fold-const.c (fold_div_compare): New function to optimize X/C1 op C2 where op is...

	* fold-const.c (fold_div_compare): New function to optimize X/C1 op C2
	where op is a comparison operator and C1 and C2 are integer constants
	into a range check.
	(fold): Call fold_div_compare.

	* gcc.c-torture/execute/divcmp-1.c: New test case.
	* gcc.c-torture/execute/divcmp-2.c: New test case.
	* gcc.c-torture/execute/divcmp-3.c: New test case.

From-SVN: r81645

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 545eed8..9b395e8 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2004-05-08  Roger Sayle  <roger@eyesopen.com>
+
+       * fold-const.c (fold_div_compare): New function to optimize X/C1 op C2
+       where op is a comparison operator and C1 and C2 are integer constants
+       into a range check.
+       (fold): Call fold_div_compare.
+
 2004-05-08  Eric Botcazou  <ebotcazou@libertysurf.fr>
 
        * doc/install.texi (sparc-sun-solaris2*): Document bootstrap

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 1c2bdf4..7d04db6 100644 (file)
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -109,6 +109,7 @@ static bool fold_real_zero_addition_p (tree, tree, int);
 static tree fold_mathfn_compare (enum built_in_function, enum tree_code,
                                 tree, tree, tree);
 static tree fold_inf_compare (enum tree_code, tree, tree, tree);
+static tree fold_div_compare (enum tree_code, tree, tree, tree);
 static bool reorder_operands_p (tree, tree);
 static bool tree_swap_operands_p (tree, tree, bool);
 
@@ -5215,6 +5216,156 @@ fold_inf_compare (enum tree_code code, tree type, tree arg0, tree arg1)
   return NULL_TREE;
 }
 
