cse.c (find_comparison_args): Use val_mode_signbit_set_p.

	* cse.c (find_comparison_args): Use val_mode_signbit_set_p.
	* simplify-rtx.c (mode_signbit_p): Use GET_MODE_PRECISION.
	(val_mode_signbit_p, val_mode_signbit_set_p): New functions.
	(simplify_const_unary_operation, simplify_binary_operation_1,
	simplify_const_binary_operation,
	simplify_const_relational_operation): Use them.  Use
	GET_MODE_MASK for masking and sign-extensions.
	* combine.c (set_nonzero_bits_and_sign_copies, simplify_set,
	combine_simplify_rtx, force_to_mode, reg_nonzero_bits_for_combine,
	simplify_shift_const_1, simplify_comparison): Likewise.
	* expr.c (convert_modes): Likewise.
	* rtlanal.c (nonzero_bits1, canonicalize_condition): Likewise.
	* expmed.c (emit_cstore, emit_store_flag_1, emit_store_flag):
	Likewise.
	* rtl.h (val_mode_signbit_p, val_mode_signbit_set_p): Declare.

From-SVN: r175917

8 files changed, 147 insertions, 134 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 57c5390..e06f369 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,21 @@
+2011-07-06  Bernd Schmidt  <bernds@codesourcery.com>
+
+	* cse.c (find_comparison_args): Use val_mode_signbit_set_p.
+	* simplify-rtx.c (mode_signbit_p): Use GET_MODE_PRECISION.
+	(val_mode_signbit_p, val_mode_signbit_set_p): New functions.
+	(simplify_const_unary_operation, simplify_binary_operation_1,
+	simplify_const_binary_operation,
+	simplify_const_relational_operation): Use them.  Use
+	GET_MODE_MASK for masking and sign-extensions.
+	* combine.c (set_nonzero_bits_and_sign_copies, simplify_set,
+	combine_simplify_rtx, force_to_mode, reg_nonzero_bits_for_combine,
+	simplify_shift_const_1, simplify_comparison): Likewise.
+	* expr.c (convert_modes): Likewise.
+	* rtlanal.c (nonzero_bits1, canonicalize_condition): Likewise.
+	* expmed.c (emit_cstore, emit_store_flag_1, emit_store_flag):
+	Likewise.
+	* rtl.h (val_mode_signbit_p, val_mode_signbit_set_p): Declare.
+
 2011-07-06  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/49645
diff --git a/gcc/combine.c b/gcc/combine.c
index 737f300..7ac4613 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -1627,15 +1627,11 @@ set_nonzero_bits_and_sign_copies (rtx x, const_rtx set, void *data)
 	     ??? For 2.5, try to tighten up the MD files in this regard
 	     instead of this kludge.  */
 
-	  if (GET_MODE_BITSIZE (GET_MODE (x)) < BITS_PER_WORD
+	  if (GET_MODE_PRECISION (GET_MODE (x)) < BITS_PER_WORD
 	      && CONST_INT_P (src)
 	      && INTVAL (src) > 0
-	      && 0 != (UINTVAL (src)
-		       & ((unsigned HOST_WIDE_INT) 1
-			  << (GET_MODE_BITSIZE (GET_MODE (x)) - 1))))
-	    src = GEN_INT (UINTVAL (src)
-			   | ((unsigned HOST_WIDE_INT) (-1)
-			      << GET_MODE_BITSIZE (GET_MODE (x))));
+	      && val_signbit_known_set_p (GET_MODE (x), INTVAL (src)))
+	    src = GEN_INT (INTVAL (src) | ~GET_MODE_MASK (GET_MODE (x)));
 #endif
 
