arm: Improve code generation for BFI and BFC [PR105090]

arm: Improve code generation for BFI and BFC [PR105090]

This patch, in response to PR105090, makes some general improvements
to the code generation when BFI and BFC instructions are available.
Firstly we handle more cases where the RTL does not generate an INSV
operation due to a lack of a tie between the input and output, but we
nevertheless need to emit BFI later on; we handle this by requiring
the register allocator to tie the operands.  Secondly we handle some
cases where we were previously emitting BFC, but AND with an immediate
would be better; we do this by converting all BFC patterns into AND
using a split pattern.  And finally, we handle some cases where
previously we would emit multiple BIC operations to clear a value, but
could instead use a single BFC instruction.

BFC and BFI express the mask as a pair of values, one for the number
of bits to clear and another for the location of the least significant
bit.  We handle these with a single new output modifier letter that
causes both values to be printed; we use an 'inverted' value so that
it can be used directly with the constant used in an AND rtl
construct.  We've run out of 'new' letters, so to do this we re-use
one of the long-obsoleted Maverick output modifiers.

gcc/ChangeLog:

	PR target/105090
	* config/arm/arm.cc (arm_bfi_1_p): New function.
	(arm_bfi_p): New function.
	(arm_rtx_costs_internal): Add costs for BFI idioms.
	(arm_print_operand [case 'V']): Format output for BFI/BFC masks.
	* config/arm/constraints.md (Dj): New constraint.
	* config/arm/arm.md (arm_andsi3_insn): Add alternative to use BFC.
	(insv_zero): Convert to an insn with a split.
	(*bfi, *bfi_alt1, *bfi_alt2, *bfi_alt3): New patterns.