Convert V1TImode register to TImode in debug insn

Convert V1TImode register to TImode in debug insn

TImode register referenced in debug insn can be converted to V1TImode by
scalar to vector optimization.  When converting a TImode store to V1TImode,
we need to check all debug insns on its use chain to convert the V1TImode
register to SUBREG TImode if source register is undefined.

gcc/

	PR target/72748
	* config/i386/i386.c (timode_scalar_chain::convert_insn): Call
	fix_debug_reg_uses after changing source register mode to
	V1TImode if source register is undefined.

gcc/testsuite/

	PR target/72748
	* gcc.target/i386/pr72748.c: New test.

From-SVN: r238956