double-int.h (lshift): New overload without precision and arith argument.

2013-05-03  Richard Biener  <rguenther@suse.de>

	* double-int.h (lshift): New overload without precision
	and arith argument.
	(operator *=, operator +=, operator -=): Move ...
	* double-int.c (operator *=, operator +=, operator -=): ... here
	and implement more efficiently.
	(mul_double_with_sign): Remove.
	(lshift_double): Adjust to take unsinged shift argument, push
	dispatching code to callers.
	(mul_double_wide_with_sign): Add early out for callers that
	are not interested in high parts or overflow.
	(lshift): New function.
	(lshift, rshift, alshift, arshift, llshift, lrshift): Add
	dispatch code here.
	(lrotate, rrotate): Use logical shifts.
	* expr.c (get_inner_reference): Use lshift.
	* fixed-value.c (do_fixed_divide): Likewise.
	* tree-dfa.c (get_ref_base_and_extent): Likewise.
	* tree-ssa-alias.c (indirect_ref_may_alias_decl_p): Likewise.
	(indirect_refs_may_alias_p): Likewise.
	(stmt_kills_ref_p_1): Likewise.

From-SVN: r198576

7 files changed, 151 insertions, 108 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6894860..ad545ae 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,26 @@
+2013-05-03  Richard Biener  <rguenther@suse.de>
+
+	* double-int.h (lshift): New overload without precision
+	and arith argument.
+	(operator *=, operator +=, operator -=): Move ...
+	* double-int.c (operator *=, operator +=, operator -=): ... here
+	and implement more efficiently.
+	(mul_double_with_sign): Remove.
+	(lshift_double): Adjust to take unsinged shift argument, push
+	dispatching code to callers.
+	(mul_double_wide_with_sign): Add early out for callers that
+	are not interested in high parts or overflow.
+	(lshift): New function.
+	(lshift, rshift, alshift, arshift, llshift, lrshift): Add
+	dispatch code here.
+	(lrotate, rrotate): Use logical shifts.
+	* expr.c (get_inner_reference): Use lshift.
+	* fixed-value.c (do_fixed_divide): Likewise.
+	* tree-dfa.c (get_ref_base_and_extent): Likewise.
+	* tree-ssa-alias.c (indirect_ref_may_alias_decl_p): Likewise.
+	(indirect_refs_may_alias_p): Likewise.
+	(stmt_kills_ref_p_1): Likewise.
+
 2013-05-03  Vidya Praveen  <vidyapraveen@arm.com>
 
 	* config/aarch64/aarch64-simd.md (simd_fabd): Correct the description.
diff --git a/gcc/double-int.c b/gcc/double-int.c
index 918ce22..b098f57 100644
--- a/gcc/double-int.c
+++ b/gcc/double-int.c
@@ -34,11 +34,6 @@ static int add_double_with_sign (unsigned HOST_WIDE_INT, HOST_WIDE_INT,
 static int neg_double (unsigned HOST_WIDE_INT, HOST_WIDE_INT,
 		       unsigned HOST_WIDE_INT *, HOST_WIDE_INT *);
 
-static int mul_double_with_sign (unsigned HOST_WIDE_INT, HOST_WIDE_INT,
-				 unsigned HOST_WIDE_INT, HOST_WIDE_INT,
-				 unsigned HOST_WIDE_INT *, HOST_WIDE_INT *,
-				 bool);
-
 static int mul_double_wide_with_sign (unsigned HOST_WIDE_INT, HOST_WIDE_INT,
 				      unsigned HOST_WIDE_INT, HOST_WIDE_INT,
 				      unsigned HOST_WIDE_INT *, HOST_WIDE_INT *,
@@ -46,11 +41,7 @@ static int mul_double_wide_with_sign (unsigned HOST_WIDE_INT, HOST_WIDE_INT,
 				      bool);
 
