On 10/19/20 1:23 PM, Aldy Hernandez wrote:
Rebased on current trunk.

There is one adjustment to a C++ test which now gives a false positive.
After talking with Martin Sebor, we've concluded this is expected.  There
is no way to communicate that libstdc++ allocated objects are always
less than PTRDIFF_MAX.

I think you have addressed the various issues with Martin, as much as can be.

we'll address a mechanism to access a ranger instance from the memref and access classes later, as well as the get_size_range duality. I  dont think we should hold this up as it isn't an issue for other passes, and we'll consider a more central solution down the road.

OK

Andrew


OK?

     gcc/ChangeLog:

             * calls.c (get_size_range): Adjust to work with ranger.
             * calls.h (get_size_range): Add ranger argument to prototype.
             * gimple-ssa-warn-restrict.c (class wrestrict_dom_walker): Remove.
             (check_call): Pull out of wrestrict_dom_walker into a
             static function.
             (wrestrict_dom_walker::before_dom_children): Rename to...
             (wrestrict_walk): ...this.
             (pass_wrestrict::execute): Instantiate ranger.
             (class builtin_memref): Add stmt and query fields.
             (builtin_access::builtin_access): Add range_query field.
             (builtin_memref::builtin_memref): Same.
             (builtin_memref::extend_offset_range): Same.
             (builtin_access::builtin_access): Make work with ranger.
             (wrestrict_dom_walker::check_call): Pull out into...
             (check_call): ...here.
             (check_bounds_or_overlap): Add range_query argument.
             * gimple-ssa-warn-restrict.h (check_bounds_or_overlap):
             Add range_query and gimple stmt arguments.

     gcc/testsuite/ChangeLog:

         * gcc.dg/Wrestrict-22.c: New test.
         * g++.dg/torture/pr92421.C: Adjust for ranger.

     libstdc++-v3/ChangeLog:

        * testsuite/21_strings/basic_string/capacity/1.cc: Pass
        -Wno-stringop-overflow to test.
---
  gcc/calls.c                                   | 26 ++++-
  gcc/calls.h                                   |  2 +
  gcc/gimple-ssa-warn-restrict.c                | 99 +++++++++++--------
  gcc/gimple-ssa-warn-restrict.h                |  3 +
  gcc/testsuite/g++.dg/torture/pr92421.C        |  4 +
  gcc/testsuite/gcc.dg/Wrestrict-22.c           |  9 ++
  .../21_strings/basic_string/capacity/1.cc     |  2 +
  7 files changed, 104 insertions(+), 41 deletions(-)
  create mode 100644 gcc/testsuite/gcc.dg/Wrestrict-22.c

