On Tue Nov 8 11, Dimitry Andric wrote:
> On 2011-11-08 22:04, Alexander Best wrote:
> ...
> > for me -march=native reports:
> >
> > otaku% gcc -march=native -E -v - </dev/null
> > Using built-in specs.
> > Target: amd64-undermydesk-freebsd
> > Configured with: FreeBSD/amd64 system compiler
> > Thread model: posix
> > gcc version 4.2.2 20070831 prerelease [FreeBSD]
> > /usr/libexec/cc1 -E -quiet -v -D_LONGLONG - -march=nocona -mtune=generic
> > #include "..." search starts here:
> > #include <...> search starts here:
> > /usr/include/gcc/4.2
> > /usr/include
> > End of search list.
> > # 1 "<stdin>"
> > # 1 "<built-in>"
> > # 1 "<command-line>"
> > # 1 "<stdin>"
> >
> > where instead of nocona, core2 would have been the better choice:
> >
> > [1.000000] CPU: Intel(R) Pentium(R) Dual CPU E2160 @ 1.80GHz
> > (1800.00-MHz K8-class CPU)
> > [1.000000] Origin = "GenuineIntel" Id = 0x6fd Family = 6 Model = f
> > Stepping = 13
> > [1.000000]
> > Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
> > [1.000000]
> > Features2=0xe39d<SSE3,DTES64,MON,DS_CPL,EST,TM2,SSSE3,CX16,xTPR,PDCM>
> > [1.000000] AMD Features=0x20100800<SYSCALL,NX,LM>
> > [1.000000] AMD Features2=0x1<LAHF>
> > [1.000000] TSC: P-state invariant, performance statistics
>
> That's weird, the logic in gcc goes:
>
> cpuid (1, eax, ebx, ecx, edx);
> ...
> has_ssse3 = !!(ecx & bit_SSSE3);
> ...
> if (arch)
> {
> if (has_ssse3)
> cpu = "core2";
> else if (has_sse3)
> {
> if (has_longmode)
> cpu = "nocona";
> else
> cpu = "prescott";
> }
> else if (has_sse2)
> cpu = "pentium4";
> else if (has_cmov)
> cpu = "pentiumpro";
> else if (has_mmx)
> cpu = "pentium-mmx";
> else if (has_cmpxchg8b)
> cpu = "pentium";
> else
> cpu = "i386";
> }
> else
> cpu = "generic";
> goto done;
>
> E.g. it seems to conclude your cpu *doesn't* have SSSE3, but does have
> long mode, and thus jumps to nocona.
>
> You might be able to debug this, by putting some printfs in this
> function. :)
same on ref9-amd64.freebsd.org:
ref9-amd64% clang -march=native -### blabla.c
FreeBSD clang version 3.0 (trunk 135360) 20110717
Target: x86_64-unknown-freebsd9.0
Thread model: posix
"/usr/bin/clang" "-cc1" "-triple" "x86_64-unknown-freebsd9.0" "-emit-obj"
"-mrelax-all" "-disable-free" "-main-file-name" "tower.c" "-mrelocation-model"
"static" "-mdisable-fp-elim" "-masm-verbose" "-mconstructor-aliases"
"-munwind-tables" "-target-cpu" "core2" "-momit-leaf-frame-pointer"
"-resource-dir" "/usr/bin/../lib/clang/3.0" "-ferror-limit" "19"
"-fmessage-length" "275" "-fdiagnostics-show-option" "-fcolor-diagnostics" "-o"
"/tmp/cc-ImChyq.o" "-x" "c" "tower.c"
"/usr/bin/ld" "--eh-frame-hdr" "-dynamic-linker" "/libexec/ld-elf.so.1" "-o"
"tower" "/usr/lib/crt1.o" "/usr/lib/crti.o" "/usr/lib/crtbegin.o" "-L/usr/lib"
"/tmp/cc-ImChyq.o" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc"
"-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "/usr/lib/crtend.o"
"/usr/lib/crtn.o"
BUT
ref9-amd64% gcc -march=native -E -v - </dev/null
Using built-in specs.
Target: amd64-undermydesk-freebsd
Configured with: FreeBSD/amd64 system compiler
Thread model: posix
gcc version 4.2.2 20070831 prerelease [FreeBSD]
/usr/libexec/cc1 -E -quiet -v -D_LONGLONG - -march=nocona -mtune=generic
#include "..." search starts here:
#include <...> search starts here:
/usr/include/gcc/4.2
/usr/include
End of search list.
# 1 "<stdin>"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "<stdin>"
cheers.
alex
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