tree-ssa-uninit: avoid ICE with BIT_AND_EXPR (PR 90394)

2019-05-16  Vladislav Ivanishin  <vlad@ispras.ru>

	PR tree-optimization/90394
	* tree-ssa-uninit.c (is_pred_expr_subset_of): Potentially give false
	positives rather than ICE for cases where (code2 == NE_EXPR
	&& code1 == BIT_AND_EXPR).

testsuite/
	* gcc.dg/uninit-pr90394-1-gimple.c: New test.
	* gcc.dg/uninit-pr90394.c: New test.

From-SVN: r271287

gcc/ChangeLog

+2019-05-16  Vladislav Ivanishin  <vlad@ispras.ru>
+
+	PR tree-optimization/90394
+	* tree-ssa-uninit.c (is_pred_expr_subset_of): Potentially give false
+	positives rather than ICE for cases where (code2 == NE_EXPR
+	&& code1 == BIT_AND_EXPR).
+
 2019-05-16  Jakub Jelinek  <jakub@redhat.com>
 
 	PR fortran/90329

gcc/testsuite/ChangeLog

+2019-05-16  Vladislav Ivanishin  <vlad@ispras.ru>
+
+	PR tree-optimization/90394
+	* gcc.dg/uninit-pr90394-1-gimple.c: New test.
+	* gcc.dg/uninit-pr90394.c: New test.
+
 2019-05-16  Richard Biener  <rguenther@suse.de>
 
 	PR testsuite/90502

gcc/testsuite/gcc.dg/uninit-pr90394-1-gimple.c

+/* { dg-do compile } */
+/* { dg-options "-fgimple -O -Wmaybe-uninitialized" } */
+
+unsigned int __GIMPLE (ssa,startwith("uninit1"))
+foo (unsigned int v)
+{
+  /* The warning is not bogus, because (5 & 3) != 0 and therefore if v == 5,
+     the value of undef is used without being initialized.  */
+  unsigned int undef;        /* { dg-warning "may be used uninitialized" } */
+  unsigned int _2;
+  unsigned int _9;
+  unsigned int _10;
+  unsigned pred;
+
+  __BB(2):
+  if (v_4(D) != 5u)
+    goto __BB3;
+  else
+    goto __BB4;
+
+  /* 'undef' is defined conditionally (under 'v != 5' predicate)  */
+  __BB(3):
+  undef_8 = 8u;
+  goto __BB4;
+
+  /* An undef value flows into a phi.  */
+  __BB(4):
+  undef_1 = __PHI (__BB2: undef_5(D), __BB3: undef_8);
+  pred = v_4(D) & 3u;
+  if (pred != 0u)
+    goto __BB5;
+  else
+    goto __BB6;
+
+  /* The phi value is used here (under 'v & 3' predicate).  */
+  __BB(5):
+  _9 = undef_1;
+  goto __BB7;
+
+  __BB(6):
+  _10 = v_4(D);
+  goto __BB7;
+
+  __BB(7):
+  _2 = __PHI (__BB5: _9, __BB6: _10);
+  return _2;
+}

gcc/testsuite/gcc.dg/uninit-pr90394.c

+/* { dg-do compile } */
+/* { dg-options "-O1 -fno-tree-fre -Wuninitialized" } */
+int pz;
+int zi;
+
+void
+uk (void)
+{
+  int th = 1;
+  int *gw = &zi;
+
+  for (zi = 0; zi < 2; ++zi)
+    {
+      int a2 = 0;
+
+      for (zi = 0; zi < 1; ++zi)
+        {
+          th = a2 * 2;
+
+ og:
+          for (pz = 0; pz < 1; ++pz)
+            {
+            }
+        }
+
+      pz = !!*gw ? *gw : pz;
+      pz = (!!th ? (pz & 1) : 0);
+      if (pz == 0)
+        ++a2;
+    }
+
+  goto og;
+}

gcc/tree-ssa-uninit.c

@@ -1471,7 +1471,7 @@ is_pred_expr_subset_of (pred_info expr1, pred_info expr2)
   if (code2 == NE_EXPR && code1 == NE_EXPR)
     return false;
 
-  if (code2 == NE_EXPR)
+  if (code2 == NE_EXPR && code1 != BIT_AND_EXPR)
     return !is_value_included_in (expr2.pred_rhs, expr1.pred_rhs, code1);
 
   if ((code1 == EQ_EXPR || code1 == BIT_AND_EXPR) && code2 == BIT_AND_EXPR)