 	  /* Don't call nonzero_bits if it cannot change anything.  */
@@ -5887,8 +5883,7 @@ combine_simplify_rtx (rtx x, enum machine_mode op0_mode, int in_dest,
 	     going to test the sign bit.  */
 	  if (new_code == NE && GET_MODE_CLASS (mode) == MODE_INT
 	      && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
-	      && ((STORE_FLAG_VALUE & GET_MODE_MASK (mode))
-		  == (unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1))
+	      && val_signbit_p (mode, STORE_FLAG_VALUE)
 	      && op1 == const0_rtx
 	      && mode == GET_MODE (op0)
 	      && (i = exact_log2 (nonzero_bits (op0, mode))) >= 0)
@@ -6551,10 +6546,8 @@ simplify_set (rtx x)
       enum machine_mode inner_mode = GET_MODE (inner);
 
       /* Here we make sure that we don't have a sign bit on.  */
-      if (GET_MODE_BITSIZE (inner_mode) <= HOST_BITS_PER_WIDE_INT
-	  && (nonzero_bits (inner, inner_mode)
-	      < ((unsigned HOST_WIDE_INT) 1
-		 << (GET_MODE_BITSIZE (GET_MODE (src)) - 1))))
+      if (val_signbit_known_clear_p (GET_MODE (src),
+				     nonzero_bits (inner, inner_mode)))
 	{
 	  SUBST (SET_SRC (x), inner);
 	  src = SET_SRC (x);
@@ -8445,9 +8438,7 @@ force_to_mode (rtx x, enum machine_mode mode, unsigned HOST_WIDE_INT mask,
     case ASHIFTRT:
       /* If we are just looking for the sign bit, we don't need this shift at
 	 all, even if it has a variable count.  */
-      if (GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT
-	  && (mask == ((unsigned HOST_WIDE_INT) 1
-		       << (GET_MODE_BITSIZE (GET_MODE (x)) - 1))))
+      if (val_signbit_p (GET_MODE (x), mask))
 	return force_to_mode (XEXP (x, 0), mode, mask, next_select);
 
       /* If this is a shift by a constant, get a mask that contains those bits
@@ -9589,15 +9580,11 @@ reg_nonzero_bits_for_combine (const_rtx x, enum machine_mode mode,
 	 ??? For 2.5, try to tighten up the MD files in this regard
 	 instead of this kludge.  */
 
-      if (GET_MODE_BITSIZE (GET_MODE (x)) < GET_MODE_BITSIZE (mode)
+      if (GET_MODE_PRECISION (GET_MODE (x)) < GET_MODE_PRECISION (mode)
 	  && CONST_INT_P (tem)
 	  && INTVAL (tem) > 0
-	  && 0 != (UINTVAL (tem)
-		   & ((unsigned HOST_WIDE_INT) 1
-		      << (GET_MODE_BITSIZE (GET_MODE (x)) - 1))))
-	tem = GEN_INT (UINTVAL (tem)
-		       | ((unsigned HOST_WIDE_INT) (-1)
-			  << GET_MODE_BITSIZE (GET_MODE (x))));
+	  && val_signbit_known_set_p (GET_MODE (x), INTVAL (tem)))
+	tem = GEN_INT (INTVAL (tem) | ~GET_MODE_MASK (GET_MODE (x)));
 #endif
       return tem;
     }
@@ -9987,11 +9974,9 @@ simplify_shift_const_1 (enum rtx_code code, enum machine_mode result_mode,
 	 ASHIFTRT to LSHIFTRT if we know the sign bit is clear.
 	 `make_compound_operation' will convert it to an ASHIFTRT for
 	 those machines (such as VAX) that don't have an LSHIFTRT.  */
-      if (GET_MODE_BITSIZE (shift_mode) <= HOST_BITS_PER_WIDE_INT
-	  && code == ASHIFTRT
-	  && ((nonzero_bits (varop, shift_mode)
-	       & ((unsigned HOST_WIDE_INT) 1
-		  << (GET_MODE_BITSIZE (shift_mode) - 1))) == 0))
+      if (code == ASHIFTRT
+	  && val_signbit_known_clear_p (shift_mode,
+					nonzero_bits (varop, shift_mode)))
 	code = LSHIFTRT;
 
