Move cabs expansion from powcabs to complex lowering [PR115710]

Move cabs expansion from powcabs to complex lowering [PR115710]

Expanding cabs in powcab might be too late as forwprop might
recombine the load from a memory with the complex expr. Moving
instead to complex lowering allows us to use directly the real/imag
component from the loads instead. This allows for vectorization too.

Bootstrapped and tested on x86_64-linux-gnu with no regressions.

	PR tree-optimization/115710

gcc/ChangeLog:

	* tree-complex.cc (init_dont_simulate_again): Handle CABS.
	(gimple_expand_builtin_cabs): New function, moved mostly
	from tree-ssa-math-opts.cc.
	(expand_complex_operations_1): Call gimple_expand_builtin_cabs.
	* tree-ssa-math-opts.cc (gimple_expand_builtin_cabs): Remove.
	(build_and_insert_binop): Remove.
	(pass_data_expand_powcabs): Update comment.
	(pass_expand_powcabs::execute): Don't handle CABS.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/cabs-1.c: New test.
	* gcc.dg/tree-ssa/cabs-2.c: New test.
	* gfortran.dg/vect/pr115710.f90: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>