re PR tree-optimization/47967 (ICE: verify_stmts failed: conversion of register to a different size with -fipa-cp on undefined code)

	PR tree-optimization/47967
	* ipa-cp.c (build_const_val): Return NULL instead of creating
	VIEW_CONVERT_EXPR for mismatching sizes.
	(ipcp_create_replace_map): Return NULL if build_const_val failed.
	(ipcp_insert_stage): If ipcp_create_replace_map returns NULL,
	give up on versioning.

	* gcc.c-torture/compile/pr47967.c: New test.

From-SVN: r170689