       if (((code == LSHIFTRT
@@ -11424,10 +11409,7 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
 	  mode = GET_MODE (XEXP (op0, 0));
 	  if (mode != VOIDmode && GET_MODE_CLASS (mode) == MODE_INT
 	      && ! unsigned_comparison_p
-	      && (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
-	      && ((unsigned HOST_WIDE_INT) const_op
-		  < (((unsigned HOST_WIDE_INT) 1
-		      << (GET_MODE_BITSIZE (mode) - 1))))
+	      && val_signbit_known_clear_p (mode, const_op)
 	      && have_insn_for (COMPARE, mode))
 	    {
 	      op0 = XEXP (op0, 0);
@@ -11614,11 +11596,7 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
 	  /* Check for the cases where we simply want the result of the
 	     earlier test or the opposite of that result.  */
 	  if (code == NE || code == EQ
-	      || (GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT
-		  && GET_MODE_CLASS (GET_MODE (op0)) == MODE_INT
-		  && (STORE_FLAG_VALUE
-		      & (((unsigned HOST_WIDE_INT) 1
-			  << (GET_MODE_BITSIZE (GET_MODE (op0)) - 1))))
+	      || (val_signbit_known_set_p (GET_MODE (op0), STORE_FLAG_VALUE)
 		  && (code == LT || code == GE)))
 	    {
 	      enum rtx_code new_code;
diff --git a/gcc/cse.c b/gcc/cse.c
index 8a31cd1..9dc27c3 100644
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -3063,12 +3063,8 @@ find_comparison_args (enum rtx_code code, rtx *parg1, rtx *parg2,
 		 for STORE_FLAG_VALUE, also look at LT and GE operations.  */
 	      || ((code == NE
 		   || (code == LT
-		       && GET_MODE_CLASS (inner_mode) == MODE_INT
-		       && (GET_MODE_BITSIZE (inner_mode)
-			   <= HOST_BITS_PER_WIDE_INT)
-		       && (STORE_FLAG_VALUE
-			   & ((HOST_WIDE_INT) 1
-			      << (GET_MODE_BITSIZE (inner_mode) - 1))))
+		       && val_signbit_known_set_p (inner_mode,
+						   STORE_FLAG_VALUE))
 #ifdef FLOAT_STORE_FLAG_VALUE
 		   || (code == LT
 		       && SCALAR_FLOAT_MODE_P (inner_mode)
@@ -3083,12 +3079,8 @@ find_comparison_args (enum rtx_code code, rtx *parg1, rtx *parg2,
 	    }
 	  else if ((code == EQ
 		    || (code == GE
-			&& GET_MODE_CLASS (inner_mode) == MODE_INT
-			&& (GET_MODE_BITSIZE (inner_mode)
-			    <= HOST_BITS_PER_WIDE_INT)
-			&& (STORE_FLAG_VALUE
-			    & ((HOST_WIDE_INT) 1
-			       << (GET_MODE_BITSIZE (inner_mode) - 1))))
+			&& val_signbit_known_set_p (inner_mode,
+						    STORE_FLAG_VALUE))
 #ifdef FLOAT_STORE_FLAG_VALUE
 		    || (code == GE
 			&& SCALAR_FLOAT_MODE_P (inner_mode)
diff --git a/gcc/expmed.c b/gcc/expmed.c
index 314fac7..e9b6016 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -5039,10 +5039,8 @@ emit_cstore (rtx target, enum insn_code icode, enum rtx_code code,
   if (GET_MODE_SIZE (target_mode) > GET_MODE_SIZE (result_mode))
     {
       convert_move (target, subtarget,
-		    (GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT)
-		    && 0 == (STORE_FLAG_VALUE
-			     & ((HOST_WIDE_INT) 1
-				<< (GET_MODE_BITSIZE (result_mode) -1))));
+		    val_signbit_known_clear_p (result_mode,
+					       STORE_FLAG_VALUE));
       op0 = target;
       result_mode = target_mode;
     }
@@ -5066,9 +5064,7 @@ emit_cstore (rtx target, enum insn_code icode, enum rtx_code code,
   /* We don't want to use STORE_FLAG_VALUE < 0 below since this makes
      it hard to use a value of just the sign bit due to ANSI integer
      constant typing rules.  */
-  else if (GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT
-	   && (STORE_FLAG_VALUE
-	       & ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (result_mode) - 1))))
+  else if (val_signbit_known_set_p (result_mode, STORE_FLAG_VALUE))
     op0 = expand_shift (RSHIFT_EXPR, result_mode, op0,
 			GET_MODE_BITSIZE (result_mode) - 1, subtarget,
 			normalizep == 1);
@@ -5206,9 +5202,9 @@ emit_store_flag_1 (rtx target, enum rtx_code code, rtx op0, rtx op1,
 	    target = gen_reg_rtx (target_mode);
 
