Use unsigned(-1) for lshift

[Marc Glisse <marc dot glisse at inria dot fr>]

Hello,

this is a simple patch to reduce a bit the noise in PR57324 (undefined 
behavior flagged by clang). I only handled some of the most obvious ones.
Passes bootstrap+testsuite on x86_64-linux-gnu.


2013-05-24  Marc Glisse  <marc.glisse@inria.fr>

	PR other/57324
	* expmed.c (expand_smod_pow2): Use an unsigned -1 for lshift.
	* fold-const.c (fold_unary_loc): Likewise.
	* double-int.c (rshift_double, lshift_double): Likewise.
	* cse.c (cse_insn): Likewise.
	* tree.c (integer_pow2p, tree_log2, tree_floor_log2): Likewise.
	* tree-ssa-structalias.c (UNKNOWN_OFFSET): Shift 1 instead of -1.

--
Marc Glisse

Index: gcc/double-int.c
===================================================================
--- gcc/double-int.c	(revision 199256)
+++ gcc/double-int.c	(working copy)
@@ -264,21 +264,22 @@ rshift_double (unsigned HOST_WIDE_INT l1
 
   if (count >= prec)
     {
       *hv = signmask;
       *lv = signmask;
     }
   else if ((prec - count) >= HOST_BITS_PER_DOUBLE_INT)
     ;
   else if ((prec - count) >= HOST_BITS_PER_WIDE_INT)
     {
-      *hv &= ~((HOST_WIDE_INT) (-1) << (prec - count - HOST_BITS_PER_WIDE_INT));
+      *hv &= ~((unsigned HOST_WIDE_INT) (-1)
+	       << (prec - count - HOST_BITS_PER_WIDE_INT));
       *hv |= signmask << (prec - count - HOST_BITS_PER_WIDE_INT);
     }
   else
     {
       *hv = signmask;
       *lv &= ~((unsigned HOST_WIDE_INT) (-1) << (prec - count));
       *lv |= signmask << (prec - count);
     }
 }
 
@@ -321,21 +322,21 @@ lshift_double (unsigned HOST_WIDE_INT l1
 
   signmask = -((prec > HOST_BITS_PER_WIDE_INT
 		? ((unsigned HOST_WIDE_INT) *hv
 		   >> (prec - HOST_BITS_PER_WIDE_INT - 1))
 		: (*lv >> (prec - 1))) & 1);
 
   if (prec >= HOST_BITS_PER_DOUBLE_INT)
     ;
   else if (prec >= HOST_BITS_PER_WIDE_INT)
     {
-      *hv &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
+      *hv &= ~((unsigned HOST_WIDE_INT) -1 << (prec - HOST_BITS_PER_WIDE_INT));
       *hv |= signmask << (prec - HOST_BITS_PER_WIDE_INT);
     }
   else
     {
       *hv = signmask;
       *lv &= ~((unsigned HOST_WIDE_INT) (-1) << prec);
       *lv |= signmask << prec;
     }
 }
 
Index: gcc/tree-ssa-structalias.c
===================================================================
--- gcc/tree-ssa-structalias.c	(revision 199256)
+++ gcc/tree-ssa-structalias.c	(working copy)
@@ -475,21 +475,21 @@ struct constraint_expr
 
   /* Offset, in bits, of this constraint from the beginning of
      variables it ends up referring to.
 
      IOW, in a deref constraint, we would deref, get the result set,
      then add OFFSET to each member.   */
   HOST_WIDE_INT offset;
 };
 
 /* Use 0x8000... as special unknown offset.  */
-#define UNKNOWN_OFFSET ((HOST_WIDE_INT)-1 << (HOST_BITS_PER_WIDE_INT-1))
+#define UNKNOWN_OFFSET ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT-1))
 
 typedef struct constraint_expr ce_s;
 static void get_constraint_for_1 (tree, vec<ce_s> *, bool, bool);
 static void get_constraint_for (tree, vec<ce_s> *);
 static void get_constraint_for_rhs (tree, vec<ce_s> *);
 static void do_deref (vec<ce_s> *);
 
 /* Our set constraints are made up of two constraint expressions, one
    LHS, and one RHS.
 
