[committed] v3: vrp_prop: Use dom_walker for -Warray-bounds (PR tree-optimization/83312)

Message ID 1513272476-37848-1-git-send-email-dmalcolm@redhat.com
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  • [committed] v3: vrp_prop: Use dom_walker for -Warray-bounds (PR tree-optimization/83312)
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Commit Message

David Malcolm Dec. 14, 2017, 5:27 p.m.
On Thu, 2017-12-14 at 11:53 +0100, Richard Biener wrote:
> On Wed, Dec 13, 2017 at 10:30 PM, David Malcolm <dmalcolm@redhat.com>

> wrote:

> > On Wed, 2017-12-13 at 10:47 -0700, Jeff Law wrote:

> > > On 12/13/2017 09:24 AM, Richard Biener wrote:

> > > > > 

> > > > > Alternately we could to the dom_walker ctor that an initial

> > > > > state

> > > > > of

> > > > > EDGE_EXECUTABLE is already set.

> > > > 

> > > > I'm quite sure that wouldn't help for VRP.

> > > 

> > > Not sure why.  But it's not worth digging deep into.

> > > 

> > > I do think the current structure could still fail to pick up some

> > > secondary cases where blocks become unreachable as a result of

> > > both

> > > not

> > > needing to visit during the lattice propagation step and the

> > > substitution step.  But I'd expect this to be rare.

> > > 

> > > > I think David's approach is fine just we don't need any other

> > > > API

> > > > to get at a known executable outgoing edge. We can improve the

> > > > existing one or just add the trivial folding required.

> > > 

> > > I think Michael's suggestion to pass in NULL for the value and

> > > allow

> > > find_edge to try and determine the value makes the most sense

> > > here.

> > > 

> > > Jeff

> > 

> > Michael: thanks for the hint about find_taken_edge; I assumed that

> > such

> > a "find the relevant out-edge" function would already exist; but I

> > didn't find it (I'm relatively unfamiliar with this part of the

> > code).

> > 

> > Here's an updated version of the patch, which eliminates the stuff

> > I

> > added to gimple.h/gimple.c changes in favor of using

> >     find_taken_edge (bb, NULL_TREE),

> > generalizing it to work with arbitrary bbs, so that the dom_walker

> > vfunc can simply use:

> >   return find_taken_edge (bb, NULL_TREE);

> > without having to check e.g. for there being a last stmt (ENTRY

> > and EXIT), or having to check that it is indeed a control statement

> > (is there a requirement at this point of the IR that we don't just

> > fall off the last statment through an out-edge?)

> > 

> > I handled var == NULL_TREE for GIMPLE_COND and GIMPLE_SWITCH,

> > but not for computed goto (find_taken_edge already handles that by

> > bailing out).

> > 

> > I also made some things "const" whilst I was touching it.

> > 

> > Successfully bootstrapped&regrtested on x86_64-pc-linux-gnu.

> > 

> > OK for trunk?

> > 

> > gcc/ChangeLog:

> >         PR tree-optimization/83312

> >         * domwalk.h (dom_walker::dom_walker): Fix typo in comment.

> >         * tree-cfg.c (find_taken_edge): Update to handle NULL_TREE

> > for

> >         "val" param, and to cope with arbitrary basic blocks.

> >         (find_taken_edge_cond_expr): Add "cond_stmt" param and use

> > it to

> >         handle NULL_TREE for "val".

> >         (find_taken_edge_switch_expr): Make "switch_stmt" param

> > const.

> >         Handle NULL_TREE for "val".

> >         (find_case_label_for_value): Make "switch_stmt" param

> > const.

> >         * tree-vrp.c (class check_array_bounds_dom_walker): New

> > subclass

> >         of dom_walker.

> >         (vrp_prop::check_all_array_refs): Reimplement as...

> >         (check_array_bounds_dom_walker::before_dom_children):

> > ...this new

> >         vfunc.  Replace linear search through BB block list,

> > excluding

> >         those with non-executable in-edges via dominator walk.

> > 

> > gcc/testsuite/ChangeLog:

> >         PR tree-optimization/83312

> >         * gcc.dg/pr83312.c: New test case.