 #define mul_double(l1,h1,l2,h2,lv,hv) \
-  mul_double_with_sign (l1, h1, l2, h2, lv, hv, false)
-
-static void lshift_double (unsigned HOST_WIDE_INT, HOST_WIDE_INT,
-			   HOST_WIDE_INT, unsigned int,
-			   unsigned HOST_WIDE_INT *, HOST_WIDE_INT *, bool);
+  mul_double_wide_with_sign (l1, h1, l2, h2, lv, hv, NULL, NULL, false)
 
 static int div_and_round_double (unsigned, int, unsigned HOST_WIDE_INT,
 				 HOST_WIDE_INT, unsigned HOST_WIDE_INT,
@@ -158,25 +149,13 @@ neg_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
     }
 }
 
-/* Multiply two doubleword integers with doubleword result.
+/* Multiply two doubleword integers with quadword result.
    Return nonzero if the operation overflows according to UNSIGNED_P.
    Each argument is given as two `HOST_WIDE_INT' pieces.
    One argument is L1 and H1; the other, L2 and H2.
-   The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV.  */
-
-static int
-mul_double_with_sign (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
-		      unsigned HOST_WIDE_INT l2, HOST_WIDE_INT h2,
-		      unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv,
-		      bool unsigned_p)
-{
-  unsigned HOST_WIDE_INT toplow;
-  HOST_WIDE_INT tophigh;
-
-  return mul_double_wide_with_sign (l1, h1, l2, h2,
-				    lv, hv, &toplow, &tophigh,
-				    unsigned_p);
-}
+   The value is stored as four `HOST_WIDE_INT' pieces in *LV and *HV,
+   *LW and *HW.
+   If lw is NULL then only the low part and no overflow is computed.  */
 
 static int
 mul_double_wide_with_sign (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
@@ -215,6 +194,11 @@ mul_double_wide_with_sign (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
     }
 
   decode (prod, lv, hv);
+
+  /* We are not interested in the wide part nor in overflow.  */
+  if (lw == NULL)
+    return 0;
+
   decode (prod + 4, lw, hw);
 
   /* Unsigned overflow is immediate.  */
@@ -306,17 +290,11 @@ rshift_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
 
 static void
 lshift_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
-	       HOST_WIDE_INT count, unsigned int prec,
-	       unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv, bool arith)
+	       unsigned HOST_WIDE_INT count, unsigned int prec,
+	       unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv)
 {
   unsigned HOST_WIDE_INT signmask;
 
-  if (count < 0)
-    {
-      rshift_double (l1, h1, absu_hwi (count), prec, lv, hv, arith);
-      return;
-    }
-
   if (SHIFT_COUNT_TRUNCATED)
     count %= prec;
 
@@ -832,6 +810,15 @@ double_int::operator * (double_int b) const
   return ret;
 }
 
+/* Multiplies *this with B and returns a reference to *this.  */
+
+double_int &
+double_int::operator *= (double_int b)
+{
+  mul_double (low, high, b.low, b.high, &low, &high);
+  return *this;
+}
+
 /* Returns A * B. If the operation overflows according to UNSIGNED_P,
    *OVERFLOW is set to nonzero.  */
 
@@ -839,9 +826,10 @@ double_int
 double_int::mul_with_sign (double_int b, bool unsigned_p, bool *overflow) const
 {
   const double_int &a = *this;
-  double_int ret;
-  *overflow = mul_double_with_sign (a.low, a.high, b.low, b.high,
-                                    &ret.low, &ret.high, unsigned_p);
+  double_int ret, tem;
+  *overflow = mul_double_wide_with_sign (a.low, a.high, b.low, b.high,
+					 &ret.low, &ret.high,
+					 &tem.low, &tem.high, unsigned_p);
   return ret;
 }
 
@@ -869,6 +857,16 @@ double_int::operator + (double_int b) const
   return ret;
 }
 
+/* Adds B to *this and returns a reference to *this.  */
+
+double_int &
+double_int::operator += (double_int b)
+{
+  add_double (low, high, b.low, b.high, &low, &high);
+  return *this;
+}
+
+
 /* Returns A + B. If the operation overflows according to UNSIGNED_P,
    *OVERFLOW is set to nonzero.  */
 
