On 30/09/2016 05:04, waltdnes@xxxxxxxxxxxx wrote: > On Thu, Sep 29, 2016 at 10:21:46AM +0100, Andrew Haley wrote > >> That sounds fine. Intel have used the "Atom" trademark to refer to >> Bonnell, Silvermont, and Goldmont processors. We like to be more >> specific. > > Thanks. For future reference, what does "-march=atom" do? Do I get > a "bonnell" build, or generic, or something else? As far as I can tell, the -march=atom option was documented until gcc 4.8 https://gcc.gnu.org/onlinedocs/gcc-4.8.4/gcc/i386-and-x86-64-Options.html 'atom' Intel Atom CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3 and SSSE3 instruction set support. Then they changed the doc for gcc 4.9 'bonnell' Intel Bonnell CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3 and SSSE3 instruction set support. 'silvermont' Intel Silvermont CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, AES, PCLMUL and RDRND instruction set support. It does look like 'atom' and 'bonnell' are similar. I don't have 4.9 handy, try this: echo | gcc -xc -S -fverbose-asm -march=atom -o v1.s - echo | gcc -xc -S -fverbose-asm -march=bonnell -o v2.s - diff -u v1.s v2.s Maybe they are identical? Regards.
