2006-02-17 Stuart Hastings <stuart@apple.com>apple/gcc-5325

	* Radar 4356747
	(marked APPLE LOCAL "4356747 stack realign")
	doc/extend.texi (force_align_arg_pointer): Document.
	doc/invoke.texi (-mstackrealign): Document.
	config/i386/i386.h (TARGET_OPTIONS): Add -mstackrealgin.
	config/i386/i386.c (ix86_force_align_arg_pointer): New.
	(ix86_force_align_arg_pointer_string): New.
	(ix86_attribute_table): Add "force_align_arg_pointer" attribute.
	(ix86_function_regparm): Compensate for new attribute.
	(ix86_internal_arg_pointer): Check for new attribute.

2005-11-02  Richard Henderson  <rth@redhat.com>

	(marked APPLE LOCAL "mainline 2006-02-17 4356747 stack realign")
	PR target/9350
	PR target/24374
	* dwarf2out.c (dwarf2out_reg_save_reg): New.
	(dwarf2out_frame_debug_expr): Return after dwarf_handle_frame_unspec.
	* function.c (assign_parms): Use calls.internal_arg_pointer.
	(expand_main_function): Remove FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN
	code.
	* target-def.h (TARGET_INTERNAL_ARG_POINTER): New.
	(TARGET_CALLS): Add it.
	* target.h (struct gcc_target): Add calls.internal_arg_pointer.
	* targhooks.c (default_internal_arg_pointer): New.
	* targhooks.h (default_internal_arg_pointer): Declare.
	* tree.h (dwarf2out_reg_save_reg): Declare.
	* doc/tm.texi (FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN): Remove.
	* config/i386/i386.c (dbx_register_map): Add return column.
	(dbx64_register_map, svr4_dbx_register_map): Likewise.
	(TARGET_INTERNAL_ARG_POINTER, ix86_internal_arg_pointer): New.
	(TARGET_DWARF_HANDLE_FRAME_UNSPEC, ix86_dwarf_handle_frame_unspec): New.
	(ix86_function_ok_for_sibcall): Disable if force_align_arg_pointer.
	(ix86_save_reg): Save force_align_arg_pointer.
	(ix86_emit_save_regs): Make regno unsigned.
	(ix86_emit_save_regs_using_mov): Likewise.
	(ix86_expand_prologue): Handle force_align_arg_pointer.
	(ix86_expand_epilogue): Likewise.
	* config/i386/i386.h: (dbx_register_map): Update.
	(dbx64_register_map, svr4_dbx_register_map): Update.
	(struct machine_function): Add force_align_arg_pointer.
	* config/i386/i386.md (UNSPEC_REG_SAVE, UNSPEC_DEF_CFA): New.
	(UNSPEC_TP, UNSPEC_TLS_GD, UNSPEC_TLS_LD_BASE): Renumber.
	(TARGET_PUSH_MEMORY peepholes): Disable if RTX_FRAME_RELATED_P.

2006-02-27  Stuart Hastings  <stuart@apple.com>

	Radar 4448096
	* testsuite/gcc.target/i386/4448096-1.c: New.
	* testsuite/g++.dg/4448096-2.C: New.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/apple-local-200502-branch@111503 138bc75d-0d04-0410-961f-82ee72b054a4

21 files changed, 555 insertions, 76 deletions

diff --git a/gcc/ChangeLog.apple-ppc b/gcc/ChangeLog.apple-ppc
index 6ce5864f83a..74bfa4dbc09 100644
--- a/gcc/ChangeLog.apple-ppc
+++ b/gcc/ChangeLog.apple-ppc
@@ -1,3 +1,50 @@
+2006-02-17  Stuart Hastings  <stuart@apple.com>
+
+	* Radar 4356747
+	(marked APPLE LOCAL "4356747 stack realign")
+	doc/extend.texi (force_align_arg_pointer): Document.
+	doc/invoke.texi (-mstackrealign): Document.
+	config/i386/i386.h (TARGET_OPTIONS): Add -mstackrealgin.
+	config/i386/i386.c (ix86_force_align_arg_pointer): New.
+	(ix86_force_align_arg_pointer_string): New.
+	(ix86_attribute_table): Add "force_align_arg_pointer" attribute.
+	(ix86_function_regparm): Compensate for new attribute.
+	(ix86_internal_arg_pointer): Check for new attribute.
+
+2005-11-02  Richard Henderson  <rth@redhat.com>
+
+	(marked APPLE LOCAL "mainline 2006-02-17 4356747 stack realign")
+	PR target/9350
+	PR target/24374
+	* dwarf2out.c (dwarf2out_reg_save_reg): New.
+	(dwarf2out_frame_debug_expr): Return after dwarf_handle_frame_unspec.
+	* function.c (assign_parms): Use calls.internal_arg_pointer.
+	(expand_main_function): Remove FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN
+	code.
+	* target-def.h (TARGET_INTERNAL_ARG_POINTER): New.
+	(TARGET_CALLS): Add it.
+	* target.h (struct gcc_target): Add calls.internal_arg_pointer.
+	* targhooks.c (default_internal_arg_pointer): New.
+	* targhooks.h (default_internal_arg_pointer): Declare.
+	* tree.h (dwarf2out_reg_save_reg): Declare.
+	* doc/tm.texi (FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN): Remove.
+	* config/i386/i386.c (dbx_register_map): Add return column.
+	(dbx64_register_map, svr4_dbx_register_map): Likewise.
+	(TARGET_INTERNAL_ARG_POINTER, ix86_internal_arg_pointer): New.
+	(TARGET_DWARF_HANDLE_FRAME_UNSPEC, ix86_dwarf_handle_frame_unspec): New.
+	(ix86_function_ok_for_sibcall): Disable if force_align_arg_pointer.
+	(ix86_save_reg): Save force_align_arg_pointer.
+	(ix86_emit_save_regs): Make regno unsigned.
+	(ix86_emit_save_regs_using_mov): Likewise.
+	(ix86_expand_prologue): Handle force_align_arg_pointer.
+	(ix86_expand_epilogue): Likewise.
+	* config/i386/i386.h: (dbx_register_map): Update.
+	(dbx64_register_map, svr4_dbx_register_map): Update.
+	(struct machine_function): Add force_align_arg_pointer.
+	* config/i386/i386.md (UNSPEC_REG_SAVE, UNSPEC_DEF_CFA): New.
+	(UNSPEC_TP, UNSPEC_TLS_GD, UNSPEC_TLS_LD_BASE): Renumber.
+	(TARGET_PUSH_MEMORY peepholes): Disable if RTX_FRAME_RELATED_P.
+
 2006-02-27  Stuart Hastings  <stuart@apple.com>
 