@@ -894,6 +892,17 @@ double_int::operator - (double_int b) const
   return ret;
 }
 
+/* Subtracts B from *this and returns a reference to *this.  */
+
+double_int &
+double_int::operator -= (double_int b)
+{
+  neg_double (b.low, b.high, &b.low, &b.high);
+  add_double (low, high, b.low, b.high, &low, &high);
+  return *this;
+}
+
+
 /* Returns A - B. If the operation overflows via inconsistent sign bits,
    *OVERFLOW is set to nonzero.  */
 
@@ -1076,6 +1085,37 @@ double_int::trailing_zeros () const
   return bits;
 }
 
+/* Shift A left by COUNT places.  */
+
+double_int
+double_int::lshift (HOST_WIDE_INT count) const
+{
+  double_int ret;
+
+  gcc_checking_assert (count >= 0);
+
+  if (count >= HOST_BITS_PER_DOUBLE_INT)
+    {
+      /* Shifting by the host word size is undefined according to the
+	 ANSI standard, so we must handle this as a special case.  */
+      ret.high = 0;
+      ret.low = 0;
+    }
+  else if (count >= HOST_BITS_PER_WIDE_INT)
+    {
+      ret.high = low << (count - HOST_BITS_PER_WIDE_INT);
+      ret.low = 0;
+    }
+  else
+    {
+      ret.high = (((unsigned HOST_WIDE_INT) high << count)
+	     | (low >> (HOST_BITS_PER_WIDE_INT - count - 1) >> 1));
+      ret.low = low << count;
+    }
+
+  return ret;
+}
+
 /* Shift A left by COUNT places keeping only PREC bits of result.  Shift
    right if COUNT is negative.  ARITH true specifies arithmetic shifting;
    otherwise use logical shift.  */
@@ -1083,9 +1123,11 @@ double_int::trailing_zeros () const
 double_int
 double_int::lshift (HOST_WIDE_INT count, unsigned int prec, bool arith) const
 {
-  const double_int &a = *this;
   double_int ret;
-  lshift_double (a.low, a.high, count, prec, &ret.low, &ret.high, arith);
+  if (count > 0)
+    lshift_double (low, high, count, prec, &ret.low, &ret.high);
+  else
+    rshift_double (low, high, absu_hwi (count), prec, &ret.low, &ret.high, arith);
   return ret;
 }
 
@@ -1096,9 +1138,11 @@ double_int::lshift (HOST_WIDE_INT count, unsigned int prec, bool arith) const
 double_int
 double_int::rshift (HOST_WIDE_INT count, unsigned int prec, bool arith) const
 {
-  const double_int &a = *this;
   double_int ret;
-  lshift_double (a.low, a.high, -count, prec, &ret.low, &ret.high, arith);
+  if (count > 0)
+    rshift_double (low, high, count, prec, &ret.low, &ret.high, arith);
+  else
+    lshift_double (low, high, absu_hwi (count), prec, &ret.low, &ret.high);
   return ret;
 }
 
@@ -1109,7 +1153,10 @@ double_int
 double_int::alshift (HOST_WIDE_INT count, unsigned int prec) const
 {
   double_int r;
-  lshift_double (low, high, count, prec, &r.low, &r.high, true);
+  if (count > 0)
+    lshift_double (low, high, count, prec, &r.low, &r.high);
+  else
+    rshift_double (low, high, absu_hwi (count), prec, &r.low, &r.high, true);
   return r;
 }
 
@@ -1120,7 +1167,10 @@ double_int
 double_int::arshift (HOST_WIDE_INT count, unsigned int prec) const
 {
   double_int r;
-  lshift_double (low, high, -count, prec, &r.low, &r.high, true);
+  if (count > 0)
+    rshift_double (low, high, count, prec, &r.low, &r.high, true);
+  else
+    lshift_double (low, high, absu_hwi (count), prec, &r.low, &r.high);
   return r;
 }
 