Index: gcc/cse.c
===================================================================
--- gcc/cse.c	(revision 199256)
+++ gcc/cse.c	(working copy)
@@ -5374,21 +5374,21 @@ cse_insn (rtx insn)
 	 may not equal what was stored, due to truncation.  */
 
       if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT)
 	{
 	  rtx width = XEXP (SET_DEST (sets[i].rtl), 1);
 
 	  if (src_const != 0 && CONST_INT_P (src_const)
 	      && CONST_INT_P (width)
 	      && INTVAL (width) < HOST_BITS_PER_WIDE_INT
 	      && ! (INTVAL (src_const)
-		    & ((HOST_WIDE_INT) (-1) << INTVAL (width))))
+		    & ((unsigned HOST_WIDE_INT) (-1) << INTVAL (width))))
 	    /* Exception: if the value is constant,
 	       and it won't be truncated, record it.  */
 	    ;
 	  else
 	    {
 	      /* This is chosen so that the destination will be invalidated
 		 but no new value will be recorded.
 		 We must invalidate because sometimes constant
 		 values can be recorded for bitfields.  */
 	      sets[i].src_elt = 0;
Index: gcc/expmed.c
===================================================================
--- gcc/expmed.c	(revision 199256)
+++ gcc/expmed.c	(working copy)
@@ -3688,39 +3688,39 @@ expand_smod_pow2 (enum machine_mode mode
     }
 
   /* Mask contains the mode's signbit and the significant bits of the
      modulus.  By including the signbit in the operation, many targets
      can avoid an explicit compare operation in the following comparison
      against zero.  */
 
   masklow = ((HOST_WIDE_INT) 1 << logd) - 1;
   if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
     {
-      masklow |= (HOST_WIDE_INT) -1 << (GET_MODE_BITSIZE (mode) - 1);
+      masklow |= (unsigned HOST_WIDE_INT) -1 << (GET_MODE_BITSIZE (mode) - 1);
       maskhigh = -1;
     }
   else
-    maskhigh = (HOST_WIDE_INT) -1
+    maskhigh = (unsigned HOST_WIDE_INT) -1
 		 << (GET_MODE_BITSIZE (mode) - HOST_BITS_PER_WIDE_INT - 1);
 
   temp = expand_binop (mode, and_optab, op0,
 		       immed_double_const (masklow, maskhigh, mode),
 		       result, 1, OPTAB_LIB_WIDEN);
   if (temp != result)
     emit_move_insn (result, temp);
 
   label = gen_label_rtx ();
   do_cmp_and_jump (result, const0_rtx, GE, mode, label);
 
   temp = expand_binop (mode, sub_optab, result, const1_rtx, result,
 		       0, OPTAB_LIB_WIDEN);
-  masklow = (HOST_WIDE_INT) -1 << logd;
+  masklow = (unsigned HOST_WIDE_INT) -1 << logd;
   maskhigh = -1;
   temp = expand_binop (mode, ior_optab, temp,
 		       immed_double_const (masklow, maskhigh, mode),
 		       result, 1, OPTAB_LIB_WIDEN);
   temp = expand_binop (mode, add_optab, temp, const1_rtx, result,
 		       0, OPTAB_LIB_WIDEN);
   if (temp != result)
     emit_move_insn (result, temp);
   emit_label (label);
   return result;
Index: gcc/tree.c
===================================================================
--- gcc/tree.c	(revision 199256)
+++ gcc/tree.c	(working copy)
@@ -1935,26 +1935,26 @@ integer_pow2p (const_tree expr)
   prec = TYPE_PRECISION (TREE_TYPE (expr));
   high = TREE_INT_CST_HIGH (expr);
   low = TREE_INT_CST_LOW (expr);
 
