https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77438
Bug ID: 77438
Summary: MMX intrinsic on x86_64 generates bloated code
Product: gcc
Version: 4.8.4
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: acahalan at gmail dot com
Target Milestone: ---
__m64 __attribute__((noinline)) mmx(__m64 x, __m64 y){return _mm_add_pi8(x,y);}
That gives 6 lines of assembly. (movq,movdq2q,paddb,movq,movq,ret) Stuff even
gets moved to the stack. Good code would just do the operation in an xmm
register instead of moving it to a mm register. Failing that, gcc could at
least avoid using the stack.
