On 05/25/2010 09:28 AM, Amker.Cheng wrote: > Hi all, > I compared assembly files of a function compiled by GCC4.3.4 and GCC3.4.4. > The function focuses on array computation and has no branch, or any > loop structure, > The command line is like "-march=mips32r2 -O3", and here is the > instruction statics: > > total : 1879 : 1534 > addiu : 6 : 6 > addu : 216 : 129 > jr : 1 : 1 > lui : 5 : 5 > lw : 396 : 353 > madd : 41 : 0 > mfhi : 80 : 80 > mflo : 121 : 86 > move : 0 : 21 > mtlo : 39 : 0 > mul : 85 : 0 > mult : 18 : 80 > multu : 64 : 0 > or : 80 : 80 > sll : 80 : 80 > sra : 79 : 47 > srl : 80 : 80 > subu : 80 : 80 > sw : 408 : 406 > > Considering there is no any branch or loop structure ,It seems result > of GCC3.4.4 > is much better, since generating much less instructions. > > secondly, GCC4.3.4 does consume less stack slots(1224 bytes against 1408). > > So, any comments? Thanks in advance. You're using -O3, which means "optimize as much as possible, don't worry about code size". Andrew.