diff --git a/gcc/calls.c b/gcc/calls.c
index d3120b23f60..a12b84744c0 100644
--- a/gcc/calls.c
+++ b/gcc/calls.c
@@ -59,6 +59,7 @@ along with GCC; see the file COPYING3.  If not see
  #include "builtins.h"
  #include "gimple-fold.h"
  #include "attr-fnspec.h"
+#include "value-query.h"
#include "tree-pretty-print.h" @@ -1244,7 +1245,8 @@ alloc_max_size (void)
     in a multi-range, otherwise to the smallest valid subrange.  */
bool
-get_size_range (tree exp, tree range[2], int flags /* = 0 */)
+get_size_range (range_query *query, tree exp, gimple *stmt, tree range[2],
+               int flags /* = 0 */)
  {
    if (!exp)
      return false;
@@ -1263,7 +1265,21 @@ get_size_range (tree exp, tree range[2], int flags /* = 
0 */)
    enum value_range_kind range_type;
if (integral)
-    range_type = determine_value_range (exp, &min, &max);
+    {
+      value_range vr;
+      if (query && query->range_of_expr (vr, exp, stmt))
+       {
+         range_type = vr.kind ();
+         if (!vr.undefined_p ())
+           {
+             min = wi::to_wide (vr.min ());
+             max = wi::to_wide (vr.max ());
+           }
+       }
+      else
+       range_type = determine_value_range (exp, &min, &max);
+
+    }
    else
      range_type = VR_VARYING;
@@ -1369,6 +1385,12 @@ get_size_range (tree exp, tree range[2], int flags /* = 0 */)
    return true;
  }
+bool
+get_size_range (tree exp, tree range[2], int flags /* = 0 */)
+{
+  return get_size_range (/*query=*/NULL, exp, /*stmt=*/NULL, range, flags);
+}
+
  /* Diagnose a call EXP to function FN decorated with attribute alloc_size
     whose argument numbers given by IDX with values given by ARGS exceed
     the maximum object size or cause an unsigned oveflow (wrapping) when
diff --git a/gcc/calls.h b/gcc/calls.h
index 644ec45d92c..f32b6308b58 100644
--- a/gcc/calls.h
+++ b/gcc/calls.h
@@ -142,6 +142,8 @@ enum size_range_flags
     SR_USE_LARGEST = 2
    };
  extern bool get_size_range (tree, tree[2], int = 0);
+extern bool get_size_range (class range_query *, tree, gimple *,
+                           tree[2], int = 0);
  extern rtx rtx_for_static_chain (const_tree, bool);
  extern bool cxx17_empty_base_field_p (const_tree);
diff --git a/gcc/gimple-ssa-warn-restrict.c b/gcc/gimple-ssa-warn-restrict.c
index e2734c81456..3a79e7240f9 100644
--- a/gcc/gimple-ssa-warn-restrict.c
+++ b/gcc/gimple-ssa-warn-restrict.c
@@ -25,7 +25,6 @@
  #include "backend.h"
  #include "tree.h"
  #include "gimple.h"
-#include "domwalk.h"
  #include "tree-pass.h"
  #include "builtins.h"
  #include "ssa.h"
@@ -41,6 +40,7 @@
  #include "calls.h"
  #include "cfgloop.h"
  #include "intl.h"
+#include "gimple-range.h"
namespace { @@ -77,21 +77,10 @@ pass_wrestrict::gate (function *fun ATTRIBUTE_UNUSED)
    return warn_array_bounds || warn_restrict || warn_stringop_overflow;
  }
-/* Class to walk the basic blocks of a function in dominator order. */
-class wrestrict_dom_walker : public dom_walker
-{
- public:
-  wrestrict_dom_walker () : dom_walker (CDI_DOMINATORS) {}
+static void check_call (range_query *, gimple *);
- edge before_dom_children (basic_block) FINAL OVERRIDE;
-  bool handle_gimple_call (gimple_stmt_iterator *);
-
- private:
-  void check_call (gimple *);
-};
-
-edge
-wrestrict_dom_walker::before_dom_children (basic_block bb)
+static void
+wrestrict_walk (range_query *query, basic_block bb)
  {
    /* Iterate over statements, looking for function calls.  */
    for (gimple_stmt_iterator si = gsi_start_bb (bb); !gsi_end_p (si);
@@ -101,21 +90,17 @@ wrestrict_dom_walker::before_dom_children (basic_block bb)
        if (!is_gimple_call (stmt))
        continue;
- check_call (stmt);
+      check_call (query, stmt);
      }
-
-  return NULL;
  }
-/* Execute the pass for function FUN, walking in dominator order. */
-
  unsigned
  pass_wrestrict::execute (function *fun)
  {
-  calculate_dominance_info (CDI_DOMINATORS);
-
-  wrestrict_dom_walker walker;
-  walker.walk (ENTRY_BLOCK_PTR_FOR_FN (fun));
+  gimple_ranger ranger;
+  basic_block bb;
+  FOR_EACH_BB_FN (bb, fun)
+    wrestrict_walk (&ranger, bb);
