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Remove host_integerp tests with variable signedness

From: Richard Sandiford <rdsandiford at googlemail dot com>
To: gcc-patches at gcc dot gnu dot org
Date: Thu, 14 Nov 2013 21:04:34 +0000
Subject: Remove host_integerp tests with variable signedness
Authentication-results: sourceware.org; auth=none

Apart from the case in the C front end, there are 4 calls to host_integerp
with a variable "pos" argument.  These "pos" arguments are all taken from
TYPE_UNSIGNED.  In the dwarf2out.c case we go on to require:

  simple_type_size_in_bits (TREE_TYPE (value)) <= HOST_BITS_PER_WIDE_INT
  || host_integerp (value, 0)

The host_integerp (value, 0) makes the first host_integerp trivially
redundant for !TYPE_UNSIGNED.  Checking that the precision is
<= HOST_BITS_PER_WIDE_INT makes the first host_integerp redundant
for TYPE_UNSIGNED too, since all unsigned types of those precisions
will fit in an unsigned HWI.  We already know that we're dealing with
an INTEGER_CST, so there's no need for a code check either.

vect_recog_divmod_pattern is similar in the sense that we already know
that we have an INTEGER_CST and that we specifically check for precisions
<= HOST_BITS_PER_WIDE_INT.

In the other two cases we don't know whether we're dealing with an
INTEGER_CST but we do check for precisions <= HOST_BITS_PER_WIDE_INT.
So these host_integerps reduce to code tests.  (The precision check
for expand_vector_divmod doesn't show up in the context but is at
the top of the function:

  if (prec > HOST_BITS_PER_WIDE_INT)
    return NULL_TREE;
)

I also replaced the associated tree_low_csts with TREE_INT_CST_LOWs.

Tested on x86_64-linux-gnu.  OK to install?

Thanks,
Richard


gcc/
	* dwarf2out.c (gen_enumeration_type_die): Remove unnecessary
	host_integerp test.
	* tree-vect-patterns.c (vect_recog_divmod_pattern): Likewise.
	Use TREE_INT_CST_LOW rather than tree_low_cst when reading the
	constant.
	* fold-const.c (fold_binary_loc): Replace a host_integerp/tree_low_cst
	pair with a TREE_CODE test and TREE_INT_CST_LOW.
	* tree-vect-generic.c (expand_vector_divmod): Likewise.

Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c	2013-11-14 20:21:27.183058648 +0000
+++ gcc/dwarf2out.c	2013-11-14 20:22:18.128829681 +0000
@@ -17321,9 +17321,8 @@ gen_enumeration_type_die (tree type, dw_
 	  if (TREE_CODE (value) == CONST_DECL)
 	    value = DECL_INITIAL (value);
 
-	  if (host_integerp (value, TYPE_UNSIGNED (TREE_TYPE (value)))
-	      && (simple_type_size_in_bits (TREE_TYPE (value))
-		  <= HOST_BITS_PER_WIDE_INT || host_integerp (value, 0)))
+	  if (simple_type_size_in_bits (TREE_TYPE (value))
+	      <= HOST_BITS_PER_WIDE_INT || host_integerp (value, 0))
 	    /* DWARF2 does not provide a way of indicating whether or
 	       not enumeration constants are signed or unsigned.  GDB
 	       always assumes the values are signed, so we output all
Index: gcc/tree-vect-patterns.c
===================================================================
--- gcc/tree-vect-patterns.c	2013-11-14 20:21:27.183058648 +0000
+++ gcc/tree-vect-patterns.c	2013-11-14 20:22:18.129829676 +0000
@@ -2064,9 +2064,8 @@ vect_recog_divmod_pattern (vec<gimple> *
       return pattern_stmt;
     }
 
-  if (!host_integerp (oprnd1, TYPE_UNSIGNED (itype))
-      || integer_zerop (oprnd1)
-      || prec > HOST_BITS_PER_WIDE_INT)
+  if (prec > HOST_BITS_PER_WIDE_INT
+      || integer_zerop (oprnd1))
     return NULL;
 
   if (!can_mult_highpart_p (TYPE_MODE (vectype), TYPE_UNSIGNED (itype)))
@@ -2078,8 +2077,8 @@ vect_recog_divmod_pattern (vec<gimple> *
     {
       unsigned HOST_WIDE_INT mh, ml;
       int pre_shift, post_shift;
-      unsigned HOST_WIDE_INT d = tree_low_cst (oprnd1, 1)
-				 & GET_MODE_MASK (TYPE_MODE (itype));
+      unsigned HOST_WIDE_INT d = (TREE_INT_CST_LOW (oprnd1)
+				  & GET_MODE_MASK (TYPE_MODE (itype)));
       tree t1, t2, t3, t4;
 