+/* Subroutine of fold() that optimizes comparisons of a division by
+   a non-zero integer constant against an integer constant, i.e.
+   X/C1 op C2.
+
+   CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
+   GE_EXPR or LE_EXPR.  TYPE is the type of the result and ARG0 and ARG1
+   are the operands of the comparison.  ARG1 must be a TREE_REAL_CST.
+
+   The function returns the constant folded tree if a simplification
+   can be made, and NULL_TREE otherwise.  */
+
+static tree
+fold_div_compare (enum tree_code code, tree type, tree arg0, tree arg1)
+{
+  tree prod, tmp, hi, lo;
+  tree arg00 = TREE_OPERAND (arg0, 0);
+  tree arg01 = TREE_OPERAND (arg0, 1);
+  unsigned HOST_WIDE_INT lpart;
+  HOST_WIDE_INT hpart;
+  int overflow;
+
+  /* We have to do this the hard way to detect unsigned overflow.
+     prod = int_const_binop (MULT_EXPR, arg01, arg1, 0);  */
+  overflow = mul_double (TREE_INT_CST_LOW (arg01),
+                        TREE_INT_CST_HIGH (arg01),
+                        TREE_INT_CST_LOW (arg1),
+                        TREE_INT_CST_HIGH (arg1), &lpart, &hpart);
+  prod = build_int_2 (lpart, hpart);
+  TREE_TYPE (prod) = TREE_TYPE (arg00);
+  TREE_OVERFLOW (prod) = force_fit_type (prod, overflow)
+                        || TREE_INT_CST_HIGH (prod) != hpart
+                        || TREE_INT_CST_LOW (prod) != lpart;
+  TREE_CONSTANT_OVERFLOW (prod) = TREE_OVERFLOW (prod);
+
+  if (TYPE_UNSIGNED (TREE_TYPE (arg0)))
+    {
+      tmp = int_const_binop (MINUS_EXPR, arg01, integer_one_node, 0);
+      lo = prod;
+
+      /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0).  */
+      overflow = add_double (TREE_INT_CST_LOW (prod),
+                            TREE_INT_CST_HIGH (prod),
+                            TREE_INT_CST_LOW (tmp),
+                            TREE_INT_CST_HIGH (tmp),
+                            &lpart, &hpart);
+      hi = build_int_2 (lpart, hpart);
+      TREE_TYPE (hi) = TREE_TYPE (arg00);
+      TREE_OVERFLOW (hi) = force_fit_type (hi, overflow)
+                          || TREE_INT_CST_HIGH (hi) != hpart
+                          || TREE_INT_CST_LOW (hi) != lpart
+                          || TREE_OVERFLOW (prod);
+      TREE_CONSTANT_OVERFLOW (hi) = TREE_OVERFLOW (hi);
+    }
+  else if (tree_int_cst_sgn (arg01) >= 0)
+    {
+      tmp = int_const_binop (MINUS_EXPR, arg01, integer_one_node, 0);
+      switch (tree_int_cst_sgn (arg1))
+       {
+       case -1:
+         lo = int_const_binop (MINUS_EXPR, prod, tmp, 0);
+         hi = prod;
+         break;
+
+       case  0:
+         lo = fold_negate_const (tmp, TREE_TYPE (arg0));
+         hi = tmp;
+         break;
+
+       case  1:
+          hi = int_const_binop (PLUS_EXPR, prod, tmp, 0);
+         lo = prod;
+         break;
+
+       default:
+         abort ();
+       }
+    }
+  else
+    {
+      tmp = int_const_binop (PLUS_EXPR, arg01, integer_one_node, 0);
+      switch (tree_int_cst_sgn (arg1))
+       {
+       case -1:
+         hi = int_const_binop (MINUS_EXPR, prod, tmp, 0);
+         lo = prod;
+         break;
+
+       case  0:
+         hi = fold_negate_const (tmp, TREE_TYPE (arg0));
+         lo = tmp;
+         break;
+
+       case  1:
+          lo = int_const_binop (PLUS_EXPR, prod, tmp, 0);
+         hi = prod;
+         break;
+
+       default:
+         abort ();
+       }
+    }
+
+  switch (code)
+    {
+    case EQ_EXPR:
+      if (TREE_OVERFLOW (lo) && TREE_OVERFLOW (hi))
+       return omit_one_operand (type, integer_zero_node, arg00);
+      if (TREE_OVERFLOW (hi))
+       return fold (build2 (GE_EXPR, type, arg00, lo));
+      if (TREE_OVERFLOW (lo))
+       return fold (build2 (LE_EXPR, type, arg00, hi));
+      return build_range_check (type, arg00, 1, lo, hi);
+
+    case NE_EXPR:
+      if (TREE_OVERFLOW (lo) && TREE_OVERFLOW (hi))
+       return omit_one_operand (type, integer_one_node, arg00);
+      if (TREE_OVERFLOW (hi))
+       return fold (build2 (LT_EXPR, type, arg00, lo));
+      if (TREE_OVERFLOW (lo))
+       return fold (build2 (GT_EXPR, type, arg00, hi));
+      return build_range_check (type, arg00, 0, lo, hi);
+
+    case LT_EXPR:
+      if (TREE_OVERFLOW (lo))
+       return omit_one_operand (type, integer_zero_node, arg00);
+      return fold (build2 (LT_EXPR, type, arg00, lo));
+
+    case LE_EXPR:
+      if (TREE_OVERFLOW (hi))
+       return omit_one_operand (type, integer_one_node, arg00);
+      return fold (build2 (LE_EXPR, type, arg00, hi));
+
+    case GT_EXPR:
+      if (TREE_OVERFLOW (hi))
+       return omit_one_operand (type, integer_zero_node, arg00);
+      return fold (build2 (GT_EXPR, type, arg00, hi));
+
+    case GE_EXPR:
+      if (TREE_OVERFLOW (lo))
+       return omit_one_operand (type, integer_one_node, arg00);
+      return fold (build2 (GE_EXPR, type, arg00, lo));
+
+    default:
+      break;
+    }
+
+  return NULL_TREE;
+}
+
+
 /* If CODE with arguments ARG0 and ARG1 represents a single bit
    equality/inequality test, then return a simplified form of
    the test using shifts and logical operations.  Otherwise return
@@ -7902,6 +8053,20 @@ fold (tree expr)
                                integer_zero_node));
        }
 
+      /* We can fold X/C1 op C2 where C1 and C2 are integer constants
+        into a single range test.  */
+      if (TREE_CODE (arg0) == TRUNC_DIV_EXPR
+         && TREE_CODE (arg1) == INTEGER_CST
+         && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST
+         && !integer_zerop (TREE_OPERAND (arg0, 1))
+         && !TREE_OVERFLOW (TREE_OPERAND (arg0, 1))
+         && !TREE_OVERFLOW (arg1))
+       {
+         t1 = fold_div_compare (code, type, arg0, arg1);
+         if (t1 != NULL_TREE)
+           return t1;
+       }
+
       /* Both ARG0 and ARG1 are known to be constants at this point.  */
       t1 = fold_relational_const (code, type, arg0, arg1);
       return (t1 == NULL_TREE ? t : t1);

