backport: re PR tree-optimization/77309 (wrong code at -Os and above on x86_64-linux...

backport: re PR tree-optimization/77309 (wrong code at -Os and above on x86_64-linux-gnu (in the 64-bit mode))

	Backport from mainline
	2016-11-07  Bernd Schmidt  <bschmidt@redhat.com>

        PR rtl-optimization/77309
        * combine.c (make_compound_operation): Allow EQ for IN_CODE, and
        don't assume an equality comparison for plain COMPARE.
        (simplify_comparison): Pass a more accurate code to
        make_compound_operation.

        PR rtl-optimization/77309
        * gcc.dg/torture/pr77309.c: New test.

From-SVN: r243550