defaults.h (CLZ_DEFINED_VALUE_AT_ZERO): New.

        * defaults.h (CLZ_DEFINED_VALUE_AT_ZERO): New.
        (CTZ_DEFINED_VALUE_AT_ZERO): New.
        * doc/rtl.texi, doc/tm.texi: Document them.

        * combine.c (nonzero_bits) [CLZ, CTZ]: Handle the definedness
        of the value at zero properly.
        * fold-const.c (tree_expr_nonnegative_p): Likewise.
        * simplify-rtx.c (simplify_unary_operation): Likewise.

        * config/alpha/alpha.h (CLZ_DEFINED_VALUE_AT_ZERO): New.
        (CTZ_DEFINED_VALUE_AT_ZERO): New.

        * config/arm/arm.c (TARGET_INIT_BUILTINS): Remove.
        (TARGET_EXPAND_BUILTIN): Remove.
        (def_builtin, arm_init_builtins, arm_expand_builtin): Remove.
        * config/arm/arm.h (CLZ_DEFINED_VALUE_AT_ZERO): New.
        (enum arm_builtins): Remove.
        * config/arm/arm.md (UNSPEC_CLZ): Remove.
        (clzsi2): Rename from clz; use clz instead of unspec.
        (ctzsi2): New.
        * config/arm/arm-protos.h: Update.

From-SVN: r62453

12 files changed, 126 insertions, 112 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4c27343..3b9e6c0 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,27 @@
+2003-02-05  Richard Henderson  <rth@redhat.com>
+
+	* defaults.h (CLZ_DEFINED_VALUE_AT_ZERO): New.
+	(CTZ_DEFINED_VALUE_AT_ZERO): New.
+	* doc/rtl.texi, doc/tm.texi: Document them.
+
+	* combine.c (nonzero_bits) [CLZ, CTZ]: Handle the definedness
+	of the value at zero properly.
+	* fold-const.c (tree_expr_nonnegative_p): Likewise.
+	* simplify-rtx.c (simplify_unary_operation): Likewise.
+
+	* config/alpha/alpha.h (CLZ_DEFINED_VALUE_AT_ZERO): New.
+	(CTZ_DEFINED_VALUE_AT_ZERO): New.
+
+	* config/arm/arm.c (TARGET_INIT_BUILTINS): Remove.
+	(TARGET_EXPAND_BUILTIN): Remove.
+	(def_builtin, arm_init_builtins, arm_expand_builtin): Remove.
+	* config/arm/arm.h (CLZ_DEFINED_VALUE_AT_ZERO): New.
+	(enum arm_builtins): Remove.
+	* config/arm/arm.md (UNSPEC_CLZ): Remove.
+	(clzsi2): Rename from clz; use clz instead of unspec.
+	(ctzsi2): New.
+	* config/arm/arm-protos.h: Update.
+
 Wed Feb  5 23:12:57 CET 2003  Jan Hubicka  <jh@suse.cz>
 
 	* i386-protos.h (x86_emit_floatuns):  Declare.
diff --git a/gcc/combine.c b/gcc/combine.c
index aeb5c2f..6566823 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -8547,11 +8547,28 @@ nonzero_bits (x, mode)
       break;
 
     case FFS:
-    case CLZ:
-    case CTZ:
     case POPCOUNT:
       /* This is at most the number of bits in the mode.  */
-      nonzero = ((HOST_WIDE_INT) 1 << (floor_log2 (mode_width) + 1)) - 1;
+      nonzero = ((HOST_WIDE_INT) 2 << (floor_log2 (mode_width))) - 1;
+      break;
+
+    case CLZ:
+      /* If CLZ has a known value at zero, then the nonzero bits are
+	 that value, plus the number of bits in the mode minus one.  */
+      if (CLZ_DEFINED_VALUE_AT_ZERO (mode, nonzero))
+	nonzero |= ((HOST_WIDE_INT) 1 << (floor_log2 (mode_width))) - 1;
+      else
+	nonzero = -1;
+      break;
+
+    case CTZ:
+      /* If CTZ has a known value at zero, then the nonzero bits are
+	 that value, plus the number of bits in the mode minus one.  */
+      if (CTZ_DEFINED_VALUE_AT_ZERO (mode, nonzero))
+	nonzero |= ((HOST_WIDE_INT) 1 << (floor_log2 (mode_width))) - 1;
+      else
+	nonzero = -1;
+      break;
       break;
 
     case PARITY:
diff --git a/gcc/config/alpha/alpha.h b/gcc/config/alpha/alpha.h
index 8824f12..2c79fa8 100644
--- a/gcc/config/alpha/alpha.h
+++ b/gcc/config/alpha/alpha.h
@@ -1493,6 +1493,10 @@ do {									     \
 
