expmed.c (extract_bit_field): Do not use insv/extv/extzv patterns if the bitsize is zero.

	* expmed.c (extract_bit_field): Do not use insv/extv/extzv patterns
	if the bitsize is zero.
	* doc/md.texi (Standard Pattern Names): Document it.

	* config/ia64/ia64.c (ia64_pass_by_reference): Delete.
	(TARGET_PASS_BY_REFERENCE): Likewise.

From-SVN: r106605

gcc/ChangeLog

+2005-11-07  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* expmed.c (extract_bit_field): Do not use insv/extv/extzv patterns
+	if the bitsize is zero.
+	* doc/md.texi (Standard Pattern Names): Document it.
+
+	* config/ia64/ia64.c (ia64_pass_by_reference): Delete.
+	(TARGET_PASS_BY_REFERENCE): Likewise.
+
 2005-11-07  Ian Lance Taylor  <ian@airs.com>
 
 	PR rtl-optimization/24683

gcc/config/ia64/ia64.c

@@ -176,8 +176,6 @@ static rtx gen_fr_restore_x (rtx, rtx, rtx);
 static enum machine_mode hfa_element_mode (tree, bool);
 static void ia64_setup_incoming_varargs (CUMULATIVE_ARGS *, enum machine_mode,
 					 tree, int *, int);
-static bool ia64_pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
-				    tree, bool);
 static int ia64_arg_partial_bytes (CUMULATIVE_ARGS *, enum machine_mode,
 				   tree, bool);
 static bool ia64_function_ok_for_sibcall (tree, tree);
@@ -349,8 +347,6 @@ static const struct attribute_spec ia64_attribute_table[] =
 
 #undef TARGET_FUNCTION_OK_FOR_SIBCALL
 #define TARGET_FUNCTION_OK_FOR_SIBCALL ia64_function_ok_for_sibcall
-#undef TARGET_PASS_BY_REFERENCE
-#define TARGET_PASS_BY_REFERENCE ia64_pass_by_reference
 #undef TARGET_ARG_PARTIAL_BYTES
 #define TARGET_ARG_PARTIAL_BYTES ia64_arg_partial_bytes
 
@@ -4221,17 +4217,6 @@ ia64_function_arg_boundary (enum machine_mode mode, tree type)
     return PARM_BOUNDARY;
 }
 
-/* Variable sized types are passed by reference.  */
-/* ??? At present this is a GCC extension to the IA-64 ABI.  */
-
-static bool
-ia64_pass_by_reference (CUMULATIVE_ARGS *cum ATTRIBUTE_UNUSED,
-			enum machine_mode mode ATTRIBUTE_UNUSED,
-			tree type, bool named ATTRIBUTE_UNUSED)
-{
-  return type && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST;
-}
-
 /* True if it is OK to do sibling call optimization for the specified
    call expression EXP.  DECL will be the called function, or NULL if
    this is an indirect call.  */

gcc/doc/md.texi

@@ -3551,7 +3551,7 @@ Operand 1 may have mode @code{byte_mode} or @code{word_mode}; often
 be valid for @code{word_mode}.
 
 The RTL generation pass generates this instruction only with constants
-for operands 2 and 3.
+for operands 2 and 3 and the constant is never zero for operand 2.
 
 The bit-field value is sign-extended to a full word integer
 before it is stored in operand 0.
@@ -3569,7 +3569,7 @@ operand 2 the starting bit.  Operand 0 may have mode @code{byte_mode} or
 Operands 1 and 2 must be valid for @code{word_mode}.
 
 The RTL generation pass generates this instruction only with constants
-for operands 1 and 2.
+for operands 1 and 2 and the constant is never zero for operand 1.
 
 @cindex @code{mov@var{mode}cc} instruction pattern
 @item @samp{mov@var{mode}cc}

gcc/expmed.c

@@ -608,8 +608,8 @@ store_bit_field (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
   if (HAVE_insv
       && GET_MODE (value) != BLKmode
       && !(bitsize == 1 && GET_CODE (value) == CONST_INT)
-      /* Ensure insv's size is wide enough for this field.  */
-      && (GET_MODE_BITSIZE (op_mode) >= bitsize)
+      && bitsize > 0
+      && GET_MODE_BITSIZE (op_mode) >= bitsize
       && ! ((REG_P (op0) || GET_CODE (op0) == SUBREG)
 	    && (bitsize + bitpos > GET_MODE_BITSIZE (op_mode))))
     {
@@ -1356,7 +1356,8 @@ extract_bit_field (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
   if (unsignedp)
     {
       if (HAVE_extzv
-	  && (GET_MODE_BITSIZE (extzv_mode) >= bitsize)
+	  && bitsize > 0
+	  && GET_MODE_BITSIZE (extzv_mode) >= bitsize
 	  && ! ((REG_P (op0) || GET_CODE (op0) == SUBREG)
 		&& (bitsize + bitpos > GET_MODE_BITSIZE (extzv_mode))))
 	{
@@ -1488,7 +1489,8 @@ extract_bit_field (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
   else
     {
       if (HAVE_extv
-	  && (GET_MODE_BITSIZE (extv_mode) >= bitsize)
+	  && bitsize > 0
+	  && GET_MODE_BITSIZE (extv_mode) >= bitsize
 	  && ! ((REG_P (op0) || GET_CODE (op0) == SUBREG)
 		&& (bitsize + bitpos > GET_MODE_BITSIZE (extv_mode))))
 	{