re PR middle-end/78416 (wrong code for division by (u128)~INT64_MAX at -O0)

	PR middle-end/78416
	* expmed.c (expand_divmod): Use wide_int for computation of
	op1_is_pow2.  Don't set it if op1 is 0.  Formatting fixes.
	Use size <= HOST_BITS_PER_WIDE_INT instead of
	HOST_BITS_PER_WIDE_INT >= size.

	* gcc.dg/torture/pr78416.c: New test.

From-SVN: r242690

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c97934882eb2b631cd0ca7981ffbadf1595e422a..0402b3949f3841b3a69815715c611f1b53cf175b 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,11 @@
 2016-11-22  Jakub Jelinek  <jakub@redhat.com>
 
+       PR middle-end/78416
+       * expmed.c (expand_divmod): Use wide_int for computation of
+       op1_is_pow2.  Don't set it if op1 is 0.  Formatting fixes.
+       Use size <= HOST_BITS_PER_WIDE_INT instead of
+       HOST_BITS_PER_WIDE_INT >= size.
+
        PR tree-optimization/78445
        * tree-if-conv.c (tree_if_conversion): If any_pred_load_store or
        any_complicated_phi, version loop even if flag_tree_loop_if_convert is

diff --git a/gcc/expmed.c b/gcc/expmed.c
index a21a632ab189f9226879ccf3704401060e61df0e..fa710565f304652b12fb5239911b4d05e2d94186 100644 (file)
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -3994,11 +3994,10 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
   op1_is_constant = CONST_INT_P (op1);
   if (op1_is_constant)
     {
-      unsigned HOST_WIDE_INT ext_op1 = UINTVAL (op1);
-      if (unsignedp)
-       ext_op1 &= GET_MODE_MASK (mode);
-      op1_is_pow2 = ((EXACT_POWER_OF_2_OR_ZERO_P (ext_op1)
-                    || (! unsignedp && EXACT_POWER_OF_2_OR_ZERO_P (-ext_op1))));
+      wide_int ext_op1 = rtx_mode_t (op1, mode);
+      op1_is_pow2 = (wi::popcount (ext_op1) == 1
+                    || (! unsignedp
+                        && wi::popcount (wi::neg (ext_op1)) == 1));
     }
 
   /*
@@ -4079,11 +4078,10 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
      not straightforward to generalize this.  Maybe we should make an array
      of possible modes in init_expmed?  Save this for GCC 2.7.  */
 
-  optab1 = ((op1_is_pow2 && op1 != const0_rtx)
+  optab1 = (op1_is_pow2
            ? (unsignedp ? lshr_optab : ashr_optab)
            : (unsignedp ? udiv_optab : sdiv_optab));
-  optab2 = ((op1_is_pow2 && op1 != const0_rtx)
-           ? optab1
+  optab2 = (op1_is_pow2 ? optab1
            : (unsignedp ? udivmod_optab : sdivmod_optab));
 
   for (compute_mode = mode; compute_mode != VOIDmode;
@@ -4139,10 +4137,15 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
       /* convert_modes may have placed op1 into a register, so we
         must recompute the following.  */
       op1_is_constant = CONST_INT_P (op1);
-      op1_is_pow2 = (op1_is_constant
-                    && ((EXACT_POWER_OF_2_OR_ZERO_P (INTVAL (op1))
-                         || (! unsignedp
-                             && EXACT_POWER_OF_2_OR_ZERO_P (-UINTVAL (op1))))));
+      if (op1_is_constant)
+       {
+         wide_int ext_op1 = rtx_mode_t (op1, compute_mode);
+         op1_is_pow2 = (wi::popcount (ext_op1) == 1
+                        || (! unsignedp
+                            && wi::popcount (wi::neg (ext_op1)) == 1));
+       }
+      else
+       op1_is_pow2 = 0;
     }
 
   /* If one of the operands is a volatile MEM, copy it into a register.  */
@@ -4182,10 +4185,10 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
                unsigned HOST_WIDE_INT mh, ml;
                int pre_shift, post_shift;
                int dummy;
-               unsigned HOST_WIDE_INT d = (INTVAL (op1)
-                                           & GET_MODE_MASK (compute_mode));
+               wide_int wd = rtx_mode_t (op1, compute_mode);
+               unsigned HOST_WIDE_INT d = wd.to_uhwi ();
 
