Patchwork [split] Revert REG_CFA_TEMPORARY, bring in 32-bit fixes

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Submitter Ian Taylor
Date Sept. 24, 2010, 9:16 p.m.
Message ID <mcrsk0yzvsl.fsf@google.com>
Download mbox | patch
Permalink /patch/65692/
State New
Headers show

Comments

Ian Taylor - Sept. 24, 2010, 9:16 p.m.
This patch reverts the REG_CFA_TEMPORARY changes, and brings in the
32-bit fixes.  Committed to split branch.

Ian

Patch

Index: dwarf2out.c
===================================================================
--- dwarf2out.c	(revision 164490)
+++ dwarf2out.c	(working copy)
@@ -473,7 +473,6 @@  static void output_call_frame_info (int)
 static void dwarf2out_note_section_used (void);
 static bool clobbers_queued_reg_save (const_rtx);
 static void dwarf2out_frame_debug_expr (rtx, const char *);
-static void dwarf2out_frame_debug_remember_state (void);
 
 /* Support for complex CFA locations.  */
 static void output_cfa_loc (dw_cfi_ref);
@@ -2827,17 +2826,6 @@  dwarf2out_frame_debug (rtx insn, bool af
 	handled_one = true;
 	break;
 
-      case REG_CFA_TEMPORARY:
-	if (!after_p)
-	  {
-	    dwarf2out_frame_debug_remember_state ();
-	    dwarf2out_frame_debug_def_cfa (XEXP (note, 0), label);
-	  }
-	else
-	  dwarf2out_frame_debug_restore_state ();
-	handled_one = true;
-	break;
-
       default:
 	break;
       }
@@ -2926,17 +2914,9 @@  dwarf2out_cfi_begin_epilogue (rtx insn)
     }
   emit_note_before (NOTE_INSN_CFA_RESTORE_STATE, i);
 
-  dwarf2out_frame_debug_remember_state ();
-}
-
-/* Remember the current state.  */
-
-static void
-dwarf2out_frame_debug_remember_state (void)
-{
   emit_cfa_remember = true;
 
-  /* Emulate the state save.  */
+  /* And emulate the state save.  */
   gcc_assert (!cfa_remember.in_use);
   cfa_remember = cfa;
   cfa_remember.in_use = 1;
Index: config/i386/i386.md
===================================================================
--- config/i386/i386.md	(revision 164490)
+++ config/i386/i386.md	(working copy)
@@ -11642,23 +11642,25 @@ 
 ;; In order to support the call/return predictor, we use a return
 ;; instruction which the middle-end doesn't see.
 (define_insn "split_stack_return"
-  [(unspec_volatile [(const_int 0)] UNSPEC_STACK_CHECK)]
-  ""
-  "ret"
-  [(set_attr "length" "1")
-   (set_attr "atom_unit" "jeu")
-   (set_attr "length_immediate" "0")
-   (set_attr "modrm" "0")])
-
-(define_insn "split_stack_pop_return"
   [(unspec_volatile [(match_operand:SI 0 "const_int_operand" "")]
 		    UNSPEC_STACK_CHECK)]
   ""
-  "ret\t%0"
-  [(set_attr "length" "3")
-   (set_attr "atom_unit" "jeu")
-   (set_attr "length_immediate" "2")
-   (set_attr "modrm" "0")])
+{
+  if (operands[0] == const0_rtx)
+    return "ret";
+  else
+    return "ret\t%0";
+}
+  [(set_attr "atom_unit" "jeu")
+   (set_attr "modrm" "0")
+   (set (attr "length")
+	(if_then_else (match_operand:SI 0 "const0_operand" "")
+		      (const_int 1)
+		      (const_int 3)))
+   (set (attr "length_immediate")
+	(if_then_else (match_operand:SI 0 "const0_operand" "")
+		      (const_int 0)
+		      (const_int 2)))])
 
