Unintentional use of SSE

[Andrew Gaul]

Some code unintentionally uses SSE:

unsigned int fp_func(unsigned int x) { return x * 0.8; }
unsigned int int_func(unsigned int x) { return x * 10 / 8; }

The integer version is shorter and more efficient:

$ gcc -O2 -S -o - foo.c | as -al
...
   9 0000 89FF           movl %edi,%edi
  10 0002 660FEFC0       pxor %xmm0,%xmm0
  11 0006 F2480F2A       cvtsi2sdq %rdi,%xmm0
  11      C7
  12 000b F20F5905       mulsd .LC0(%rip),%xmm0
  12      00000000 
  13 0013 F2480F2C       cvttsd2siq %xmm0,%rax
  13      C0
  14 0018 C3             ret
...
  24 0020 8D04BF         leal (%rdi,%rdi,4),%eax
  25 0023 01C0           addl %eax,%eax
  26 0025 C1E803         shrl $3,%eax
  27 0028 C3             ret
...
  33                    .LC0:
  34 0000 9A999999       .long -1717986918
  35 0004 9999E93F       .long 1072273817