 	Radar 4448096
diff --git a/gcc/config/i386/i386-protos.h b/gcc/config/i386/i386-protos.h
index 226326da18f..53b52aa72ca 100644
--- a/gcc/config/i386/i386-protos.h
+++ b/gcc/config/i386/i386-protos.h
@@ -285,3 +285,8 @@ extern bool cw_print_op (char *buf, tree arg, unsigned argnum, tree *uses,
 			 bool must_be_reg, bool must_not_be_reg, void *);
 extern void x86_cw_print_prefix (char *buf, tree prefix_list);
 /* APPLE LOCAL end CW asm blocks */
+
+/* APPLE LOCAL begin 4356747 stack realign */
+/* Note to merger: this decl will vanish when the i386.opt file arrives in the merge.  */
+extern int ix86_force_align_arg_pointer;
+/* APPLE LOCAL end 4356747 stack realign */
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 123400c734a..6d2302e92b4 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -664,7 +664,8 @@ enum reg_class const regclass_map[FIRST_PSEUDO_REGISTER] =
 
 /* The "default" register map used in 32bit mode.  */
 
-int const dbx_register_map[FIRST_PSEUDO_REGISTER] =
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+int const dbx_register_map[FIRST_PSEUDO_REGISTER+1] =
 {
   0, 2, 1, 3, 6, 7, 4, 5,		/* general regs */
   12, 13, 14, 15, 16, 17, 18, 19,	/* fp regs */
@@ -673,7 +674,9 @@ int const dbx_register_map[FIRST_PSEUDO_REGISTER] =
   29, 30, 31, 32, 33, 34, 35, 36,       /* MMX */
   -1, -1, -1, -1, -1, -1, -1, -1,	/* extended integer registers */
   -1, -1, -1, -1, -1, -1, -1, -1,	/* extended SSE registers */
+  8					/* return column */
 };
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
 
 static int const x86_64_int_parameter_registers[6] =
 {
@@ -687,7 +690,8 @@ static int const x86_64_int_return_registers[4] =
 };
 
 /* The "default" register map used in 64bit mode.  */
-int const dbx64_register_map[FIRST_PSEUDO_REGISTER] =
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+int const dbx64_register_map[FIRST_PSEUDO_REGISTER+1] =
 {
   0, 1, 2, 3, 4, 5, 6, 7,		/* general regs */
   33, 34, 35, 36, 37, 38, 39, 40,	/* fp regs */
@@ -696,7 +700,9 @@ int const dbx64_register_map[FIRST_PSEUDO_REGISTER] =
   41, 42, 43, 44, 45, 46, 47, 48,       /* MMX */
   8,9,10,11,12,13,14,15,		/* extended integer registers */
   25, 26, 27, 28, 29, 30, 31, 32,	/* extended SSE registers */
+  16					/* return column */
 };
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
 
 /* Define the register numbers to be used in Dwarf debugging information.
    The SVR4 reference port C compiler uses the following register numbers
@@ -752,7 +758,8 @@ int const dbx64_register_map[FIRST_PSEUDO_REGISTER] =
 	17 for %st(6) (gcc regno = 14)
 	18 for %st(7) (gcc regno = 15)
 */
-int const svr4_dbx_register_map[FIRST_PSEUDO_REGISTER] =
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+int const svr4_dbx_register_map[FIRST_PSEUDO_REGISTER+1] =
 {
   0, 2, 1, 3, 6, 7, 5, 4,		/* general regs */
   11, 12, 13, 14, 15, 16, 17, 18,	/* fp regs */
@@ -761,7 +768,9 @@ int const svr4_dbx_register_map[FIRST_PSEUDO_REGISTER] =
   29, 30, 31, 32, 33, 34, 35, 36,	/* MMX registers */
   -1, -1, -1, -1, -1, -1, -1, -1,	/* extended integer registers */
   -1, -1, -1, -1, -1, -1, -1, -1,	/* extended SSE registers */
+  8					/* return column */
 };
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
 
 /* Test and compare insns in i386.md store the information needed to
    generate branch and scc insns here.  */
@@ -869,6 +878,25 @@ const char *ix86_align_jumps_string;
 /* Power of two alignment for stack boundary in bytes.  */
 const char *ix86_preferred_stack_boundary_string;
 
+/* APPLE LOCAL begin 4356747 stack realign */
+/* -mstackrealign option */
+/* extern *//* Note #1 to merger: This decl will move to "i386.opt" in
+	       the next FSF merge, and then we'll need an 'extern'
+	       here.  */
+const char *ix86_force_align_arg_pointer;
+static const char const ix86_force_align_arg_pointer_string[] = "force_align_arg_pointer";
+/* Note #2 to merger: The -mstackrealign stuff was submitted to FSF trunk
+on 10feb2006: http://gcc.gnu.org/ml/gcc-patches/2006-02/msg00854.html
+Apple needed this enhancement promptly (before the FSF acted on that patch), so
+A) I copied in a previous, necessary trunk patch:
+   http://gcc.gnu.org/ml/gcc-patches/2005-10/msg00931.html
+   This patch is marked "mainline 2006-02-17 4356747 stack realign".
+B) I added my own patch (URL above), marked "4356747 stack realign".
+C) I had to modify my patch to work without the "i386.opt" file (I was too lazy
+to merge this non-trivial change into Apple's Curry branch).
+HTH.  */
+/* APPLE LOCAL end 4356747 stack realign */
+
 /* Preferred alignment for stack boundary in bits.  */
 unsigned int ix86_preferred_stack_boundary;
 
@@ -977,6 +1005,11 @@ static bool ix86_pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 static void ix86_init_builtins (void);
 static rtx ix86_expand_builtin (tree, rtx, rtx, enum machine_mode, int);
 