 ;; If there are operand 0 bytes available on the stack, jump to
 ;; operand 1.
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 164490)
+++ config/i386/i386.c	(working copy)
@@ -3651,7 +3651,7 @@  ix86_option_override_internal (bool main
 
   /* If using typedef char *va_list, signal that __builtin_va_start (&ap, 0)
      can be optimized to ap = __builtin_next_arg (0).  */
-  if (!TARGET_64BIT)
+  if (!TARGET_64BIT && !flag_split_stack)
     targetm.expand_builtin_va_start = NULL;
 
   if (TARGET_64BIT)
@@ -7259,7 +7259,6 @@  ix86_va_start (tree valist, rtx nextarg)
   if (flag_split_stack
       && cfun->machine->split_stack_varargs_pointer == NULL_RTX)
     {
-      rtx reg, seq;
       unsigned int scratch_regno;
 
       /* When we are splitting the stack, we can't refer to the stack
@@ -7270,23 +7269,29 @@  ix86_va_start (tree valist, rtx nextarg)
 	 stack prologue can't set the pseudo-register directly because
 	 it (the prologue) runs before any registers have been saved.  */
 
-      reg = gen_reg_rtx (Pmode);
-      cfun->machine->split_stack_varargs_pointer = reg;
       scratch_regno = split_stack_prologue_scratch_regno ();
-      start_sequence ();
-      emit_move_insn (reg, gen_rtx_REG (Pmode, scratch_regno));
-      seq = get_insns ();
-      end_sequence ();
+      if (scratch_regno != INVALID_REGNUM)
+	{
+	  rtx reg, seq;
+
+	  reg = gen_reg_rtx (Pmode);
+	  cfun->machine->split_stack_varargs_pointer = reg;
 
-      push_topmost_sequence ();
-      emit_insn_after (seq, entry_of_function ());
-      pop_topmost_sequence ();
+	  start_sequence ();
+	  emit_move_insn (reg, gen_rtx_REG (Pmode, scratch_regno));
+	  seq = get_insns ();
+	  end_sequence ();
+
+	  push_topmost_sequence ();
+	  emit_insn_after (seq, entry_of_function ());
+	  pop_topmost_sequence ();
+	}
     }
 
   /* Only 64bit target needs something special.  */
   if (!TARGET_64BIT || is_va_list_char_pointer (TREE_TYPE (valist)))
     {
-      if (!flag_split_stack)
+      if (cfun->machine->split_stack_varargs_pointer == NULL_RTX)
 	std_expand_builtin_va_start (valist, nextarg);
       else
 	{
@@ -7344,7 +7349,7 @@  ix86_va_start (tree valist, rtx nextarg)
 
