Correct x86: Call ix86_access_stack_p only for larger alignment

Correct x86: Call ix86_access_stack_p only for larger alignment

commit f511bf93f947199a9f9099fee87b7052e5515fb9
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Sun Mar 29 14:30:28 2026 -0700

    x86: Call ix86_access_stack_p only for larger alignment

has 2 issues:

1. It didn't exclude memory with SYMBOLIC_CONST when checking for stack
access.
2. It replaced:

  HARD_REG_SET hard_stack_slot_access = stack_slot_access;
  ...
      bool symbolic_const_load_p = false;

      if (!TEST_HARD_REG_BIT (hard_stack_slot_access, regno))
	...
        symbolic_const_load_p = true;
      ...

      if (!symbolic_const_load_p
          || ix86_access_stack_p...)
	call ix86_update_stack_alignment.

with

      if (ix86_need_alignment_p...
          && ix86_access_stack_p...)
	call ix86_update_stack_alignment.

Since ix86_access_stack_p excludes registers on hard_stack_slot_access,
stack alignment isn't updated for registers on hard_stack_slot_access.
Instead, we should do

      if (ix86_need_alignment_p...
          && (TEST_HARD_REG_BIT (hard_stack_slot_access, regno)
              || ix86_access_stack_p...))
        call ix86_update_stack_alignment.

The compile times of PR target/124165 and PR target/124684 test are
unchanged.

      if (ix86_need_alignment_p...
          && (TEST_HARD_REG_BIT (hard_stack_slot_access, regno)
	      || ix86_access_stack_p...))
	call ix86_update_stack_alignment.

gcc/

	PR target/124759
	PR target/124789
	* config/i386/i386.cc (ix86_need_alignment_p_2): New function.
	Exclude memory with SYMBOLIC_CONST.
	(ix86_need_alignment_p_1): Call ix86_need_alignment_p_2.
	(ix86_find_max_used_stack_alignment): Restore
	hard_stack_slot_access handling.

gcc/testsuite/

	PR target/124759
	PR target/124789
	* gcc.target/i386/pr124759.c: New test.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>