Does gcc 4.8.1 enable sse by default?

Question

I experienced crashes running an old code of mine on a system which doesn't support SSE4.1, I debugged a bit and found SSE instructions in the glibc, is that possible? Why isn't this reported in gcc 4.8.1 release notes?

glibc isn't gcc and vice versa. Where exactly did you see what ? — nos, Nov 22 '13 at 16:57

Christophe Vu-Brugier · Accepted Answer · 2013-11-23T08:19:59.247

57

You can see what optimizations are used by GCC with the following command:

$ gcc -Q --help=target

For instance, on my machine, GCC does not enable sse4.1 by default:

$ gcc -Q --help=target | grep msse4.1
  -msse4.1                              [disabled]

However, it is supported because it appears in /proc/cpuinfo. And indeed, if I ask GCC to optimize the generated code for my machine, it enables sse4.1:

$ gcc -Q --help=target -march=native | grep msse4.1
  -msse4.1                              [enabled]

edited Nov 23 '13 at 08:19

answered Nov 22 '13 at 21:30

Christophe Vu-Brugier

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I forgot all about these options - I wish I could upvote multiple times. – Michael Burr Nov 22 '13 at 21:37
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This should be the answer of the day! Didn't know about this! Thanks! – higuaro Nov 22 '13 at 23:31

Does gcc 4.8.1 enable sse by default?

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