       if (d >= ((unsigned HOST_WIDE_INT) 1 << (prec - 1)))
@@ -2195,7 +2194,7 @@ vect_recog_divmod_pattern (vec<gimple> *
     {
       unsigned HOST_WIDE_INT ml;
       int post_shift;
-      HOST_WIDE_INT d = tree_low_cst (oprnd1, 0);
+      HOST_WIDE_INT d = TREE_INT_CST_LOW (oprnd1);
       unsigned HOST_WIDE_INT abs_d;
       bool add = false;
       tree t1, t2, t3, t4;
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c	2013-11-14 20:21:27.183058648 +0000
+++ gcc/fold-const.c	2013-11-14 20:22:18.124829699 +0000
@@ -12032,16 +12032,15 @@ fold_binary_loc (location_t loc,
 	 if the new mask might be further optimized.  */
       if ((TREE_CODE (arg0) == LSHIFT_EXPR
 	   || TREE_CODE (arg0) == RSHIFT_EXPR)
-	  && host_integerp (TREE_OPERAND (arg0, 1), 1)
-	  && host_integerp (arg1, TYPE_UNSIGNED (TREE_TYPE (arg1)))
-	  && tree_low_cst (TREE_OPERAND (arg0, 1), 1)
-	     < TYPE_PRECISION (TREE_TYPE (arg0))
 	  && TYPE_PRECISION (TREE_TYPE (arg0)) <= HOST_BITS_PER_WIDE_INT
-	  && tree_low_cst (TREE_OPERAND (arg0, 1), 1) > 0)
+	  && TREE_CODE (arg1) == INTEGER_CST
+	  && host_integerp (TREE_OPERAND (arg0, 1), 1)
+	  && tree_low_cst (TREE_OPERAND (arg0, 1), 1) > 0
+	  && (tree_low_cst (TREE_OPERAND (arg0, 1), 1)
+	      < TYPE_PRECISION (TREE_TYPE (arg0))))
 	{
 	  unsigned int shiftc = tree_low_cst (TREE_OPERAND (arg0, 1), 1);
-	  unsigned HOST_WIDE_INT mask
-	    = tree_low_cst (arg1, TYPE_UNSIGNED (TREE_TYPE (arg1)));
+	  unsigned HOST_WIDE_INT mask = TREE_INT_CST_LOW (arg1);
 	  unsigned HOST_WIDE_INT newmask, zerobits = 0;
 	  tree shift_type = TREE_TYPE (arg0);
 
Index: gcc/tree-vect-generic.c
===================================================================
--- gcc/tree-vect-generic.c	2013-11-14 20:21:27.183058648 +0000
+++ gcc/tree-vect-generic.c	2013-11-14 20:22:18.129829676 +0000
@@ -431,7 +431,7 @@ expand_vector_divmod (gimple_stmt_iterat
       tree cst = VECTOR_CST_ELT (op1, i);
       unsigned HOST_WIDE_INT ml;
 
-      if (!host_integerp (cst, unsignedp) || integer_zerop (cst))
+      if (TREE_CODE (cst) != INTEGER_CST || integer_zerop (cst))
 	return NULL_TREE;
       pre_shifts[i] = 0;
       post_shifts[i] = 0;
@@ -452,7 +452,7 @@ expand_vector_divmod (gimple_stmt_iterat
       if (unsignedp)
 	{
 	  unsigned HOST_WIDE_INT mh;
-	  unsigned HOST_WIDE_INT d = tree_low_cst (cst, 1) & mask;
+	  unsigned HOST_WIDE_INT d = TREE_INT_CST_LOW (cst) & mask;
 
 	  if (d >= ((unsigned HOST_WIDE_INT) 1 << (prec - 1)))
 	    /* FIXME: Can transform this into op0 >= op1 ? 1 : 0.  */
@@ -522,7 +522,7 @@ expand_vector_divmod (gimple_stmt_iterat
 	}
       else
 	{
-	  HOST_WIDE_INT d = tree_low_cst (cst, 0);
+	  HOST_WIDE_INT d = TREE_INT_CST_LOW (cst);
 	  unsigned HOST_WIDE_INT abs_d;
 
 	  if (d == -1)

Follow-Ups:
- Re: Remove host_integerp tests with variable signedness
  - From: Richard Biener

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