2016-11-23  Richard Biener  <rguenther@suse.de>
	    Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.rog>

	PR tree-optimization/78154
	* tree-vrp.c (gimple_stmt_nonzero_warnv_p): Return true if function
	returns it's argument and the argument is nonnull.
	* builtin-attrs.def: Define ATTR_RETURNS_NONNULL,
	ATT_RETNONNULL_NOTHROW_LEAF.
	* builtins.def (BUILT_IN_MEMPCPY): Change attribute to
	ATTR_RETNONNULL_NOTHROW_LEAF.
	(BUILT_IN_STPCPY): Likewise.
	(BUILT_IN_STPNCPY): Likewise.
	(BUILT_IN_MEMPCPY_CHK): Likewise.
	(BUILT_IN_STPCPY_CHK): Likewise.
	(BUILT_IN_STPNCPY_CHK): Likewise.
	(BUILT_IN_STRCAT): Change attribute to ATTR_RET1_NOTHROW_NONNULL_LEAF.
	(BUILT_IN_STRNCAT): Likewise.
	(BUILT_IN_STRNCPY): Likewise.
	(BUILT_IN_MEMSET_CHK): Likewise.
	(BUILT_IN_STRCAT_CHK): Likewise.
	(BUILT_IN_STRCPY_CHK): Likewise.
	(BUILT_IN_STRNCAT_CHK): Likewise.
	(BUILT_IN_STRNCPY_CHK): Likewise.

testsuite/
	* gcc.dg/tree-ssa/pr78154.c: New test.

Co-Authored-By: Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>

From-SVN: r242745