return 0;
  }
@@ -159,11 +144,15 @@ public:
       only the destination reference is.  */
    bool strbounded_p;
- builtin_memref (tree, tree);
+  builtin_memref (range_query *, gimple *, tree, tree);
tree offset_out_of_bounds (int, offset_int[3]) const; private:
+  /* Call statement to the built-in.  */
+  gimple *stmt;
+
+  range_query *query;
/* Ctor helper to set or extend OFFRANGE based on argument. */
    void extend_offset_range (tree);
@@ -197,7 +186,7 @@ class builtin_access
            && detect_overlap != &builtin_access::no_overlap);
    }
- builtin_access (gimple *, builtin_memref &, builtin_memref &);
+  builtin_access (range_query *, gimple *, builtin_memref &, builtin_memref &);
/* Entry point to determine overlap. */
    bool overlap ();
@@ -233,9 +222,10 @@ class builtin_access
/* Initialize a memory reference representation from a pointer EXPR and
     a size SIZE in bytes.  If SIZE is NULL_TREE then the size is assumed
-   to be unknown.  */
+   to be unknown.  STMT is the statement in which expr appears in.  */
-builtin_memref::builtin_memref (tree expr, tree size)
+builtin_memref::builtin_memref (range_query *query, gimple *stmt, tree expr,
+                               tree size)
  : ptr (expr),
    ref (),
    base (),
@@ -245,7 +235,9 @@ builtin_memref::builtin_memref (tree expr, tree size)
    offrange (),
    sizrange (),
    maxobjsize (tree_to_shwi (max_object_size ())),
-  strbounded_p ()
+  strbounded_p (),
+  stmt (stmt),
+  query (query)
  {
    /* Unfortunately, wide_int default ctor is a no-op so array members
       of the type must be set individually.  */
@@ -264,7 +256,7 @@ builtin_memref::builtin_memref (tree expr, tree size)
        tree range[2];
        /* Determine the size range, allowing for the result to be [0, 0]
         for SIZE in the anti-range ~[0, N] where N >= PTRDIFF_MAX.  */
-      get_size_range (size, range, SR_ALLOW_ZERO);
+      get_size_range (query, size, stmt, range, SR_ALLOW_ZERO);
        sizrange[0] = wi::to_offset (range[0]);
        sizrange[1] = wi::to_offset (range[1]);
        /* get_size_range returns SIZE_MAX for the maximum size.
@@ -341,7 +333,24 @@ builtin_memref::extend_offset_range (tree offset)
        /* A pointer offset is represented as sizetype but treated
         as signed.  */
        wide_int min, max;
-      value_range_kind rng = get_range_info (offset, &min, &max);
+      value_range_kind rng;
+      value_range vr;
+      if (query && query->range_of_expr (vr, offset, stmt))
+       {
+         rng = vr.kind ();
+         if (!vr.undefined_p ())
+           {
+             min = wi::to_wide (vr.min ());
+             max = wi::to_wide (vr.max ());
+           }
+       }
+      else
+       {
+         /* There is a global version here because
+            check_bounds_or_overlap may be called from gimple
+            fold during gimple lowering.  */
+         rng = get_range_info (offset, &min, &max);
+       }
        if (rng == VR_ANTI_RANGE && wi::lts_p (max, min))
        {
          /* Convert an anti-range whose upper bound is less than
@@ -658,7 +667,8 @@ builtin_memref::offset_out_of_bounds (int strict, 
offset_int ooboff[3]) const
  /* Create an association between the memory references DST and SRC
     for access by a call EXPR to a memory or string built-in funtion.  */
-builtin_access::builtin_access (gimple *call, builtin_memref &dst,
+builtin_access::builtin_access (range_query *query, gimple *call,
+                               builtin_memref &dst,
                                builtin_memref &src)
  : dstref (&dst), srcref (&src), sizrange (), ovloff (), ovlsiz (),
    dstoff (), srcoff (), dstsiz (), srcsiz ()
@@ -797,7 +807,7 @@ builtin_access::builtin_access (gimple *call, builtin_memref 
&dst,
tree size = gimple_call_arg (call, sizeargno);
        tree range[2];
-      if (get_size_range (size, range, true))
+      if (get_size_range (query, size, call, range, true))
        {
          bounds[0] = wi::to_offset (range[0]);
          bounds[1] = wi::to_offset (range[1]);
