arm.h (arm_stack_offsets): Add locals_base field.

	* arm.h (arm_stack_offsets): Add locals_base field.
	* arm.c (arm_get_frame_offsets): Compute it.
	(thumb_compute_initial_elimination offset): Make the Thumb frame
	pointer point to the base of the local variables.
	(thumb_expand_prologue): Update accordingly.
	(thumb_expand_epilogue): Likewise.

	* arm.md (thumb_movhi_clobber): Make this insn a define_expand.  Change
	mode of clobbered scratch to DImode.  Handle a case that's known to
	need this.

From-SVN: r103301

gcc/ChangeLog

+2005-08-20  Richard Earnshaw  <richard.earnshaw@arm.com>
+
+	* arm.h (arm_stack_offsets): Add locals_base field.
+	* arm.c (arm_get_frame_offsets): Compute it.
+	(thumb_compute_initial_elimination offset): Make the Thumb frame
+	pointer point to the base of the local variables.
+	(thumb_expand_prologue): Update accordingly.
+	(thumb_expand_epilogue): Likewise.
+
+	* arm.md (thumb_movhi_clobber): Make this insn a define_expand.  Change
+	mode of clobbered scratch to DImode.  Handle a case that's known to
+	need this.
+
 2005-08-19  David Edelsohn  <edelsohn@gnu.org>
 
 	* config/rs6000/rs6000.md (gt0<mode>): Delete.

gcc/config/arm/arm.c

@@ -9992,7 +9992,7 @@ thumb_force_lr_save (void)
                             |    | \
                             |    |   local
                             |    |   variables
-                            |    | /
+     locals base pointer -> |    | /
                               --
                             |    | \
                             |    |   outgoing
@@ -10109,8 +10109,9 @@ arm_get_frame_offsets (void)
       && (offsets->soft_frame & 7))
     offsets->soft_frame += 4;
 
-  offsets->outgoing_args = offsets->soft_frame + frame_size
-			   + current_function_outgoing_args_size;
+  offsets->locals_base = offsets->soft_frame + frame_size;
+  offsets->outgoing_args = (offsets->locals_base
+			    + current_function_outgoing_args_size);
 
   if (ARM_DOUBLEWORD_ALIGN)
     {
@@ -13158,8 +13159,10 @@ arm_init_expanders (void)
 }
 
 
-/* Like arm_compute_initial_elimination offset.  Simpler because
-   THUMB_HARD_FRAME_POINTER isn't actually the ABI specified frame pointer.  */
+/* Like arm_compute_initial_elimination offset.  Simpler because there
+   isn't an ABI specified frame pointer for Thumb.  Instead, we set it
+   to point at the base of the local variables after static stack
+   space for a function has been allocated.  */
 
 HOST_WIDE_INT
 thumb_compute_initial_elimination_offset (unsigned int from, unsigned int to)
@@ -13179,10 +13182,12 @@ thumb_compute_initial_elimination_offset (unsigned int from, unsigned int to)
 	case FRAME_POINTER_REGNUM:
 	  return offsets->soft_frame - offsets->saved_args;
 
-	case THUMB_HARD_FRAME_POINTER_REGNUM:
 	case ARM_HARD_FRAME_POINTER_REGNUM:
 	  return offsets->saved_regs - offsets->saved_args;
 
+	case THUMB_HARD_FRAME_POINTER_REGNUM:
+	  return offsets->locals_base - offsets->saved_args;
+
 	default:
 	  gcc_unreachable ();
 	}
@@ -13194,10 +13199,12 @@ thumb_compute_initial_elimination_offset (unsigned int from, unsigned int to)
 	case STACK_POINTER_REGNUM:
 	  return offsets->outgoing_args - offsets->soft_frame;
 
-	case THUMB_HARD_FRAME_POINTER_REGNUM:
 	case ARM_HARD_FRAME_POINTER_REGNUM:
 	  return offsets->saved_regs - offsets->soft_frame;
 
+	case THUMB_HARD_FRAME_POINTER_REGNUM:
+	  return offsets->locals_base - offsets->soft_frame;
+
 	default:
 	  gcc_unreachable ();
 	}
@@ -13239,18 +13246,11 @@ thumb_expand_prologue (void)
   if (flag_pic)
     arm_load_pic_register (live_regs_mask);
 
