[Bug tree-optimization/14741] missing transformations lead to poorly optimized code

[jv244 at cam dot ac dot uk]

------- Additional Comments From jv244 at cam dot ac dot uk  2005-01-28 15:59 -------
Hi Steven, I now ( gcc version 4.0.0 20050128 (experimental) )get the following,
where the first number is the timing.

multgen/basic_mult> gfortran -O3 -ffast-math mult.f90
multgen/basic_mult> ./a.out
   59.0300000000000        10.2400000000000     

which is good as compared to
multgen/basic_mult> ifort -O3 mult.f90
multgen/basic_mult> ./a.out
   64.8900000000000        10.2399999999998     

but very bad (factor 20) as compared to

multgen/basic_mult> ifort -O3 -xN mult.f90
mult.f90(4) : (col. 0) remark: LOOP WAS VECTORIZED.
mult.f90(5) : (col. 0) remark: LOOP WAS VECTORIZED.
mult.f90(6) : (col. 0) remark: LOOP WAS VECTORIZED.
multgen/basic_mult> ./a.out
   2.13000000000000        10.2399999999998     

I'll try to attach the relevant asm for this.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14741