gcc/:

	* common.opt (fsplit-stack): New option.
	* opts.c (decode_options): Set flag_split_stack to final value.
	* target.def (supports_split_stack): New hook.
	* gcc.c (STACK_SPLIT_SPEC): Define.
	(LINK_COMMAND_SPEC): Use STACK_SPLIT_SPEC.
	* doc/invoke.texi (Option Summary): Mention -fsplit-stack.
	(Code Gen Options): Document -fsplit-stack.
	* doc/extend.texi (Function Attributes): Mention no_split_stack.
	(Function Attributes): Document no_split_stack.
	* doc/tm.texi.in (Stack Smashing Protection): Add @hook
	TARGET_SUPPORTS_SPLIT_STACK.
	* doc/tm.texi: Rebuild.
	* function.c (thread_prologue_and_epilogue_insns): If
	flag_split_stack, add split stack prologue.
	* explow.c (allocate_dynamic_stack_space): Support -fsplit-stack.
	* varasm.c (saw_no_split_stack): New static variable.
	(assemble_start_function): Set saw_no_split_stack if the function
	has the no_split_stack attribute.
	(file_end_indicate_split_stack): New function.
	* output.h (file_end_indicate_split_stack): Declare.
	* libgcc-std.ver (GCC_4.6.0): Add -fsplit-stack support variables
	and function.
	* doc/libgcc.texi (Miscellaneous routines): Document -fsplit-stack
	routines.
	* config/i386/i386.c (ix86_option_override_internal): Don't set
	expand_builtin_va_start to NULL if -fsplit-stack.
	(ix86_function_regparm): Reduce local regparm by 1 for 32-bit
	-fsplit-stack.
	(ix86_va_start): If -fsplit-stack, get overflow pointer	from
	scratch register set by prologue.
	(ix86_code_end): If -fsplit-stack, call
	file_end_indicate_split_stack.
	(ix86_supports_split_stack): New static function.
	(SPLIT_STACK_AVAILABLE): Define.
	(split_stack_prologue_scratch_regno): New static function.
	(split_stack_fn): New static variable.
	(ix86_expand_split_stack_prologue): New function.
	(ix86_live_on_entry): New static function.
	(ix86_legitimate_address_p): Handle UNSPEC_STACK_CHECK.
	(output_pic_addr_const): Likewise.
	(i386_asm_output_addr_const_extra): Likewise.
	(ix86_expand_call): Change return type to rtx.  Return the new
	call instruction.
	(TARGET_SUPPORTS_SPLIT_STACK): Define.
	(TARGET_EXTRA_LIVE_ON_ENTRY): Define.
	* config/i386/i386.md (UNSPEC_STACK_CHECK): Define.
	(split_stack_prologue, split_stack_return): New insns.
	(split_stack_space_check): New insn.
	* config/i386/i386.h (struct machine_function): Add
	split_stack_varargs_pointer field.
	* config/i386/linux.h (TARGET_CAN_SPLIT_STACK): Define.
	(TARGET_THREAD_SPLIT_STACK_OFFSET): Define.
	* config/i386/linux64.h (TARGET_CAN_SPLIT_STACK): Define.
	(TARGET_THREAD_SPLIT_STACK_OFFSET): Define.
	* config/i386/i386-protos.h (ix86_expand_split_stack_prologue):
	Declare.
	(ix86_expand_call): Update declaration.
gcc/c-family/:
	* c-common.c (c_common_attribute_table): Add no_split_stack.
	(handle_no_split_stack_attribute): New static function.
gcc/testsuite/:
	* lib/target-supports.exp (check_effective_target_split_stack):
	New procedure.
	* gcc.dg/split-1.c: New test.
	* gcc.dg/split-2.c: New test.
	* gcc.dg/split-3.c: New test.
	* gcc.dg/split-4.c: New test.
libgcc/:
	* generic-morestack.h: New file.
	* generic-morestack.c: New file.
	* generic-morestack-thread.c: New file.
	* config/i386/morestack.S: New file.
	* config/t-stack: New file.
	* config/i386/t-stack-i386: New file.
	* config.host (i[34567]86-*-linux* and friends): Add t-stack and
	i386/t-stack-i386 to tmake_file.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@164661 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 65 insertions, 9 deletions

diff --git a/gcc/explow.c b/gcc/explow.c
index 2024b5324d8..21af58a7c81 100644
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -1,6 +1,6 @@
 /* Subroutines for manipulating rtx's in semantically interesting ways.
    Copyright (C) 1987, 1991, 1994, 1995, 1996, 1997, 1998,
-   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -1146,6 +1146,7 @@ allocate_dynamic_stack_space (rtx size, rtx target, int known_align,
 {
   HOST_WIDE_INT stack_usage_size = -1;
   bool known_align_valid = true;
+  rtx final_label, final_target;
 