 	  convert_move (target, tem,
-			0 == ((normalizep ? normalizep : STORE_FLAG_VALUE)
-			      & ((HOST_WIDE_INT) 1
-				 << (GET_MODE_BITSIZE (word_mode) -1))));
+			!val_signbit_known_set_p (word_mode,
+						  (normalizep ? normalizep
+						   : STORE_FLAG_VALUE)));
 	  return target;
 	}
     }
@@ -5218,10 +5214,7 @@ emit_store_flag_1 (rtx target, enum rtx_code code, rtx op0, rtx op1,
   if (op1 == const0_rtx && (code == LT || code == GE)
       && GET_MODE_CLASS (mode) == MODE_INT
       && (normalizep || STORE_FLAG_VALUE == 1
-	  || (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
-	      && ((STORE_FLAG_VALUE & GET_MODE_MASK (mode))
-		  == ((unsigned HOST_WIDE_INT) 1
-		      << (GET_MODE_BITSIZE (mode) - 1))))))
+	  || val_signbit_p (mode, STORE_FLAG_VALUE)))
     {
       subtarget = target;
 
@@ -5330,9 +5323,7 @@ emit_store_flag (rtx target, enum rtx_code code, rtx op0, rtx op1,
       if (STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1)
 	normalizep = STORE_FLAG_VALUE;
 
-      else if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
-	       && ((STORE_FLAG_VALUE & GET_MODE_MASK (mode))
-		   == (unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1)))
+      else if (val_signbit_p (mode, STORE_FLAG_VALUE))
 	;
       else
 	return 0;
diff --git a/gcc/expr.c b/gcc/expr.c
index 176978a..e225d24 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -764,14 +764,13 @@ convert_modes (enum machine_mode mode, enum machine_mode oldmode, rtx x, int uns
 	  && GET_MODE_SIZE (mode) > GET_MODE_SIZE (oldmode))
 	{
 	  HOST_WIDE_INT val = INTVAL (x);
-	  int width = GET_MODE_BITSIZE (oldmode);
 
 	  /* We must sign or zero-extend in this case.  Start by
 	     zero-extending, then sign extend if we need to.  */
-	  val &= ((HOST_WIDE_INT) 1 << width) - 1;
+	  val &= GET_MODE_MASK (oldmode);
 	  if (! unsignedp
-	      && (val & ((HOST_WIDE_INT) 1 << (width - 1))))
-	    val |= (HOST_WIDE_INT) (-1) << width;
+	      && val_signbit_known_set_p (oldmode, val))
+	    val |= ~GET_MODE_MASK (oldmode);
 
 	  return gen_int_mode (val, mode);
 	}
diff --git a/gcc/rtl.h b/gcc/rtl.h
index da18788..2f2aaca 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -1816,6 +1816,11 @@ extern rtx simplify_rtx (const_rtx);
 extern rtx avoid_constant_pool_reference (rtx);
 extern rtx delegitimize_mem_from_attrs (rtx);
 extern bool mode_signbit_p (enum machine_mode, const_rtx);
+extern bool val_signbit_p (enum machine_mode, unsigned HOST_WIDE_INT);
+extern bool val_signbit_known_set_p (enum machine_mode,
+				     unsigned HOST_WIDE_INT);
+extern bool val_signbit_known_clear_p (enum machine_mode,
+				       unsigned HOST_WIDE_INT);
 