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+static rtx ix86_internal_arg_pointer (void);
+static void ix86_dwarf_handle_frame_unspec (const char *, rtx, int);
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
+
 /* This function is only used on Solaris.  */
 static void i386_solaris_elf_named_section (const char *, unsigned int, tree)
   ATTRIBUTE_UNUSED;
@@ -1129,6 +1162,12 @@ static void init_ext_80387_constants (void);
 #define TARGET_MUST_PASS_IN_STACK ix86_must_pass_in_stack
 #undef TARGET_PASS_BY_REFERENCE
 #define TARGET_PASS_BY_REFERENCE ix86_pass_by_reference
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+#undef TARGET_INTERNAL_ARG_POINTER
+#define TARGET_INTERNAL_ARG_POINTER ix86_internal_arg_pointer
+#undef TARGET_DWARF_HANDLE_FRAME_UNSPEC
+#define TARGET_DWARF_HANDLE_FRAME_UNSPEC ix86_dwarf_handle_frame_unspec
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
 
 #undef TARGET_GIMPLIFY_VA_ARG_EXPR
 #define TARGET_GIMPLIFY_VA_ARG_EXPR ix86_gimplify_va_arg
@@ -1789,6 +1828,11 @@ const struct attribute_spec ix86_attribute_table[] =
   { "regparmandstackparm", 0, 0, false, true, true, ix86_handle_cconv_attribute },
   { "regparmandstackparmee", 0, 0, false, true, true, ix86_handle_cconv_attribute },
   /* APPLE LOCAL end regparmandstackparm */
+  /* APPLE LOCAL begin 4356747 stack realign */
+  /* force_align_arg_pointer says this function realigns the stack at entry.  */
+  { ix86_force_align_arg_pointer_string, 0, 0,
+    false, true,  true, ix86_handle_cconv_attribute },
+  /* APPLE LOCAL end 4356747 stack realign */
 #if TARGET_DLLIMPORT_DECL_ATTRIBUTES
   { "dllimport", 0, 0, false, false, false, handle_dll_attribute },
   { "dllexport", 0, 0, false, false, false, handle_dll_attribute },
@@ -1872,6 +1916,13 @@ ix86_function_ok_for_sibcall (tree decl, tree exp)
     return false;
 #endif
 
+  /* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+  /* If we forced aligned the stack, then sibcalling would unalign the
+     stack, which may break the called function.  */
+  if (cfun->machine->force_align_arg_pointer)
+    return false;
+  /* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
+
   /* Otherwise okay.  That also includes certain types of indirect calls.  */
   return true;
 }
@@ -1993,6 +2044,8 @@ ix86_handle_cconv_attribute (tree *node, tree name,
     }
 
   /* Can combine sseregparm with all attributes.  */
+  /* APPLE LOCAL 4356747 stack realign */
+  /* Can combine force_align_arg_pointer with all attributes.  */
 
   return NULL_TREE;
 }
@@ -2039,8 +2092,9 @@ ix86_comp_type_attributes (tree type1, tree type2)
 static int
 ix86_function_regparm (tree type, tree decl)
 {
+  /* APPLE LOCAL mainline 2006-02-17 4356747 stack realign (function body) */
   tree attr;
-  int regparm = ix86_regparm;
+  int local_regparm = ix86_regparm;
   bool user_convention = false;
 
   if (!TARGET_64BIT)
@@ -2048,7 +2102,7 @@ ix86_function_regparm (tree type, tree decl)
       attr = lookup_attribute ("regparm", TYPE_ATTRIBUTES (type));
       if (attr)
 	{
-	  regparm = TREE_INT_CST_LOW (TREE_VALUE (TREE_VALUE (attr)));
+	  local_regparm = TREE_INT_CST_LOW (TREE_VALUE (TREE_VALUE (attr)));
 	  user_convention = true;
 	}
 
@@ -2057,7 +2111,7 @@ ix86_function_regparm (tree type, tree decl)
 	  || lookup_attribute ("regparmandstackparmee", TYPE_ATTRIBUTES (type)))
       /* APPLE LOCAL end regparmandstackparm */
 	{
-	  regparm = 2;
+	  local_regparm = 2;
 	  user_convention = true;
 	}
 
@@ -2071,13 +2125,18 @@ ix86_function_regparm (tree type, tree decl)
 	      /* We can't use regparm(3) for nested functions as these use
 		 static chain pointer in third argument.  */
 	      if (DECL_CONTEXT (decl) && !DECL_NO_STATIC_CHAIN (decl))
-		regparm = 2;
+		local_regparm = 2;
 	      else
-		regparm = 3;
+		local_regparm = 3;
+	      /* If the function realigns its stackpointer, it
+		 clobbers %ecx to deref unaligned arguments.  */
+	      if (cfun->machine->force_align_arg_pointer)
+		local_regparm = 2;
 	    }
 	}
     }
-  return regparm;
+  return local_regparm;
+  /* APPLE LOCAL end 4356747 stack realign (function body) */
 }
 
 /* APPLE LOCAL begin mainline 2005-09-20 4205103 */
@@ -4454,6 +4513,12 @@ ix86_save_reg (unsigned int regno, int maybe_eh_return)
 	}
     }
 
+  /* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+  if (cfun->machine->force_align_arg_pointer
+      && regno == REGNO (cfun->machine->force_align_arg_pointer))
+    return 1;
+  /* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
+
   return (regs_ever_live[regno]
 	  && !call_used_regs[regno]
 	  && !fixed_regs[regno]
@@ -4669,15 +4734,17 @@ ix86_compute_frame_layout (struct ix86_frame *frame)
 static void
 ix86_emit_save_regs (void)
 {
-  int regno;
+  /* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign (function body) */
+  unsigned int regno;
   rtx insn;
 
-  for (regno = FIRST_PSEUDO_REGISTER - 1; regno >= 0; regno--)
+  for (regno = FIRST_PSEUDO_REGISTER; regno-- > 0; )
     if (ix86_save_reg (regno, true))
       {
 	insn = emit_insn (gen_push (gen_rtx_REG (Pmode, regno)));
 	RTX_FRAME_RELATED_P (insn) = 1;
       }
+  /* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign (function body) */
 }
 
 /* Emit code to save registers using MOV insns.  First register
@@ -4685,7 +4752,8 @@ ix86_emit_save_regs (void)
 static void
 ix86_emit_save_regs_using_mov (rtx pointer, HOST_WIDE_INT offset)
 {
-  int regno;
+  /* APPLE LOCAL mainline 2006-02-17 4356747 stack realign */
+  unsigned int regno;
   rtx insn;
 
   for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
@@ -4740,6 +4808,70 @@ pro_epilogue_adjust_stack (rtx dest, rtx src, rtx offset, int style)
 #endif
 /* APPLE LOCAL end fix-and-continue x86 */
 
