Improving Performance with Interprocedural Optimization
The compiler may be able to perform additional optimizations if it is able to optimize across source line boundaries. These may include, but are not limited to, function inlining. This is enabled with the -ipo option.
Recompile the program using the -ipo option to enable interprocedural optimization.
icc -std=c99 -qopt-report=2 -qopt-report-phase=vec -D NOALIAS -D ALIGNED -ipo Multiply.c Driver.c -o MatVector
Note that the vectorization messages now appear at the point of inlining in Driver.c (line 150) and this is found in the file ipo_out.optrpt.
LOOP BEGIN at Driver.c(152,16) remark #15542: loop was not vectorized: inner loop was already vectorized LOOP BEGIN at Multiply.c(37,5) inlined into Driver.c(150,9) remark #15542: loop was not vectorized: inner loop was already vectorized LOOP BEGIN at Multiply.c(49,9) inlined into Driver.c(150,9) remark #15300: LOOP WAS VECTORIZED LOOP END LOOP BEGIN at Multiply.c(49,9) inlined into Driver.c(150,9) <Remainder loop for vectorization> remark #15335: remainder loop was not vectorized: vectorization possible but seems inefficient. Use vector always directive or -vec-threshold0 to override LOOP END LOOP END LOOP END LOOP BEGIN at Driver.c(74,5) inlined into Driver.c(159,5) remark #15300: LOOP WAS VECTORIZED LOOP END
Now, run the executable and record the execution time.
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