simplify-rtx: Fix compare of comparisons (PR60818)

simplify-rtx: Fix compare of comparisons (PR60818)

The function simplify_binary_operation_1 has code that does
/* Convert (compare (gt (flags) 0) (lt (flags) 0)) to (flags).  */
but this transformation is only valid if "flags" has the same machine
mode as the outer compare.  This fixes it.

	PR rtl-optimization/60818
	* simplify-rtx.c (simplify_binary_operation_1): Do not replace
	a compare of comparisons with the thing compared if this results
	in a different machine mode.

gcc/testsuite/
	PR rtl-optimization/60818
	* gcc.c-torture/compile/pr60818.c: New testcase.

From-SVN: r246666