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+/* Handle the TARGET_INTERNAL_ARG_POINTER hook.  */
+
+static rtx
+ix86_internal_arg_pointer (void)
+{
+  /* APPLE LOCAL begin 4356747 stack realign */
+  /* Note to merger: this function is from FSF mainline, AND it has
+     been altered with a local patch that is pending in FSF.  */
+  bool has_force_align_arg_pointer =
+    (0 != lookup_attribute (ix86_force_align_arg_pointer_string,
+			    TYPE_ATTRIBUTES (TREE_TYPE (current_function_decl))));
+  if ((FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN
+       && DECL_NAME (current_function_decl)
+       && MAIN_NAME_P (DECL_NAME (current_function_decl))
+       && DECL_FILE_SCOPE_P (current_function_decl))
+      || ix86_force_align_arg_pointer
+      || has_force_align_arg_pointer)
+    {
+      /* Nested functions can't realign the stack due to a register
+	 conflict.  */
+      if (DECL_CONTEXT (current_function_decl)
+	  && TREE_CODE (DECL_CONTEXT (current_function_decl)) == FUNCTION_DECL)
+	{
+	  if (ix86_force_align_arg_pointer)
+	    warning ("-mstackrealign ignored for nested functions");
+	  if (has_force_align_arg_pointer)
+	    error ("%s not supported for nested functions",
+		   ix86_force_align_arg_pointer_string);
+	  return virtual_incoming_args_rtx;
+	}
+      cfun->machine->force_align_arg_pointer = gen_rtx_REG (Pmode, 2);
+      return copy_to_reg (cfun->machine->force_align_arg_pointer);
+    }
+  else
+    return virtual_incoming_args_rtx;
+  /* APPLE LOCAL end 4356747 stack realign */
+}
+
+/* Handle the TARGET_DWARF_HANDLE_FRAME_UNSPEC hook.
+   This is called from dwarf2out.c to emit call frame instructions
+   for frame-related insns containing UNSPECs and UNSPEC_VOLATILEs. */
+static void
+ix86_dwarf_handle_frame_unspec (const char *label, rtx pattern, int index)
+{
+  rtx unspec = SET_SRC (pattern);
+  gcc_assert (GET_CODE (unspec) == UNSPEC);
+
+  switch (index)
+    {
+    case UNSPEC_REG_SAVE:
+      dwarf2out_reg_save_reg (label, XVECEXP (unspec, 0, 0),
+			      SET_DEST (pattern));
+      break;
+    case UNSPEC_DEF_CFA:
+      dwarf2out_def_cfa (label, REGNO (SET_DEST (pattern)),
+			 INTVAL (XVECEXP (unspec, 0, 0)));
+      break;
+    default:
+      gcc_unreachable ();
+    }
+}
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
+
 /* Expand the prologue into a bunch of separate insns.  */
 
 void
@@ -4769,6 +4901,54 @@ ix86_expand_prologue (void)
 
   ix86_compute_frame_layout (&frame);
 
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+  if (cfun->machine->force_align_arg_pointer)
+    {
+      rtx x, y;
+
+      /* Grab the argument pointer.  */
+      x = plus_constant (stack_pointer_rtx, 4);
+      y = cfun->machine->force_align_arg_pointer;
+      insn = emit_insn (gen_rtx_SET (VOIDmode, y, x));
+      RTX_FRAME_RELATED_P (insn) = 1;
+
+      /* The unwind info consists of two parts: install the fafp as the cfa,
+	 and record the fafp as the "save register" of the stack pointer.
+	 The later is there in order that the unwinder can see where it
+	 should restore the stack pointer across the and insn.  */
+      x = gen_rtx_UNSPEC (VOIDmode, gen_rtvec (1, const0_rtx), UNSPEC_DEF_CFA);
+      x = gen_rtx_SET (VOIDmode, y, x);
+      RTX_FRAME_RELATED_P (x) = 1;
+      y = gen_rtx_UNSPEC (VOIDmode, gen_rtvec (1, stack_pointer_rtx),
+			  UNSPEC_REG_SAVE);
+      y = gen_rtx_SET (VOIDmode, cfun->machine->force_align_arg_pointer, y);
+      RTX_FRAME_RELATED_P (y) = 1;
+      x = gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, x, y));
+      x = gen_rtx_EXPR_LIST (REG_FRAME_RELATED_EXPR, x, NULL);
+      REG_NOTES (insn) = x;
+
+      /* Align the stack.  */
+      emit_insn (gen_andsi3 (stack_pointer_rtx, stack_pointer_rtx,
+			     GEN_INT (-16)));
+
+      /* And here we cheat like madmen with the unwind info.  We force the
+	 cfa register back to sp+4, which is exactly what it was at the
+	 start of the function.  Re-pushing the return address results in
+	 the return at the same spot relative to the cfa, and thus is 
+	 correct wrt the unwind info.  */
+      x = cfun->machine->force_align_arg_pointer;
+      x = gen_frame_mem (Pmode, plus_constant (x, -4));
+      insn = emit_insn (gen_push (x));
+      RTX_FRAME_RELATED_P (insn) = 1;
+
+      x = GEN_INT (4);
+      x = gen_rtx_UNSPEC (VOIDmode, gen_rtvec (1, x), UNSPEC_DEF_CFA);
+      x = gen_rtx_SET (VOIDmode, stack_pointer_rtx, x);
+      x = gen_rtx_EXPR_LIST (REG_FRAME_RELATED_EXPR, x, NULL);
+      REG_NOTES (insn) = x;
+    }
+  /* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
+
   /* Note: AT&T enter does NOT have reversed args.  Enter is probably
      slower on all targets.  Also sdb doesn't like it.  */
 
@@ -5059,6 +5239,15 @@ ix86_expand_epilogue (int style)
 	}
     }
 
+  /* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+  if (cfun->machine->force_align_arg_pointer)
+    {
+      emit_insn (gen_addsi3 (stack_pointer_rtx,
+			     cfun->machine->force_align_arg_pointer,
+			     GEN_INT (-4)));
+    }
+  /* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
+
   /* Sibcall epilogues don't want a return instruction.  */
   if (style == 0)
     return;
diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index 323cf47faa5..b02a6c51f47 100644
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -517,6 +517,11 @@ extern int x86_prefetch_sse;
     N_("Use given assembler dialect"), 0},			\
   { "tls-dialect=", &ix86_tls_dialect_string,			\
     N_("Use given thread-local storage dialect"), 0},		\
+  /* APPLE LOCAL begin 4356747 stack realign */			\
+  { "stackrealign",						\
+    &ix86_force_align_arg_pointer,				\
+    N_("Realign stack in prologue"), 0},			\
+  /* APPLE LOCAL end 4356747 stack realign */			\
   SUBTARGET_OPTIONS						\
 }
 