> > ---

> >  gcc/domwalk.h                  |  2 +-

> >  gcc/testsuite/gcc.dg/pr83312.c | 30 +++++++++++++++++

> >  gcc/tree-cfg.c                 | 59 +++++++++++++++++++++---------

> > --

> >  gcc/tree-vrp.c                 | 76 ++++++++++++++++++++++++++--

> > --------------

> >  4 files changed, 117 insertions(+), 50 deletions(-)

> >  create mode 100644 gcc/testsuite/gcc.dg/pr83312.c

> > 

> > diff --git a/gcc/domwalk.h b/gcc/domwalk.h

> > index 6ac93eb..c7e3450 100644

> > --- a/gcc/domwalk.h

> > +++ b/gcc/domwalk.h

> > @@ -32,7 +32,7 @@ class dom_walker

> >  public:

> >    static const edge STOP;

> > 

> > -  /* Use SKIP_UNREACHBLE_BLOCKS = true when your client can

> > discover

> > +  /* Use SKIP_UNREACHABLE_BLOCKS = true when your client can

> > discover

> >       that some edges are not executable.

> > 

> >       If a client can discover that a COND, SWITCH or GOTO has a

> > static

> > diff --git a/gcc/testsuite/gcc.dg/pr83312.c

> > b/gcc/testsuite/gcc.dg/pr83312.c

> > new file mode 100644

> > index 0000000..2eb241d

> > --- /dev/null

> > +++ b/gcc/testsuite/gcc.dg/pr83312.c

> > @@ -0,0 +1,30 @@

> > +/* { dg-options "-O2 -Warray-bounds" } */

> > +

> > +struct ptlrpcd_ctl {

> > +  char pc_name[20];

> > +};

> > +struct ptlrpcd {

> > +  struct ptlrpcd_ctl pd_threads[6];

> > +};

> > +struct ptlrpcd *ptlrpcd_init_pd;

> > +static void ptlrpcd_ctl_init(struct ptlrpcd_ctl *pc, int index) {

> > +  if (index < 0)

> > +    __builtin_snprintf(pc->pc_name, sizeof(pc->pc_name),

> > "ptlrpcd_rcv");

> > +  else

> > +    __builtin_snprintf(pc->pc_name, sizeof(pc->pc_name),

> > "ptlrpcd_%d", index);

> > +}

> > +int ptlrpcd_init_ncpts;

> > +static int ptlrpcd_init(int nthreads) {

> > +  int j;

> > +  if (ptlrpcd_init_ncpts) {

> > +    ptlrpcd_ctl_init(&ptlrpcd_init_pd->pd_threads[0], -1);

> > +    for (j = 1; j < nthreads; j++)

> > +      ptlrpcd_ctl_init(&ptlrpcd_init_pd->pd_threads[j], j);

> > +  }

> > +  return 0;

> > +}

> > +int ptlrpcd_init_groupsize;

> > +void ptlrpcd_addref(void) {

> > +    ptlrpcd_init(ptlrpcd_init_groupsize);

> > +}

> > +

> > diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c

> > index 4d09b2c..7ecc5c8 100644

> > --- a/gcc/tree-cfg.c

> > +++ b/gcc/tree-cfg.c

> > @@ -170,9 +170,9 @@ static void gimple_merge_blocks (basic_block,

> > basic_block);

> >  static bool gimple_can_merge_blocks_p (basic_block, basic_block);

> >  static void remove_bb (basic_block);

> >  static edge find_taken_edge_computed_goto (basic_block, tree);

> > -static edge find_taken_edge_cond_expr (basic_block, tree);

> > -static edge find_taken_edge_switch_expr (gswitch *, basic_block,

> > tree);

> > -static tree find_case_label_for_value (gswitch *, tree);

> > +static edge find_taken_edge_cond_expr (const gcond *, basic_block,

> > tree);

> > +static edge find_taken_edge_switch_expr (const gswitch *,

> > basic_block, tree);

> > +static tree find_case_label_for_value (const gswitch *, tree);

> >  static void lower_phi_internal_fn ();

> > 

> >  void

> > @@ -2254,9 +2254,10 @@ remove_bb (basic_block bb)

> >  }

> > 

> > 

> > -/* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR,

> > and a

> > -   predicate VAL, return the edge that will be taken out of the

> > block.