 /* In reginfo.c  */
 extern enum machine_mode choose_hard_reg_mode (unsigned int, unsigned int,
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index 0be6504..9ac347e 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -3849,6 +3849,7 @@ nonzero_bits1 (const_rtx x, enum machine_mode mode, const_rtx known_x,
   unsigned HOST_WIDE_INT nonzero = GET_MODE_MASK (mode);
   unsigned HOST_WIDE_INT inner_nz;
   enum rtx_code code;
+  enum machine_mode inner_mode;
   unsigned int mode_width = GET_MODE_BITSIZE (mode);
 
   /* For floating-point and vector values, assume all bits are needed.  */
@@ -4028,9 +4029,7 @@ nonzero_bits1 (const_rtx x, enum machine_mode mode, const_rtx known_x,
       if (GET_MODE (XEXP (x, 0)) != VOIDmode)
 	{
 	  inner_nz &= GET_MODE_MASK (GET_MODE (XEXP (x, 0)));
-	  if (inner_nz
-	      & (((unsigned HOST_WIDE_INT) 1
-		  << (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) - 1))))
+	  if (val_signbit_known_set_p (GET_MODE (XEXP (x, 0)), inner_nz))
 	    inner_nz |= (GET_MODE_MASK (mode)
 			 & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0))));
 	}
@@ -4153,12 +4152,12 @@ nonzero_bits1 (const_rtx x, enum machine_mode mode, const_rtx known_x,
 		  & cached_nonzero_bits (SUBREG_REG (x), GET_MODE (x),
 					 known_x, known_mode, known_ret);
 
