------- Additional Comments From uros at kss-loka dot si 2004-11-05 08:00 ------- Another comment on code in comment #3:
LEA instruction uses only 32bit constant as a displacement. The code size of inner loop is considerably bigger in gcc-4.0 compiled code. (Note that LEA with a scale factor should be replaced by a shift in P4 case...) Another feature would be to use an %ecx as a count register in inner loops. In this case, TARGET_USE_LOOP architectures (such as K6) could use a loop insn for inner loops. gcc-4.0 (21 bytes) 23: 8d 04 d5 00 00 00 00 lea 0x0(,%edx,8),%eax 2a: dd 04 01 fldl (%ecx,%eax,1) 2d: dd 1c 03 fstpl (%ebx,%eax,1) 30: 83 c2 01 add $0x1,%edx 33: 39 55 0c cmp %edx,0xc(%ebp) 36: 7f eb jg 23 <LU_copy_matrix+0x23> gcc-3.2 (13 bytes): 22: dd 04 c2 fldl (%edx,%eax,8) 25: dd 1c c1 fstpl (%ecx,%eax,8) 28: 83 c0 01 add $0x1,%eax 2b: 39 f0 cmp %esi,%eax 2d: 7c f3 jl 22 <LU_copy_matrix+0x22> -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17647
