Summary: | Tree-vectorizer: VecCost tuning for X2: Without vectorization 30% faster | ||
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Product: | gcc | Reporter: | Tobias Burnus <burnus> |
Component: | tree-optimization | Assignee: | Not yet assigned to anyone <unassigned> |
Status: | UNCONFIRMED --- | ||
Severity: | normal | CC: | burnus, gcc-bugs |
Priority: | P3 | Keywords: | missed-optimization |
Version: | 4.5.0 | ||
Target Milestone: | --- | ||
Host: | Target: | ||
Build: | Known to work: | ||
Known to fail: | Last reconfirmed: | ||
Bug Depends on: | |||
Bug Blocks: | 53947 |
Description
Tobias Burnus
2009-08-19 07:46:53 UTC
Link to vectorizer missed-optimization meta-bug. Adding CC. It would be nice to see where we are today with respect to the cost model / vectorizing / not vectorizing. (In reply to comment #3) > It would be nice to see where we are today with respect to the cost model / > vectorizing / not vectorizing. Answer: It became much worse (compared to GCC 4.5 of comment 0): Using gcc version 4.8.0 20130308 [trunk revision 196547], the induct runtimes are: gfortran -march=native -ffast-math -O3 -ftree-vectorize -fvect-cost-model induct.f90 real 0m47.142s / user 0m47.072s / sys 0m0.020s gfortran-4.8 -march=native -ffast-math -O3 -ftree-vectorize -fno-vect-cost-model induct.f90 real 0m35.713s / user 0m35.236s / sys 0m0.052s time gfortran-4.8 -march=native -ffast-math -O3 -fno-tree-vectorize induct.f90 real 0m47.837s / user 0m47.388s / sys 0m0.028s real 0m47.514s / user 0m47.428s / sys 0m0.044s gfortran -march=opteron -ffast-math -funroll-loops -fno-tree-vectorize -ftree-loop-linear -msse3 -O3 induct.f90 real 0m44.676s / user 0m44.640s / sys 0m0.032s gfortran-4.5 -march=opteron -ffast-math -funroll-loops -fno-tree-vectorize -ftree-loop-linear -msse3 -O3 induct.f90; time ./a.out real 0m34.591s / user 0m34.524s / sys 0m0.020s |