+      inner_mode = GET_MODE (SUBREG_REG (x));
       /* If the inner mode is a single word for both the host and target
 	 machines, we can compute this from which bits of the inner
 	 object might be nonzero.  */
-      if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) <= BITS_PER_WORD
-	  && (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x)))
-	      <= HOST_BITS_PER_WIDE_INT))
+      if (GET_MODE_BITSIZE (inner_mode) <= BITS_PER_WORD
+	  && (GET_MODE_BITSIZE (inner_mode) <= HOST_BITS_PER_WIDE_INT))
 	{
 	  nonzero &= cached_nonzero_bits (SUBREG_REG (x), mode,
 					  known_x, known_mode, known_ret);
@@ -4166,12 +4165,9 @@ nonzero_bits1 (const_rtx x, enum machine_mode mode, const_rtx known_x,
 #if defined (WORD_REGISTER_OPERATIONS) && defined (LOAD_EXTEND_OP)
 	  /* If this is a typical RISC machine, we only have to worry
 	     about the way loads are extended.  */
-	  if ((LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (x))) == SIGN_EXTEND
-	       ? (((nonzero
-		    & (((unsigned HOST_WIDE_INT) 1
-			<< (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) - 1))))
-		   != 0))
-	       : LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (x))) != ZERO_EXTEND)
+	  if ((LOAD_EXTEND_OP (inner_mode) == SIGN_EXTEND
+	       ? val_signbit_known_set_p (inner_mode, nonzero)
+	       : LOAD_EXTEND_OP (inner_mode) != ZERO_EXTEND)
 	      || !MEM_P (SUBREG_REG (x)))
 #endif
 	    {
@@ -4179,9 +4175,9 @@ nonzero_bits1 (const_rtx x, enum machine_mode mode, const_rtx known_x,
 		 causes the high-order bits to become undefined.  So they are
 		 not known to be zero.  */
 	      if (GET_MODE_SIZE (GET_MODE (x))
-		  > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
+		  > GET_MODE_SIZE (inner_mode))
 		nonzero |= (GET_MODE_MASK (GET_MODE (x))
-			    & ~GET_MODE_MASK (GET_MODE (SUBREG_REG (x))));
+			    & ~GET_MODE_MASK (inner_mode));
 	    }
 	}
       break;
@@ -4921,12 +4917,8 @@ canonicalize_condition (rtx insn, rtx cond, int reverse, rtx *earliest,
 	  if ((GET_CODE (SET_SRC (set)) == COMPARE
 	       || (((code == NE
 		     || (code == LT
-			 && GET_MODE_CLASS (inner_mode) == MODE_INT
-			 && (GET_MODE_BITSIZE (inner_mode)
-			     <= HOST_BITS_PER_WIDE_INT)
-			 && (STORE_FLAG_VALUE
-			     & ((unsigned HOST_WIDE_INT) 1
-				<< (GET_MODE_BITSIZE (inner_mode) - 1))))
+			 && val_signbit_known_set_p (inner_mode,
+						     STORE_FLAG_VALUE))
 #ifdef FLOAT_STORE_FLAG_VALUE
 		     || (code == LT
 			 && SCALAR_FLOAT_MODE_P (inner_mode)
@@ -4941,12 +4933,8 @@ canonicalize_condition (rtx insn, rtx cond, int reverse, rtx *earliest,
 	    x = SET_SRC (set);
 	  else if (((code == EQ
 		     || (code == GE
-			 && (GET_MODE_BITSIZE (inner_mode)
-			     <= HOST_BITS_PER_WIDE_INT)
-			 && GET_MODE_CLASS (inner_mode) == MODE_INT
-			 && (STORE_FLAG_VALUE
-			     & ((unsigned HOST_WIDE_INT) 1
-				<< (GET_MODE_BITSIZE (inner_mode) - 1))))
+			 && val_signbit_known_set_p (inner_mode,
+						     STORE_FLAG_VALUE))
 #ifdef FLOAT_STORE_FLAG_VALUE
 		     || (code == GE
 			 && SCALAR_FLOAT_MODE_P (inner_mode)
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index f7669b1..6a5ec1a 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -82,7 +82,7 @@ mode_signbit_p (enum machine_mode mode, const_rtx x)
   if (GET_MODE_CLASS (mode) != MODE_INT)
     return false;
 
-  width = GET_MODE_BITSIZE (mode);
+  width = GET_MODE_PRECISION (mode);
   if (width == 0)
     return false;
 
@@ -103,6 +103,62 @@ mode_signbit_p (enum machine_mode mode, const_rtx x)
     val &= ((unsigned HOST_WIDE_INT) 1 << width) - 1;
   return val == ((unsigned HOST_WIDE_INT) 1 << (width - 1));
 }
+
+/* Test whether VAL is equal to the most significant bit of mode MODE
+   (after masking with the mode mask of MODE).  Returns false if the
+   precision of MODE is too large to handle.  */
+
+bool
+val_signbit_p (enum machine_mode mode, unsigned HOST_WIDE_INT val)
+{
+  unsigned int width;
+
+  if (GET_MODE_CLASS (mode) != MODE_INT)
+    return false;
+
+  width = GET_MODE_PRECISION (mode);
+  if (width == 0 || width > HOST_BITS_PER_WIDE_INT)
+    return false;
+
+  val &= GET_MODE_MASK (mode);
+  return val == ((unsigned HOST_WIDE_INT) 1 << (width - 1));
+}
+
+/* Test whether the most significant bit of mode MODE is set in VAL.
+   Returns false if the precision of MODE is too large to handle.  */
+bool
+val_signbit_known_set_p (enum machine_mode mode, unsigned HOST_WIDE_INT val)
+{
+  unsigned int width;
+
+  if (GET_MODE_CLASS (mode) != MODE_INT)
+    return false;
+
+  width = GET_MODE_PRECISION (mode);
+  if (width == 0 || width > HOST_BITS_PER_WIDE_INT)
+    return false;
+
+  val &= (unsigned HOST_WIDE_INT) 1 << (width - 1);
+  return val != 0;
+}
+
+/* Test whether the most significant bit of mode MODE is clear in VAL.
+   Returns false if the precision of MODE is too large to handle.  */
+bool
+val_signbit_known_clear_p (enum machine_mode mode, unsigned HOST_WIDE_INT val)
+{
+  unsigned int width;
+
+  if (GET_MODE_CLASS (mode) != MODE_INT)
+    return false;
+
+  width = GET_MODE_PRECISION (mode);
+  if (width == 0 || width > HOST_BITS_PER_WIDE_INT)
+    return false;
+
+  val &= (unsigned HOST_WIDE_INT) 1 << (width - 1);
+  return val == 0;
+}
 
