This backport contains 3 patch from releases/gcc-8.3.0 stream tree.
The commit id of these patchs list as following in the order of time.

0001-tree-ssa-pre.c-print_pre_expr-Handle-NULL-expr.patch
34e5c5116fa58f77ea5eef61d8fb6b9e91c92d79

0001-re-PR-tree-optimization-81900-GCC-trunk-miscompiles-.patch
404938eda1ea3f5dcbca089aa7b23dc04f75b9e0

0001-re-PR-tree-optimization-83685-ICE-SSA-corruption.patch
e207c07997748ec104a1caf295e66abb75f0eb3f


diff --git a/gcc/cfganal.c b/gcc/cfganal.c
index 7377a7a04..3c127d6a4 100644
--- a/gcc/cfganal.c
+++ b/gcc/cfganal.c
@@ -752,23 +752,24 @@ post_order_compute (int *post_order, bool include_entry_exit,
 basic_block
 dfs_find_deadend (basic_block bb)
 {
-  bitmap visited = BITMAP_ALLOC (NULL);
+  auto_bitmap visited;
+  basic_block next = bb;
 
   for (;;)
     {
-      if (EDGE_COUNT (bb->succs) == 0
-	  || ! bitmap_set_bit (visited, bb->index))
-        {
-          BITMAP_FREE (visited);
-          return bb;
-        }
+      if (EDGE_COUNT (next->succs) == 0)
+	return next;
+
+      if (! bitmap_set_bit (visited, next->index))
+	return bb;
 
+      bb = next;
       /* If we are in an analyzed cycle make sure to try exiting it.
          Note this is a heuristic only and expected to work when loop
 	 fixup is needed as well.  */
       if (! bb->loop_father
 	  || ! loop_outer (bb->loop_father))
-	bb = EDGE_SUCC (bb, 0)->dest;
+	next = EDGE_SUCC (bb, 0)->dest;
       else
 	{
 	  edge_iterator ei;
@@ -776,7 +777,7 @@ dfs_find_deadend (basic_block bb)
 	  FOR_EACH_EDGE (e, ei, bb->succs)
 	    if (loop_exit_edge_p (bb->loop_father, e))
 	      break;
-	  bb = e ? e->dest : EDGE_SUCC (bb, 0)->dest;
+	  next = e ? e->dest : EDGE_SUCC (bb, 0)->dest;
 	}
     }
 
diff --git a/gcc/testsuite/gcc.dg/torture/pr81900.c b/gcc/testsuite/gcc.dg/torture/pr81900.c
new file mode 100644
index 000000000..9e4e8f4a7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr81900.c
@@ -0,0 +1,19 @@
+/* PR/81900 */
+/* { dg-do compile } */
+/* { dg-skip-if "" { *-*-* } { "-flto" } { "" } } */
+/* { dg-options "-fdump-tree-optimized" } */
+
+void Perl_croak() __attribute__((noreturn));
+char *Perl_sv_gets();
+void __attribute__((returns_twice)) __sigsetjmp ();
+void a() {
+    __sigsetjmp();
+    char *b;
+    if ((b = Perl_sv_gets()) == 0)
+      Perl_croak("No Perl script found in input\n");
+    if (*b == '#')
+      __asm__("" : : ""("badbad"));
+}
+
+/* Do not elide the test against zero.  */
+/* { dg-final { scan-tree-dump " == 0B" "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/torture/pr83685.c b/gcc/testsuite/gcc.dg/torture/pr83685.c
new file mode 100644
index 000000000..062f75d23
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr83685.c
@@ -0,0 +1,20 @@
+/* { dg-do compile }  */
+
+int _setjmp (void *);
+void foo (int);
+
+void
+bar (int e, int b, char c, void *d)
+{
+  while (b)
+    {
+      if (_setjmp (d))
+	foo (e);
+      if (c)
+	{
+	  e--;
+	  foo (0);
+	}
+      e++;
+    }
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/split-path-5.c b/gcc/testsuite/gcc.dg/tree-ssa/split-path-5.c
index 5044c7301..95aabdaf6 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/split-path-5.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/split-path-5.c
@@ -41,20 +41,4 @@ bmhi_init (const char *pattern)
     }
 }
 
-char *
-bmhi_search (const char *string, const int stringlen)
-{
-  int i, j;
-  char *s;
-  for (;;)
-    {
-      while (--j >= 0 && (
-			   {
-			   __typeof__ (s[j]) __x = (s[j]);
-			   ((((__ctype_ptr__ +
-			       sizeof (""[__x]))[(int) (__x)]) &
-			     (01 | 02)) ==
-			    02) ? (int) __x - 'a' +
-			   'A' : (int) __x;}) == pat[j]);
-}}
-/* { dg-final { scan-tree-dump-times "Duplicating join block" 2 "split-paths" } } */
+/* { dg-final { scan-tree-dump-times "Duplicating join block" 1 "split-paths" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dce-3.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dce-3.c
index 64b30ca1e..863aa79b4 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dce-3.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dce-3.c
@@ -26,9 +26,6 @@ int main(void)
    by marking the j % 7 condition as useful.  See PR45178.  */
 