   /* Find the overflow area.  */
   type = TREE_TYPE (ovf);
-  if (!flag_split_stack)
+  if (cfun->machine->split_stack_varargs_pointer == NULL_RTX)
     ovf_rtx = crtl->args.internal_arg_pointer;
   else
     ovf_rtx = cfun->machine->split_stack_varargs_pointer;
@@ -10404,8 +10409,11 @@  split_stack_prologue_scratch_regno (void
       if (is_fastcall)
 	{
 	  if (DECL_STATIC_CHAIN (cfun->decl))
-	    sorry ("-fsplit-stack does not support fastcall with "
-		   "nested function");
+	    {
+	      sorry ("-fsplit-stack does not support fastcall with "
+		     "nested function");
+	      return INVALID_REGNUM;
+	    }
 	  return AX_REG;
 	}
       else if (regparm < 3)
@@ -10415,8 +10423,11 @@  split_stack_prologue_scratch_regno (void
 	  else
 	    {
 	      if (regparm >= 2)
-		sorry ("-fsplit-stack does not support 2 register "
-		       " parameters for a nested function");
+		{
+		  sorry ("-fsplit-stack does not support 2 register "
+			 " parameters for a nested function");
+		  return INVALID_REGNUM;
+		}
 	      return DX_REG;
 	    }
 	}
@@ -10425,7 +10436,7 @@  split_stack_prologue_scratch_regno (void
 	  /* FIXME: We could make this work by pushing a register
 	     around the addition and comparison.  */
 	  sorry ("-fsplit-stack does not support 3 register parameters");
-	  return CX_REG;
+	  return INVALID_REGNUM;
 	}
     }
 }
@@ -10481,25 +10492,23 @@  ix86_expand_split_stack_prologue (void)
 	 register which is not used for parameters.  */
       offset = GEN_INT (- allocate);
       scratch_regno = split_stack_prologue_scratch_regno ();
+      if (scratch_regno == INVALID_REGNUM)
+	return;
       scratch_reg = gen_rtx_REG (Pmode, scratch_regno);
-      if (!TARGET_64BIT)
-	emit_insn (gen_addsi3 (scratch_reg, stack_pointer_rtx, offset));
+      if (!TARGET_64BIT || x86_64_immediate_operand (offset, Pmode))
+	{
+	  /* We don't use ix86_gen_add3 in this case because it will
+	     want to split to lea, but when not optimizing the insn
+	     will not be split after this point.  */
+	  emit_insn (gen_rtx_SET (VOIDmode, scratch_reg,
+				  gen_rtx_PLUS (Pmode, stack_pointer_rtx,
+						offset)));
+	}
       else
 	{
-	  if (x86_64_immediate_operand (offset, Pmode))
-	    {
-	      /* We don't use gen_adddi3 in this case because it will
-		 want to split to lea, but when not optimizing the
-		 insn will not be split after this point.  */
-	      emit_move_insn (scratch_reg,
-			      gen_rtx_PLUS (Pmode, stack_pointer_rtx, offset));
-	    }
-	  else
-	    {
-	      emit_move_insn (scratch_reg, offset);
-	      emit_insn (gen_adddi3 (scratch_reg, scratch_reg,
-				     stack_pointer_rtx));
-	    }
+	  emit_move_insn (scratch_reg, offset);
+	  emit_insn (gen_adddi3 (scratch_reg, scratch_reg,
+				 stack_pointer_rtx));
 	}
       current = scratch_reg;
     }
@@ -10520,12 +10529,7 @@  ix86_expand_split_stack_prologue (void)
   allocate_rtx = GEN_INT (allocate);
   args_size = crtl->args.size >= 0 ? crtl->args.size : 0;
   call_fusage = NULL_RTX;
-  if (!TARGET_64BIT)
-    {
-      emit_insn (gen_push (GEN_INT (args_size)));
-      emit_insn (gen_push (allocate_rtx));
-    }
-  else
+  if (TARGET_64BIT)
     {
       rtx reg;
 
@@ -10548,6 +10552,11 @@  ix86_expand_split_stack_prologue (void)
       emit_move_insn (reg, GEN_INT (args_size));
       use_reg (&call_fusage, reg);
     }
+  else
+    {
+      emit_insn (gen_push (GEN_INT (args_size)));
+      emit_insn (gen_push (allocate_rtx));
+    }
   if (split_stack_fn == NULL_RTX)
     split_stack_fn = gen_rtx_SYMBOL_REF (Pmode, "__morestack");
   call_insn = ix86_expand_call (NULL_RTX, gen_rtx_MEM (QImode, split_stack_fn),
@@ -10559,27 +10568,11 @@  ix86_expand_split_stack_prologue (void)
      to execute a return instruction.  See
      libgcc/config/i386/morestack.S for the details on how this works.
 