 /* Make a binary operation by properly ordering the operands and
    seeing if the expression folds.  */
@@ -908,12 +964,8 @@ simplify_unary_operation_1 (enum rtx_code code, enum machine_mode mode, rtx op)
 
       /* If operand is something known to be positive, ignore the ABS.  */
       if (GET_CODE (op) == FFS || GET_CODE (op) == ABS
-	  || ((GET_MODE_BITSIZE (GET_MODE (op))
-	       <= HOST_BITS_PER_WIDE_INT)
-	      && ((nonzero_bits (op, GET_MODE (op))
-		   & ((unsigned HOST_WIDE_INT) 1
-		      << (GET_MODE_BITSIZE (GET_MODE (op)) - 1)))
-		  == 0)))
+	  || val_signbit_known_clear_p (GET_MODE (op),
+					nonzero_bits (op, GET_MODE (op))))
 	return op;
 
       /* If operand is known to be only -1 or 0, convert ABS to NEG.  */
@@ -1425,8 +1477,7 @@ simplify_const_unary_operation (enum rtx_code code, enum machine_mode mode,
 	      val = arg0;
 	    }
 	  else if (GET_MODE_BITSIZE (op_mode) < HOST_BITS_PER_WIDE_INT)
-	    val = arg0 & ~((unsigned HOST_WIDE_INT) (-1)
-			   << GET_MODE_BITSIZE (op_mode));
+	    val = arg0 & GET_MODE_MASK (op_mode);
 	  else
 	    return 0;
 	  break;
@@ -1444,13 +1495,9 @@ simplify_const_unary_operation (enum rtx_code code, enum machine_mode mode,
 	    }
 	  else if (GET_MODE_BITSIZE (op_mode) < HOST_BITS_PER_WIDE_INT)
 	    {
-	      val
-		= arg0 & ~((unsigned HOST_WIDE_INT) (-1)
-			   << GET_MODE_BITSIZE (op_mode));
-	      if (val & ((unsigned HOST_WIDE_INT) 1
-			 << (GET_MODE_BITSIZE (op_mode) - 1)))
-		val
-		  -= (unsigned HOST_WIDE_INT) 1 << GET_MODE_BITSIZE (op_mode);
+	      val = arg0 & GET_MODE_MASK (op_mode);
+	      if (val_signbit_known_set_p (op_mode, val))
+		val |= ~GET_MODE_MASK (op_mode);
 	    }
 	  else
 	    return 0;
@@ -1602,10 +1649,8 @@ simplify_const_unary_operation (enum rtx_code code, enum machine_mode mode,
 	  else
 	    {
 	      lv = l1 & GET_MODE_MASK (op_mode);
-	      if (GET_MODE_BITSIZE (op_mode) < HOST_BITS_PER_WIDE_INT
-		  && (lv & ((unsigned HOST_WIDE_INT) 1
-			    << (GET_MODE_BITSIZE (op_mode) - 1))) != 0)
-		lv -= (unsigned HOST_WIDE_INT) 1 << GET_MODE_BITSIZE (op_mode);
+	      if (val_signbit_known_set_p (op_mode, lv))
+		lv |= ~GET_MODE_MASK (op_mode);
 
 	      hv = HWI_SIGN_EXTEND (lv);
 	    }
@@ -2663,9 +2708,7 @@ simplify_binary_operation_1 (enum rtx_code code, enum machine_mode mode,
 