 /* We should eliminate the inner condition, but the loop must be preserved
-   as it is infinite.  Therefore there should be just one phi node (for i):  */
-/* { dg-final { scan-tree-dump-times "PHI " 1 "cddce1" { xfail *-*-* } } } */
-
-/* And one if (for the exit condition of the loop):  */
-/* { dg-final { scan-tree-dump-times "if " 1 "cddce1" } } */
-
+   as it is infinite.  Therefore there should be just one goto and no PHI.  */
+/* { dg-final { scan-tree-dump-times "PHI " 0 "cddce1" } } */
+/* { dg-final { scan-tree-dump-times "goto" 1 "cddce1" } } */
diff --git a/gcc/testsuite/gcc.dg/uninit-23.c b/gcc/testsuite/gcc.dg/uninit-23.c
index b38e1d08e..d64eb7d2e 100644
--- a/gcc/testsuite/gcc.dg/uninit-23.c
+++ b/gcc/testsuite/gcc.dg/uninit-23.c
@@ -15,10 +15,10 @@ ql (void)
       for (;;)
       {
         int *go;
-        int *t4 = go;
+        int *t4 = go; /* { dg-warning "is used uninitialized" } */
 
  l1:
-        *t4 = (*t4 != 0) ? 0 : 2; /* { dg-warning "may be used uninitialized" } */
+        *t4 = (*t4 != 0) ? 0 : 2;
       }
 
     if (ij != 0)
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index 0ab36bb64..b7cc7a399 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -834,7 +834,7 @@ bitmap_set_and (bitmap_set_t dest, bitmap_set_t orig)
     }
 }
 
-/* Subtract all values and expressions contained in ORIG from DEST.  */
+/* Subtract all expressions contained in ORIG from DEST.  */
 
 static bitmap_set_t
 bitmap_set_subtract (bitmap_set_t dest, bitmap_set_t orig)
@@ -856,7 +856,7 @@ bitmap_set_subtract (bitmap_set_t dest, bitmap_set_t orig)
   return result;
 }
 
-/* Subtract all the values in bitmap set B from bitmap set A.  */
+/* Subtract all values in bitmap set B from bitmap set A.  */
 
 static void
 bitmap_set_subtract_values (bitmap_set_t a, bitmap_set_t b)
@@ -982,6 +982,11 @@ bitmap_value_insert_into_set (bitmap_set_t set, pre_expr expr)
 static void
 print_pre_expr (FILE *outfile, const pre_expr expr)
 {
+  if (! expr)
+    {
+      fprintf (outfile, "NULL");
+      return;
+    }
   switch (expr->kind)
     {
     case CONSTANT:
@@ -2097,16 +2102,15 @@ static sbitmap has_abnormal_preds;
 static bool
 compute_antic_aux (basic_block block, bool block_has_abnormal_pred_edge)
 {
-  bool changed = false;
   bitmap_set_t S, old, ANTIC_OUT;
   bitmap_iterator bi;
   unsigned int bii;
   edge e;
   edge_iterator ei;
-  bool was_visited = BB_VISITED (block);
 
-  old = ANTIC_OUT = S = NULL;
+  bool changed = ! BB_VISITED (block);
   BB_VISITED (block) = 1;
+  old = ANTIC_OUT = S = NULL;
 
   /* If any edges from predecessors are abnormal, antic_in is empty,
      so do nothing.  */
@@ -2195,7 +2199,7 @@ compute_antic_aux (basic_block block, bool block_has_abnormal_pred_edge)
   /* clean (ANTIC_IN (block)) is defered to after the iteration converged
      because it can cause non-convergence, see for example PR81181.  */
 
-  if (!was_visited || !bitmap_set_equal (old, ANTIC_IN (block)))
+  if (!bitmap_set_equal (old, ANTIC_IN (block)))
     changed = true;
 
  maybe_dump_sets:
@@ -2374,9 +2378,6 @@ compute_antic (void)
 	if (e->flags & EDGE_ABNORMAL)
 	  {
 	    bitmap_set_bit (has_abnormal_preds, block->index);
-
-	    /* We also anticipate nothing.  */
-	    BB_VISITED (block) = 1;
 	    break;
 	  }
 
@@ -2396,7 +2397,9 @@ compute_antic (void)
   int postorder_num = inverted_post_order_compute (postorder);
 
   auto_sbitmap worklist (last_basic_block_for_fn (cfun) + 1);
-  bitmap_ones (worklist);
+  bitmap_clear (worklist);
+  FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds)
+    bitmap_set_bit (worklist, e->src->index);
   while (changed)
     {
       if (dump_file && (dump_flags & TDF_DETAILS))
@@ -2770,6 +2773,8 @@ create_expression_by_pieces (basic_block block, pre_expr expr,
        that value numbering saw through.  */
     case NAME:
       folded = PRE_EXPR_NAME (expr);
+      if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (folded))
+	return NULL_TREE;
       if (useless_type_conversion_p (exprtype, TREE_TYPE (folded)))
 	return folded;
       break;