• Next Thread Prev Thread

• Posts   Search Threads

• pravinkenator August 14, 2011 11:23 PM PDT    Turning off loop blocking and unrolling Hello, I'm currently using icc version 12.0.4 20110427. I read in the compiler optimization manual that. -O3 option, by default switches on the loop unrolling and loop blocking. I want to turn off these optimizations. How to do it ? Aubrey W. (Intel) August 15, 2011 8:49 AM PDT Rate   #1 Turning off loop blocking and unrolling Hello, I will move this to our Intel(R) C++ Compiler forum where our engineers can have a look at your question. Best regards, == Aubrey W. Intel(R) Software Network Support TimP (Intel) August 15, 2011 9:07 AM PDT Rate   #2 Turning off loop blocking and unrolling There's a documented compiler switch -unroll0 which should turn off unrolling (beyond what is inherent in vectorization).  For an individual loop, $pragma unroll(0) or other pragmas may be useful. In general, -O2 is already fairly aggressive in most situations, and we've had to drop back to it frequently in order to avoid additional optimizations presented by -O3. If you mean loop distribution and fusion (altering the boundaries of for loops), besides considering -O2, you could consider placing #pragma distribute point immediately after the for(), so as to prevent the compiler from splitting the loop, or between loops, to prevent fusion.

• = Best Answer

  Next Thread Prev Thread

Intel Software Network Forums Statistics

17,025 users have contributed to 48,317 threads and 172,754 posts to date.

For more complete information about compiler optimizations, see our Optimization Notice.