@@ -1131,7 +1181,10 @@ double_int
 double_int::llshift (HOST_WIDE_INT count, unsigned int prec) const
 {
   double_int r;
-  lshift_double (low, high, count, prec, &r.low, &r.high, false);
+  if (count > 0)
+    lshift_double (low, high, count, prec, &r.low, &r.high);
+  else
+    rshift_double (low, high, absu_hwi (count), prec, &r.low, &r.high, false);
   return r;
 }
 
@@ -1142,7 +1195,10 @@ double_int
 double_int::lrshift (HOST_WIDE_INT count, unsigned int prec) const
 {
   double_int r;
-  lshift_double (low, high, -count, prec, &r.low, &r.high, false);
+  if (count > 0)
+    rshift_double (low, high, count, prec, &r.low, &r.high, false);
+  else
+    lshift_double (low, high, absu_hwi (count), prec, &r.low, &r.high);
   return r;
 }
 
@@ -1158,8 +1214,8 @@ double_int::lrotate (HOST_WIDE_INT count, unsigned int prec) const
   if (count < 0)
     count += prec;
 
-  t1 = this->lshift (count, prec, false);
-  t2 = this->rshift (prec - count, prec, false);
+  t1 = this->llshift (count, prec);
+  t2 = this->lrshift (prec - count, prec);
 
   return t1 | t2;
 }
@@ -1176,8 +1232,8 @@ double_int::rrotate (HOST_WIDE_INT count, unsigned int prec) const
   if (count < 0)
     count += prec;
 
-  t1 = this->rshift (count, prec, false);
-  t2 = this->lshift (prec - count, prec, false);
+  t1 = this->lrshift (count, prec);
+  t2 = this->llshift (prec - count, prec);
 
   return t1 | t2;
 }
diff --git a/gcc/double-int.h b/gcc/double-int.h
index 5c425a8..39929d2 100644
--- a/gcc/double-int.h
+++ b/gcc/double-int.h
@@ -128,6 +128,7 @@ struct double_int
   double_int operator ^ (double_int) const;
   double_int and_not (double_int) const;
 
+  double_int lshift (HOST_WIDE_INT count) const;
   double_int lshift (HOST_WIDE_INT count, unsigned int prec, bool arith) const;
   double_int rshift (HOST_WIDE_INT count, unsigned int prec, bool arith) const;
   double_int alshift (HOST_WIDE_INT count, unsigned int prec) const;
@@ -258,27 +259,6 @@ double_int::operator -- ()
 }
 
 inline double_int &
-double_int::operator *= (double_int b)
-{
-  *this = *this * b;
-  return *this;
-}
-
-inline double_int &
-double_int::operator += (double_int b)
-{
-  *this = *this + b;
-  return *this;
-}
-
-inline double_int &
-double_int::operator -= (double_int b)
-{
-  *this = *this - b;
-  return *this;
-}
-
-inline double_int &
 double_int::operator &= (double_int b)
 {
   *this = *this & b;
diff --git a/gcc/expr.c b/gcc/expr.c
index e3fb0b6..acf282e 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -6704,9 +6704,8 @@ get_inner_reference (tree exp, HOST_WIDE_INT *pbitsize,
 	      if (!integer_zerop (off))
 		{
 		  double_int boff, coff = mem_ref_offset (exp);
-		  boff = coff.alshift (BITS_PER_UNIT == 8
-				       ? 3 : exact_log2 (BITS_PER_UNIT),
-				       HOST_BITS_PER_DOUBLE_INT);
+		  boff = coff.lshift (BITS_PER_UNIT == 8
+				      ? 3 : exact_log2 (BITS_PER_UNIT));
 		  bit_offset += boff;
 		}
 	      exp = TREE_OPERAND (TREE_OPERAND (exp, 0), 0);
@@ -6732,8 +6731,7 @@ get_inner_reference (tree exp, HOST_WIDE_INT *pbitsize,
     {
       double_int tem = tree_to_double_int (offset);
       tem = tem.sext (TYPE_PRECISION (sizetype));
-      tem = tem.alshift (BITS_PER_UNIT == 8 ? 3 : exact_log2 (BITS_PER_UNIT),
-			 HOST_BITS_PER_DOUBLE_INT);
+      tem = tem.lshift (BITS_PER_UNIT == 8 ? 3 : exact_log2 (BITS_PER_UNIT));
       tem += bit_offset;
       if (tem.fits_shwi ())
 	{
diff --git a/gcc/fixed-value.c b/gcc/fixed-value.c
index 18ce47e..8ba7876 100644
--- a/gcc/fixed-value.c
+++ b/gcc/fixed-value.c
@@ -569,14 +569,14 @@ do_fixed_divide (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a,
 	  int leftmost_mod = (mod.high < 0);
 