@@ -1873,8 +1883,8 @@ maybe_diag_access_bounds (gimple *call, tree func, int 
strict,
  /* Check a CALL statement for restrict-violations and issue warnings
     if/when appropriate.  */
-void
-wrestrict_dom_walker::check_call (gimple *call)
+static void
+check_call (range_query *query, gimple *call)
  {
    /* Avoid checking the call if it has already been diagnosed for
       some reason.  */
@@ -1964,7 +1974,7 @@ wrestrict_dom_walker::check_call (gimple *call)
        || (dstwr && !INTEGRAL_TYPE_P (TREE_TYPE (dstwr))))
      return;
- if (!check_bounds_or_overlap (call, dst, src, dstwr, NULL_TREE))
+  if (!check_bounds_or_overlap (query, call, dst, src, dstwr, NULL_TREE))
      return;
/* Avoid diagnosing the call again. */
@@ -1984,15 +1994,26 @@ int
  check_bounds_or_overlap (gimple *call, tree dst, tree src, tree dstsize,
                         tree srcsize, bool bounds_only /* = false */,
                         bool do_warn /* = true */)
+{
+  return check_bounds_or_overlap (/*range_query=*/NULL,
+                                 call, dst, src, dstsize, srcsize,
+                                 bounds_only, do_warn);
+}
+
+int
+check_bounds_or_overlap (range_query *query,
+                        gimple *call, tree dst, tree src, tree dstsize,
+                        tree srcsize, bool bounds_only /* = false */,
+                        bool do_warn /* = true */)
  {
    tree func = gimple_call_fndecl (call);
- builtin_memref dstref (dst, dstsize);
-  builtin_memref srcref (src, srcsize);
+  builtin_memref dstref (query, call, dst, dstsize);
+  builtin_memref srcref (query, call, src, srcsize);
/* Create a descriptor of the access. This may adjust both DSTREF
       and SRCREF based on one another and the kind of the access.  */
-  builtin_access acs (call, dstref, srcref);
+  builtin_access acs (query, call, dstref, srcref);
/* Set STRICT to the value of the -Warray-bounds=N argument for
       string functions or when N > 1.  */
diff --git a/gcc/gimple-ssa-warn-restrict.h b/gcc/gimple-ssa-warn-restrict.h
index 7bae95a9ad1..3dba9c0fe58 100644
--- a/gcc/gimple-ssa-warn-restrict.h
+++ b/gcc/gimple-ssa-warn-restrict.h
@@ -22,5 +22,8 @@
extern int check_bounds_or_overlap (gimple *, tree, tree, tree, tree,
                                    bool = false, bool = true);
+extern int check_bounds_or_overlap (class range_query *, gimple *,
+                                   tree, tree, tree, tree,
+                                   bool = false, bool = true);
#endif /* GIMPLE_SSA_WARN_RESTRICT_H */
diff --git a/gcc/testsuite/g++.dg/torture/pr92421.C 
b/gcc/testsuite/g++.dg/torture/pr92421.C
index 2146e9416db..0489eb75d9a 100644
--- a/gcc/testsuite/g++.dg/torture/pr92421.C
+++ b/gcc/testsuite/g++.dg/torture/pr92421.C
@@ -2,6 +2,10 @@
  // { dg-do compile }
  // { dg-additional-options "-Wno-return-type" }
+// VRP jump threading will create additional __builtin___memcpy_chk calls that
+// may be out of bounds.
+// { dg-additional-options "-Wno-stringop-overflow" }
+
  typedef long a;
  void *b, *c;
  template <typename, typename> class d {};
diff --git a/gcc/testsuite/gcc.dg/Wrestrict-22.c 
b/gcc/testsuite/gcc.dg/Wrestrict-22.c
new file mode 100644
index 00000000000..46f507b56b6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wrestrict-22.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wrestrict" } */
+
+void test_memcpy_warn (char *d, unsigned n)
+{
+  for (unsigned i = n; i < 30; ++i)
+    if (i > 10)
+      __builtin_memcpy (d, d + 2, i); /* { dg-warning "overlaps" } */
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/capacity/1.cc 
b/libstdc++-v3/testsuite/21_strings/basic_string/capacity/1.cc
index a60f2d62da8..92f2bf40f14 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/capacity/1.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/capacity/1.cc
@@ -17,6 +17,8 @@
  // with this library; see the file COPYING3.  If not see
  // <http://www.gnu.org/licenses/>.
+// { dg-options "-Wno-stringop-overflow" }
+
  // 21.3.3 string capacity
#include <string>

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