> > -   If VAL does not match a unique edge, NULL is returned.  */

> > +/* Given a basic block BB and a predicate VAL for use in the final

> > statement

> > +   of the block, return the edge that will be taken out of the

> > block.

> > +   If VAL does not match a unique edge, NULL is returned.

> > +   If VAL is NULL_TREE, then the current value of the predicate is

> > used.  */

> > 

> >  edge

> >  find_taken_edge (basic_block bb, tree val)

> > @@ -2265,10 +2266,12 @@ find_taken_edge (basic_block bb, tree val)

> > 

> >    stmt = last_stmt (bb);

> > 

> > -  gcc_assert (is_ctrl_stmt (stmt));

> > +  /* Handle ENTRY and EXIT.  */

> > +  if (!stmt)

> > +    return NULL;

> > 

> >    if (gimple_code (stmt) == GIMPLE_COND)

> > -    return find_taken_edge_cond_expr (bb, val);

> > +    return find_taken_edge_cond_expr (as_a <gcond *> (stmt), bb,

> > val);

> > 

> >    if (gimple_code (stmt) == GIMPLE_SWITCH)

> >      return find_taken_edge_switch_expr (as_a <gswitch *> (stmt),

> > bb, val);

> > @@ -2285,10 +2288,10 @@ find_taken_edge (basic_block bb, tree val)

> >           && (TREE_CODE (val) == ADDR_EXPR || TREE_CODE (val) ==

> > LABEL_EXPR)

> >           && TREE_CODE (TREE_OPERAND (val, 0)) == LABEL_DECL)

> >         return find_taken_edge_computed_goto (bb, TREE_OPERAND

> > (val, 0));

> > -      return NULL;

> >      }

> > 

> > -  gcc_unreachable ();

> > +  /* Unable to find a unique edge.  */

> > +  return NULL;

> 

> Not sure if important but if you want to handle arbitrary BBs then

> surely

> a single successor edge (a fallthru) would qualify?  I think your

> updated

> comment doesn't reflect that passing a BB without a "predicate" is a

> valid input.

> So...

> 

>     return single_succ_p (bb) ? single_succ_edge (bb) : NULL;

> 

> ?


This isn't needed for the "dom_walker with skip_unreachable_blocks"
case in the patch, since dom_walker::walk merely uses this result to
clear the EDGE_EXECUTABLE flag from the other edges, and there won't
be any.

That said, if find_taken_edge is to support arbitrary BBs it seems
like the thing to do, and the test is cheap, so I added it.

> >  }

> > 

> >  /* Given a constant value VAL and the entry block BB to a

> > GOTO_EXPR

> > @@ -2313,15 +2316,25 @@ find_taken_edge_computed_goto (basic_block

> > bb, tree val)

> > 

> >  /* Given a constant value VAL and the entry block BB to a

> > COND_EXPR

> >     statement, determine which of the two edges will be taken out

> > of the

> > -   block.  Return NULL if either edge may be taken.  */

> > +   block.  Return NULL if either edge may be taken.

> > +   If VAL is NULL_TREE, then the current value of the predicate is

> > used.  */

> > 

> >  static edge

> > -find_taken_edge_cond_expr (basic_block bb, tree val)

> > +find_taken_edge_cond_expr (const gcond *cond_stmt, basic_block bb,

> > tree val)

> >  {

> 

> here and below the BB argument is somewhat redundant given the stmt

> has a reference to it via gimple_bb ().  Let's remove it.


Done.

> Ok with those changes.

> 

> Richard.


[...]

For reference, here's what I committed to trunk (as r255649, after
successfully bootstrap&regrtest on x86_64-pc-linux-gnu).

gcc/ChangeLog:
	PR tree-optimization/83312
	* domwalk.h (dom_walker::dom_walker): Fix typo in comment.
	* tree-cfg.c (find_taken_edge): Update to handle NULL_TREE for
	"val" param, and to cope with arbitrary basic blocks.
	(find_taken_edge_cond_expr): Add "cond_stmt" param and use it to
	handle NULL_TREE for "val", dropping "bb" param.
	(find_taken_edge_switch_expr): Make "switch_stmt" param const and
	drop "bb" param.  Handle NULL_TREE for "val".
	(find_case_label_for_value): Make "switch_stmt" param const.
	* tree-vrp.c (class check_array_bounds_dom_walker): New subclass
	of dom_walker.
	(vrp_prop::check_all_array_refs): Reimplement as...
	(check_array_bounds_dom_walker::before_dom_children): ...this new
	vfunc.  Replace linear search through BB block list, excluding
	those with non-executable in-edges via dominator walk.

