Re: Move some bit and binary optimizations in simplify and match

["Hurugalawadi, Naveen" <Naveen dot Hurugalawadi at caviumnetworks dot com>]

Hi Richard,

Thanks for the comments. Sorry, I was confused with handling the const and variable 
together part. Have modified them.
Also, considered that both (X & Y) can be const or variable in those cases
for which match patterns have been added.
Please let me know whether its correct or only "Y" should be both const and variable
whereas the "X" should be variable always.

Please find attached the patch as per your comments.
Please review the patch and let me know if any further modifications 
are required.

Am learning lots of useful stuff while porting these patches. 
Thanks for all the help again.

>> Looks like I really need to make 'match' handle these kind of things.
I assume that its for bit ops, and binary operations like (A & B) and so on.
Should I try doing that part? Also, how do we know which patterns should
be const or variable or supports both?

Thanks,
Naveen

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index de45a2c..2d81b2c 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -9232,26 +9232,6 @@ fold_binary_loc (location_t loc,
       return NULL_TREE;
 
     case PLUS_EXPR:
-      if (INTEGRAL_TYPE_P (type) || VECTOR_INTEGER_TYPE_P (type))
-	{
-	  /* X + (X / CST) * -CST is X % CST.  */
-	  if (TREE_CODE (arg1) == MULT_EXPR
-	      && TREE_CODE (TREE_OPERAND (arg1, 0)) == TRUNC_DIV_EXPR
-	      && operand_equal_p (arg0,
-				  TREE_OPERAND (TREE_OPERAND (arg1, 0), 0), 0))
-	    {
-	      tree cst0 = TREE_OPERAND (TREE_OPERAND (arg1, 0), 1);
-	      tree cst1 = TREE_OPERAND (arg1, 1);
-	      tree sum = fold_binary_loc (loc, PLUS_EXPR, TREE_TYPE (cst1),
-				      cst1, cst0);
-	      if (sum && integer_zerop (sum))
-		return fold_convert_loc (loc, type,
-					 fold_build2_loc (loc, TRUNC_MOD_EXPR,
-						      TREE_TYPE (arg0), arg0,
-						      cst0));
-	    }
-	}
-
       /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
 	 one.  Make sure the type is not saturating and has the signedness of
 	 the stripped operands, as fold_plusminus_mult_expr will re-associate.
@@ -9692,28 +9672,6 @@ fold_binary_loc (location_t loc,
 			    fold_convert_loc (loc, type,
 					      TREE_OPERAND (arg0, 0)));
 
-      if (! FLOAT_TYPE_P (type))
-	{
-	  /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
-	     any power of 2 minus 1.  */
-	  if (TREE_CODE (arg0) == BIT_AND_EXPR
-	      && TREE_CODE (arg1) == BIT_AND_EXPR
-	      && operand_equal_p (TREE_OPERAND (arg0, 0),
-				  TREE_OPERAND (arg1, 0), 0))
-	    {
-	      tree mask0 = TREE_OPERAND (arg0, 1);
-	      tree mask1 = TREE_OPERAND (arg1, 1);
-	      tree tem = fold_build1_loc (loc, BIT_NOT_EXPR, type, mask0);
-
-	      if (operand_equal_p (tem, mask1, 0))
-		{
-		  tem = fold_build2_loc (loc, BIT_XOR_EXPR, type,
-				     TREE_OPERAND (arg0, 0), mask1);
-		  return fold_build2_loc (loc, MINUS_EXPR, type, tem, mask1);
-		}
-	    }
-	}
-
       /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
 	 __complex__ ( x, -y ).  This is not the same for SNaNs or if
 	 signed zeros are involved.  */
@@ -9803,20 +9761,6 @@ fold_binary_loc (location_t loc,
       goto associate;
 
     case MULT_EXPR:
-      /* (-A) * (-B) -> A * B  */
-      if (TREE_CODE (arg0) == NEGATE_EXPR && negate_expr_p (arg1))
-	return fold_build2_loc (loc, MULT_EXPR, type,
-			    fold_convert_loc (loc, type,
-					      TREE_OPERAND (arg0, 0)),
-			    fold_convert_loc (loc, type,
-					      negate_expr (arg1)));
-      if (TREE_CODE (arg1) == NEGATE_EXPR && negate_expr_p (arg0))
-	return fold_build2_loc (loc, MULT_EXPR, type,
-			    fold_convert_loc (loc, type,
-					      negate_expr (arg0)),
-			    fold_convert_loc (loc, type,
-					      TREE_OPERAND (arg1, 0)));
-
       if (! FLOAT_TYPE_P (type))
 	{
 	  /* Transform x * -C into -x * C if x is easily negatable.  */
@@ -9830,16 +9774,6 @@ fold_binary_loc (location_t loc,
 						  negate_expr (arg0)),
 				tem);
 
