rx.c (rx_expand_epilogue): Add checks for sibcalls being used incorrectly.

        * config/rx/rx.c (rx_expand_epilogue): Add checks for sibcalls
        being used incorrectly.
        (rx_function_ok_for_sibcall): New function.  Do not allow indirect
        sibcalls, or sibcalls from interrupt functions.
        (TARGET_FUNCTION_OK_FOR_SIBCALL): Define.
        * config/rx/rx.md (sibcall): Convert to a define_expand.  Check
        for a MEM inside a MEM.
        (sibcall_value): Likewise.
        (sibcall_internal): New pattern containing old sibcall pattern.
        (sibcall_value_internal): Likewise.

From-SVN: r154671

3 files changed, 103 insertions, 15 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e57f787..f493283 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,16 @@
+2009-11-26  Nick Clifton  <nickc@redhat.com>
+
+	* config/rx/rx.c (rx_expand_epilogue): Add checks for sibcalls
+	being used incorrectly.
+	(rx_function_ok_for_sibcall): New function.  Do not allow indirect
+	sibcalls, or sibcalls from interrupt functions.
+	(TARGET_FUNCTION_OK_FOR_SIBCALL): Define.
+	* config/rx/rx.md (sibcall): Convert to a define_expand.  Check
+	for a MEM inside a MEM.
+	(sibcall_value): Likewise.
+	(sibcall_internal): New pattern containing old sibcall pattern.
+	(sibcall_value_internal): Likewise.
+
 2009-11-25  Richard Henderson  <rth@redhat.com>
 
 	* config/i386/i386-builtin-types.awk (DEF_VECTOR_TYPE): Allow an
diff --git a/gcc/config/rx/rx.c b/gcc/config/rx/rx.c
index 885f525..14cf09b 100644
--- a/gcc/config/rx/rx.c
+++ b/gcc/config/rx/rx.c
@@ -1190,7 +1190,7 @@ mark_frame_related (rtx insn)
     {
       unsigned int i;
 
-      for (i = 0; i < XVECLEN (insn, 0); i++)
+      for (i = 0; i < (unsigned) XVECLEN (insn, 0); i++)
 	RTX_FRAME_RELATED_P (XVECEXP (insn, 0, i)) = 1;
     }
 }
@@ -1454,8 +1454,26 @@ rx_expand_epilogue (bool is_sibcall)
   unsigned int reg;
   unsigned HOST_WIDE_INT total_size;
 
+  /* FIXME: We do not support indirect sibcalls at the moment becaause we
+     cannot guarantee that the register holding the function address is a
+     call-used register.  If it is a call-saved register then the stack
+     pop instructions generated in the epilogue will corrupt the address
+     before it is used.
+
+     Creating a new call-used-only register class works but then the
+     reload pass gets stuck because it cannot always find a call-used
+     register for spilling sibcalls.
+
+     The other possible solution is for this pass to scan forward for the
+     sibcall instruction (if it has been generated) and work out if it
+     is an indirect sibcall using a call-saved register.  If it is then
+     the address can copied into a call-used register in this epilogue
+     code and the sibcall instruction modified to use that register.  */
+
   if (is_naked_func (NULL_TREE))
     {
+      gcc_assert (! is_sibcall);
+
       /* Naked functions use their own, programmer provided epilogues.
 	 But, in order to keep gcc happy we have to generate some kind of
 	 epilogue RTL.  */
@@ -1547,9 +1565,15 @@ rx_expand_epilogue (bool is_sibcall)
 	}
 
       if (is_fast_interrupt_func (NULL_TREE))
-	emit_jump_insn (gen_fast_interrupt_return ());
+	{
+	  gcc_assert (! is_sibcall);
+	  emit_jump_insn (gen_fast_interrupt_return ());
+	}
       else if (is_interrupt_func (NULL_TREE))
-	emit_jump_insn (gen_exception_return ());
+	{
+	  gcc_assert (! is_sibcall);
+	  emit_jump_insn (gen_exception_return ());
+	}
       else if (! is_sibcall)
 	emit_jump_insn (gen_simple_return ());
 
@@ -2107,6 +2131,26 @@ rx_func_attr_inlinable (const_tree decl)
     &&   ! is_naked_func (decl);  
 }
 