gcc/testsuite/ChangeLog:
	PR tree-optimization/83312
	* gcc.dg/pr83312.c: New test case.
---
 gcc/domwalk.h                  |  2 +-
 gcc/testsuite/gcc.dg/pr83312.c | 30 ++++++++++++++++
 gcc/tree-cfg.c                 | 79 +++++++++++++++++++++++++++---------------
 gcc/tree-vrp.c                 | 76 ++++++++++++++++++++++++----------------
 4 files changed, 129 insertions(+), 58 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr83312.c

-- 
1.8.5.3

Patch

diff --git a/gcc/domwalk.h b/gcc/domwalk.h
index 6ac93eb..c7e3450 100644
--- a/gcc/domwalk.h
+++ b/gcc/domwalk.h
@@ -32,7 +32,7 @@  class dom_walker
 public:
   static const edge STOP;
 
-  /* Use SKIP_UNREACHBLE_BLOCKS = true when your client can discover
+  /* Use SKIP_UNREACHABLE_BLOCKS = true when your client can discover
      that some edges are not executable.
 
      If a client can discover that a COND, SWITCH or GOTO has a static
diff --git a/gcc/testsuite/gcc.dg/pr83312.c b/gcc/testsuite/gcc.dg/pr83312.c
new file mode 100644
index 0000000..2eb241d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr83312.c
@@ -0,0 +1,30 @@ 
+/* { dg-options "-O2 -Warray-bounds" } */
+
+struct ptlrpcd_ctl {
+  char pc_name[20];
+};
+struct ptlrpcd {
+  struct ptlrpcd_ctl pd_threads[6];
+};
+struct ptlrpcd *ptlrpcd_init_pd;
+static void ptlrpcd_ctl_init(struct ptlrpcd_ctl *pc, int index) {
+  if (index < 0)
+    __builtin_snprintf(pc->pc_name, sizeof(pc->pc_name), "ptlrpcd_rcv");
+  else
+    __builtin_snprintf(pc->pc_name, sizeof(pc->pc_name), "ptlrpcd_%d", index);
+}
+int ptlrpcd_init_ncpts;
+static int ptlrpcd_init(int nthreads) {
+  int j;
+  if (ptlrpcd_init_ncpts) {
+    ptlrpcd_ctl_init(&ptlrpcd_init_pd->pd_threads[0], -1);
+    for (j = 1; j < nthreads; j++)
+      ptlrpcd_ctl_init(&ptlrpcd_init_pd->pd_threads[j], j);
+  }
+  return 0;
+}
+int ptlrpcd_init_groupsize;
+void ptlrpcd_addref(void) {
+    ptlrpcd_init(ptlrpcd_init_groupsize);
+}
+
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 4d09b2c..c1a73d1 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -170,9 +170,9 @@  static void gimple_merge_blocks (basic_block, basic_block);
 static bool gimple_can_merge_blocks_p (basic_block, basic_block);
 static void remove_bb (basic_block);
 static edge find_taken_edge_computed_goto (basic_block, tree);
-static edge find_taken_edge_cond_expr (basic_block, tree);
-static edge find_taken_edge_switch_expr (gswitch *, basic_block, tree);
-static tree find_case_label_for_value (gswitch *, tree);
+static edge find_taken_edge_cond_expr (const gcond *, tree);
+static edge find_taken_edge_switch_expr (const gswitch *, tree);
+static tree find_case_label_for_value (const gswitch *, tree);
 static void lower_phi_internal_fn ();
 
 void
@@ -2254,9 +2254,12 @@  remove_bb (basic_block bb)
 }
 
 
-/* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
-   predicate VAL, return the edge that will be taken out of the block.
-   If VAL does not match a unique edge, NULL is returned.  */
+/* Given a basic block BB and a value VAL for use in the final statement
+   of the block (if a GIMPLE_COND, GIMPLE_SWITCH, or computed goto), return
+   the edge that will be taken out of the block.
+   If VAL is NULL_TREE, then the current value of the final statement's
+   predicate or index is used.
+   If the value does not match a unique edge, NULL is returned.  */
 
 edge
 find_taken_edge (basic_block bb, tree val)
@@ -2265,13 +2268,15 @@  find_taken_edge (basic_block bb, tree val)
 
   stmt = last_stmt (bb);
 
