Bug 5812 – Power expression optimisation: constant fold (x^^0) = 1

CTFE testcases (that currently fail) const x = 3; static assert((7 ^^ 0) == 1); static assert((7 ^^ 0.0) == 1); static assert((x ^^ 0) == 1); static assert((x ^^ 0.0) == 1); Patch: --- dmd.orig/expression.c 2011-02-18 01:15:38.000000000 +0000 +++ dmd/expression.c 2011-04-04 02:05:38.631620650 +0100 @@ -10302,6 +10302,15 @@ Expression *PowExp::semantic(Scope *sc) e = e->semantic(sc); return e; } + // Replace x ^^ 0 or x^^0.0 by (x, 1) + if ((e2->op == TOKint64 && e2->toInteger() == 0) || + (e2->op == TOKfloat64 && e2->toReal() == 0.0)) + { + typeCombine(sc); + e = new CommaExp(loc, e1, new IntegerExp(loc, 1, Type::tint32)); + e = e->semantic(sc); + return e; + } // Replace -1 ^^ x by (x&1) ? -1 : 1, where x is integral if (e2->type->isintegral() && e1->op == TOKint64 && (sinteger_t)e1->toInteger() == -1L) { Feel free to improve it. Regards

You can also optimize: x^^1 => (x) x^^-1 => (1/x) And that will remove two other scenarios from requiring std.math to compute the result. Regards

Created attachment 937 implement noted foldable code in this report

Created attachment 938 just noticed previous patch allows to bypass an error - fixed