arm.c (arm_compute_static_chain_stack_bytes): New function.

	* config/arm/arm.c (arm_compute_static_chain_stack_bytes): New
	function.
	(arm_compute_initial_elimination_offset): Use it.
	(arm_compute_save_reg_mask): Include static chain save slot when
	calculating alignment.
	(arm_get_frame_offsets): Ditto.
	(thumb1_compute_save_reg_mask): Ensure we have a low register saved
	that we can use to decrement the stack when the stack decrement
	could be too big for an immediate value in a single insn.
	(thumb1_expand_prologue): Avoid using r12 for stack decrement.

From-SVN: r138327

1 files changed, 66 insertions, 62 deletions

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 7410517..a89229e 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -62,6 +62,7 @@ const struct attribute_spec arm_attribute_table[];
 void (*arm_lang_output_object_attributes_hook)(void);
 
 /* Forward function declarations.  */
+static int arm_compute_static_chain_stack_bytes (void);
 static arm_stack_offsets *arm_get_frame_offsets (void);
 static void arm_add_gc_roots (void);
 static int arm_gen_constant (enum rtx_code, enum machine_mode, rtx,
@@ -10792,6 +10793,24 @@ arm_compute_save_reg0_reg12_mask (void)
 }
 
 
+/* Compute the number of bytes used to store the static chain register on the 
+   stack, above the stack frame. We need to know this accurately to get the
+   alignment of the rest of the stack frame correct. */
+
+static int arm_compute_static_chain_stack_bytes (void)
+{
+  unsigned long func_type = arm_current_func_type ();
+  int static_chain_stack_bytes = 0;
+
+  if (TARGET_APCS_FRAME && frame_pointer_needed && TARGET_ARM &&
+      IS_NESTED (func_type) &&
+      df_regs_ever_live_p (3) && crtl->args.pretend_args_size == 0)
+    static_chain_stack_bytes = 4;
+
+  return static_chain_stack_bytes;
+}
+
+
 /* Compute a bit mask of which registers need to be
    saved on the stack for the current function.
    This is used by arm_get_frame_offsets, which may add extra registers.  */
@@ -10844,7 +10863,9 @@ arm_compute_save_reg_mask (void)
 
   if (TARGET_REALLY_IWMMXT
       && ((bit_count (save_reg_mask)
-	   + ARM_NUM_INTS (crtl->args.pretend_args_size)) % 2) != 0)
+	   + ARM_NUM_INTS (crtl->args.pretend_args_size +
+			   arm_compute_static_chain_stack_bytes())
+	   ) % 2) != 0)
     {
       /* The total number of registers that are going to be pushed
 	 onto the stack is odd.  We need to ensure that the stack
@@ -10929,6 +10950,26 @@ thumb1_compute_save_reg_mask (void)
 	mask |= 1 << reg;
     }
 
+  /* The 504 below is 8 bytes less than 512 because there are two possible
+     alignment words.  We can't tell here if they will be present or not so we
+     have to play it safe and assume that they are. */
+  if ((CALLER_INTERWORKING_SLOT_SIZE +
+       ROUND_UP_WORD (get_frame_size ()) +
+       crtl->outgoing_args_size) >= 504)
+    {
+      /* This is the same as the code in thumb1_expand_prologue() which
+	 determines which register to use for stack decrement. */
+      for (reg = LAST_ARG_REGNUM + 1; reg <= LAST_LO_REGNUM; reg++)
+	if (mask & (1 << reg))
+	  break;
+
+      if (reg > LAST_LO_REGNUM)
+	{
+	  /* Make sure we have a register available for stack decrement. */
+	  mask |= 1 << LAST_LO_REGNUM;
+	}
+    }
+
   return mask;
 }
 
@@ -12064,7 +12105,8 @@ arm_get_frame_offsets (void)
   offsets->saved_args = crtl->args.pretend_args_size;
 
   /* In Thumb mode this is incorrect, but never used.  */
-  offsets->frame = offsets->saved_args + (frame_pointer_needed ? 4 : 0);
+  offsets->frame = offsets->saved_args + (frame_pointer_needed ? 4 : 0) +
+                   arm_compute_static_chain_stack_bytes();
 
   if (TARGET_32BIT)
     {
@@ -12111,7 +12153,8 @@ arm_get_frame_offsets (void)
     }
 