-  gcc_assert (is_ctrl_stmt (stmt));
+  /* Handle ENTRY and EXIT.  */
+  if (!stmt)
+    return NULL;
 
   if (gimple_code (stmt) == GIMPLE_COND)
-    return find_taken_edge_cond_expr (bb, val);
+    return find_taken_edge_cond_expr (as_a <gcond *> (stmt), val);
 
   if (gimple_code (stmt) == GIMPLE_SWITCH)
-    return find_taken_edge_switch_expr (as_a <gswitch *> (stmt), bb, val);
+    return find_taken_edge_switch_expr (as_a <gswitch *> (stmt), val);
 
   if (computed_goto_p (stmt))
     {
@@ -2285,10 +2290,10 @@  find_taken_edge (basic_block bb, tree val)
 	  && (TREE_CODE (val) == ADDR_EXPR || TREE_CODE (val) == LABEL_EXPR)
 	  && TREE_CODE (TREE_OPERAND (val, 0)) == LABEL_DECL)
 	return find_taken_edge_computed_goto (bb, TREE_OPERAND (val, 0));
-      return NULL;
     }
 
-  gcc_unreachable ();
+  /* Otherwise we only know the taken successor edge if it's unique.  */
+  return single_succ_p (bb) ? single_succ_edge (bb) : NULL;
 }
 
 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
@@ -2311,31 +2316,44 @@  find_taken_edge_computed_goto (basic_block bb, tree val)
   return e;
 }
 
-/* Given a constant value VAL and the entry block BB to a COND_EXPR
-   statement, determine which of the two edges will be taken out of the
-   block.  Return NULL if either edge may be taken.  */
+/* Given COND_STMT and a constant value VAL for use as the predicate,
+   determine which of the two edges will be taken out of
+   the statement's block.  Return NULL if either edge may be taken.
+   If VAL is NULL_TREE, then the current value of COND_STMT's predicate
+   is used.  */
 
 static edge
-find_taken_edge_cond_expr (basic_block bb, tree val)
+find_taken_edge_cond_expr (const gcond *cond_stmt, tree val)
 {
   edge true_edge, false_edge;
 
-  if (val == NULL
-      || TREE_CODE (val) != INTEGER_CST)
+  if (val == NULL_TREE)
+    {
+      /* Use the current value of the predicate.  */
+      if (gimple_cond_true_p (cond_stmt))
+	val = integer_one_node;
+      else if (gimple_cond_false_p (cond_stmt))
+	val = integer_zero_node;
+      else
+	return NULL;
+    }
+  else if (TREE_CODE (val) != INTEGER_CST)
     return NULL;
 
-  extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
+  extract_true_false_edges_from_block (gimple_bb (cond_stmt),
+				       &true_edge, &false_edge);
 
   return (integer_zerop (val) ? false_edge : true_edge);
 }
 
-/* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
-   statement, determine which edge will be taken out of the block.  Return
-   NULL if any edge may be taken.  */
+/* Given SWITCH_STMT and an INTEGER_CST VAL for use as the index, determine
+   which edge will be taken out of the statement's block.  Return NULL if any
+   edge may be taken.
+   If VAL is NULL_TREE, then the current value of SWITCH_STMT's index
+   is used.  */
 
 static edge
-find_taken_edge_switch_expr (gswitch *switch_stmt, basic_block bb,
-			     tree val)
+find_taken_edge_switch_expr (const gswitch *switch_stmt, tree val)
 {
   basic_block dest_bb;
   edge e;
@@ -2343,13 +2361,18 @@  find_taken_edge_switch_expr (gswitch *switch_stmt, basic_block bb,
 
   if (gimple_switch_num_labels (switch_stmt) == 1)
     taken_case = gimple_switch_default_label (switch_stmt);
-  else if (! val || TREE_CODE (val) != INTEGER_CST)
-    return NULL;
   else
-    taken_case = find_case_label_for_value (switch_stmt, val);
+    {
+      if (val == NULL_TREE)
+	val = gimple_switch_index (switch_stmt);
+      if (TREE_CODE (val) != INTEGER_CST)
+	return NULL;
+      else
+	taken_case = find_case_label_for_value (switch_stmt, val);
+    }
   dest_bb = label_to_block (CASE_LABEL (taken_case));
 