-     In order to support backtracing, we need to set the CFA around
-     the call, so that the unwinder knows how to correctly pick up the
-     return address.  We set the CFA around the call because the
-     unwinder looks up to the point of the call but not after the
-     call.  */
-  add_reg_note (call_insn, REG_CFA_TEMPORARY,
-		gen_rtx_PLUS (Pmode, gen_rtx_REG (Pmode, SP_REG),
-			      GEN_INT (UNITS_PER_WORD)));
-  RTX_FRAME_RELATED_P (call_insn) = 1;
-
-  /* For flow purposes gcc must not see this as a return
+     For flow purposes gcc must not see this as a return
      instruction--we need control flow to continue at the subsequent
      label.  Therefore, we use an unspec.  */
-  if (crtl->args.pops_args == 0)
-    emit_insn (gen_split_stack_return ());
-  else
-    {
-      gcc_assert (!TARGET_64BIT);
-      gcc_assert (crtl->args.pops_args < 65536);
-      emit_insn (gen_split_stack_pop_return (GEN_INT (crtl->args.pops_args)));
-    }
+  gcc_assert (crtl->args.pops_args < 65536);
+  emit_insn (gen_split_stack_return (GEN_INT (crtl->args.pops_args)));
 
   /* If we are in 64-bit mode and this function uses a static chain,
      we saved %r10 in %rax before calling _morestack.  */
@@ -10599,20 +10592,32 @@  ix86_expand_split_stack_prologue (void)
     {
       unsigned int scratch_regno;
       rtx frame_reg;
+      int words;
 
       scratch_regno = split_stack_prologue_scratch_regno ();
       scratch_reg = gen_rtx_REG (Pmode, scratch_regno);
       frame_reg = gen_rtx_REG (Pmode, BP_REG);
 
-      /* fp -> old fp value
+      /* 64-bit:
+	 fp -> old fp value
 	       return address within this function
 	       return address of caller of this function
 	       stack arguments
 	 So we add three words to get to the stack arguments.
+
+	 32-bit:
+	 fp -> old fp value
+	       return address within this function
+               first argument to __morestack
+               second argument to __morestack
+               return address of caller of this function
+               stack arguments
+         So we add five words to get to the stack arguments.
       */
-      emit_move_insn (scratch_reg,
-		      gen_rtx_PLUS (Pmode, frame_reg,
-				    GEN_INT (3 * UNITS_PER_WORD)));
+      words = TARGET_64BIT ? 3 : 5;
+      emit_insn (gen_rtx_SET (VOIDmode, scratch_reg,
+			      gen_rtx_PLUS (Pmode, frame_reg,
+					    GEN_INT (words * UNITS_PER_WORD))));
 
       varargs_label = gen_label_rtx ();
       emit_jump_insn (gen_jump (varargs_label));
@@ -10629,9 +10634,9 @@  ix86_expand_split_stack_prologue (void)
      case we need to set it based on the stack pointer.  */
   if (cfun->machine->split_stack_varargs_pointer != NULL_RTX)
     {
-      emit_move_insn (scratch_reg,
-		      gen_rtx_PLUS (Pmode, stack_pointer_rtx,
-				    GEN_INT (UNITS_PER_WORD)));
+      emit_insn (gen_rtx_SET (VOIDmode, scratch_reg,
+			      gen_rtx_PLUS (Pmode, stack_pointer_rtx,
+					    GEN_INT (UNITS_PER_WORD))));
 
       emit_label (varargs_label);
       LABEL_NUSES (varargs_label) = 1;
Index: reg-notes.def
===================================================================
--- reg-notes.def	(revision 164490)
+++ reg-notes.def	(working copy)
@@ -165,13 +165,6 @@  REG_NOTE (CFA_RESTORE)
    to the argument, if it is a MEM, it is ignored.  */
 REG_NOTE (CFA_SET_VDRAP)
 
-/* Temporarily set the CFA for just one insn.  This saves the old
-   state, sets the CFA, and then restores the state after the insn.
-   The pattern for this note is the new CFA value.  This is used by
-   the split stack code to support unwinding through the call into the
-   split stack routine.  */
-REG_NOTE (CFA_TEMPORARY)
-
 /* Indicates that REG holds the exception context for the function.
    This context is shared by inline functions, so the code to acquire
    the real exception context is delayed until after inlining.  */