(global_alloc): Make a more accurate attempt to see if the frame pointer will be...

(global_alloc): Make a more accurate attempt to see if the frame pointer will
be used.
If it is, show HARD_FRAME_POINTER_REGNUM used if its not the same as
FRAME_POINTER_REGNUM.

From-SVN: r7604

diff --git a/gcc/global.c b/gcc/global.c
index c3dc7493ee52c2f9fae51318701b8877c58c0e6c..297e9307b77776b2ada90e837a01ba1c7e53fbb5 100644 (file)
--- a/gcc/global.c
+++ b/gcc/global.c
@@ -246,7 +246,7 @@ static struct { int allocno1, allocno2;}
 static rtx *regs_set;
 static int n_regs_set;
 
-/* All register that can be eliminated.  */
+/* All registers that can be eliminated.  */
 
 static HARD_REG_SET eliminable_regset;
 
@@ -279,6 +279,13 @@ global_alloc (file)
 #ifdef ELIMINABLE_REGS
   static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
 #endif
+  int need_fp
+    = (! flag_omit_frame_pointer
+#ifdef EXIT_IGNORE_STACK
+       || (current_function_calls_alloca && EXIT_IGNORE_STACK)
+#endif
+       || FRAME_POINTER_REQUIRED);
+
   register int i;
   rtx x;
 
@@ -302,20 +309,18 @@ global_alloc (file)
       SET_HARD_REG_BIT (eliminable_regset, eliminables[i].from);
 
       if (! CAN_ELIMINATE (eliminables[i].from, eliminables[i].to)
-         || (eliminables[i].from == HARD_FRAME_POINTER_REGNUM
-             && (! flag_omit_frame_pointer || FRAME_POINTER_REQUIRED)))
+         || (eliminables[i].to == STACK_POINTER_REGNUM && need_fp))
        SET_HARD_REG_BIT (no_global_alloc_regs, eliminables[i].from);
     }
 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
-  if (!flag_omit_frame_pointer || FRAME_POINTER_REQUIRED)
+  SET_HARD_REG_BIT (eliminable_regset, HARD_FRAME_POINTER_REGNUM);
+  if (need_fp)
     SET_HARD_REG_BIT (no_global_alloc_regs, HARD_FRAME_POINTER_REGNUM);
 #endif
+
 #else
   SET_HARD_REG_BIT (eliminable_regset, FRAME_POINTER_REGNUM);
-
-  /* If we know we will definitely not be eliminating the frame pointer,
-     don't allocate it.  */
-  if (! flag_omit_frame_pointer || FRAME_POINTER_REQUIRED)
+  if (need_fp)
     SET_HARD_REG_BIT (no_global_alloc_regs, FRAME_POINTER_REGNUM);
 #endif