PR target/59644

	* config/i386/i386.h (struct machine_function): Add
	no_drap_save_restore field.
	* config/i386/i386.c (ix86_save_reg): Use
	!cfun->machine->no_drap_save_restore instead of
	crtl->stack_realign_needed.
	(ix86_finalize_stack_realign_flags): Don't clear drap_reg unless
	this function clears frame_pointer_needed.  Set
	cfun->machine->no_drap_save_restore if clearing frame_pointer_needed
	and DRAP reg is needed.

	* gcc.target/i386/pr59644.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@206375 138bc75d-0d04-0410-961f-82ee72b054a4

2 files changed, 6 insertions, 13 deletions

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 39891c96402..32b6418320f 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -9281,7 +9281,7 @@ ix86_save_reg (unsigned int regno, bool maybe_eh_return)
 
   if (crtl->drap_reg
       && regno == REGNO (crtl->drap_reg)
-      && crtl->stack_realign_needed)
+      && !cfun->machine->no_drap_save_restore)
     return true;
 
   return (df_regs_ever_live_p (regno)
@@ -10519,18 +10519,6 @@ ix86_finalize_stack_realign_flags (void)
       return;
     }
 
-  /* If drap has been set, but it actually isn't live at the start
-     of the function and !stack_realign, there is no reason to set it up.  */
-  if (crtl->drap_reg && !stack_realign)
-    {
-      basic_block bb = ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb;
-      if (! REGNO_REG_SET_P (DF_LR_IN (bb), REGNO (crtl->drap_reg)))
-	{
-	  crtl->drap_reg = NULL_RTX;
-	  crtl->need_drap = false;
-	}
-    }
-
   /* If the only reason for frame_pointer_needed is that we conservatively
      assumed stack realignment might be needed, but in the end nothing that
      needed the stack alignment had been spilled, clear frame_pointer_needed
@@ -10584,6 +10572,8 @@ ix86_finalize_stack_realign_flags (void)
 	      crtl->need_drap = false;
 	    }
 	}
+      else
+	cfun->machine->no_drap_save_restore = true;
 
       frame_pointer_needed = false;
       stack_realign = false;
diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index cdaab3684e1..ab7489a0c1b 100644
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -2419,6 +2419,9 @@ struct GTY(()) machine_function {
      stack below the return address.  */
   BOOL_BITFIELD static_chain_on_stack : 1;
 
+  /* If true, it is safe to not save/restore DRAP register.  */
+  BOOL_BITFIELD no_drap_save_restore : 1;
+
   /* During prologue/epilogue generation, the current frame state.
      Otherwise, the frame state at the end of the prologue.  */
   struct machine_frame_state fs;