[cig-commits] [commit] devel, master: added a comment about -DFORCE_VECTORIZATION (567cb26)

[cig_noreply at geodynamics.org]

Repository : https://github.com/geodynamics/specfem3d_globe

On branches: devel,master
Link       : https://github.com/geodynamics/specfem3d_globe/compare/bc58e579b3b0838a0968725a076f5904845437ca...be63f20cbb6f462104e949894dbe205d2398cd7f

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commit 567cb265c435d1e46b899eb1f78c513813ff1561
Author: Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr>
Date:   Wed Apr 23 01:36:14 2014 +0200

    added a comment about -DFORCE_VECTORIZATION


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567cb265c435d1e46b899eb1f78c513813ff1561
 flags.guess | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/flags.guess b/flags.guess
index 3c0c454..c0afe83 100644
--- a/flags.guess
+++ b/flags.guess
@@ -5,6 +5,11 @@
 # can add -DUSE_SERIAL_CASCADE_FOR_IOs to the compiler options to make the mesher output mesh data
 # to the disk for one MPI slice after the other, and to make the solver do the same thing when reading the files back from disk.
 
+# can also add -DFORCE_VECTORIZATION to force vectorization and unrolling of some critical loops, however this breaks
+# range checking options at run time (for instance -check all for Intel ifort) and, more importantly, modern compilers
+# vectorize the SPECFEM3D_GLOBE code very well and in practice this option only makes the code 3% to 5% faster in the best case,
+# therefore we suggest not activating it.
+
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