 	  /* Shift left mod by 1 bit.  */
-	  mod = mod.llshift (1, HOST_BITS_PER_DOUBLE_INT);
+	  mod = mod.lshift (1);
 
 	  /* Test the leftmost bit of s to add to mod.  */
 	  if (s.high < 0)
 	    mod.low += 1;
 
 	  /* Shift left quo_s by 1 bit.  */
-	  quo_s = quo_s.llshift (1, HOST_BITS_PER_DOUBLE_INT);
+	  quo_s = quo_s.lshift (1);
 
 	  /* Try to calculate (mod - pos_b).  */
 	  temp = mod - pos_b;
@@ -588,7 +588,7 @@ do_fixed_divide (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a,
 	    }
 
 	  /* Shift left s by 1 bit.  */
-	  s = s.llshift (1, HOST_BITS_PER_DOUBLE_INT);
+	  s = s.lshift (1);
 
 	}
 
diff --git a/gcc/tree-dfa.c b/gcc/tree-dfa.c
index 23fae4f..57aae95 100644
--- a/gcc/tree-dfa.c
+++ b/gcc/tree-dfa.c
@@ -433,9 +433,8 @@ get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
 	    if (this_offset && TREE_CODE (this_offset) == INTEGER_CST)
 	      {
 		double_int doffset = tree_to_double_int (this_offset);
-		doffset = doffset.alshift (BITS_PER_UNIT == 8
-					   ? 3 : exact_log2 (BITS_PER_UNIT),
-					   HOST_BITS_PER_DOUBLE_INT);
+		doffset = doffset.lshift (BITS_PER_UNIT == 8
+					  ? 3 : exact_log2 (BITS_PER_UNIT));
 		doffset += tree_to_double_int (DECL_FIELD_BIT_OFFSET (field));
 		bit_offset = bit_offset + doffset;
 
@@ -501,9 +500,8 @@ get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
 		  = (TREE_INT_CST (index) - TREE_INT_CST (low_bound))
 		    .sext (TYPE_PRECISION (TREE_TYPE (index)));
 		doffset *= tree_to_double_int (unit_size);
-		doffset = doffset.alshift (BITS_PER_UNIT == 8
-					   ? 3 : exact_log2 (BITS_PER_UNIT),
-					   HOST_BITS_PER_DOUBLE_INT);
+		doffset = doffset.lshift (BITS_PER_UNIT == 8
+					  ? 3 : exact_log2 (BITS_PER_UNIT));
 		bit_offset = bit_offset + doffset;
 
