i386: Optimize lea with zero-extend. [PR 101716]

i386: Optimize lea with zero-extend. [PR 101716]

For ASHIFT + ZERO_EXTEND pattern, combine pass failed to
match it to lea since it will generate non-canonical
zero-extend. Adjust predicate and cost_model to allow combine
for lea.

gcc/ChangeLog:

	PR target/101716
	* config/i386/i386.c (ix86_live_on_entry): Adjust comment.
	(ix86_decompose_address): Remove retval check for ASHIFT,
	allow non-canonical zero extend if AND mask covers ASHIFT
	count.
	(ix86_legitimate_address_p): Adjust condition for decompose.
	(ix86_rtx_costs): Adjust cost for lea with non-canonical
	zero-extend.

	Co-Authored by: Uros Bizjak <ubizjak@gmail.com>

gcc/testsuite/ChangeLog:

	PR target/101716
	* gcc.target/i386/pr101716.c: New test.