http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54966
--- Comment #9 from vincenzo Innocente <vincenzo.innocente at cern dot ch>
2012-11-09 06:52:22 UTC ---
better and worse!
better than 4.7.2
lto is worse in 4.8
Attached is a test case, just one file
bzip2 -d smatrix.ii.bz2
the main component is this
three different way of computing the same matrix multiplication with more and
more
explicit temporaries..
tvc =
//33 3N NN NM MM
-ve * (Transpose(a)) * tw * b * s;
}
void compute2() {
// NM NM MM
AlgebraicMatrixNM twbs = tw * b * s;
tvc =
//33 3N
-ve * (Transpose(a)) * twbs;
}
void compute3() {
// NM NM MM
AlgebraicMatrixNM twbs = tw * b * s;
// 33 3N
AlgebraicMatrix3N tmpM1 = -ve * (Transpose(a));
tvc = tmpM1 * twbs;
}
timing is in cycle using __rdtsc(); on Inel x86_64
stability maybe 10%…
Target: x86_64-unknown-linux-gnu
gcc version 4.7.2 (GCC)
[vocms123] ~/public/ctest/bugs48 $ c++ -O2 smatrix.ii; ./a.out
size 5. v1: time in cycles 30159.6
size 5. v2: time in cycles 6031.1
size 5. v3: time in cycles 3388.17
size 6. v1: time in cycles 60336.6
size 6. v2: time in cycles 10366.8
size 6. v3: time in cycles 5955.81
[vocms123] ~/public/ctest/bugs48 $ c++ -O2 smatrix.ii -flto; ./a.out
size 5. v1: time in cycles 12818.8
size 5. v2: time in cycles 10453.9
size 5. v3: time in cycles 5954.23
size 6. v1: time in cycles 46293.1
size 6. v2: time in cycles 12309.2
size 6. v3: time in cycles 11621.8
[vocms123] ~/public/ctest/bugs48 $ c++ -O3 smatrix.ii; ./a.out
size 5. v1: time in cycles 39630.3
size 5. v2: time in cycles 5869.96
size 5. v3: time in cycles 1966.87
size 6. v1: time in cycles 69531.4
size 6. v2: time in cycles 9020.06
size 6. v3: time in cycles 4732.99
[vocms123] ~/public/ctest/bugs48 $ c++ -O3 smatrix.ii -flto; ./a.out
size 5. v1: time in cycles 12425.1
size 5. v2: time in cycles 9650.03
size 5. v3: time in cycles 5340.79
size 6. v1: time in cycles 45998
size 6. v2: time in cycles 11128.1
size 6. v3: time in cycles 10383
gcc version 4.8.0 20121108 (experimental) [trunk revision 193333] (GCC)
[vocms123] ~/public/ctest/bugs48 $ c++ -O2 smatrix.ii ; ./a.out
size 5. v1: time in cycles 14040.5
size 5. v2: time in cycles 3264.85
size 5. v3: time in cycles 3457.25
size 6. v1: time in cycles 37368.4
size 6. v2: time in cycles 5813.81
size 6. v3: time in cycles 6224.37
[vocms123] ~/public/ctest/bugs48 $ c++ -O2 smatrix.ii -flto ; ./a.out
size 5. v1: time in cycles 20705.2
size 5. v2: time in cycles 6333.17
size 5. v3: time in cycles 6654.85
size 6. v1: time in cycles 49788.8
size 6. v2: time in cycles 6828.72
size 6. v3: time in cycles 7188.28
[vocms123] ~/public/ctest/bugs48 $ c++ -O3 smatrix.ii ; ./a.out
size 5. v1: time in cycles 17350.4
size 5. v2: time in cycles 2355.68
size 5. v3: time in cycles 1891.62
size 6. v1: time in cycles 38002
size 6. v2: time in cycles 4046.09
size 6. v3: time in cycles 3954.97
[vocms123] ~/public/ctest/bugs48 $ c++ -O3 smatrix.ii -flto; ./a.out
size 5. v1: time in cycles 20380.9
size 5. v2: time in cycles 4504.76
size 5. v3: time in cycles 4576.5
size 6. v1: time in cycles 42327.9
size 6. v2: time in cycles 3405.72
size 6. v3: time in cycles 3314.2
stability test
[vocms123] ~/public/ctest/bugs48 $ c++ -O3 smatrix.ii -flto ; ./a.out
size 5. v1: time in cycles 20447.2
size 5. v2: time in cycles 4509.64
size 5. v3: time in cycles 4580.46
size 6. v1: time in cycles 42361.2
size 6. v2: time in cycles 3407.53
size 6. v3: time in cycles 3316.36
[vocms123] ~/public/ctest/bugs48 $ ./a.out
size 5. v1: time in cycles 23968.7
size 5. v2: time in cycles 5277.67
size 5. v3: time in cycles 5353.72
size 6. v1: time in cycles 49573
size 6. v2: time in cycles 4023.34
size 6. v3: time in cycles 3862.6