   /* First clear all bits that are beyond the type's precision in case
      we've been sign extended.  */
 
   if (prec == HOST_BITS_PER_DOUBLE_INT)
     ;
   else if (prec > HOST_BITS_PER_WIDE_INT)
-    high &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
+    high &= ~((unsigned HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
   else
     {
       high = 0;
       if (prec < HOST_BITS_PER_WIDE_INT)
-	low &= ~((HOST_WIDE_INT) (-1) << prec);
+	low &= ~((unsigned HOST_WIDE_INT) (-1) << prec);
     }
 
   if (high == 0 && low == 0)
     return 0;
 
   return ((high == 0 && (low & (low - 1)) == 0)
 	  || (low == 0 && (high & (high - 1)) == 0));
 }
 
 /* Return 1 if EXPR is an integer constant other than zero or a
@@ -1999,26 +1999,26 @@ tree_log2 (const_tree expr)
   prec = TYPE_PRECISION (TREE_TYPE (expr));
   high = TREE_INT_CST_HIGH (expr);
   low = TREE_INT_CST_LOW (expr);
 
   /* First clear all bits that are beyond the type's precision in case
      we've been sign extended.  */
 
   if (prec == HOST_BITS_PER_DOUBLE_INT)
     ;
   else if (prec > HOST_BITS_PER_WIDE_INT)
-    high &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
+    high &= ~((unsigned HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
   else
     {
       high = 0;
       if (prec < HOST_BITS_PER_WIDE_INT)
-	low &= ~((HOST_WIDE_INT) (-1) << prec);
+	low &= ~((unsigned HOST_WIDE_INT) (-1) << prec);
     }
 
   return (high != 0 ? HOST_BITS_PER_WIDE_INT + exact_log2 (high)
 	  : exact_log2 (low));
 }
 
 /* Similar, but return the largest integer Y such that 2 ** Y is less
    than or equal to EXPR.  */
 
 int
@@ -2036,26 +2036,26 @@ tree_floor_log2 (const_tree expr)
   high = TREE_INT_CST_HIGH (expr);
   low = TREE_INT_CST_LOW (expr);
 
   /* First clear all bits that are beyond the type's precision in case
      we've been sign extended.  Ignore if type's precision hasn't been set
      since what we are doing is setting it.  */
 
   if (prec == HOST_BITS_PER_DOUBLE_INT || prec == 0)
     ;
   else if (prec > HOST_BITS_PER_WIDE_INT)
-    high &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
+    high &= ~((unsigned HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
   else
     {
       high = 0;
       if (prec < HOST_BITS_PER_WIDE_INT)
-	low &= ~((HOST_WIDE_INT) (-1) << prec);
+	low &= ~((unsigned HOST_WIDE_INT) (-1) << prec);
     }
 
   return (high != 0 ? HOST_BITS_PER_WIDE_INT + floor_log2 (high)
 	  : floor_log2 (low));
 }
 
 /* Return 1 if EXPR is the real constant zero.  Trailing zeroes matter for
    decimal float constants, so don't return 1 for them.  */
 
 int
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c	(revision 199256)
+++ gcc/fold-const.c	(working copy)
@@ -8049,21 +8049,21 @@ fold_unary_loc (location_t loc, enum tre
 	      || (TYPE_PRECISION (type)
 		  <= TYPE_PRECISION (TREE_TYPE (and_expr))))
 	    change = 1;
 	  else if (TYPE_PRECISION (TREE_TYPE (and1))
 		   <= HOST_BITS_PER_WIDE_INT
 		   && host_integerp (and1, 1))
 	    {
 	      unsigned HOST_WIDE_INT cst;
 
 	      cst = tree_low_cst (and1, 1);
-	      cst &= (HOST_WIDE_INT) -1
+	      cst &= (unsigned HOST_WIDE_INT) -1
 		     << (TYPE_PRECISION (TREE_TYPE (and1)) - 1);
 	      change = (cst == 0);
 #ifdef LOAD_EXTEND_OP
 	      if (change
 		  && !flag_syntax_only
 		  && (LOAD_EXTEND_OP (TYPE_MODE (TREE_TYPE (and0)))
 		      == ZERO_EXTEND))
 		{
 		  tree uns = unsigned_type_for (TREE_TYPE (and0));
 		  and0 = fold_convert_loc (loc, uns, and0);