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| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | builtin.c | 10 |
2 files changed, 15 insertions, 2 deletions
@@ -1,3 +1,10 @@ +2014-04-20 Arnold D. Robbins <arnold@skeeve.com> + + * builtin.c (do_rand): Make calls to random() in predictable + order to avoid order of evaluation differences amongst compilers. + Thanks to Anders Magnusson <ragge@ludd.ltu.se> (of the PCC team) + for the suggestion. + 2014-04-18 Arnold D. Robbins <arnold@skeeve.com> * configure.ac: Change adding of -export-dynamic for GCC to be @@ -2454,8 +2454,14 @@ do_rand(int nargs ATTRIBUTE_UNUSED) */ do { - tmprand = 0.5 + ( (random()/RAND_DIVISOR + random()) - / RAND_DIVISOR); + long d1, d2; + /* + * Do the calls in predictable order to avoid + * compiler differences in order of evaluation. + */ + d1 = random(); + d2 = random(); + tmprand = 0.5 + ( (d1/RAND_DIVISOR + d2) / RAND_DIVISOR ); tmprand -= 0.5; } while (tmprand == 1.0); |