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index cb5a6b8..09ca29a 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2004-05-08  Roger Sayle  <roger@eyesopen.com>
+
+       * gcc.c-torture/execute/divcmp-1.c: New test case.
+       * gcc.c-torture/execute/divcmp-2.c: New test case.
+       * gcc.c-torture/execute/divcmp-3.c: New test case.
+
 2004-05-07  Eric Botcazou <ebotcazou@libertysurf.fr>
 
        * g++.dg/other/pragma-re-2.C: New test.

diff --git a/gcc/testsuite/gcc.c-torture/execute/divcmp-1.c b/gcc/testsuite/gcc.c-torture/execute/divcmp-1.c
new file mode 100644 (file)
index 0000000..0a7f305
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/divcmp-1.c
@@ -0,0 +1,356 @@
+extern void abort(void);
+
+int test1(int x)
+{
+  return x/10 == 2;
+}
+
+int test1u(unsigned int x)
+{
+  return x/10U == 2;
+}
+
+int test2(int x)
+{
+  return x/10 == 0;
+}
+
+int test2u(unsigned int x)
+{
+  return x/10U == 0;
+}
+
+int test3(int x)
+{
+  return x/10 != 2;
+}
+
+int test3u(unsigned int x)
+{
+  return x/10U != 2;
+}
+
+int test4(int x)
+{
+  return x/10 != 0;
+}
+
+int test4u(unsigned int x)
+{
+  return x/10U != 0;
+}
+
+int test5(int x)
+{
+  return x/10 < 2;
+}
+
+int test5u(unsigned int x)
+{
+  return x/10U < 2;
+}
+
+int test6(int x)
+{
+  return x/10 < 0;
+}
+
+int test7(int x)
+{
+  return x/10  <= 2;
+}
+
+int test7u(unsigned int x)
+{
+  return x/10U <= 2;
+}
+
+int test8(int x)
+{
+  return x/10 <= 0;
+}
+
+int test8u(unsigned int x)
+{
+  return x/10U <= 0;
+}
+
+int test9(int x)
+{
+  return x/10 > 2;
+}
+
+int test9u(unsigned int x)
+{
+  return x/10U > 2;
+}
+
+int test10(int x)
+{
+  return x/10 > 0;
+}
+
+int test10u(unsigned int x)
+{
+  return x/10U > 0;
+}
+
+int test11(int x)
+{
+  return x/10 >= 2;
+}
+
+int test11u(unsigned int x)
+{
+  return x/10U >= 2;
+}
+
+int test12(int x)
+{
+  return x/10 >= 0;
+}
+
+
+int main()
+{
+  if (test1(19) != 0)
+    abort ();
+  if (test1(20) != 1)
+    abort ();
+  if (test1(29) != 1)
+    abort ();
+  if (test1(30) != 0)
+    abort ();
+
+  if (test1u(19) != 0)
+    abort ();
+  if (test1u(20) != 1)
+    abort ();
+  if (test1u(29) != 1)
+    abort ();
+  if (test1u(30) != 0)
+    abort ();
+
+  if (test2(0) != 1)
+    abort ();
+  if (test2(9) != 1)
+    abort ();
+  if (test2(10) != 0)
+    abort ();
+  if (test2(-1) != 1)
+    abort ();
+  if (test2(-9) != 1)
+    abort ();
+  if (test2(-10) != 0)
+    abort ();
+
+  if (test2u(0) != 1)
+    abort ();
+  if (test2u(9) != 1)
+    abort ();
+  if (test2u(10) != 0)
+    abort ();
+  if (test2u(-1) != 0)
+    abort ();
+  if (test2u(-9) != 0)
+    abort ();
+  if (test2u(-10) != 0)
+    abort ();
+
+  if (test3(19) != 1)
+    abort ();
+  if (test3(20) != 0)
+    abort ();
+  if (test3(29) != 0)
+    abort ();
+  if (test3(30) != 1)
+    abort ();
+
+  if (test3u(19) != 1)
+    abort ();
+  if (test3u(20) != 0)
+    abort ();
+  if (test3u(29) != 0)
+    abort ();
+  if (test3u(30) != 1)
+    abort ();
+
+  if (test4(0) != 0)
+    abort ();
+  if (test4(9) != 0)
+    abort ();
