Error handling for hard register constraints

Error handling for hard register constraints

This implements error handling for hard register constraints including
potential conflicts with register asm operands.

In contrast to register asm operands, hard register constraints allow
more than just one register per operand.  Even more than just one
register per alternative.  For example, a valid constraint for an
operand is "{r0}{r1}m,{r2}".  However, this also means that we have to
make sure that each register is used at most once in each alternative
over all outputs and likewise over all inputs.  For asm statements this
is done by this patch during gimplification.  For hard register
constraints used in machine description, error handling is still a todo
and I haven't investigated this so far and consider this rather a low
priority.

gcc/ada/ChangeLog:

	* gcc-interface/trans.cc (gnat_to_gnu): Pass null pointer to
	parse_{input,output}_constraint().

gcc/analyzer/ChangeLog:

	* region-model-asm.cc (region_model::on_asm_stmt): Pass null
	pointer to parse_{input,output}_constraint().

gcc/c/ChangeLog:

	* c-typeck.cc (build_asm_expr): Pass null pointer to
	parse_{input,output}_constraint().

gcc/ChangeLog:

	* cfgexpand.cc (n_occurrences): Move this ...
	(check_operand_nalternatives): and this ...
	(expand_asm_stmt): and the call to gimplify.cc.
	* config/s390/s390.cc (s390_md_asm_adjust): Pass null pointer to
	parse_{input,output}_constraint().
	* gimple-walk.cc (walk_gimple_asm): Pass null pointer to
	parse_{input,output}_constraint().
	(walk_stmt_load_store_addr_ops): Ditto.
	* gimplify-me.cc (gimple_regimplify_operands): Ditto.
	* gimplify.cc (num_occurrences): Moved from cfgexpand.cc.
	(num_alternatives): Ditto.
	(gimplify_asm_expr): Deal with hard register constraints.
	* stmt.cc (eliminable_regno_p): New helper.
	(hardreg_ok_p): Perform a similar check as done in
	make_decl_rtl().
	(parse_output_constraint): Add parameter for gimplify_reg_info
	and validate hard register constrained operands.
	(parse_input_constraint): Ditto.
	* stmt.h (class gimplify_reg_info): Forward declaration.
	(parse_output_constraint): Add parameter.
	(parse_input_constraint): Ditto.
	* tree-ssa-operands.cc
	(operands_scanner::get_asm_stmt_operands): Pass null pointer
	to parse_{input,output}_constraint().
	* tree-ssa-structalias.cc (find_func_aliases): Pass null pointer
	to parse_{input,output}_constraint().
	* varasm.cc (assemble_asm): Pass null pointer to
	parse_{input,output}_constraint().
	* gimplify_reg_info.h: New file.

gcc/cp/ChangeLog:

	* semantics.cc (finish_asm_stmt): Pass null pointer to
	parse_{input,output}_constraint().

gcc/d/ChangeLog:

	* toir.cc: Pass null pointer to
	parse_{input,output}_constraint().

gcc/testsuite/ChangeLog:

	* gcc.dg/pr87600-2.c: Split test into two files since errors for
	functions test{0,1} are thrown during expand, and for
	test{2,3} during gimplification.
	* lib/scanasm.exp: On s390, skip lines beginning with #.
	* gcc.dg/asm-hard-reg-error-1.c: New test.
	* gcc.dg/asm-hard-reg-error-2.c: New test.
	* gcc.dg/asm-hard-reg-error-3.c: New test.
	* gcc.dg/asm-hard-reg-error-4.c: New test.
	* gcc.dg/asm-hard-reg-error-5.c: New test.
	* gcc.dg/pr87600-3.c: New test.
	* gcc.target/aarch64/asm-hard-reg-2.c: New test.
	* gcc.target/s390/asm-hard-reg-7.c: New test.