-  e = find_edge (bb, dest_bb);
+  e = find_edge (gimple_bb (switch_stmt), dest_bb);
   gcc_assert (e);
   return e;
 }
@@ -2360,7 +2383,7 @@  find_taken_edge_switch_expr (gswitch *switch_stmt, basic_block bb,
    sorted: We can do a binary search for a case matching VAL.  */
 
 static tree
-find_case_label_for_value (gswitch *switch_stmt, tree val)
+find_case_label_for_value (const gswitch *switch_stmt, tree val)
 {
   size_t low, high, n = gimple_switch_num_labels (switch_stmt);
   tree default_case = gimple_switch_default_label (switch_stmt);
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index a86b382..fe778b0 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -5000,44 +5000,62 @@  check_array_bounds (tree *tp, int *walk_subtree, void *data)
   return NULL_TREE;
 }
 
-/* Walk over all statements of all reachable BBs and call check_array_bounds
-   on them.  */
+/* A dom_walker subclass for use by vrp_prop::check_all_array_refs,
+   to walk over all statements of all reachable BBs and call
+   check_array_bounds on them.  */
 
-void
-vrp_prop::check_all_array_refs ()
+class check_array_bounds_dom_walker : public dom_walker
 {
-  basic_block bb;
-  gimple_stmt_iterator si;
+ public:
+  check_array_bounds_dom_walker (vrp_prop *prop)
+    : dom_walker (CDI_DOMINATORS, true), m_prop (prop) {}
+  ~check_array_bounds_dom_walker () {}
 
-  FOR_EACH_BB_FN (bb, cfun)
-    {
-      edge_iterator ei;
-      edge e;
-      bool executable = false;
+  edge before_dom_children (basic_block) FINAL OVERRIDE;
 
-      /* Skip blocks that were found to be unreachable.  */
-      FOR_EACH_EDGE (e, ei, bb->preds)
-	executable |= !!(e->flags & EDGE_EXECUTABLE);
-      if (!executable)
-	continue;
+ private:
+  vrp_prop *m_prop;
+};
 
-      for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
-	{
-	  gimple *stmt = gsi_stmt (si);
-	  struct walk_stmt_info wi;
-	  if (!gimple_has_location (stmt)
-	      || is_gimple_debug (stmt))
-	    continue;
+/* Implementation of dom_walker::before_dom_children.
 
-	  memset (&wi, 0, sizeof (wi));
+   Walk over all statements of BB and call check_array_bounds on them,
+   and determine if there's a unique successor edge.  */
 
-	  wi.info = this;
+edge
+check_array_bounds_dom_walker::before_dom_children (basic_block bb)
+{
+  gimple_stmt_iterator si;
+  for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
+    {
+      gimple *stmt = gsi_stmt (si);
+      struct walk_stmt_info wi;
+      if (!gimple_has_location (stmt)
+	  || is_gimple_debug (stmt))
+	continue;
 
-	  walk_gimple_op (gsi_stmt (si),
-			  check_array_bounds,
-			  &wi);
-	}
+      memset (&wi, 0, sizeof (wi));
+
+      wi.info = m_prop;
+
+      walk_gimple_op (stmt, check_array_bounds, &wi);
     }
+
+  /* Determine if there's a unique successor edge, and if so, return
+     that back to dom_walker, ensuring that we don't visit blocks that
+     became unreachable during the VRP propagation
+     (PR tree-optimization/83312).  */
+  return find_taken_edge (bb, NULL_TREE);
+}
+
+/* Walk over all statements of all reachable BBs and call check_array_bounds
+   on them.  */
+
+void
+vrp_prop::check_all_array_refs ()
+{
+  check_array_bounds_dom_walker w (this);
+  w.walk (ENTRY_BLOCK_PTR_FOR_FN (cfun));
 }
 
 /* Return true if all imm uses of VAR are either in STMT, or