+/* Return nonzero if it is ok to make a tail-call to DECL,
+   a function_decl or NULL if this is an indirect call, using EXP  */
+
+static bool
+rx_function_ok_for_sibcall (tree decl, tree exp)
+{
+  /* Do not allow indirect tailcalls.  The
+     sibcall patterns do not support them.  */
+  if (decl == NULL)
+    return false;
+
+  /* Never tailcall from inside interrupt handlers or naked functions.  */
+  if (is_fast_interrupt_func (NULL_TREE)
+      || is_interrupt_func (NULL_TREE)
+      || is_naked_func (NULL_TREE))
+    return false;
+
+  return true;
+}
+
 static void
 rx_file_start (void)
 {
@@ -2485,6 +2529,9 @@ rx_trampoline_init (rtx tramp, tree fndecl, rtx chain)
 #undef  TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P
 #define TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P 	rx_func_attr_inlinable
 
+#undef  TARGET_FUNCTION_OK_FOR_SIBCALL
+#define TARGET_FUNCTION_OK_FOR_SIBCALL		rx_function_ok_for_sibcall
+
 #undef  TARGET_SET_CURRENT_FUNCTION
 #define TARGET_SET_CURRENT_FUNCTION		rx_set_current_function
 
diff --git a/gcc/config/rx/rx.md b/gcc/config/rx/rx.md
index 360f623..a2c1c7c 100644
--- a/gcc/config/rx/rx.md
+++ b/gcc/config/rx/rx.md
@@ -388,7 +388,7 @@
 	 (match_operand:SI         1 "general_operand" "g,g"))]
   ""
   "@
-  jsr\t%A0
+  jsr\t%0
   bsr\t%A0"
   [(set_attr "length" "2,4")
    (set_attr "timings" "33")]
@@ -415,32 +415,60 @@
 	      (match_operand:SI         2 "general_operand"   "g,g")))]
   ""
   "@
-  jsr\t%A1
+  jsr\t%1
   bsr\t%A1"
   [(set_attr "length" "2,4")
    (set_attr "timings" "33")]
 )
 
-(define_insn "sibcall"
- [(call (mem:QI (match_operand:SI 0 "rx_symbolic_call_operand" "Symbol"))
-	(match_operand:SI         1 "general_operand"          "g"))
-  (return)
-  (use (match_operand             2 "" ""))]
+;; Note - we do not allow indirect sibcalls (with the address
+;; held in a register) because we cannot guarantee that the register
+;; chosen will be a call-used one.  If it is a call-saved register,
+;; then the epilogue code will corrupt it by popping the saved value
+;; off of the stack.
+(define_expand "sibcall"
+  [(parallel
+    [(call (mem:QI (match_operand:SI 0 "rx_symbolic_call_operand"))
+	   (match_operand:SI         1 "general_operand"))
+     (return)])]
+  ""
+  {
+    if (MEM_P (operands[0]))
+      operands[0] = XEXP (operands[0], 0);
+  }
+)
+
+(define_insn "sibcall_internal"
+  [(call (mem:QI (match_operand:SI 0 "rx_symbolic_call_operand" "Symbol"))
+	 (match_operand:SI         1 "general_operand"          "g"))
+   (return)]
   ""
   "bra\t%A0"
-  [(set_attr "length" "4")
+  [(set_attr "length"  "4")
    (set_attr "timings" "33")]
 )
 
-(define_insn "sibcall_value"
+(define_expand "sibcall_value"
+ [(parallel
+   [(set (match_operand                  0 "register_operand")
+	 (call (mem:QI (match_operand:SI 1 "rx_symbolic_call_operand"))
+	       (match_operand:SI         2 "general_operand")))
+    (return)])]
+  ""
+  {
+    if (MEM_P (operands[1]))
+      operands[1] = XEXP (operands[1], 0);
+  }
+)
+
+(define_insn "sibcall_value_internal"
  [(set (match_operand                  0 "register_operand"         "=r")
        (call (mem:QI (match_operand:SI 1 "rx_symbolic_call_operand" "Symbol"))
 	     (match_operand:SI         2 "general_operand"          "g")))
-  (return)
-  (use (match_operand                  3 "" ""))]
+  (return)]
   ""
   "bra\t%A1"
-  [(set_attr "length" "4")
+  [(set_attr "length"  "4")
    (set_attr "timings" "33")]
 )