+  if (test4(10) != 1)
+    abort ();
+  if (test4(-1) != 0)
+    abort ();
+  if (test4(-9) != 0)
+    abort ();
+  if (test4(-10) != 1)
+    abort ();
+
+  if (test4u(0) != 0)
+    abort ();
+  if (test4u(9) != 0)
+    abort ();
+  if (test4u(10) != 1)
+    abort ();
+  if (test4u(-1) != 1)
+    abort ();
+  if (test4u(-9) != 1)
+    abort ();
+  if (test4u(-10) != 1)
+    abort ();
+
+  if (test5(19) != 1)
+    abort ();
+  if (test5(20) != 0)
+    abort ();
+  if (test5(29) != 0)
+    abort ();
+  if (test5(30) != 0)
+    abort ();
+
+  if (test5u(19) != 1)
+    abort ();
+  if (test5u(20) != 0)
+    abort ();
+  if (test5u(29) != 0)
+    abort ();
+  if (test5u(30) != 0)
+    abort ();
+
+  if (test6(0) != 0)
+    abort ();
+  if (test6(9) != 0)
+    abort ();
+  if (test6(10) != 0)
+    abort ();
+  if (test6(-1) != 0)
+    abort ();
+  if (test6(-9) != 0)
+    abort ();
+  if (test6(-10) != 1)
+    abort ();
+
+  if (test7(19) != 1)
+    abort ();
+  if (test7(20) != 1)
+    abort ();
+  if (test7(29) != 1)
+    abort ();
+  if (test7(30) != 0)
+    abort ();
+
+  if (test7u(19) != 1)
+    abort ();
+  if (test7u(20) != 1)
+    abort ();
+  if (test7u(29) != 1)
+    abort ();
+  if (test7u(30) != 0)
+    abort ();
+
+  if (test8(0) != 1)
+    abort ();
+  if (test8(9) != 1)
+    abort ();
+  if (test8(10) != 0)
+    abort ();
+  if (test8(-1) != 1)
+    abort ();
+  if (test8(-9) != 1)
+    abort ();
+  if (test8(-10) != 1)
+    abort ();
+
+  if (test8u(0) != 1)
+    abort ();
+  if (test8u(9) != 1)
+    abort ();
+  if (test8u(10) != 0)
+    abort ();
+  if (test8u(-1) != 0)
+    abort ();
+  if (test8u(-9) != 0)
+    abort ();
+  if (test8u(-10) != 0)
+    abort ();
+
+  if (test9(19) != 0)
+    abort ();
+  if (test9(20) != 0)
+    abort ();
+  if (test9(29) != 0)
+    abort ();
+  if (test9(30) != 1)
+    abort ();
+
+  if (test9u(19) != 0)
+    abort ();
+  if (test9u(20) != 0)
+    abort ();
+  if (test9u(29) != 0)
+    abort ();
+  if (test9u(30) != 1)
+    abort ();
+
+  if (test10(0) != 0)
+    abort ();
+  if (test10(9) != 0)
+    abort ();
+  if (test10(10) != 1)
+    abort ();
+  if (test10(-1) != 0)
+    abort ();
+  if (test10(-9) != 0)
+    abort ();
+  if (test10(-10) != 0)
+    abort ();
+
+  if (test10u(0) != 0)
+    abort ();
+  if (test10u(9) != 0)
+    abort ();
+  if (test10u(10) != 1)
+    abort ();
+  if (test10u(-1) != 1)
+    abort ();
+  if (test10u(-9) != 1)
+    abort ();
+  if (test10u(-10) != 1)
+    abort ();
+
+  if (test11(19) != 0)
+    abort ();
+  if (test11(20) != 1)
+    abort ();
+  if (test11(29) != 1)
+    abort ();
+  if (test11(30) != 1)
+    abort ();
+
+  if (test11u(19) != 0)
+    abort ();
+  if (test11u(20) != 1)
+    abort ();
+  if (test11u(29) != 1)
+    abort ();
+  if (test11u(30) != 1)
+    abort ();
+
+  if (test12(0) != 1)
+    abort ();
+  if (test12(9) != 1)
+    abort ();
+  if (test12(10) != 1)
+    abort ();
+  if (test12(-1) != 1)
+    abort ();
+  if (test12(-9) != 1)
+    abort ();
+  if (test12(-10) != 0)
+    abort ();
+
+  return 0;
+}
+

