* fold-const.c (fold <ABS_EXPR>): Re-fold the result of folding
fabs(-x) into fabs(x). Use tree_expr_nonnegative_p to determine
when the ABS_EXPR (fabs or abs) is not required.
(tree_expr_nonnegative_p): Move the logic that sqrt and exp are
always nonnegative from fold to here. Additionally, cabs and fabs
are always non-negative, and pow and atan are non-negative if
their first argument is non-negative.
* builtins.c (fold_builtin_cabs): New function to fold cabs{,f,l}.
Evaluate cabs of a constant at compile-time. Convert cabs of a
non-complex argument into fabs. Convert cabs(z) into
sqrt(z.r*z.r + z.i*z.i) at the tree-level with -ffast-math or
-funsafe-math-optimizations or -ffast-math.
(fold_builtin): Convert BUILT_IN_FABS{,F,L} into an ABS_EXPR.
Fold BUILT_IN_CABS{,F,L} using fold_builtin_cabs.
* gcc.dg/builtins-2.c: Add some more tests.
* gcc.dg/builtins-18.c: New test case.
* gcc.dg/builtins-19.c: New test case.
From-SVN: r67541