 #define STORE_FLAG_VALUE 1
 
+/* The CIX ctlz and cttz instructions return 64 for zero.  */
+#define CLZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE)  ((VALUE) = 64, TARGET_CIX)
+#define CTZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE)  ((VALUE) = 64, TARGET_CIX)
+
 /* Define the value returned by a floating-point comparison instruction.  */
 
 #define FLOAT_STORE_FLAG_VALUE(MODE) \
diff --git a/gcc/config/arm/arm-protos.h b/gcc/config/arm/arm-protos.h
index 6fce0ce..8923dd0 100644
--- a/gcc/config/arm/arm-protos.h
+++ b/gcc/config/arm/arm-protos.h
@@ -209,12 +209,6 @@ extern void arm_mark_dllexport 		PARAMS ((tree));
 extern void arm_mark_dllimport 		PARAMS ((tree));
 #endif
 
-extern void arm_init_builtins		PARAMS ((void));
-#if defined (TREE_CODE) && defined (RTX_CODE)
-extern rtx arm_expand_builtin		PARAMS ((tree, rtx, rtx,
-					       enum machine_mode, int));
-#endif
-
 extern void arm_pr_long_calls		PARAMS ((struct cpp_reader *));
 extern void arm_pr_no_long_calls	PARAMS ((struct cpp_reader *));
 extern void arm_pr_long_calls_off	PARAMS ((struct cpp_reader *));
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index fe306fd..e59f461 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -187,12 +187,6 @@ static int arm_address_cost			PARAMS ((rtx));
 #undef  TARGET_SET_DEFAULT_TYPE_ATTRIBUTES
 #define TARGET_SET_DEFAULT_TYPE_ATTRIBUTES arm_set_default_type_attributes
 
-#undef  TARGET_INIT_BUILTINS
-#define TARGET_INIT_BUILTINS arm_init_builtins
-
-#undef  TARGET_EXPAND_BUILTIN
-#define TARGET_EXPAND_BUILTIN arm_expand_builtin
-
 #undef  TARGET_SCHED_ADJUST_COST
 #define TARGET_SCHED_ADJUST_COST arm_adjust_cost
 
@@ -9981,82 +9975,6 @@ arm_debugger_arg_offset (value, addr)
 
   return value;
 }
-
-#define def_builtin(NAME, TYPE, CODE) \
-  builtin_function ((NAME), (TYPE), (CODE), BUILT_IN_MD, NULL, NULL_TREE)
-
-void
-arm_init_builtins ()
-{
-  tree endlink = void_list_node;
-  tree int_endlink = tree_cons (NULL_TREE, integer_type_node, endlink);
-  tree pchar_type_node = build_pointer_type (char_type_node);
-
-  tree int_ftype_int, void_ftype_pchar;
-
-  /* void func (char *) */
-  void_ftype_pchar
-    = build_function_type_list (void_type_node, pchar_type_node, NULL_TREE);
-
-  /* int func (int) */
-  int_ftype_int
-    = build_function_type (integer_type_node, int_endlink);
-
-  /* Initialize arm V5 builtins.  */
-  if (arm_arch5)
-    def_builtin ("__builtin_arm_clz", int_ftype_int, ARM_BUILTIN_CLZ);
-}
-
-/* Expand an expression EXP that calls a built-in function,
-   with result going to TARGET if that's convenient
-   (and in mode MODE if that's convenient).
-   SUBTARGET may be used as the target for computing one of EXP's operands.
-   IGNORE is nonzero if the value is to be ignored.  */
-
-rtx
-arm_expand_builtin (exp, target, subtarget, mode, ignore)
-     tree exp;
-     rtx target;
-     rtx subtarget ATTRIBUTE_UNUSED;
-     enum machine_mode mode ATTRIBUTE_UNUSED;
-     int ignore ATTRIBUTE_UNUSED;
-{
-  enum insn_code icode;
-  tree fndecl = TREE_OPERAND (TREE_OPERAND (exp, 0), 0);
-  tree arglist = TREE_OPERAND (exp, 1);
-  tree arg0;
-  rtx op0, pat;
-  enum machine_mode tmode, mode0;
-  int fcode = DECL_FUNCTION_CODE (fndecl);
-
-  switch (fcode)
-    {
-    default:
-      break;
-      
-    case ARM_BUILTIN_CLZ:
-      icode = CODE_FOR_clz;
-      arg0 = TREE_VALUE (arglist);
-      op0 = expand_expr (arg0, NULL_RTX, VOIDmode, 0);
-      tmode = insn_data[icode].operand[0].mode;
-      mode0 = insn_data[icode].operand[1].mode;
-
-      if (! (*insn_data[icode].operand[1].predicate) (op0, mode0))
-	op0 = copy_to_mode_reg (mode0, op0);
-      if (target == 0
-	  || GET_MODE (target) != tmode
-	  || ! (*insn_data[icode].operand[0].predicate) (target, tmode))
-	target = gen_reg_rtx (tmode);
-      pat = GEN_FCN (icode) (target, op0);
-      if (! pat)
-	return 0;
-      emit_insn (pat);
-      return target;
-    }
-
-  /* @@@ Should really do something sensible here.  */
-  return NULL_RTX;
-}
 
