(clrstrsi): Correct check for constant size.

(allocate_stack{,_worker}): New patterns.

From-SVN: r12708

gcc/config/i386/i386.md

@@ -58,6 +58,8 @@
 ;;    operand 0 is the argument for `sin'.
 ;; 2  This is a `cos' operation.  The mode of the UNSPEC is MODE_FLOAT.
 ;;    operand 0 is the argument for `cos'.
+;; 3  This is part of a `stack probe' operation.  The mode of the UNSPEC is 
+;;    always SImode.  operand 0 is the size of the stack allocation.
 
 ;; This shadows the processor_type enumeration, so changes must be made
 ;; to i386.h at the same time.
@@ -6183,7 +6185,7 @@
 {
   rtx addr0, addr1;
 
-  if (GET_CODE (operands[2]) != CONST_INT)
+  if (GET_CODE (operands[1]) != CONST_INT)
     FAIL;
 
   addr0 = copy_to_mode_reg (Pmode, XEXP (operands[0], 0));
@@ -7048,3 +7050,29 @@
   "(TARGET_USE_Q_REG && optimize > 1)"
   "* return output_strlen_unroll (operands);"
 )
+
+(define_insn "allocate_stack_worker"
+  [(unspec:SI [(match_operand:SI 0 "register_operand" "a")] 3)
+   (set (reg:SI 7) (minus:SI (reg:SI 7) (match_dup 0)))
+   (clobber (match_dup 0))]
+  "TARGET_STACK_PROBE"
+  "* return AS1(call,__alloca);")
+
+(define_expand "allocate_stack"
+  [(set (reg:SI 7)
+	(minus:SI (reg:SI 7) (match_operand:SI 0 "general_operand" "")))]
+  "TARGET_STACK_PROBE"
+  "
+{
+#ifdef CHECK_STACK_LIMIT
+  if (GET_CODE (operands[0]) == CONST_INT
+      && INTVAL (operands[0]) < CHECK_STACK_LIMIT)
+    emit_insn (gen_subsi3 (stack_pointer_rtx, stack_pointer_rtx,
+			   operands[0]));
+  else 
+#endif
+    emit_insn (gen_allocate_stack_worker (copy_to_mode_reg (SImode,
+							    operands[0])));
+
+  DONE;
+}")