MATCH: Simplify zero/sign extension bit operations [PR122848]

MATCH: Simplify zero/sign extension bit operations [PR122848]

Fold bitwise operations involving zero and sign extensions from the same
low-precision value.  The AND case folds to the zero extension, and the
OR case folds to the sign extension.

	PR tree-optimization/122848

gcc/ChangeLog:

	* match.pd (zero_extend & sign_extend -> zero_extend): New pattern.
	(zero_extend | sign_extend -> sign_extend): Likewise.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/pr122848.c: New test.

Signed-off-by: Eikansh Gupta <eikansh.gupta@oss.qualcomm.com>