Date: Tue, 08 Nov 2011 23:06:09 +0100 From: Dimitry Andric <dim@FreeBSD.org> To: Alexander Best <arundel@freebsd.org> Cc: freebsd-toolchain@freebsd.org Subject: Re: CPUTYPE=native handling Message-ID: <4EB9A7D1.9030800@FreeBSD.org> In-Reply-To: <20111108210420.GA37161@freebsd.org> References: <20111108002556.GA91218@freebsd.org> <4EB8E07B.5070908@FreeBSD.org> <20111108153856.GA90966@freebsd.org> <20111108210420.GA37161@freebsd.org>
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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. :)
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