@@ -2288,9 +2293,11 @@ number as al, and ax.
 #define DBX_REGISTER_NUMBER(N) \
   (TARGET_64BIT ? dbx64_register_map[(N)] : dbx_register_map[(N)])
 
-extern int const dbx_register_map[FIRST_PSEUDO_REGISTER];
-extern int const dbx64_register_map[FIRST_PSEUDO_REGISTER];
-extern int const svr4_dbx_register_map[FIRST_PSEUDO_REGISTER];
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+extern int const dbx_register_map[FIRST_PSEUDO_REGISTER+1];
+extern int const dbx64_register_map[FIRST_PSEUDO_REGISTER+1];
+extern int const svr4_dbx_register_map[FIRST_PSEUDO_REGISTER+1];
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
 
 /* Before the prologue, RA is at 0(%esp).  */
 #define INCOMING_RETURN_ADDR_RTX \
@@ -2587,6 +2594,8 @@ struct machine_function GTY(())
 {
   struct stack_local_entry *stack_locals;
   const char *some_ld_name;
+  /* APPLE LOCAL mainline 2006-02-17 4356747 stack realign */
+  rtx force_align_arg_pointer;
   int save_varrargs_registers;
   int accesses_prev_frame;
   int optimize_mode_switching;
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index a61c80bdea7..ddedbbc375e 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -66,11 +66,15 @@
    (UNSPEC_STACK_ALLOC		11)
    (UNSPEC_SET_GOT		12)
    (UNSPEC_SSE_PROLOGUE_SAVE	13)
+   ; APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign
+   (UNSPEC_REG_SAVE		14)
+   (UNSPEC_DEF_CFA		15)
 
    ; TLS support
-   (UNSPEC_TP			15)
-   (UNSPEC_TLS_GD		16)
-   (UNSPEC_TLS_LD_BASE		17)
+   (UNSPEC_TP			16)
+   (UNSPEC_TLS_GD		17)
+   (UNSPEC_TLS_LD_BASE		18)
+   ; APPLE LOCAL end mainline 2006-02-17 4356747 stack realign
 
    ; Other random patterns
    (UNSPEC_SCAS			20)
@@ -18511,7 +18515,10 @@
   [(set (match_operand:SI 0 "push_operand" "")
 	(match_operand:SI 1 "memory_operand" ""))
    (match_scratch:SI 2 "r")]
-  "! optimize_size && ! TARGET_PUSH_MEMORY"
+   ;; APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign
+  "!optimize_size && !TARGET_PUSH_MEMORY
+   && !RTX_FRAME_RELATED_P (peep2_next_insn (0))"
+   ;; APPLE LOCAL end mainline 2006-02-17 4356747 stack realign
   [(set (match_dup 2) (match_dup 1))
    (set (match_dup 0) (match_dup 2))]
   "")
@@ -18520,7 +18527,10 @@
   [(set (match_operand:DI 0 "push_operand" "")
 	(match_operand:DI 1 "memory_operand" ""))
    (match_scratch:DI 2 "r")]
-  "! optimize_size && ! TARGET_PUSH_MEMORY"
+   ;; APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign
+  "!optimize_size && !TARGET_PUSH_MEMORY
+   && !RTX_FRAME_RELATED_P (peep2_next_insn (0))"
+   ;; APPLE LOCAL end mainline 2006-02-17 4356747 stack realign
   [(set (match_dup 2) (match_dup 1))
    (set (match_dup 0) (match_dup 2))]
   "")
@@ -18531,7 +18541,10 @@
   [(set (match_operand:SF 0 "push_operand" "")
 	(match_operand:SF 1 "memory_operand" ""))
    (match_scratch:SF 2 "r")]
-  "! optimize_size && ! TARGET_PUSH_MEMORY"
+   ;; APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign
+  "!optimize_size && !TARGET_PUSH_MEMORY
+   && !RTX_FRAME_RELATED_P (peep2_next_insn (0))"
+   ;; APPLE LOCAL end mainline 2006-02-17 4356747 stack realign
   [(set (match_dup 2) (match_dup 1))
    (set (match_dup 0) (match_dup 2))]
   "")
@@ -18540,7 +18553,10 @@
   [(set (match_operand:HI 0 "push_operand" "")
 	(match_operand:HI 1 "memory_operand" ""))
    (match_scratch:HI 2 "r")]
-  "! optimize_size && ! TARGET_PUSH_MEMORY"
+   ;; APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign
+  "!optimize_size && !TARGET_PUSH_MEMORY
+   && !RTX_FRAME_RELATED_P (peep2_next_insn (0))"
+   ;; APPLE LOCAL end mainline 2006-02-17 4356747 stack realign
   [(set (match_dup 2) (match_dup 1))
    (set (match_dup 0) (match_dup 2))]
   "")
@@ -18549,7 +18565,10 @@
   [(set (match_operand:QI 0 "push_operand" "")
 	(match_operand:QI 1 "memory_operand" ""))
    (match_scratch:QI 2 "q")]
-  "! optimize_size && ! TARGET_PUSH_MEMORY"
+   ;; APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign
+  "!optimize_size && !TARGET_PUSH_MEMORY
+   && !RTX_FRAME_RELATED_P (peep2_next_insn (0))"
+   ;; APPLE LOCAL end mainline 2006-02-17 4356747 stack realign
   [(set (match_dup 2) (match_dup 1))
    (set (match_dup 0) (match_dup 2))]
   "")
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index e91ca054a12..c655b8fb9d2 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -2168,6 +2168,22 @@ safe since the loaders there save all registers.  (Lazy binding can be
 disabled with the linker or the loader if desired, to avoid the
 problem.)
 
