PR target/42172
	* config/arm/arm.c (thumb1_rtx_costs): Improve support for SIGN_EXTEND
	and ZERO_EXTEND.
	(arm_rtx_costs_1): Likewise.
	(arm_size_rtx_costs): Use arm_rtx_costs_1 for these codes.
	* config/arm/arm.md (is_arch6): New attribute.
	(zero_extendhisi2, zero_extendqisi2, extendhisi2,
	extendqisi2): Tighten the code somewhat, avoiding invalid
	RTL to occur in the expander patterns.
	(thumb1_zero_extendhisi2): Merge with thumb1_zero_extendhisi2_v6.
	(thumb1_zero_extendhisi2_v6): Delete.
	(thumb1_extendhisi2): Merge with thumb1_extendhisi2_v6.
	(thumb1_extendhisi2_v6): Delete.
	(thumb1_extendqisi2): Merge with thumb1_extendhisi2_v6.
	(thumb1_extendqisi2_v6): Delete.
	(zero_extendhisi2 for register input splitter): New.
	(zero_extendqisi2 for register input splitter): New.
	(thumb1_extendhisi2 for register input splitter): New.
	(extendhisi2 for register input splitter): New.
	(extendqisi2 for register input splitter): New.
	(TARGET_THUMB1 extendqisi2 for memory input splitter): New.
	(arm_zero_extendhisi2): Allow nonimmediate_operand for operand 1,
	and add support for a register alternative requiring a split.
	(thumb1_zero_extendqisi2): Likewise.
	(arm_zero_extendqisi2): Likewise.
	(arm_extendhisi2): Likewise.
	(arm_extendqisi2): Likewise.

testsuite/
	PR target/42172
	* gcc.target/arm/pr42172-1.c: New test.

From-SVN: r161726