[PR103676] LRA: Calculate and exclude some start hard registers for reload pseudos

LRA and old reload pass uses only one register class for reload pseudos even if
operand constraints contain more one register class.  Let us consider
constraint 'lh' for thumb arm which means low and high thumb registers.
Reload pseudo for such constraint will have general reg class (union of
low and high reg classes).  Assigning the last low register to the reload
pseudo is wrong if the pseudo is of DImode as it requires two hard regs.
But it is considered OK if we use general reg class.  The following patch
solves this problem for LRA.

gcc/ChangeLog:

	PR target/103676
	* ira.h (struct target_ira): Add member
	x_ira_exclude_class_mode_regs.
	(ira_exclude_class_mode_regs): New macro.
	* lra.h (lra_create_new_reg): Add arg exclude_start_hard_regs and
	move from here ...
	* lra-int.h: ... to here.
	(lra_create_new_reg_with_unique_value): Add arg
	exclude_start_hard_regs.
	(class lra_reg): Add member exclude_start_hard_regs.
	* lra-assigns.cc (find_hard_regno_for_1): Setup
	impossible_start_hard_regs from exclude_start_hard_regs.
	* lra-constraints.cc (get_reload_reg): Add arg exclude_start_hard_regs and pass
	it lra_create_new_reg[_with_unique_value].
	(match_reload): Ditto.
	(check_and_process_move): Pass NULL
	exclude_start_hard_regs to lra_create_new_reg_with_unique_value.
	(goal_alt_exclude_start_hard_regs): New static variable.
	(process_addr_reg, simplify_operand_subreg): Pass NULL
	exclude_start_hard_regs to lra_create_new_reg_with_unique_value
	and get_reload_reg.
	(process_alt_operands): Setup goal_alt_exclude_start_hard_regs.
	Use this_alternative_exclude_start_hard_regs additionally to find
	winning operand alternative.
	(base_to_reg, base_plus_disp_to_reg, index_part_to_reg): Pass NULL
	exclude_start_hard_regs to lra_create_new_reg.
	(process_address_1, emit_inc): Ditto.
	(curr_insn_transform): Pass exclude_start_hard_regs value to
	lra_create_new_reg, get_reload_reg, match_reload.
	(inherit_reload_reg, split_reg): Pass NULL exclude_start_hard_regs
	to lra_create_new_reg.
	(process_invariant_for_inheritance): Ditto.
	* lra-remat.cc (update_scratch_ops): Ditto.
	* lra.cc (lra_create_new_reg_with_unique_value): Add arg
	exclude_start_hard_regs.  Setup the corresponding member of
	lra reg info.
	(lra_create_new_reg): Add arg exclude_start_hard_regs and pass it
	to lra_create_new_reg_with_unique_value.
	(initialize_lra_reg_info_element): Initialize member
	exclude_start_hard_regs.
	(get_scratch_reg): Pass NULL to lra_create_new_reg.
	* ira.cc (setup_prohibited_class_mode_regs): Rename to
	setup_prohibited_and_exclude_class_mode_regs and calculate
	ira_exclude_class_mode_regs.

gcc/testsuite/ChangeLog:

	PR target/103676
	* g++.target/arm/pr103676.C: New.

1 files changed, 0 insertions, 2 deletions

diff --git a/gcc/lra.h b/gcc/lra.h
index 85713bb..4dd6cac 100644
--- a/gcc/lra.h
+++ b/gcc/lra.h
@@ -34,8 +34,6 @@ lra_get_allocno_class (int regno)
   return reg_allocno_class (regno);
 }
 
-extern rtx lra_create_new_reg (machine_mode, rtx, enum reg_class,
-			       const char *);
 extern rtx lra_eliminate_regs (rtx, machine_mode, rtx);
 extern void lra (FILE *);
 extern void lra_init_once (void);