-	  /* (a * (1 << b)) is (a << b)  */
-	  if (TREE_CODE (arg1) == LSHIFT_EXPR
-	      && integer_onep (TREE_OPERAND (arg1, 0)))
-	    return fold_build2_loc (loc, LSHIFT_EXPR, type, op0,
-				TREE_OPERAND (arg1, 1));
-	  if (TREE_CODE (arg0) == LSHIFT_EXPR
-	      && integer_onep (TREE_OPERAND (arg0, 0)))
-	    return fold_build2_loc (loc, LSHIFT_EXPR, type, op1,
-				TREE_OPERAND (arg0, 1));
-
 	  /* (A + A) * C -> A * 2 * C  */
 	  if (TREE_CODE (arg0) == PLUS_EXPR
 	      && TREE_CODE (arg1) == INTEGER_CST
@@ -9882,21 +9816,6 @@ fold_binary_loc (location_t loc,
 	}
       else
 	{
-	  /* Convert (C1/X)*C2 into (C1*C2)/X.  This transformation may change
-             the result for floating point types due to rounding so it is applied
-             only if -fassociative-math was specify.  */
-	  if (flag_associative_math
-	      && TREE_CODE (arg0) == RDIV_EXPR
-	      && TREE_CODE (arg1) == REAL_CST
-	      && TREE_CODE (TREE_OPERAND (arg0, 0)) == REAL_CST)
-	    {
-	      tree tem = const_binop (MULT_EXPR, TREE_OPERAND (arg0, 0),
-				      arg1);
-	      if (tem)
-		return fold_build2_loc (loc, RDIV_EXPR, type, tem,
-				    TREE_OPERAND (arg0, 1));
-	    }
-
           /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y.  */
 	  if (operand_equal_p (arg0, arg1, 0))
 	    {
@@ -10013,28 +9932,6 @@ fold_binary_loc (location_t loc,
 				    arg1);
 	}
 
-      /* (X & ~Y) | (~X & Y) is X ^ Y */
-      if (TREE_CODE (arg0) == BIT_AND_EXPR
-	  && TREE_CODE (arg1) == BIT_AND_EXPR)
-        {
-	  tree a0, a1, l0, l1, n0, n1;
-
-	  a0 = fold_convert_loc (loc, type, TREE_OPERAND (arg1, 0));
-	  a1 = fold_convert_loc (loc, type, TREE_OPERAND (arg1, 1));
-
-	  l0 = fold_convert_loc (loc, type, TREE_OPERAND (arg0, 0));
-	  l1 = fold_convert_loc (loc, type, TREE_OPERAND (arg0, 1));
-	  
-	  n0 = fold_build1_loc (loc, BIT_NOT_EXPR, type, l0);
-	  n1 = fold_build1_loc (loc, BIT_NOT_EXPR, type, l1);
-	  
-	  if ((operand_equal_p (n0, a0, 0)
-	       && operand_equal_p (n1, a1, 0))
-	      || (operand_equal_p (n0, a1, 0)
-		  && operand_equal_p (n1, a0, 0)))
-	    return fold_build2_loc (loc, BIT_XOR_EXPR, type, l0, n1);
-	}
-
       /* See if this can be simplified into a rotate first.  If that
 	 is unsuccessful continue in the association code.  */
       goto bit_rotate;
@@ -10053,22 +9950,6 @@ fold_binary_loc (location_t loc,
       goto bit_rotate;
 
     case BIT_AND_EXPR:
-      /* ~X & X, (X == 0) & X, and !X & X are always zero.  */
-      if ((TREE_CODE (arg0) == BIT_NOT_EXPR
-	   || TREE_CODE (arg0) == TRUTH_NOT_EXPR
-	   || (TREE_CODE (arg0) == EQ_EXPR
-	       && integer_zerop (TREE_OPERAND (arg0, 1))))
-	  && operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0))
-	return omit_one_operand_loc (loc, type, integer_zero_node, arg1);
-
-      /* X & ~X , X & (X == 0), and X & !X are always zero.  */
-      if ((TREE_CODE (arg1) == BIT_NOT_EXPR
-	   || TREE_CODE (arg1) == TRUTH_NOT_EXPR
-	   || (TREE_CODE (arg1) == EQ_EXPR
-	       && integer_zerop (TREE_OPERAND (arg1, 1))))
-	  && operand_equal_p (arg0, TREE_OPERAND (arg1, 0), 0))
-	return omit_one_operand_loc (loc, type, integer_zero_node, arg0);
-
       /* Fold (X ^ 1) & 1 as (X & 1) == 0.  */
       if (TREE_CODE (arg0) == BIT_XOR_EXPR
 	  && INTEGRAL_TYPE_P (type)
diff --git a/gcc/match.pd b/gcc/match.pd
index b02dd03..2d73a05 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -316,6 +316,70 @@ along with GCC; see the file COPYING3.  If not see
   (coss (op @0))
    (coss @0))))
 