+@c APPLE LOCAL begin 4356747 stack realign
+@item force_align_arg_pointer
+@cindex @code{force_align_arg_pointer} attribute
+On the Intel x86, the @code{force_align_arg_pointer} attribute may be
+applied to individual function definitions, generating an alternate
+prologue and epilogue that realigns the runtime stack.  This supports
+mixing legacy codes that run with a 4-byte aligned stack with modern
+codes that keep a 16-byte stack for SSE compatibility.  The alternate
+prologue/epilogue is slower and bigger than the regular one, and it
+requires one dedicated register for the life of the function.  This
+also lowers the number of registers available if used in conjunction
+with the @code{regparm} attribute.  The @code{force_align_arg_pointer}
+attribute is incompatible with nested functions; this is considered a
+hard error.
+@c APPLE LOCAL end 4356747 stack realign
+
 @item saveall
 @cindex save all registers on the Blackfin, H8/300, H8/300H, and H8S
 Use this attribute on the Blackfin, H8/300, H8/300H, and H8S to indicate that
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index ac974df892b..618e3fd1296 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -374,6 +374,8 @@ Objective-C and Objective-C++ Dialects}.
 -fno-inline  -fno-math-errno  -fno-peephole  -fno-peephole2 @gol
 -funsafe-math-optimizations  -ffinite-math-only @gol
 -fno-trapping-math  -fno-zero-initialized-in-bss @gol
+@c APPLE LOCAL 4356747 stack realign
+-mstackrealign @gol
 -fomit-frame-pointer  -foptimize-register-move @gol
 -foptimize-sibling-calls  -fprefetch-loop-arrays @gol
 -fprofile-generate -fprofile-use @gol
@@ -9468,6 +9470,22 @@ function by using the function attribute @samp{regparm}.
 value, including any libraries.  This includes the system libraries and
 startup modules.
 
+@c APPLE LOCAL begin 4356747 stack realign
+@item -mstackrealign
+@opindex mstackrealign
+Realign the stack at entry.  On the Intel x86, the
+@option{-mstackrealign} option will generate an alternate
+prologue/epilogue that realigns the runtime stack.  This supports
+mixing legacy codes that keep a 4-byte aligned stack with modern codes
+that keep a 16-byte stack for SSE compatibility.  The alternate
+prologue and epilogue are slower and bigger than the regular ones, and
+they require one dedicated register for the entire function.  This
+also lowers the number of registers available if used in conjunction
+with the @code{regparm} attribute.  Nested functions encountered while
+@option{-mstackrealign} is on will generate warnings, and they will
+not realign the stack when called.
+@c APPLE LOCAL end 4356747 stack realign
+
 @item -mpreferred-stack-boundary=@var{num}
 @opindex mpreferred-stack-boundary
 Attempt to keep the stack boundary aligned to a 2 raised to @var{num}
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 3d07181e1d6..255726038de 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -1258,6 +1258,32 @@ clobbers_queued_reg_save (rtx insn)
   return false;
 }
 
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+/* Entry point for saving the first register into the second.  */
+
+void
+dwarf2out_reg_save_reg (const char *label, rtx reg, rtx sreg)
+{
+  size_t i;
+  unsigned int regno, sregno;
+
+  for (i = 0; i < num_regs_saved_in_regs; i++)
+    if (REGNO (regs_saved_in_regs[i].orig_reg) == REGNO (reg))
+      break;
+  if (i == num_regs_saved_in_regs)
+    {
+      gcc_assert (i != ARRAY_SIZE (regs_saved_in_regs));
+      num_regs_saved_in_regs++;
+    }
+  regs_saved_in_regs[i].orig_reg = reg;
+  regs_saved_in_regs[i].saved_in_reg = sreg;
+
+  regno = DWARF_FRAME_REGNUM (REGNO (reg));
+  sregno = DWARF_FRAME_REGNUM (REGNO (sreg));
+  reg_save (label, regno, sregno, 0);
+}
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
+
 /* What register, if any, is currently saved in REG?  */
 
 static rtx
@@ -1646,7 +1672,8 @@ dwarf2out_frame_debug_expr (rtx expr, const char *label)
 	case UNSPEC_VOLATILE:
 	  gcc_assert (targetm.dwarf_handle_frame_unspec);
 	  targetm.dwarf_handle_frame_unspec (label, expr, XINT (src, 1));
-	  break;
+	  /* APPLE LOCAL mainline 2006-02-17 4356747 stack realign */
+	  return;
 
 	default:
 	  gcc_unreachable ();
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 37bd66587d8..606b76b2e0f 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -606,6 +606,33 @@ gen_const_mem (enum machine_mode mode, rtx addr)
   return mem;
 }
 
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+/* Generate a MEM referring to fixed portions of the frame, e.g., register
+   save areas.  */
+
+rtx
+gen_frame_mem (enum machine_mode mode, rtx addr)
+{
+  rtx mem = gen_rtx_MEM (mode, addr);
+  MEM_NOTRAP_P (mem) = 1;
+  set_mem_alias_set (mem, get_frame_alias_set ());
+  return mem;
+}
+
+/* Generate a MEM referring to a temporary use of the stack, not part
+    of the fixed stack frame.  For example, something which is pushed
+    by a target splitter.  */
+rtx
+gen_tmp_stack_mem (enum machine_mode mode, rtx addr)
+{
+  rtx mem = gen_rtx_MEM (mode, addr);
+  MEM_NOTRAP_P (mem) = 1;
+  if (!current_function_calls_alloca)
+    set_mem_alias_set (mem, get_frame_alias_set ());
+  return mem;
+}
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
+
 /* We want to create (subreg:OMODE (obj:IMODE) OFFSET).  Return true if
    this construct would be valid, and false otherwise.  */
 
diff --git a/gcc/function.c b/gcc/function.c
index f17dd551ad5..5ea2def46d4 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -3061,24 +3061,14 @@ assign_parms (tree fndecl)
 {
   struct assign_parm_data_all all;
   tree fnargs, parm;
-  rtx internal_arg_pointer;
+  /* APPLE LOCAL deletion mainline 2006-02-17 4356747 stack realign */
   /* APPLE LOCAL AltiVec */
   int pass, last_pass;
 
