2005-05-25 Adrian Straetling <straetling@de.ibm.com>

	* loop-doloop.c: Include "target.h".
	  (doloop_valid_p): Move tests to function in targhooks.c.
	* target.h (struct gcc_target): New target hook
	  "insn_valid_within_doloop".
	* target-def.h: Define default value for "insn_valid_within_doloop".
	  (TARGET_INITIALIZER): Insert new target hook into initializer.
	* targhooks.c (default_insn_valid_within_doloop): New function.
	* targhooks.h (default_insn_valid_within_doloop): Declare.
	* hooks.c (hook_bool_rtx_true): New function.
	* hooks.h (hook_bool_rtx_true): Declare.
	* doc/tm.texi: Add documentation for new target hook.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@100143 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 30 insertions, 0 deletions

diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index 2bf11a431eb..1f8b5b76ee7 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -262,6 +262,36 @@ default_scalar_mode_supported_p (enum machine_mode mode)
     }
 }
 
+/* TRUE if INSN insn is valid within a low-overhead loop.
+  
+   This function checks wheter a given INSN is valid within a low-overhead
+   loop.  A called function may clobber any special registers required for
+   low-overhead looping. Additionally, some targets (eg, PPC) use the count
+   register for branch on table instructions. We reject the doloop pattern in
+   these cases.  */
+
+bool 
+default_insn_valid_within_doloop (rtx insn)
+{
+  if (CALL_P (insn))
+    {
+      if (dump_file)
+	fprintf (dump_file, "Doloop: Function call in loop.\n");
+	return false;
+    }
+  
+  if (JUMP_P (insn)
+      && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
+	  || GET_CODE (PATTERN (insn)) == ADDR_VEC))
+    {
+      if (dump_file)
+	fprintf (dump_file, "Doloop: Computed branch in the loop.\n");
+      return false;
+    }
+  
+  return true;
+}
+
 bool
 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 	CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,