+/* Fold X + (X / CST) * -CST to X % CST.  */
+(match (xdivamulminusa @0 @1)
+ (mult (trunc_div @0 @1) (negate @1)))
+(match (xdivamulminusa @0 @1)
+ (mult (trunc_div @0 INTEGER_CST@1) INTEGER_CST@2)
+  (if (wi::add (@1, @2) == 0)))
+
+(simplify
+ (plus (convert? @0) (convert? (xdivamulminusa @0 @1)))
+  (if ((INTEGRAL_TYPE_P (type) || VECTOR_INTEGER_TYPE_P (type))
+	&& tree_nop_conversion_p (type, TREE_TYPE (@0)))
+   (trunc_mod (convert @0) (convert @1))))
+
+(match (abitandnotb @0 @1)
+ (bit_and:c @0 (bit_not @1)))
+(match (abitandnotb @0 @1)
+ (bit_and:c INTEGER_CST@0 (bit_not INTEGER_CST@1)))
+(match (abitandnotb @0 @1)
+ (bit_and:c INTEGER_CST@0 (bit_not @1)))
+(match (abitandnotb @0 @1)
+ (bit_and:c @0 (bit_not INTEGER_CST@1)))
+
+(match (abitandb @0 @1)
+ (bit_and:c @0 @1))
+(match (abitandb @0 @1)
+ (bit_and:c INTEGER_CST@0 INTEGER_CST@1))
+(match (abitandb @0 @1)
+ (bit_and:c INTEGER_CST@0 @1))
+(match (abitandb @0 @1)
+ (bit_and:c @0 INTEGER_CST@1))
+
+/* Fold (A & ~B) - (A & B) into (A ^ B) - B.  */
+(simplify
+ (minus (abitandnotb @0 @1) (abitandb @0 @1))
+  (if (! FLOAT_TYPE_P (type))
+   (minus (bit_xor @0 @1) @1)))
+
+/* Fold (a * (1 << b)) into (a << b)  */
+(simplify
+ (mult:c @0 (convert? (lshift integer_onep@1 @2)))
+  (if (! FLOAT_TYPE_P (type)
+	 && tree_nop_conversion_p (type, TREE_TYPE (@0)))
+   (lshift @0 (convert @2))))
+
+/* Fold (C1/X)*C2 into (C1*C2)/X.  */
+(simplify
+ (mult (rdiv REAL_CST@0 @1) REAL_CST@2)
+  (if (flag_associative_math)
+  (with
+   { tree tem = const_binop (MULT_EXPR, type, @0, @2); }
+  (if (tem)
+   (rdiv { tem; } @1)))))
+
+/* Simplify (X & ~Y) | (~X & Y) is X ^ Y.  */
+(simplify
+ (bit_ior (bit_and:cs @0 (bit_not @1)) (abitandnotb @1 @0))
+  (bit_xor @0 @1))
+
+/* Simplify ~X & X as zero.  */
+(simplify
+ (bit_and:c (convert? @0) (convert? (bit_not @0)))
+  (if (tree_nop_conversion_p (type, TREE_TYPE (@0)))
+  { build_zero_cst (TREE_TYPE (@0)); }))
+
 /* X % Y is smaller than Y.  */
 (for cmp (lt ge)
  (simplify
@@ -535,6 +599,12 @@ along with GCC; see the file COPYING3.  If not see
 (match negate_expr_p
  VECTOR_CST
  (if (FLOAT_TYPE_P (TREE_TYPE (type)) || TYPE_OVERFLOW_WRAPS (type))))
+
+/* (-A) * (-B) -> A * B  */
+(simplify
+ (mult:c (convert? (negate @0)) (convert? negate_expr_p@1))
+  (if (tree_nop_conversion_p (type, TREE_TYPE (@0)))
+   (mult (convert @0) (convert (negate @1)))))
  
 /* -(A + B) -> (-B) - A.  */
 (simplify