-gnu/4.6/cc1 -E -quiet -v -imultilib . -imultiarch i386-linux-gnu example.c -mpreferred-stack-boundary=2 -mtune=generic -march=i686 -Wall -Wextra -fno-stack-protector -O0 -fpch-preprocess -o example.i ignoring nonexistent directory "/usr/local/include/i386-linux-gnu" ignoring nonexistent directory "/usr/lib/gcc/i686-linux-gnu/4.6/../../../../i686-linux-gnu/include" #include "..." search starts here: #include <...> search starts here: /usr/lib/gcc/i686-linux-gnu/4.6/include /usr/local/include /usr/lib/gcc/i686-linux-gnu/4.6/include-fixed /usr/include/i386-linux-gnu /usr/include End of search list. COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-O0' '-mpreferred-stack-boundary=2' '-fno-stack-protector' '-mtune=generic' '-march=i686' /usr/lib/gcc/i686-linux-gnu/4.6/cc1 -fpreprocessed example.i -quiet -dumpbase example.c -mpreferred-stack-boundary=2 -mtune=generic -march=i686 -auxbase example -O0 -Wall -Wextra -version -fno-stack-protector -o example.s GNU C (Ubuntu/Linaro 4.6.3-1ubuntu5) version 4.6.3 (i686-linux-gnu) compiled by GNU C version 4.6.3, GMP version 5.0.2, MPFR version 3.1.0-p3, MPC version 0.9 GGC heuristics: --param ggc-min-expand=63 --param ggc-min-heapsize=63477 GNU C (Ubuntu/Linaro 4.6.3-1ubuntu5) version 4.6.3 (i686-linux-gnu) compiled by GNU C version 4.6.3, GMP version 5.0.2, MPFR version 3.1.0-p3, MPC version 0.9 GGC heuristics: --param ggc-min-expand=63 --param ggc-min-heapsize=63477 Compiler executable checksum: 09c248eab598b9e2acb117da4cdbd785 COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-O0' '-mpreferred-stack-boundary=2' '-fno-stack-protector' '-mtune=generic' '-march=i686' as --32 -o example.o example.s COMPILER_PATH=/usr/lib/gcc/i686-linux-gnu/4.6/:/usr/lib/gcc/i686-linux-gnu/4.6/:/usr/lib/gcc/i686-linux-gnu/:/usr/lib/gcc/i686-linux-gnu/4.6/:/usr/lib/gcc/i686-linux-gnu/ LIBRARY_PATH=/usr/lib/gcc/i686-linux-gnu/4.6/:/usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu/:/usr/lib/gcc/i686-linux-gnu/4.6/../../../../lib/:/lib/i386-linux-gnu/:/lib/../lib/:/usr/lib/i386-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/i686-linux-gnu/4.6/../../../:/lib/:/usr/lib/ COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-O0' '-mpreferred-stack-boundary=2' '-fno-stack-protector' '-mtune=generic' '-march=i686' /usr/lib/gcc/i686-linux-gnu/4.6/collect2 --sysroot=/ --build-id --no-add-needed --as-needed --eh-frame-hdr -m elf_i386 --hash-style=gnu -dynamic-linker /lib/ld-linux.so.2 -z relro /usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu/crt1.o /usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu/crti.o /usr/lib/gcc/i686-linux-gnu/4.6/crtbegin.o -L/usr/lib/gcc/i686-linux-gnu/4.6 -L/usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu -L/usr/lib/gcc/i686-linux-gnu/4.6/../../../../lib -L/lib/i386-linux-gnu -L/lib/../lib -L/usr/lib/i386-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/i686-linux-gnu/4.6/../../.. example.o -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed /usr/lib/gcc/i686-linux-gnu/4.6/crtend.o /usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu/crtn.o