       /* (xor (comparison foo bar) (const_int sign-bit))
 	 when STORE_FLAG_VALUE is the sign bit.  */
-      if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
-	  && ((STORE_FLAG_VALUE & GET_MODE_MASK (mode))
-	      == (unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1))
+      if (val_signbit_p (mode, STORE_FLAG_VALUE)
 	  && trueop1 == const_true_rtx
 	  && COMPARISON_P (op0)
 	  && (reversed = reversed_comparison (op0, mode)))
@@ -3028,8 +3071,7 @@ simplify_binary_operation_1 (enum rtx_code code, enum machine_mode mode,
 
     case SMIN:
       if (width <= HOST_BITS_PER_WIDE_INT
-	  && CONST_INT_P (trueop1)
-	  && UINTVAL (trueop1) == (unsigned HOST_WIDE_INT) 1 << (width -1)
+	  && mode_signbit_p (mode, trueop1)
 	  && ! side_effects_p (op0))
 	return op1;
       if (rtx_equal_p (trueop0, trueop1) && ! side_effects_p (op0))
@@ -3634,16 +3676,16 @@ simplify_const_binary_operation (enum rtx_code code, enum machine_mode mode,
 
       if (width < HOST_BITS_PER_WIDE_INT)
         {
-          arg0 &= ((unsigned HOST_WIDE_INT) 1 << width) - 1;
-          arg1 &= ((unsigned HOST_WIDE_INT) 1 << width) - 1;
+          arg0 &= GET_MODE_MASK (mode);
+          arg1 &= GET_MODE_MASK (mode);
 
           arg0s = arg0;
-          if (arg0s & ((unsigned HOST_WIDE_INT) 1 << (width - 1)))
-	    arg0s |= ((unsigned HOST_WIDE_INT) (-1) << width);
+	  if (val_signbit_known_set_p (mode, arg0s))
+	    arg0s |= ~GET_MODE_MASK (mode);
 
-	  arg1s = arg1;
-	  if (arg1s & ((unsigned HOST_WIDE_INT) 1 << (width - 1)))
-	    arg1s |= ((unsigned HOST_WIDE_INT) (-1) << width);
+          arg1s = arg1;
+	  if (val_signbit_known_set_p (mode, arg1s))
+	    arg1s |= ~GET_MODE_MASK (mode);
 	}
       else
 	{
@@ -4616,14 +4658,14 @@ simplify_const_relational_operation (enum rtx_code code,
 	 we have to sign or zero-extend the values.  */
       if (width != 0 && width < HOST_BITS_PER_WIDE_INT)
 	{
-	  l0u &= ((unsigned HOST_WIDE_INT) 1 << width) - 1;
-	  l1u &= ((unsigned HOST_WIDE_INT) 1 << width) - 1;
+	  l0u &= GET_MODE_MASK (mode);
+	  l1u &= GET_MODE_MASK (mode);
 
-	  if (l0s & ((unsigned HOST_WIDE_INT) 1 << (width - 1)))
-	    l0s |= ((unsigned HOST_WIDE_INT) (-1) << width);
+	  if (val_signbit_known_set_p (mode, l0s))
+	    l0s |= ~GET_MODE_MASK (mode);
 
-	  if (l1s & ((unsigned HOST_WIDE_INT) 1 << (width - 1)))
-	    l1s |= ((unsigned HOST_WIDE_INT) (-1) << width);
+	  if (val_signbit_known_set_p (mode, l1s))
+	    l1s |= ~GET_MODE_MASK (mode);
 	}
       if (width != 0 && width <= HOST_BITS_PER_WIDE_INT)
 	h0u = h1u = 0, h0s = HWI_SIGN_EXTEND (l0s), h1s = HWI_SIGN_EXTEND (l1s);