llvm, polly, 向量化测试，GEMM非常明显

1）这是OMP的

rm -f *.o3
clang -DLARGE_DATASET -O3 -mllvm -polly-omp-backend=LLVM -mllvm -polly-num-threads=2 -I/home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities    /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities/polybench.c  /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/stencils/jacobi-2d/jacobi-2d.c  -o a3.polly.o3
time ./a3.polly.o3

real    0m9.228s
user    0m9.016s
sys    0m0.169s

2）vectorizer的结果

a@a:~/src/a3.llvm.polly/a1.polybench-c-4.2$ rm -f *.o3
clang -DLARGE_DATASET -O3 -mllvm -polly -mllvm -polly-vectorizer=stripmine -I/home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities    /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities/polybench.c  /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/stencils/jacobi-2d/jacobi-2d.c  -o a3.polly.o3
time ./a3.polly.o3

real    0m9.078s
user    0m8.851s
sys    0m0.196s

3）对于GEMM，vectorizer效果非常明显。

rm -f *.o3
clang -DLARGE_DATASET -O3 -mllvm -polly-omp-backend=LLVM -mllvm -polly-num-threads=2 -I/home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities    /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities/polybench.c  /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/linear-algebra/blas/gemm/gemm.c  -o a3.polly.o3
time ./a3.polly.o3

rm -f *.o3
clang -DLARGE_DATASET -O3 -mllvm -polly -mllvm -polly-vectorizer=stripmine -I/home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities    /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities/polybench.c  /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/linear-algebra/blas/gemm/gemm.c  -o a3.polly.o3
time ./a3.polly.o3

real    0m3.265s
user    0m3.109s
sys    0m0.132s

real    0m1.211s
user    0m1.133s
sys    0m0.076s

4）出了个小BUG：

rm -f *.o3
clang -DLARGE_DATASET -O3 -mllvm -polly -mllvm -polly-vectorizer=stripmine -I/home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities    /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities/polybench.c  /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/datamining/correlation/correlation.c  -o a3.polly.o3
time ./a3.polly.o3
/usr/bin/ld: /tmp/correlation-ceecf1.o: in function `main':
correlation.c:(.text+0x181): undefined reference to `sqrt'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
bash: ./a3.polly.o3: 没有那个文件或目录

解决方法：加上-lm

这是常见的错

5）

rm -f *.o3
clang -DLARGE_DATASET -O3 -mllvm -polly-omp-backend=LLVM -mllvm -polly-num-threads=2 -I/home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities    /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities/polybench.c  /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/datamining/correlation/correlation.c  -o a3.polly.o3 -lm
time ./a3.polly.o3

rm -f *.o3
clang -DLARGE_DATASET -O3 -mllvm -polly -mllvm -polly-vectorizer=stripmine -I/home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities    /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities/polybench.c  /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/datamining/correlation/correlation.c  -o a3.polly.o3 -lm
time ./a3.polly.o3

real    0m20.509s
user    0m20.406s
sys    0m0.072s

real    0m2.272s
user    0m2.226s
sys    0m0.036s

a@a:~/src/a3.llvm.polly/a1.polybench-c-4.2$ 
rm -f *.o3
gcc -DLARGE_DATASET -O3 -I/home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities    /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/utilities/polybench.c  /home/a/src/a3.llvm.polly/a1.polybench-c-4.2/datamining/correlation/correlation.c  -o a3.polly.o3 -lm
time ./a3.polly.o3

real    0m17.786s
user    0m17.606s
sys    0m0.153s

如果向量化是正确的话，那么效果太好。