   /* If we're asking for zero bytes, it doesn't matter what we point
      to since we can't dereference it.  But return a reasonable
@@ -1284,6 +1285,14 @@ allocate_dynamic_stack_space (rtx size, rtx target, int known_align,
 	}
     }
 
+  /* Don't use a TARGET that isn't a pseudo or is the wrong mode.  */
+  if (target == 0 || !REG_P (target)
+      || REGNO (target) < FIRST_PSEUDO_REGISTER
+      || GET_MODE (target) != Pmode)
+    target = gen_reg_rtx (Pmode);
+
+  mark_reg_pointer (target, known_align);
+
   /* The size is supposed to be fully adjusted at this point so record it
      if stack usage info is requested.  */
   if (flag_stack_usage)
@@ -1296,6 +1305,52 @@ allocate_dynamic_stack_space (rtx size, rtx target, int known_align,
 	current_function_has_unbounded_dynamic_stack_size = 1;
     }
 
+  final_label = NULL_RTX;
+  final_target = NULL_RTX;
+
+  /* If we are splitting the stack, we need to ask the backend whether
+     there is enough room on the current stack.  If there isn't, or if
+     the backend doesn't know how to tell is, then we need to call a
+     function to allocate memory in some other way.  This memory will
+     be released when we release the current stack segment.  The
+     effect is that stack allocation becomes less efficient, but at
+     least it doesn't cause a stack overflow.  */
+  if (flag_split_stack)
+    {
+      rtx available_label, space, func;
+
+      available_label = NULL_RTX;
+
+#ifdef HAVE_split_stack_space_check
+      if (HAVE_split_stack_space_check)
+	{
+	  available_label = gen_label_rtx ();
+
+	  /* This instruction will branch to AVAILABLE_LABEL if there
+	     are SIZE bytes available on the stack.  */
+	  emit_insn (gen_split_stack_space_check (size, available_label));
+	}
+#endif
+
+      func = init_one_libfunc ("__morestack_allocate_stack_space");
+
+      space = emit_library_call_value (func, target, LCT_NORMAL, Pmode,
+				       1, size, Pmode);
+
+      if (available_label == NULL_RTX)
+	return space;
+
+      final_target = gen_reg_rtx (Pmode);
+      mark_reg_pointer (final_target, known_align);
+
+      emit_move_insn (final_target, space);
+
+      final_label = gen_label_rtx ();
+      emit_jump (final_label);
+
+      emit_label (available_label);
+    }
+
   do_pending_stack_adjust ();
 
  /* We ought to be called always on the toplevel and stack ought to be aligned
@@ -1313,14 +1368,6 @@ allocate_dynamic_stack_space (rtx size, rtx target, int known_align,
   else if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK)
     probe_stack_range (STACK_CHECK_PROTECT, size);
 
-  /* Don't use a TARGET that isn't a pseudo or is the wrong mode.  */
-  if (target == 0 || !REG_P (target)
-      || REGNO (target) < FIRST_PSEUDO_REGISTER
-      || GET_MODE (target) != Pmode)
-    target = gen_reg_rtx (Pmode);
-
-  mark_reg_pointer (target, known_align);
-
   /* Perform the required allocation from the stack.  Some systems do
      this differently than simply incrementing/decrementing from the
      stack pointer, such as acquiring the space by calling malloc().  */
@@ -1413,6 +1460,15 @@ allocate_dynamic_stack_space (rtx size, rtx target, int known_align,
   if (cfun->nonlocal_goto_save_area != 0)
     update_nonlocal_goto_save_area ();
 
+  /* Finish up the split stack handling.  */
+  if (final_label != NULL_RTX)
+    {
+      gcc_assert (flag_split_stack);
+      emit_move_insn (final_target, target);
+      emit_label (final_label);
+      target = final_target;
+    }
+
   return target;
 }