by changing some integer regular arithmetic to bitwise operations.
I'm not sure that would make any difference if I used optimized
compilation, but it might still make a difference on some old
compilers.
It seems to make a difference on gcc without optimization on my Linux
machine (and, of course, it does not break the tests).
Before:
real 1m6,707s
user 1m6,035s
sys 0m0,672s
After:
real 1m6,352s
user 1m5,672s
sys 0m0,680s
The full test suite runs fine and the performance numbers are:
Before:
real 1m7,040s
user 1m6,319s
sys 0m0,716s
After:
real 1m6,707s
user 1m6,035s
sys 0m0,672s
Not bad. But mostly, it saves stack. Nice. :-)
The large arrays are now allocated on heap instead of in BSS. This
actually feels like a pretty stupid linker limitation, and the
workaround leads to code that is less readable. But it only impacts
the test program.
The issue was reported with GCC 7.3.0 and compiling for 64-bit arch on
MSYS2's MinGW compiler. GCC 7.3.0 for 64-bit on Linux (my own machine
and Travis) seems perfectly OK with a large BSS segment (around 3 GB
is what the test program uses for test data).
Reported issue:
$ make
cc -Wall -Wextra -Wpedantic -c -o test.o test.c
cc -Wall -Wextra -Wpedantic -c -o sha-256.o sha-256.c
cc test.o sha-256.o -o test
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/crt2.o: in function `__tmainCRTStartup':
C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/crtexe.c:251:(.text+0x1cd): relocation truncated to fit: R_X86_64_PC32 against symbol `__imp_Sleep' defined in .idata$5 section in C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libkernel32.a(dkhchs01360.o)
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/crtexe.c:278:(.text+0x255): relocation truncated to fit: R_X86_64_PC32 against symbol `__imp_SetUnhandledExceptionFilter' defined in .idata$5 section in C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libkernel32.a(dkhchs01346.o)
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/crtexe.c:286:(.text+0x283): relocation truncated to fit: R_X86_64_PC32 against symbol `__mingw_winmain_hInstance' defined in COMMON section in C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/crt2.o
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/crtexe.c:312:(.text+0x2f3): relocation truncated to fit: R_X86_64_PC32 against symbol `__mingw_winmain_lpCmdLine' defined in COMMON section in C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/crt2.o
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/crtexe.c:238:(.text+0x475): relocation truncated to fit: R_X86_64_PC32 against symbol `__imp_GetStartupInfoA' defined in .idata$5 section in C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libkernel32.a(dkhchs00721.o)
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libmingw32.a(lib64_libmingw32_a-gccmain.o): in function `__main':
C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/gccmain.c:74:(.text+0xb2): relocation truncated to fit: R_X86_64_PC32 against `.bss'
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/gccmain.c:76:(.text+0xc2): relocation truncated to fit: R_X86_64_PC32 against `.bss'
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libmingw32.a(lib64_libmingw32_a-charmax.o): in function `my_lconv_init':
C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/charmax.c:19:(.text+0x3): relocation truncated to fit: R_X86_64_PC32 against symbol `__imp___lconv_init' defined in .idata$5 section in C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libmsvcrt.a(dkxcbs00090.o)
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libmingw32.a(lib64_libmingw32_a-gs_support.o): in function `__security_init_cookie':
C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/gs_support.c:62:(.text+0x47): relocation truncated to fit: R_X86_64_PC32 against symbol `__imp_GetSystemTimeAsFileTime' defined in .idata$5 section in C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libkernel32.a(dkhchs00746.o)
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/gs_support.c:70:(.text+0x52): relocation truncated to fit: R_X86_64_PC32 against symbol `__imp_GetCurrentProcessId' defined in .idata$5 section in C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libkernel32.a(dkhchs00536.o)
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/gs_support.c:71:(.text+0x5b): additional relocation overflows omitted from the output
collect2.exe: error: ld returned 1 exit status
make: *** [<builtin>: test] Error 1```
Alain Mosnier