From 0cc6aabbd3f7b331c3995f11efec545499297358 Mon Sep 17 00:00:00 2001
From: Mahesh Bodapati <mbodapat@xilinx.com>
Date: Tue, 17 Jan 2017 16:42:44 +0530
Subject: [PATCH 20/54] [Patch, microblaze]: Reducing Stack space for arguments
 Currently in Microblaze target stack space for arguments in register is being
 allocated even if there are no arguments in the function. This patch will
 optimize the extra 24 bytes that are being allocated.

Signed-off-by :Nagaraju Mekala <nmekala@xilix.com>
              :Ajit Agarwal  <ajitkum@xilinx.com>

ChangeLog:
2015-04-17 Nagaraju Mekala <nmekala@xilix.com>
           Ajit Agarwal  <ajitkum@xilinx.com>

    *microblaze.c (microblaze_parm_needs_stack, microblaze_function_parms_need_stack): New
    *microblaze.c (REG_PARM_STACK_SPACE): Modify
---
 gcc/config/microblaze/microblaze-protos.h |   1 +
 gcc/config/microblaze/microblaze.c        | 134 +++++++++++++++++++++++++++++-
 gcc/config/microblaze/microblaze.h        |   4 +-
 3 files changed, 136 insertions(+), 3 deletions(-)

diff --git a/gcc/config/microblaze/microblaze-protos.h b/gcc/config/microblaze/microblaze-protos.h
index 4cbba0c..f8a56f7 100644
--- a/gcc/config/microblaze/microblaze-protos.h
+++ b/gcc/config/microblaze/microblaze-protos.h
@@ -58,6 +58,7 @@ extern int symbol_mentioned_p (rtx);
 extern int label_mentioned_p (rtx);
 extern bool microblaze_cannot_force_const_mem (machine_mode, rtx);
 extern void microblaze_eh_return (rtx op0);
+int  microblaze_reg_parm_stack_space(tree fun);
 #endif  /* RTX_CODE */
 
 /* Declare functions in microblaze-c.c.  */
diff --git a/gcc/config/microblaze/microblaze.c b/gcc/config/microblaze/microblaze.c
index 53b44df..0dec362 100644
--- a/gcc/config/microblaze/microblaze.c
+++ b/gcc/config/microblaze/microblaze.c
@@ -1989,6 +1989,138 @@ microblaze_must_save_register (int regno)
   return 0;
 }
 