   /* Saved registers include the stack frame.  */
-  offsets->saved_regs = offsets->saved_args + saved;
+  offsets->saved_regs = offsets->saved_args + saved +
+                        arm_compute_static_chain_stack_bytes();
   offsets->soft_frame = offsets->saved_regs + CALLER_INTERWORKING_SLOT_SIZE;
   /* A leaf function does not need any stack alignment if it has nothing
      on the stack.  */
@@ -12203,14 +12246,9 @@ arm_compute_initial_elimination_offset (unsigned int from, unsigned int to)
 	  return offsets->soft_frame - offsets->saved_args;
 
 	case ARM_HARD_FRAME_POINTER_REGNUM:
-	  /* If there is no stack frame then the hard
-	     frame pointer and the arg pointer coincide.  */
-	  if (offsets->frame == offsets->saved_regs)
-	    return 0;
-	  /* FIXME:  Not sure about this.  Maybe we should always return 0 ?  */
-	  return (frame_pointer_needed
-		  && cfun->static_chain_decl != NULL
-		  && ! cfun->machine->uses_anonymous_args) ? 4 : 0;
+	  /* This is only non-zero in the case where the static chain register
+	     is stored above the frame.  */
+	  return offsets->frame - offsets->saved_args - 4;
 
 	case STACK_POINTER_REGNUM:
 	  /* If nothing has been pushed on the stack at all
@@ -12498,6 +12536,9 @@ arm_expand_prologue (void)
 	    insn = emit_set_insn (gen_rtx_REG (SImode, 3), ip_rtx);
 	  else if (args_to_push == 0)
 	    {
+	      gcc_assert(arm_compute_static_chain_stack_bytes() == 4);
+	      saved_regs += 4;
+
 	      rtx dwarf;
 
 	      insn = gen_rtx_PRE_DEC (SImode, stack_pointer_rtx);
@@ -17008,62 +17049,25 @@ thumb1_expand_prologue (void)
 	     been pushed at the start of the prologue and so we can corrupt
 	     it now.  */
 	  for (regno = LAST_ARG_REGNUM + 1; regno <= LAST_LO_REGNUM; regno++)
-	    if (live_regs_mask & (1 << regno)
-		&& !(frame_pointer_needed
-		     && (regno == THUMB_HARD_FRAME_POINTER_REGNUM)))
+	    if (live_regs_mask & (1 << regno))
 	      break;
 
-	  if (regno > LAST_LO_REGNUM) /* Very unlikely.  */
-	    {
-	      rtx spare = gen_rtx_REG (SImode, IP_REGNUM);
-
-	      /* Choose an arbitrary, non-argument low register.  */
-	      reg = gen_rtx_REG (SImode, LAST_LO_REGNUM);
-
-	      /* Save it by copying it into a high, scratch register.  */
-	      emit_insn (gen_movsi (spare, reg));
-	      /* Add a USE to stop propagate_one_insn() from barfing.  */
-	      emit_insn (gen_prologue_use (spare));
+	  gcc_assert(regno <= LAST_LO_REGNUM);
 
-	      /* Decrement the stack.  */
-	      emit_insn (gen_movsi (reg, GEN_INT (- amount)));
-	      insn = emit_insn (gen_addsi3 (stack_pointer_rtx,
-					    stack_pointer_rtx, reg));
-	      RTX_FRAME_RELATED_P (insn) = 1;
-	      dwarf = gen_rtx_SET (VOIDmode, stack_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));
-
-	      /* Restore the low register's original value.  */
-	      emit_insn (gen_movsi (reg, spare));
-
-	      /* Emit a USE of the restored scratch register, so that flow
-		 analysis will not consider the restore redundant.  The
-		 register won't be used again in this function and isn't
-		 restored by the epilogue.  */
-	      emit_insn (gen_prologue_use (reg));
-	    }
-	  else
-	    {
-	      reg = gen_rtx_REG (SImode, regno);
+	  reg = gen_rtx_REG (SImode, regno);
 
-	      emit_insn (gen_movsi (reg, GEN_INT (- amount)));
+	  emit_insn (gen_movsi (reg, GEN_INT (- amount)));
 
-	      insn = emit_insn (gen_addsi3 (stack_pointer_rtx,
-					    stack_pointer_rtx, reg));
-	      RTX_FRAME_RELATED_P (insn) = 1;
-	      dwarf = gen_rtx_SET (VOIDmode, stack_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));
-	    }
+	  insn = emit_insn (gen_addsi3 (stack_pointer_rtx,
+					stack_pointer_rtx, reg));
+	  RTX_FRAME_RELATED_P (insn) = 1;
+	  dwarf = gen_rtx_SET (VOIDmode, stack_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));
 	}
     }