diff --git a/gcc/testsuite/gcc.c-torture/execute/divcmp-2.c b/gcc/testsuite/gcc.c-torture/execute/divcmp-2.c
new file mode 100644 (file)
index 0000000..b059b8f
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/divcmp-2.c
@@ -0,0 +1,92 @@
+extern void abort (void);
+
+int test1(int x)
+{
+  return x/10 == 2;
+}
+
+int test2(int x)
+{
+  return x/10 == 0;
+}
+
+int test3(int x)
+{
+  return x/10 == -2;
+}
+
+int test4(int x)
+{
+  return x/-10 == 2;
+}
+
+int test5(int x)
+{
+  return x/-10 == 0;
+}
+
+int test6(int x)
+{
+  return x/-10 == -2;
+}
+
+
+int main()
+{
+  if (test1(19) != 0)
+    abort ();
+  if (test1(20) != 1)
+    abort ();
+  if (test1(29) != 1)
+    abort ();
+  if (test1(30) != 0)
+    abort ();
+
+  if (test2(-10) != 0)
+    abort ();
+  if (test2(-9) != 1)
+    abort ();
+  if (test2(9) != 1)
+    abort ();
+  if (test2(10) != 0)
+    abort ();
+
+  if (test3(-30) != 0)
+    abort ();
+  if (test3(-29) != 1)
+    abort ();
+  if (test3(-20) != 1)
+    abort ();
+  if (test3(-19) != 0)
+    abort ();
+
+  if (test4(-30) != 0)
+    abort ();
+  if (test4(-29) != 1)
+    abort ();
+  if (test4(-20) != 1)
+    abort ();
+  if (test4(-19) != 0)
+    abort ();
+
+  if (test5(-10) != 0)
+    abort ();
+  if (test5(-9) != 1)
+    abort ();
+  if (test5(9) != 1)
+    abort ();
+  if (test5(10) != 0)
+    abort ();
+
+  if (test6(19) != 0)
+    abort ();
+  if (test6(20) != 1)
+    abort ();
+  if (test6(29) != 1)
+    abort ();
+  if (test6(30) != 0)
+    abort ();
+
+  return 0;
+}
+

diff --git a/gcc/testsuite/gcc.c-torture/execute/divcmp-3.c b/gcc/testsuite/gcc.c-torture/execute/divcmp-3.c
new file mode 100644 (file)
index 0000000..ba52c9e
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/divcmp-3.c
@@ -0,0 +1,97 @@
+extern void abort(void);
+
+int test1(char x)
+{
+  return x/100 == 3;
+}
+
+int test1u(unsigned char x)
+{
+  return x/100 == 3;
+}
+
+int test2(char x)
+{
+  return x/100 != 3;
+}
+
+int test2u(unsigned char x)
+{
+  return x/100 != 3;
+}
+
+int test3(char x)
+{
+  return x/100 < 3;
+}
+
+int test3u(unsigned char x)
+{
+  return x/100 < 3;
+}
+
+int test4(char x)
+{
+  return x/100 <= 3;
+}
+
+int test4u(unsigned char x)
+{
+  return x/100 <= 3;
+}
+
+int test5(char x)
+{
+  return x/100 > 3;
+}
+
+int test5u(unsigned char x)
+{
+  return x/100 > 3;
+}
+
+int test6(char x)
+{
+  return x/100 >= 3;
+}
+
+int test6u(unsigned char x)
+{
+  return x/100 >= 3;
+}
+
+
+int main()
+{
+  int c;
+
+  for (c=-128; c<256; c++)
+  {
+    if (test1(c) != 0)
+      abort ();
+    if (test1u(c) != 0)
+      abort ();
+    if (test2(c) != 1)
+      abort ();
+    if (test2u(c) != 1)
+      abort ();
+    if (test3(c) != 1)
+      abort ();
+    if (test3u(c) != 1)
+      abort ();
+    if (test4(c) != 1)
+      abort ();
+    if (test4u(c) != 1)
+      abort ();
+    if (test5(c) != 0)
+      abort ();
+    if (test5u(c) != 0)
+      abort ();
+    if (test6(c) != 0)
+      abort ();
+    if (test6u(c) != 0)
+      abort ();
+  }
+  return 0;
+}
+