-  offsets = arm_get_frame_offsets ();
-
-  if (frame_pointer_needed)
-    {
-      insn = emit_insn (gen_movsi (hard_frame_pointer_rtx,
-				   stack_pointer_rtx));
-      RTX_FRAME_RELATED_P (insn) = 1;
-    }
-  else if (CALLER_INTERWORKING_SLOT_SIZE > 0)
+  if (!frame_pointer_needed && CALLER_INTERWORKING_SLOT_SIZE > 0)
     emit_move_insn (gen_rtx_REG (Pmode, ARM_HARD_FRAME_POINTER_REGNUM),
 		    stack_pointer_rtx);
 
+  offsets = arm_get_frame_offsets ();
   amount = offsets->outgoing_args - offsets->saved_regs;
   if (amount)
     {
@@ -13336,12 +13336,29 @@ thumb_expand_prologue (void)
 				     REG_NOTES (insn));
 	    }
 	}
-      /* If the frame pointer is needed, emit a special barrier that
-	 will prevent the scheduler from moving stores to the frame
-	 before the stack adjustment.  */
+    }
+
   if (frame_pointer_needed)
-	emit_insn (gen_stack_tie (stack_pointer_rtx,
-				  hard_frame_pointer_rtx));
+    {
+      amount = offsets->outgoing_args - offsets->locals_base;
+      
+      if (amount < 1024)
+	insn = emit_insn (gen_addsi3 (hard_frame_pointer_rtx,
+				      stack_pointer_rtx, GEN_INT (amount)));
+      else
+	{
+	  emit_insn (gen_movsi (hard_frame_pointer_rtx, GEN_INT (amount)));
+	  insn = emit_insn (gen_addsi3 (hard_frame_pointer_rtx,
+					hard_frame_pointer_rtx,
+					stack_pointer_rtx));
+	  dwarf = gen_rtx_SET (SImode, hard_frame_pointer_rtx,
+			       plus_constant (stack_pointer_rtx, amount));
+	  RTX_FRAME_RELATED_P (dwarf) = 1;
+	  REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_FRAME_RELATED_EXPR, dwarf,
+						REG_NOTES (insn));
+	}
+
+      RTX_FRAME_RELATED_P (insn) = 1;
     }
 
   if (current_function_profile || !TARGET_SCHED_PROLOG)
@@ -13373,8 +13390,12 @@ thumb_expand_epilogue (void)
   amount = offsets->outgoing_args - offsets->saved_regs;
 
   if (frame_pointer_needed)
+    {
       emit_insn (gen_movsi (stack_pointer_rtx, hard_frame_pointer_rtx));
-  else if (amount)
+      amount = offsets->locals_base - offsets->saved_regs;
+    }
+  
+  if (amount)
     {
       if (amount < 512)
 	emit_insn (gen_addsi3 (stack_pointer_rtx, stack_pointer_rtx,

gcc/config/arm/arm.h

@@ -1476,6 +1476,7 @@ typedef struct arm_stack_offsets GTY(())
   int frame;		/* ARM_HARD_FRAME_POINTER_REGNUM.  */
   int saved_regs;
   int soft_frame;	/* FRAME_POINTER_REGNUM.  */
+  int locals_base;	/* THUMB_HARD_FRAME_POINTER_REGNUM.  */
   int outgoing_args;	/* STACK_POINTER_REGNUM.  */
 }
 arm_stack_offsets;

gcc/config/arm/arm.md

@@ -4951,13 +4951,21 @@
   [(set_attr "predicable" "yes")]
 )
 
-(define_insn "thumb_movhi_clobber"
-  [(set (match_operand:HI     0 "memory_operand"   "=m")
-	(match_operand:HI     1 "register_operand" "l"))
-   (clobber (match_operand:SI 2 "register_operand" "=&l"))]
+(define_expand "thumb_movhi_clobber"
+  [(set (match_operand:HI     0 "memory_operand"   "")
+	(match_operand:HI     1 "register_operand" ""))
+   (clobber (match_operand:DI 2 "register_operand" ""))]
   "TARGET_THUMB"
-  "*
-  gcc_unreachable ();"
+  "
+  if (strict_memory_address_p (HImode, XEXP (operands[0], 0))
+      && REGNO (operands[1]) <= LAST_LO_REGNUM)
+    {
+      emit_insn (gen_movhi (operands[0], operands[1]));
+      DONE;
+    }
+  /* XXX Fixme, need to handle other cases here as well.  */
+  gcc_unreachable ();
+  "
 )
 	
 ;; We use a DImode scratch because we may occasionally need an additional