 /* Recursively search through all of the blocks in a function
    checking to see if any of the variables created in that
diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h
index d389eb0..802e199 100644
--- a/gcc/config/arm/arm.h
+++ b/gcc/config/arm/arm.h
@@ -2146,6 +2146,8 @@ extern int making_const_table;
 
 #define STORE_FLAG_VALUE 1
 
+/* The arm5 clz instruction returns 32.  */
+#define CLZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE)  ((VALUE) = 32, 1)
 
 
 /* Gcc puts the pool in the wrong place for ARM, since we can only
@@ -2456,9 +2458,4 @@ extern int making_const_table;
 #define SPECIAL_MODE_PREDICATES			\
  "cc_register", "dominant_cc_register",
 
-enum arm_builtins
-{
-  ARM_BUILTIN_CLZ,
-  ARM_BUILTIN_MAX
-};
 #endif /* ! GCC_ARM_H */
diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index 001ea4b..b35041a 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -58,9 +58,6 @@
 			;   value to it before trying to dereference it.
    (UNSPEC_PRLG_STK  4) ; A special barrier that prevents frame accesses 
 			;   being scheduled before the stack adjustment insn.
-   (UNSPEC_CLZ	     5) ; `clz' instruction, count leading zeros (SImode):
-			;   operand 0 is the result,
-			;   operand 1 is the parameter.
    (UNSPEC_PROLOGUE_USE 6) ; As USE insns are not meaningful after reload,
    			; this unspec is used to prevent the deletion of
    			; instructions setting registers for EH handling
@@ -8851,10 +8848,9 @@
 
 ;; V5 Instructions,
 
-(define_insn "clz"
-  [(set (match_operand:SI             0 "s_register_operand" "=r")
-	(unspec:SI [(match_operand:SI 1 "s_register_operand" "r")]
-		   UNSPEC_CLZ))]
+(define_insn "clzsi2"
+  [(set (match_operand:SI 0 "s_register_operand" "=r")
+	(clz:SI (match_operand:SI 1 "s_register_operand" "r")))]
   "TARGET_ARM && arm_arch5"
   "clz\\t%0, %1")
 
@@ -8872,12 +8868,32 @@
 
     emit_insn (gen_negsi2 (t1, operands[1]));
     emit_insn (gen_andsi3 (t2, operands[1], t1));
-    emit_insn (gen_clz (t3, t2));
+    emit_insn (gen_clzsi2 (t3, t2));
     emit_insn (gen_subsi3 (operands[0], GEN_INT (32), t3));
     DONE;
   }"
 )
 
+(define_expand "ctzsi2"
+  [(set (match_operand:SI 0 "s_register_operand" "")
+	(ctz:SI (match_operand:SI 1 "s_register_operand" "")))]
+  "TARGET_ARM && arm_arch5"
+  "
+  {
+    rtx t1, t2, t3;
+
+    t1 = gen_reg_rtx (SImode);
+    t2 = gen_reg_rtx (SImode);
+    t3 = gen_reg_rtx (SImode);
+
+    emit_insn (gen_negsi2 (t1, operands[1]));
+    emit_insn (gen_andsi3 (t2, operands[1], t1));
+    emit_insn (gen_clzsi2 (t3, t2));
+    emit_insn (gen_subsi3 (operands[0], GEN_INT (31), t3));
+    DONE;
+  }"
+)
+
 ;; V5E instructions.
 
 (define_insn "prefetch"
diff --git a/gcc/defaults.h b/gcc/defaults.h
index 2dc9d74..ec504a3 100644
--- a/gcc/defaults.h
+++ b/gcc/defaults.h
@@ -644,4 +644,12 @@ You Lose!  You must define PREFERRED_DEBUGGING_TYPE!
 #define TARGET_C99_FUNCTIONS 0
 #endif
 
