PR rtl-optimization/54300

gcc/

	PR rtl-optimization/54300
	* regcprop.c (copyprop_hardreg_forward_1): Ensure any unused
	outputs in a single-set are killed from the value chains.

gcc/testsuite:

	PR rtl-optimization/54300
	* gcc.target/arm/pr54300.C: New test.

From-SVN: r205117