From: Pan Li <pan2...@intel.com>

The gen_phi_on_cond can only support below control flow for cond
from day 1.  Aka:

+------+
| def  |
| ...  |       +-----+
| cond |------>| def |
+------+       | ... |
   |           +-----+
   |              |
   v              |
+-----+           |
| PHI |<----------+
+-----+

Unfortunately, there will be more scenarios of control flow on PHI.
For example as below:

T __attribute__((noinline))                            \
sat_s_add_##T##_fmt_3 (T x, T y)                       \
{                                                      \
  T sum;                                               \
  bool overflow = __builtin_add_overflow (x, y, &sum); \
  return overflow ? x < 0 ? MIN : MAX : sum;           \
}

DEF_SAT_S_ADD_FMT_3(int8_t, uint8_t, INT8_MIN, INT8_MAX)

With expanded RTL like below.
   3   │
   4   │ __attribute__((noinline))
   5   │ int8_t sat_s_add_int8_t_fmt_3 (int8_t x, int8_t y)
   6   │ {
   7   │   signed char _1;
   8   │   signed char _2;
   9   │   int8_t _3;
  10   │   __complex__ signed char _6;
  11   │   _Bool _8;
  12   │   signed char _9;
  13   │   signed char _10;
  14   │   signed char _11;
  15   │
  16   │ ;;   basic block 2, loop depth 0
  17   │ ;;    pred:       ENTRY
  18   │   _6 = .ADD_OVERFLOW (x_4(D), y_5(D));
  19   │   _2 = IMAGPART_EXPR <_6>;
  20   │   if (_2 != 0)
  21   │     goto <bb 4>; [50.00%]
  22   │   else
  23   │     goto <bb 3>; [50.00%]
  24   │ ;;    succ:       4
  25   │ ;;                3
  26   │
  27   │ ;;   basic block 3, loop depth 0
  28   │ ;;    pred:       2
  29   │   _1 = REALPART_EXPR <_6>;
  30   │   goto <bb 5>; [100.00%]
  31   │ ;;    succ:       5
  32   │
  33   │ ;;   basic block 4, loop depth 0
  34   │ ;;    pred:       2
  35   │   _8 = x_4(D) < 0;
  36   │   _9 = (signed char) _8;
  37   │   _10 = -_9;
  38   │   _11 = _10 ^ 127;
  39   │ ;;    succ:       5
  40   │
  41   │ ;;   basic block 5, loop depth 0
  42   │ ;;    pred:       3
  43   │ ;;                4
  44   │   # _3 = PHI <_1(3), _11(4)>
  45   │   return _3;
  46   │ ;;    succ:       EXIT
  47   │
  48   │ }

The above code will have below control flow which is not supported by
the gen_phi_on_cond.

+------+
| def  |
| ...  |       +-----+
| cond |------>| def |
+------+       | ... |
   |           +-----+
   |              |
   v              |
+-----+           |
| def |           |
| ... |           |
+-----+           |
   |              |
   |              |
   v              |
+-----+           |
| PHI |<----------+
+-----+

This patch would like to add support above control flow for the
gen_phi_on_cond.

The below testsuites are passed for this patch:
* The rv64gcv fully regression test.
* The x86 bootstrap test.
* The x86 fully regression test.

gcc/ChangeLog:

        * genmatch.cc (dt_operand::gen_phi_on_cond): Add support for
        a new control flow when gen phi on condition.

Signed-off-by: Pan Li <pan2...@intel.com>
---
 gcc/genmatch.cc | 85 +++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 76 insertions(+), 9 deletions(-)

diff --git a/gcc/genmatch.cc b/gcc/genmatch.cc
index a56bd90cb2c..f538df1be62 100644
--- a/gcc/genmatch.cc
+++ b/gcc/genmatch.cc
@@ -3529,28 +3529,95 @@ dt_operand::gen_phi_on_cond (FILE *f, int indent, int 
depth)
     "basic_block _pb_0_%d = EDGE_PRED (_b%d, 0)->src;\n", depth, depth);
   fprintf_indent (f, indent,
     "basic_block _pb_1_%d = EDGE_PRED (_b%d, 1)->src;\n", depth, depth);
+
   fprintf_indent (f, indent,
-    "basic_block _db_%d = safe_dyn_cast <gcond *> (*gsi_last_bb (_pb_0_%d)) ? "
-    "_pb_0_%d : _pb_1_%d;\n", depth, depth, depth, depth);
+    "gcond *_ct_0_%d = safe_dyn_cast <gcond *> (*gsi_last_bb (_pb_0_%d));\n",
+    depth, depth);
   fprintf_indent (f, indent,
-    "basic_block _other_db_%d = safe_dyn_cast <gcond *> "
-    "(*gsi_last_bb (_pb_0_%d)) ? _pb_1_%d : _pb_0_%d;\n",
+    "gcond *_ct_1_%d = safe_dyn_cast <gcond *> (*gsi_last_bb (_pb_1_%d));\n",
+    depth, depth);
+  fprintf_indent (f, indent,
+    "gcond *_ct_a_%d = _ct_0_%d ? _ct_0_%d : _ct_1_%d;\n",
+    depth, depth, depth, depth);
+  fprintf_indent (f, indent,
+    "basic_block _db_%d = _ct_0_%d ? _pb_0_%d : _pb_1_%d;\n",
+    depth, depth, depth, depth);
+  fprintf_indent (f, indent,
+    "basic_block _other_db_%d = _ct_0_%d ? _pb_1_%d : _pb_0_%d;\n",
     depth, depth, depth, depth);
 
   fprintf_indent (f, indent,
-    "gcond *_ct_%d = safe_dyn_cast <gcond *> (*gsi_last_bb (_db_%d));\n",
-    depth, depth);
-  fprintf_indent (f, indent, "if (_ct_%d"
+    "edge _e_00_%d = _pb_0_%d->preds ? EDGE_PRED (_pb_0_%d, 0) : NULL;\n",
+    depth, depth, depth);
+  fprintf_indent (f, indent,
+    "basic_block _pb_00_%d = _e_00_%d ? _e_00_%d->src : NULL;\n",
+    depth, depth, depth);
+  fprintf_indent (f, indent,
+    "gcond *_ct_b_%d = _pb_00_%d ? "
+    "safe_dyn_cast <gcond *> (*gsi_last_bb (_pb_00_%d)) : NULL;\n",
+    depth, depth, depth);
+
+  /* Case 1 flow for PHI.
+   * +------+
+   * | def  |
+   * | ...  |       +-----+
+   * | cond |------>| def |
+   * +------+       | ... |
+   *    |           +-----+
+   *    |              |
+   *    v              |
+   * +-----+           |
+   * | PHI |<----------+
+   * +-----+
+   */
+  fprintf_indent (f, indent, "if ((_ct_a_%d"
     " && EDGE_COUNT (_other_db_%d->preds) == 1\n", depth, depth);
   fprintf_indent (f, indent,
-    "  && EDGE_COUNT (_other_db_%d->succs) == 1\n", depth);
+    "     && EDGE_COUNT (_other_db_%d->succs) == 1\n", depth);
+  fprintf_indent (f, indent,
+    "     && EDGE_PRED (_other_db_%d, 0)->src == _db_%d)\n", depth, depth);
+
+  fprintf_indent (f, indent, "    ||\n");
+
+  /* Case 2 flow for PHI.
+   * +------+
+   * | def  |
+   * | ...  |       +-----+
+   * | cond |------>| def |
+   * +------+       | ... |
+   *    |           +-----+
+   *    |              |
+   *    v              |
+   * +-----+           |
+   * | def |           |
+   * | ... |           |
+   * +-----+           |
+   *    |              |
+   *    |              |
+   *    v              |
+   * +-----+           |
+   * | PHI |<----------+
+   * +-----+
+   */
+  fprintf_indent (f, indent,
+    "    (_ct_b_%d && _pb_00_%d && EDGE_COUNT (_pb_0_%d->succs) == 1\n",
+    depth, depth, depth);
+  fprintf_indent (f, indent,
+    "     && EDGE_COUNT (_pb_0_%d->preds) == 1\n", depth);
   fprintf_indent (f, indent,
-    "  && EDGE_PRED (_other_db_%d, 0)->src == _db_%d)\n", depth, depth);
+    "     && EDGE_COUNT (_other_db_%d->preds) == 1\n", depth);
+  fprintf_indent (f, indent,
+    "     && EDGE_COUNT (_other_db_%d->succs) == 1\n", depth);
+  fprintf_indent (f, indent,
+    "     && EDGE_PRED (_other_db_%d, 0)->src == _pb_00_%d))\n", depth, depth);
 
   indent += 2;
   fprintf_indent (f, indent, "{\n");
   indent += 2;
 
+  fprintf_indent (f, indent,
+    "gcond *_ct_%d = _ct_a_%d ? _ct_a_%d : _ct_b_%d;\n",
+    depth, depth, depth, depth);
   fprintf_indent (f, indent,
     "tree _cond_lhs_%d = gimple_cond_lhs (_ct_%d);\n", depth, depth);
   fprintf_indent (f, indent,
-- 
2.43.0

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