-  /* If the reg that the virtual arg pointer will be translated into is
-     not a fixed reg or is the stack pointer, make a copy of the virtual
-     arg pointer, and address parms via the copy.  The frame pointer is
-     considered fixed even though it is not marked as such.
-
-     The second time through, simply use ap to avoid generating rtx.  */
-
-  if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
-       || ! (fixed_regs[ARG_POINTER_REGNUM]
-	     || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
-    internal_arg_pointer = copy_to_reg (virtual_incoming_args_rtx);
-  else
-    internal_arg_pointer = virtual_incoming_args_rtx;
-  current_function_internal_arg_pointer = internal_arg_pointer;
+  /* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+  current_function_internal_arg_pointer
+    = targetm.calls.internal_arg_pointer ();
+  /* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
 
   assign_parms_initialize_all (&all);
   fnargs = assign_parms_augmented_arg_list (&all);
@@ -4093,42 +4083,7 @@ init_function_for_compilation (void)
 void
 expand_main_function (void)
 {
-#ifdef FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN
-  if (FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN)
-    {
-      int align = PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT;
-      rtx tmp, seq;
-
-      start_sequence ();
-      /* Forcibly align the stack.  */
-#ifdef STACK_GROWS_DOWNWARD
-      tmp = expand_simple_binop (Pmode, AND, stack_pointer_rtx, GEN_INT(-align),
-				 stack_pointer_rtx, 1, OPTAB_WIDEN);
-#else
-      tmp = expand_simple_binop (Pmode, PLUS, stack_pointer_rtx,
-				 GEN_INT (align - 1), NULL_RTX, 1, OPTAB_WIDEN);
-      tmp = expand_simple_binop (Pmode, AND, tmp, GEN_INT (-align),
-				 stack_pointer_rtx, 1, OPTAB_WIDEN);
-#endif
-      if (tmp != stack_pointer_rtx)
-	emit_move_insn (stack_pointer_rtx, tmp);
-
-      /* Enlist allocate_dynamic_stack_space to pick up the pieces.  */
-      tmp = force_reg (Pmode, const0_rtx);
-      allocate_dynamic_stack_space (tmp, NULL_RTX, BIGGEST_ALIGNMENT);
-      seq = get_insns ();
-      end_sequence ();
-
-      for (tmp = get_last_insn (); tmp; tmp = PREV_INSN (tmp))
-	if (NOTE_P (tmp) && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_FUNCTION_BEG)
-	  break;
-      if (tmp)
-	emit_insn_before (seq, tmp);
-      else
-	emit_insn (seq);
-    }
-#endif
-
+  /* APPLE LOCAL deletion mainline 2006-02-17 4356747 stack realign */
 #ifndef HAS_INIT_SECTION
   emit_library_call (init_one_libfunc (NAME__MAIN), LCT_NORMAL, VOIDmode, 0);
 #endif
diff --git a/gcc/rtl.h b/gcc/rtl.h
index 2d45ee6a81a..f7489f5f310 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -1967,6 +1967,8 @@ extern rtx delete_insn_and_edges (rtx);
 extern void delete_insn_chain_and_edges (rtx, rtx);
 extern rtx gen_lowpart_SUBREG (enum machine_mode, rtx);
 extern rtx gen_const_mem (enum machine_mode, rtx);
+/* APPLE LOCAL mainline 2006-02-17 4356747 stack realign */
+extern rtx gen_frame_mem (enum machine_mode, rtx);
 extern bool validate_subreg (enum machine_mode, enum machine_mode,
 			     rtx, unsigned int);
 
diff --git a/gcc/target-def.h b/gcc/target-def.h
index 27a48a141fc..8fbdc56bdf4 100644
--- a/gcc/target-def.h
+++ b/gcc/target-def.h
@@ -433,6 +433,10 @@ Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 #define TARGET_CALLEE_COPIES hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false
 #define TARGET_ARG_PARTIAL_BYTES hook_int_CUMULATIVE_ARGS_mode_tree_bool_0
 
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+#define TARGET_INTERNAL_ARG_POINTER default_internal_arg_pointer
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
+
 /* APPLE LOCAL begin mainline 2005-04-14 */
 #define TARGET_CALLS {						\
    TARGET_PROMOTE_FUNCTION_ARGS,				\
@@ -453,7 +457,10 @@ Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
    TARGET_MUST_PASS_IN_STACK,					\
    TARGET_CALLEE_COPIES,					\
    TARGET_ARG_PARTIAL_BYTES,					\
-   TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN                     \
+   /* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */	\
+   TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN,			\
+   TARGET_INTERNAL_ARG_POINTER					\
+   /* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */		\
    }
 /* APPLE LOCAL end mainline 2005-04-14 */
 
diff --git a/gcc/target.h b/gcc/target.h
index 67c42fa5545..220663cd0e0 100644
--- a/gcc/target.h
+++ b/gcc/target.h
@@ -576,6 +576,12 @@ struct gcc_target
     const char *(*invalid_arg_for_unprototyped_fn) (tree typelist,
                                                     tree funcdecl, tree val);
     /* APPLE LOCAL end mainline 2005-04-14 */
+
+    /* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+    /* Return an rtx for the argument pointer incoming to the
+       current function.  */
+    rtx (*internal_arg_pointer) (void);
+    /* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
   } calls;
 
   /* Functions specific to the C++ frontend.  */
diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index c231e03f1e9..fc69a42510a 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -61,6 +61,8 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include "target.h"
 #include "tm_p.h"
 #include "target-def.h"
+/* APPLE LOCAL mainline 2006-02-17 4356747 stack realign */
+#include "hard-reg-set.h"
 
 
 void
@@ -309,3 +311,20 @@ hook_invalid_arg_for_unprototyped_fn (
   return NULL;
 }
 /* APPLE LOCAL end mainline 2005-04-14 */
+
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+rtx
+default_internal_arg_pointer (void)
+{
+  /* If the reg that the virtual arg pointer will be translated into is
+     not a fixed reg or is the stack pointer, make a copy of the virtual
+     arg pointer, and address parms via the copy.  The frame pointer is
+     considered fixed even though it is not marked as such.  */
+  if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
+       || ! (fixed_regs[ARG_POINTER_REGNUM]
+	     || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
+    return copy_to_reg (virtual_incoming_args_rtx);
+  else
+    return virtual_incoming_args_rtx;
+}
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index eccdf80d38e..2d3dde9c464 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -65,3 +65,6 @@ extern int hook_int_CUMULATIVE_ARGS_mode_tree_bool_0
 extern const char *hook_invalid_arg_for_unprototyped_fn
   (tree, tree, tree);
 /* APPLE LOCAL end mainline 2005-04-14 */
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+extern rtx default_internal_arg_pointer (void);
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
diff --git a/gcc/testsuite/ChangeLog.apple-ppc b/gcc/testsuite/ChangeLog.apple-ppc
index d9d91f6cf5b..fe7416f9d70 100644
--- a/gcc/testsuite/ChangeLog.apple-ppc
+++ b/gcc/testsuite/ChangeLog.apple-ppc
@@ -19,6 +19,14 @@
 
 2006-02-17  Stuart Hastings  <stuart@apple.com>
 
+	Radar 4356747
+	testsuite/gcc.target/i386/20060210-1.c: New.
+	testsuite/gcc.target/i386/20060210-2.c: New.
+	testsuite/gcc.target/i386/20060210-3.c: New.
+	testsuite/gcc.target/i386/20060210-4.c: New.
+
+2006-02-17  Stuart Hastings  <stuart@apple.com>
+
 	* gcc.dg/4176531.c: Fix target.
 