+/* Indicate that CLZ and CTZ are undefined at zero.  */
+#ifndef CLZ_DEFINED_VALUE_AT_ZERO 
+#define CLZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE)  0
+#endif
+#ifndef CTZ_DEFINED_VALUE_AT_ZERO 
+#define CTZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE)  0
+#endif
+
 #endif  /* ! GCC_DEFAULTS_H */
diff --git a/gcc/doc/rtl.texi b/gcc/doc/rtl.texi
index 1698517..7e696fa 100644
--- a/gcc/doc/rtl.texi
+++ b/gcc/doc/rtl.texi
@@ -1850,7 +1850,8 @@ valid.
 @item (clz:@var{m} @var{x})
 Represents the number of leading 0-bits in @var{x}, represented as an
 integer of mode @var{m}, starting at the most significant bit position.
-If @var{x} is zero, the value is undefined.  Note that this is one of
+If @var{x} is zero, the value is determined by
+@code{CLZ_DEFINED_VALUE_AT_ZERO}.  Note that this is one of
 the few expressions that is not invariant under widening.  The mode of
 @var{x} will usually be an integer mode.
 
@@ -1858,7 +1859,8 @@ the few expressions that is not invariant under widening.  The mode of
 @item (ctz:@var{m} @var{x})
 Represents the number of trailing 0-bits in @var{x}, represented as an
 integer of mode @var{m}, starting at the least significant bit position.
-If @var{x} is zero, the value is undefined.  Except for this case,
+If @var{x} is zero, the value is determined by
+@code{CTZ_DEFINED_VALUE_AT_ZERO}.  Except for this case,
 @code{ctz(x)} is equivalent to @code{ffs(@var{x}) - 1}.  The mode of
 @var{x} will usually be an integer mode.
 
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index b5cb240..0abf394 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -8800,6 +8800,25 @@ Define this macro on machine that have comparison operations that return
 floating-point values.  If there are no such operations, do not define
 this macro.
 
+@findex CLZ_DEFINED_VALUE_AT_ZERO
+@findex CTZ_DEFINED_VALUE_AT_ZERO
+@item CLZ_DEFINED_VALUE_AT_ZERO (@var{mode}, @var{value})
+@itemx CTZ_DEFINED_VALUE_AT_ZERO (@var{mode}, @var{value})
+A C expression that evaluates to true if the architecture defines a value
+for @code{clz} or @code{ctz} with a zero operand.  If so, @var{value}
+should be set to this value.  If this macro is not defined, the value of
+@code{clz} or @code{ctz} is assumed to be undefined.
+
+This macro must be defined if the target's expansion for @code{ffs}
+relies on a particular value to get correct results.  Otherwise it
+is not necessary, though it may be used to optimize some corner cases.
+
+Note that regardless of this macro the ``definedness'' of @code{clz}
+and @code{ctz} at zero do @emph{not} extend to the builtin functions
+visible to the user.  Thus one may be free to adjust the value at will
+to match the target expansion of these operations without fear of
+breaking the API.
+
 @findex Pmode
 @item Pmode
 An alias for the machine mode for pointers.  On most machines, define
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 55f4ce4..0e301a7 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -7436,11 +7436,17 @@ tree_expr_nonnegative_p (t)
     {
     case ABS_EXPR:
     case FFS_EXPR:
-    case CLZ_EXPR:
-    case CTZ_EXPR:
     case POPCOUNT_EXPR:
     case PARITY_EXPR:
       return 1;
+
+    case CLZ_EXPR:
+    case CTZ_EXPR:
+      /* These are undefined at zero.  This is true even if
+	 C[LT]Z_DEFINED_VALUE_AT_ZERO is set, since what we're
+	 computing here is a user-visible property.  */
+      return 0;
+      
     case INTEGER_CST:
       return tree_int_cst_sgn (t) >= 0;
     case TRUNC_DIV_EXPR:
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 19d664b..0298b79e 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -449,14 +449,23 @@ simplify_unary_operation (code, mode, op, op_mode)
 
 	case CLZ:
 	  arg0 &= GET_MODE_MASK (mode);
-	  val = GET_MODE_BITSIZE (mode) - floor_log2 (arg0) - 1;
+	  if (arg0 == 0 && CLZ_DEFINED_VALUE_AT_ZERO (mode, val))
+	    ;
+	  else
+	    val = GET_MODE_BITSIZE (mode) - floor_log2 (arg0) - 1;
 	  break;
 
 	case CTZ:
 	  arg0 &= GET_MODE_MASK (mode);
-	  val = arg0 == 0
-	      ? GET_MODE_BITSIZE (mode)
-	      : exact_log2 (arg0 & -arg0);
+	  if (arg0 == 0)
+	    {
+	      /* Even if the value at zero is undefined, we have to come
+		 up with some replacement.  Seems good enough.  */
+	      if (! CTZ_DEFINED_VALUE_AT_ZERO (mode, val))
+		val = GET_MODE_BITSIZE (mode);
+	    }
+	  else
+	    val = exact_log2 (arg0 & -arg0);
 	  break;
 
 	case POPCOUNT: