tree-cfg: Revert part of r8-546 [PR125290]

This reverts the group_case_labels_stmt part of r8-546-gca4d2851687875.
This is placed in the wrong location to remove the case statements that go
directly to __builtin_unreachable. In fact the removal of the case statements
make us lose optimizations in some cases (Wuninitialized-pr107919-1.C for one).

Also this fixes PR 125290 by no longer leaving around a switch which just
has a default case.

Bootstrapped and tested on x86_64-linux-gnu.

	PR tree-optimization/125290

gcc/ChangeLog:

	* tree-cfg.cc (group_case_labels_stmt): Remove code that was
	added to remove `cases` that goto blocks of unreachable.
	* tree-ssa-forwprop.cc (optimize_unreachable): Remove the
	comment about switch cases being handled.

gcc/testsuite/ChangeLog:

	* g++.dg/warn/Wuninitialized-pr107919-1.C: Remove xfail.
	* gcc.dg/analyzer/taint-assert.c: Update for the non-removal
	of block containing unreachable.
	* gcc.dg/torture/pr125290-1.c: New test.

Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>

diff --git a/gcc/testsuite/g++.dg/warn/Wuninitialized-pr107919-1.C b/gcc/testsuite/g++.dg/warn/Wuninitialized-pr107919-1.C
index 049fa4d307ae956bc5a535011463594a8082ee44..b3ed4628bddaefc8769e8ac7439532e341b06a60 100644 (file)
--- a/gcc/testsuite/g++.dg/warn/Wuninitialized-pr107919-1.C
+++ b/gcc/testsuite/g++.dg/warn/Wuninitialized-pr107919-1.C
@@ -14,4 +14,4 @@ void do_something(void* storage)
   std::swap(event, swappedValue);
 }
 
-// { dg-bogus "may be used uninitialized" "" { xfail *-*-* } 0 }
+// { dg-bogus "may be used uninitialized" "" 0 }

diff --git a/gcc/testsuite/gcc.dg/analyzer/taint-assert.c b/gcc/testsuite/gcc.dg/analyzer/taint-assert.c
index a858e996a8015ac72356d1f2e0c0a99e8f958703..e46cbe95801d1752cbf8bf179d9a8117fe50faee 100644 (file)
--- a/gcc/testsuite/gcc.dg/analyzer/taint-assert.c
+++ b/gcc/testsuite/gcc.dg/analyzer/taint-assert.c
@@ -322,8 +322,8 @@ test_switch_bogus_case_unreachable (int n)
     case 2:
       return -1;
     case 42:
-      /* This case gets optimized away before we see it.  */
-      __builtin_unreachable ();
+      /* The wording is rather inaccurate here.  */
+      __builtin_unreachable (); /* { dg-warning "use of attacked-controlled value in condition for assertion" } */
     }
 }
 

diff --git a/gcc/testsuite/gcc.dg/torture/pr125290-1.c b/gcc/testsuite/gcc.dg/torture/pr125290-1.c
new file mode 100644 (file)
index 0000000..6183cbd
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr125290-1.c
@@ -0,0 +1,40 @@
+/* PR tree-optimization/125290 */
+/* { dg-do compile } */
+
+int g21;
+int g31, f14f16_c12;
+void f14f16()
+{
+    short v7;
+    long v9;
+    long v13;
+    if (g31)
+    {
+        g21 = 0;
+        switch (v7)
+        {
+            case 4:
+            case 66: break;
+            default: __builtin_unreachable();
+        }
+    }
+    else
+    {
+    lbl_bf2:
+        v9 = g21;
+    }
+    v13 = v9;
+    switch (v13)
+    {
+        case 55:
+        case 2: goto lbl_sw12;
+        default:
+            if (f14f16_c12)
+                goto lbl_bf2;
+            else
+                return;
+    }
+lbl_sw12:
+    __builtin_unreachable();
+}
+

diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index b2968c412ed6604c9f6a319042daab7cd6647890..5f751e15d9d6a726491fcdb1534ac98a84f8f613 100644 (file)
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -1712,7 +1712,6 @@ group_case_labels_stmt (gswitch *stmt)
   int old_size = gimple_switch_num_labels (stmt);
   int i, next_index, new_size;
   basic_block default_bb = NULL;
-  hash_set<tree> *removed_labels = NULL;
 
   default_bb = gimple_switch_default_bb (cfun, stmt);
 
@@ -1728,12 +1727,9 @@ group_case_labels_stmt (gswitch *stmt)
       gcc_assert (base_case);
       base_bb = label_to_block (cfun, CASE_LABEL (base_case));
 
-      /* Discard cases that have the same destination as the default case or
-        whose destination blocks have already been removed as unreachable.  */
+      /* Discard cases that have the same destination as the default case.  */
       if (base_bb == NULL
-         || base_bb == default_bb
-         || (removed_labels
-             && removed_labels->contains (CASE_LABEL (base_case))))
+         || base_bb == default_bb)
        {
          i++;
          continue;
@@ -1756,8 +1752,6 @@ group_case_labels_stmt (gswitch *stmt)
          /* Merge the cases if they jump to the same place,
             and their ranges are consecutive.  */
          if (merge_bb == base_bb
-             && (removed_labels == NULL
-                 || !removed_labels->contains (CASE_LABEL (merge_case)))
              && wi::to_wide (CASE_LOW (merge_case)) == bhp1)
            {
              base_high
@@ -1770,46 +1764,6 @@ group_case_labels_stmt (gswitch *stmt)
            break;
        }
 
-      /* Discard cases that have an unreachable destination block.  */
-      if (EDGE_COUNT (base_bb->succs) == 0
-         && gimple_seq_unreachable_p (bb_seq (base_bb))
-         /* Don't optimize this if __builtin_unreachable () is the
-            implicitly added one by the C++ FE too early, before
-            -Wreturn-type can be diagnosed.  We'll optimize it later
-            during switchconv pass or any other cfg cleanup.  */
-         && (gimple_in_ssa_p (cfun)
-             || (LOCATION_LOCUS (gimple_location (last_nondebug_stmt (base_bb)))
-                 != BUILTINS_LOCATION)))
-       {
-         edge base_edge = find_edge (gimple_bb (stmt), base_bb);
-         if (base_edge != NULL)
-           {
-             for (gimple_stmt_iterator gsi = gsi_start_bb (base_bb);
-                  !gsi_end_p (gsi); gsi_next (&gsi))
-               if (glabel *stmt = dyn_cast <glabel *> (gsi_stmt (gsi)))
-                 {
-                   if (FORCED_LABEL (gimple_label_label (stmt))
-                       || DECL_NONLOCAL (gimple_label_label (stmt)))
-                     {
-                       /* Forced/non-local labels aren't going to be removed,
-                          but they will be moved to some neighbouring basic
-                          block. If some later case label refers to one of
-                          those labels, we should throw that case away rather
-                          than keeping it around and referring to some random
-                          other basic block without an edge to it.  */
-                       if (removed_labels == NULL)
-                         removed_labels = new hash_set<tree>;
-                       removed_labels->add (gimple_label_label (stmt));
-                     }
-                 }
-               else
-                 break;
-             remove_edge_and_dominated_blocks (base_edge);
-           }
-         i = next_index;
-         continue;
-       }
-
       if (new_size < i)
        gimple_switch_set_label (stmt, new_size,
                                 gimple_switch_label (stmt, i));
@@ -1822,7 +1776,6 @@ group_case_labels_stmt (gswitch *stmt)
   if (new_size < old_size)
     gimple_switch_set_num_labels (stmt, new_size);
 
-  delete removed_labels;
   return new_size < old_size;
 }
 

diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
index 1587fa7bd14285686d4dba93d95e51a84fa7ee19..06eb81b9a28d671f9b80f639cfacc2c5ea822fad 100644 (file)
--- a/gcc/tree-ssa-forwprop.cc
+++ b/gcc/tree-ssa-forwprop.cc
@@ -5264,8 +5264,7 @@ optimize_unreachable (basic_block bb)
        }
       else
        {
-         /* Todo: handle other cases.  Note that unreachable switch case
-            statements have already been removed.  */
+         /* Todo: handle other cases.  e.g. switch.  */
          continue;
        }