 2006-02-16  Mike Stump  <mrs@apple.com>
diff --git a/gcc/testsuite/gcc.target/i386/20060210-1.c b/gcc/testsuite/gcc.target/i386/20060210-1.c
new file mode 100644
index 00000000000..63d2ce66488
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/20060210-1.c
@@ -0,0 +1,39 @@
+/* APPLE LOCAL file 4356747 stack realign */
+/* { dg-do run { target i?86-*-darwin* i[6789]86-*-* } } */
+/* APPLE LOCAL Note: if/when this file arrives in a merge, the FSF
+   version probably won't have the -fnested-functions option, and it's
+   required on OS X.  */
+/* { dg-options "-std=gnu99 -fnested-functions" } */
+#include <stdio.h>
+#include <stdlib.h>
+#include <emmintrin.h>
+
+
+__m128i __attribute__ ((__noinline__))
+vector_using_function ()
+{
+  volatile __m128i vx;	/* We want to force a vector-aligned store into the stack.  */
+  vx = _mm_xor_si128 (vx, vx);
+  return vx;
+}
+
+int __attribute__ ((__noinline__, __force_align_arg_pointer__))
+self_aligning_function (int x, int y)
+{
+  __m128i ignored = vector_using_function ();
+  return (x + y);
+}
+
+int g_1 = 20;
+int g_2 = 22;
+
+int
+main ()
+{
+  int result;
+  asm ("pushl %esi");		/* Disalign runtime stack.  */
+  result = self_aligning_function (g_1, g_2);
+  asm ("popl %esi");
+  if (result != 42)
+    abort ();
+}
diff --git a/gcc/testsuite/gcc.target/i386/20060210-2.c b/gcc/testsuite/gcc.target/i386/20060210-2.c
new file mode 100644
index 00000000000..dee3cb7ea68
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/20060210-2.c
@@ -0,0 +1,19 @@
+/* APPLE LOCAL file 4356747 stack realign */
+/* { dg-do compile { target i?86-*-darwin* i[6789]86-*-* } } */
+/* APPLE LOCAL Note: if/when this file arrives in a merge, the FSF
+   version probably won't have the -fnested-functions option, and it's
+   required on OS X.  */
+/* { dg-options "-std=gnu99 -fnested-functions" } */
+#include <stdio.h>
+#include <stdlib.h>
+
+int
+outer_function (int x, int y)
+{
+  int __attribute__ ((__noinline__, __force_align_arg_pointer__))
+  nested_function (int x, int y)
+    { /* { dg-error "force_align_arg_pointer not supported for nested functions" } */
+      return (x + y);
+    }
+  return (3 + nested_function (x, y));
+}
diff --git a/gcc/testsuite/gcc.target/i386/20060210-3.c b/gcc/testsuite/gcc.target/i386/20060210-3.c
new file mode 100644
index 00000000000..efd3f50e386
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/20060210-3.c
@@ -0,0 +1,39 @@
+/* APPLE LOCAL file 4356747 stack realign */
+/* { dg-do run { target i?86-*-darwin* i[6789]86-*-* } } */
+/* APPLE LOCAL Note: if/when this file arrives in a merge, the FSF
+   version probably won't have the -fnested-functions option, and it's
+   required on OS X.  */
+/* { dg-options "-std=gnu99 -fnested-functions -mstackrealign" } */
+#include <stdio.h>
+#include <stdlib.h>
+#include <emmintrin.h>
+
+
+__m128i __attribute__ ((__noinline__))
+vector_using_function ()
+{
+  volatile __m128i vx;	/* We want to force a vector-aligned store into the stack.  */
+  vx = _mm_xor_si128 (vx, vx);
+  return vx;
+}
+
+int __attribute__ ((__noinline__))
+self_aligning_function (int x, int y)
+{
+  __m128i ignored = vector_using_function ();
+  return (x + y);
+}
+
+int g_1 = 20;
+int g_2 = 22;
+
+int
+main ()
+{
+  int result;
+  asm ("pushl %esi");		/* Disalign runtime stack.  */
+  result = self_aligning_function (g_1, g_2);
+  asm ("popl %esi");
+  if (result != 42)
+    abort ();
+}
diff --git a/gcc/testsuite/gcc.target/i386/20060210-4.c b/gcc/testsuite/gcc.target/i386/20060210-4.c
new file mode 100644
index 00000000000..627cc742015
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/20060210-4.c
@@ -0,0 +1,19 @@
+/* APPLE LOCAL file 4356747 stack realign */
+/* { dg-do compile { target i?86-*-darwin* i[6789]86-*-* } } */
+/* APPLE LOCAL Note: if/when this file arrives in a merge, the FSF
+   version probably won't have the -fnested-functions option, and it's
+   required on OS X.  */
+/* { dg-options "-std=gnu99 -fnested-functions -mstackrealign" } */
+#include <stdio.h>
+#include <stdlib.h>
+
+int
+outer_function (int x, int y)
+{
+  int __attribute__ ((__noinline__))
+  nested_function (int x, int y)
+    { /* { dg-error "-mstackrealign ignored for nested functions" } */
+      return (x + y);
+    }
+  return (3 + nested_function (x, y));
+}
diff --git a/gcc/tree.h b/gcc/tree.h
index 3ad60698252..19e133a5520 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -3840,6 +3840,12 @@ extern void dwarf2out_return_save (const char *, HOST_WIDE_INT);
 
 extern void dwarf2out_return_reg (const char *, unsigned);
 
+/* APPLE LOCAL begin mainline 2006-02-17 4356747 stack realign */
+/* Entry point for saving the first register into the second.  */
+
+extern void dwarf2out_reg_save_reg (const char *, rtx, rtx);
+/* APPLE LOCAL end mainline 2006-02-17 4356747 stack realign */
+
 /* In tree-inline.c  */
 
 /* The type of a set of already-visited pointers.  Functions for creating