Extend ipa-pure-const pass to propagate malloc attribute.

Extend ipa-pure-const pass to propagate malloc attribute.

2017-10-27  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>

	* cgraph.h (set_malloc_flag): Declare.
	* cgraph.c (set_malloc_flag_1): New function.
	(set_malloc_flag): Likewise.
	* ipa-fnsummary.h (ipa_call_summary): Add new field is_return_callee.
	* ipa-fnsummary.c (ipa_call_summary::reset): Set is_return_callee to
	false.
	(read_ipa_call_summary): Add support for reading is_return_callee.
	(write_ipa_call_summary): Stream is_return_callee.
	* ipa-inline.c (ipa_inline): Remove call to ipa_free_fn_summary.
	* ipa-pure-const.c: Add headers ssa.h, alloc-pool.h, symbol-summary.h,
	ipa-prop.h, ipa-fnsummary.h.
	(pure_const_names): Change to static.
	(malloc_state_e): Define.
	(malloc_state_names): Define.
	(funct_state_d): Add field malloc_state.
	(varying_state): Set malloc_state to STATE_MALLOC_BOTTOM.
	(check_retval_uses): New function.
	(malloc_candidate_p): Likewise.
	(analyze_function): Add support for malloc attribute.
	(pure_const_write_summary): Stream malloc_state.
	(pure_const_read_summary): Add support for reading malloc_state.
	(dump_malloc_lattice): New function.
	(propagate_malloc): New function.
	(warn_function_malloc): New function.
	(ipa_pure_const::execute): Call propagate_malloc and
	ipa_free_fn_summary.
	(pass_local_pure_const::execute): Add support for malloc attribute.
	* ssa-iterators.h (RETURN_FROM_IMM_USE_STMT): New macro.
	* doc/invoke.texi: Document Wsuggest-attribute=malloc.

testsuite/
	* gcc.dg/ipa/propmalloc-1.c: New test-case.
	* gcc.dg/ipa/propmalloc-2.c: Likewise.
	* gcc.dg/ipa/propmalloc-3.c: Likewise.

From-SVN: r254140