+static bool
+microblaze_parm_needs_stack (cumulative_args_t args_so_far, tree type)
+{
+  enum machine_mode mode;
+  int unsignedp;
+  rtx entry_parm;
+
+  /* Catch errors.  */
+  if (type == NULL || type == error_mark_node)
+    return true;
+
+  if (TREE_CODE (type) == POINTER_TYPE)
+    return true;
+
+  /* Handle types with no storage requirement.  */
+  if (TYPE_MODE (type) == VOIDmode)
+    return false;
+
+   /* Handle complex types.  */
+  if (TREE_CODE (type) == COMPLEX_TYPE)
+    return (microblaze_parm_needs_stack (args_so_far, TREE_TYPE (type))
+             || microblaze_parm_needs_stack (args_so_far, TREE_TYPE (type)));
+
+  /* Handle transparent aggregates.  */
+ if ((TREE_CODE (type) == UNION_TYPE || TREE_CODE (type) == RECORD_TYPE)
+     && TYPE_TRANSPARENT_AGGR (type))
+  type = TREE_TYPE (first_field (type));
+
+  /* See if this arg was passed by invisible reference.  */
+ if (pass_by_reference (get_cumulative_args (args_so_far),
+                        TYPE_MODE (type), type, true))
+    type = build_pointer_type (type);
+
+    /* Find mode as it is passed by the ABI.  */
+    unsignedp = TYPE_UNSIGNED (type);
+    mode = promote_mode (type, TYPE_MODE (type), &unsignedp);
+
+/* If there is no incoming register, we need a stack.  */
+ entry_parm = microblaze_function_arg (args_so_far, mode, type, true);
+ if (entry_parm == NULL)
+    return true;
+
+ /* Likewise if we need to pass both in registers and on the stack.  */
+ if (GET_CODE (entry_parm) == PARALLEL
+     && XEXP (XVECEXP (entry_parm, 0, 0), 0) == NULL_RTX)
+   return true;
+
+ /* Also true if we're partially in registers and partially not.  */
+  if (function_arg_partial_bytes (args_so_far, mode, type, true) != 0)
+     return true;
+
+ /* Update info on where next arg arrives in registers.  */
+ microblaze_function_arg_advance (args_so_far, mode, type, true);
+ return false;
+ }
+
+static bool
+microblaze_function_parms_need_stack (tree fun, bool incoming)
+{
+  tree fntype, result;
+  CUMULATIVE_ARGS args_so_far_v;
+  cumulative_args_t args_so_far;
+  int num_of_args = 0;
+
+  /* Must be a libcall, all of which only use reg parms.  */
+  if (!fun)
+    return true;
+
+  fntype = fun;
+  if (!TYPE_P (fun))
+    fntype = TREE_TYPE (fun);
+
+  /* Varargs functions need the parameter save area.  */
+  if ((!incoming && !prototype_p (fntype)) || stdarg_p (fntype))
+    return true;
+
+  INIT_CUMULATIVE_ARGS(args_so_far_v, fntype, NULL_RTX,0,0);
+  args_so_far = pack_cumulative_args (&args_so_far_v);
+
+  /* When incoming, we will have been passed the function decl.
+   *      It is necessary to use the decl to handle K&R style functions,
+   *      where TYPE_ARG_TYPES may not be available.  */
+  if (incoming)
+    {
+      gcc_assert (DECL_P (fun));
+      result = DECL_RESULT (fun);
+    }
+  else
+    result = TREE_TYPE (fntype);
+
+  if (result && aggregate_value_p (result, fntype))
+    {
+      if (!TYPE_P (result))
+        result = build_pointer_type (result);
+        microblaze_parm_needs_stack (args_so_far, result);
+    }
+
+  if (incoming)
+    {
+      tree parm;
+      for (parm = DECL_ARGUMENTS (fun);
+           parm && parm != void_list_node;
+           parm = TREE_CHAIN (parm))
+         if (microblaze_parm_needs_stack (args_so_far, TREE_TYPE (parm)))
+           return true;
+    }
+  else
+    {
+      function_args_iterator args_iter;
+      tree arg_type;
+
+      FOREACH_FUNCTION_ARGS (fntype, arg_type, args_iter)
+      {
+        num_of_args++;
+        if (microblaze_parm_needs_stack (args_so_far, arg_type))
+         return true;
+      }
+    }
+
+  if (num_of_args > 3) return true;
+
+  return false;
+}
+
+int  microblaze_reg_parm_stack_space(tree fun)
+{
+  if (microblaze_function_parms_need_stack (fun,false))
+    return MAX_ARGS_IN_REGISTERS * UNITS_PER_WORD;
+  else
+    return 0;
+}
+
 /* Return the bytes needed to compute the frame pointer from the current
    stack pointer.
 
@@ -3298,7 +3430,7 @@ microblaze_asm_output_mi_thunk (FILE *file, tree thunk_fndecl ATTRIBUTE_UNUSED,
   emit_insn (gen_indirect_jump (temp2));
 
   /* Run just enough of rest_of_compilation.  This sequence was
-     "borrowed" from rs6000.c.  */
+     "borrowed" from microblaze.c.  */
   insn = get_insns ();
   shorten_branches (insn);
   final_start_function (insn, file, 1);
diff --git a/gcc/config/microblaze/microblaze.h b/gcc/config/microblaze/microblaze.h
index 88e0351..9f74ec8 100644
--- a/gcc/config/microblaze/microblaze.h
+++ b/gcc/config/microblaze/microblaze.h
@@ -434,9 +434,9 @@ extern struct microblaze_frame_info current_frame_info;
 
 #define ARG_POINTER_CFA_OFFSET(FNDECL)		0
 
-#define REG_PARM_STACK_SPACE(FNDECL)  		(MAX_ARGS_IN_REGISTERS * UNITS_PER_WORD)
+#define REG_PARM_STACK_SPACE(FNDECL)  		 microblaze_reg_parm_stack_space(FNDECL)
 
-#define OUTGOING_REG_PARM_STACK_SPACE(FNTYPE)	1
+#define OUTGOING_REG_PARM_STACK_SPACE(FNTYPE)  1
 
 #define STACK_BOUNDARY				32
 
-- 
2.7.4