 		/* An array ref with a constant index up in the structure
@@ -552,9 +550,8 @@ get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
 	      else
 		{
 		  double_int off = mem_ref_offset (exp);
-		  off = off.alshift (BITS_PER_UNIT == 8
-				     ? 3 : exact_log2 (BITS_PER_UNIT),
-				     HOST_BITS_PER_DOUBLE_INT);
+		  off = off.lshift (BITS_PER_UNIT == 8
+				    ? 3 : exact_log2 (BITS_PER_UNIT));
 		  off = off + bit_offset;
 		  if (off.fits_shwi ())
 		    {
@@ -583,9 +580,8 @@ get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
 	      else
 		{
 		  double_int off = mem_ref_offset (exp);
-		  off = off.alshift (BITS_PER_UNIT == 8
-				     ? 3 : exact_log2 (BITS_PER_UNIT),
-				     HOST_BITS_PER_DOUBLE_INT);
+		  off = off.lshift (BITS_PER_UNIT == 8
+				    ? 3 : exact_log2 (BITS_PER_UNIT));
 		  off += bit_offset;
 		  if (off.fits_shwi ())
 		    {
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 70e9e00..971a347 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -882,9 +882,7 @@ indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
   /* The offset embedded in MEM_REFs can be negative.  Bias them
      so that the resulting offset adjustment is positive.  */
   moff = mem_ref_offset (base1);
-  moff = moff.alshift (BITS_PER_UNIT == 8
-		       ? 3 : exact_log2 (BITS_PER_UNIT),
-		       HOST_BITS_PER_DOUBLE_INT);
+  moff = moff.lshift (BITS_PER_UNIT == 8 ? 3 : exact_log2 (BITS_PER_UNIT));
   if (moff.is_negative ())
     offset2p += (-moff).low;
   else
@@ -960,9 +958,7 @@ indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
       || TREE_CODE (dbase2) == TARGET_MEM_REF)
     {
       double_int moff = mem_ref_offset (dbase2);
-      moff = moff.alshift (BITS_PER_UNIT == 8
-			   ? 3 : exact_log2 (BITS_PER_UNIT),
-			   HOST_BITS_PER_DOUBLE_INT);
+      moff = moff.lshift (BITS_PER_UNIT == 8 ? 3 : exact_log2 (BITS_PER_UNIT));
       if (moff.is_negative ())
 	doffset1 -= (-moff).low;
       else
@@ -1056,17 +1052,13 @@ indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
       /* The offset embedded in MEM_REFs can be negative.  Bias them
 	 so that the resulting offset adjustment is positive.  */
       moff = mem_ref_offset (base1);
-      moff = moff.alshift (BITS_PER_UNIT == 8
-			   ? 3 : exact_log2 (BITS_PER_UNIT),
-			   HOST_BITS_PER_DOUBLE_INT);
+      moff = moff.lshift (BITS_PER_UNIT == 8 ? 3 : exact_log2 (BITS_PER_UNIT));
       if (moff.is_negative ())
 	offset2 += (-moff).low;
       else
 	offset1 += moff.low;
       moff = mem_ref_offset (base2);
-      moff = moff.alshift (BITS_PER_UNIT == 8
-			   ? 3 : exact_log2 (BITS_PER_UNIT),
-			   HOST_BITS_PER_DOUBLE_INT);
+      moff = moff.lshift (BITS_PER_UNIT == 8 ? 3 : exact_log2 (BITS_PER_UNIT));
       if (moff.is_negative ())
 	offset1 += (-moff).low;
       else
@@ -2014,14 +2006,12 @@ stmt_kills_ref_p_1 (gimple stmt, ao_ref *ref)
 				       TREE_OPERAND (ref->base, 0)))
 		{
 		  double_int off1 = mem_ref_offset (base);
-		  off1 = off1.alshift (BITS_PER_UNIT == 8
-				       ? 3 : exact_log2 (BITS_PER_UNIT),
-				       HOST_BITS_PER_DOUBLE_INT);
+		  off1 = off1.lshift (BITS_PER_UNIT == 8
+				      ? 3 : exact_log2 (BITS_PER_UNIT));
 		  off1 = off1 + double_int::from_shwi (offset);
 		  double_int off2 = mem_ref_offset (ref->base);
-		  off2 = off2.alshift (BITS_PER_UNIT == 8
-				       ? 3 : exact_log2 (BITS_PER_UNIT),
-				       HOST_BITS_PER_DOUBLE_INT);
+		  off2 = off2.lshift (BITS_PER_UNIT == 8
+				      ? 3 : exact_log2 (BITS_PER_UNIT));
 		  off2 = off2 + double_int::from_shwi (ref_offset);
 		  if (off1.fits_shwi () && off2.fits_shwi ())
 		    {