-               if (EXACT_POWER_OF_2_OR_ZERO_P (d))
+               if (wi::popcount (wd) == 1)
                  {
                    pre_shift = floor_log2 (d);
                    if (rem_flag)
@@ -4325,7 +4328,7 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
                else if (d == -1)
                  quotient = expand_unop (compute_mode, neg_optab, op0,
                                          tquotient, 0);
-               else if (HOST_BITS_PER_WIDE_INT >= size
+               else if (size <= HOST_BITS_PER_WIDE_INT
                         && abs_d == HOST_WIDE_INT_1U << (size - 1))
                  {
                    /* This case is not handled correctly below.  */
@@ -4335,6 +4338,7 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
                      goto fail1;
                  }
                else if (EXACT_POWER_OF_2_OR_ZERO_P (d)
+                        && (size <= HOST_BITS_PER_WIDE_INT || d >= 0)
                         && (rem_flag
                             ? smod_pow2_cheap (speed, compute_mode)
                             : sdiv_pow2_cheap (speed, compute_mode))
@@ -4348,7 +4352,9 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
                                                compute_mode)
                                 != CODE_FOR_nothing)))
                  ;
-               else if (EXACT_POWER_OF_2_OR_ZERO_P (abs_d))
+               else if (EXACT_POWER_OF_2_OR_ZERO_P (abs_d)
+                        && (size <= HOST_BITS_PER_WIDE_INT
+                            || abs_d != (unsigned HOST_WIDE_INT) d))
                  {
                    if (rem_flag)
                      {
@@ -4483,7 +4489,7 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
       case FLOOR_DIV_EXPR:
       case FLOOR_MOD_EXPR:
       /* We will come here only for signed operations.  */
-       if (op1_is_constant && HOST_BITS_PER_WIDE_INT >= size)
+       if (op1_is_constant && size <= HOST_BITS_PER_WIDE_INT)
          {
            unsigned HOST_WIDE_INT mh, ml;
            int pre_shift, lgup, post_shift;
@@ -4552,9 +4558,8 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
                                                  op0, constm1_rtx), NULL_RTX);
                t2 = expand_binop (compute_mode, ior_optab, op0, t1, NULL_RTX,
                                   0, OPTAB_WIDEN);
-               nsign = expand_shift
-                 (RSHIFT_EXPR, compute_mode, t2,
-                  size - 1, NULL_RTX, 0);
+               nsign = expand_shift (RSHIFT_EXPR, compute_mode, t2,
+                                     size - 1, NULL_RTX, 0);
                t3 = force_operand (gen_rtx_MINUS (compute_mode, t1, nsign),
                                    NULL_RTX);
                t4 = expand_divmod (0, TRUNC_DIV_EXPR, compute_mode, t3, op1,
@@ -4663,7 +4668,10 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
       case CEIL_MOD_EXPR:
        if (unsignedp)
          {
-           if (op1_is_constant && EXACT_POWER_OF_2_OR_ZERO_P (INTVAL (op1)))
+           if (op1_is_constant
+               && EXACT_POWER_OF_2_OR_ZERO_P (INTVAL (op1))
+               && (size <= HOST_BITS_PER_WIDE_INT
+                   || INTVAL (op1) >= 0))
              {
                rtx t1, t2, t3;
                unsigned HOST_WIDE_INT d = INTVAL (op1);
@@ -4876,7 +4884,7 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
        break;
 
       case EXACT_DIV_EXPR:
-       if (op1_is_constant && HOST_BITS_PER_WIDE_INT >= size)
+       if (op1_is_constant && size <= HOST_BITS_PER_WIDE_INT)
          {
            HOST_WIDE_INT d = INTVAL (op1);
            unsigned HOST_WIDE_INT ml;

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 125b01f281719cd9ef990e43c65d0d7cbf97e9e5..c24012dee07e03739fe7dbc7ba4999eefc8b0322 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2016-11-22  Jakub Jelinek  <jakub@redhat.com>
 
+       PR middle-end/78416
+       * gcc.dg/torture/pr78416.c: New test.
+
        PR tree-optimization/78445
        * gcc.dg/pr78445.c: New test.
 

diff --git a/gcc/testsuite/gcc.dg/torture/pr78416.c b/gcc/testsuite/gcc.dg/torture/pr78416.c
new file mode 100644 (file)
index 0000000..5028156
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr78416.c
@@ -0,0 +1,17 @@
+/* PR middle-end/78416 */
+/* { dg-do run { target int128 } } */
+
+int
+main ()
+{
+  unsigned __int128 x;
+  x = 0xFFFFFFFFFFFFFFFFULL;
+  x /= ~0x7FFFFFFFFFFFFFFFLL;
+  if (x != 0)
+    __builtin_abort ();
+  x = ~0x7FFFFFFFFFFFFFFELL;
+  x /= ~0x7FFFFFFFFFFFFFFFLL;
+  if (x != 1)
+    __builtin_abort ();
+  return 0;
+}