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Currently, when a new thread needs to use the RANDOM_NUMBER intrinsic, the per-thread PRNG state is initialized by copying the master state and then jumping forwards N*2**128 entries in the stream so that the PRNG streams for different threads don't alias each other, where N is the number of threads that have so far initialized the PRNG. With this patch the master state itself is jumped forwards once each time a new thread initializes the PRNG, thus obviating the need to jump through all the N-1 previous streams. Effectively turning an O(N) algorithm into an O(1) one. Regtested on x86_64-pc-linux-gnu. libgfortran/ChangeLog: 2019-09-05 Janne Blomqvist <jb@gcc.gnu.org> * intrinsics/random.c (master_init): Replace with master_state.init. (njumps): Remove variable. (master_state): Make instance of struct prng_state. (init_rand_state): When jumping, update the master_state once instead of keeping track of how many jumps need to be done. (SZU64): Modify to handle new master_state. (SZ): Likewise. (random_seed_i4): Likewise. (random_seed_i8): Likewise. From-SVN: r275397
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