[pushed] analyzer: fix ICE on negative values for size_t [PR114472]

[pushed] analyzer: fix ICE on negative values for size_t [PR114472]

[David Malcolm]

I made several attempts to fix this properly, but for now apply
a band-aid to at least prevent crashing on such cases.

Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
Successful run of analyzer integration tests on x86_64-pc-linux-gnu.
Pushed to trunk as r14-9902-g4a94551d7eaaf7.

gcc/analyzer/ChangeLog:
	PR analyzer/114472
	* access-diagram.cc (bit_size_expr::maybe_get_formatted_str):
	Reject attempts to print sizes that are too large.
	* region.cc (region_offset::calc_symbolic_bit_offset): Use a
	typeless svalue for the bit offset.
	* store.cc (bit_range::intersects_p): Replace assertion with
	test.
	(bit_range::exceeds_p): Likewise.
	(bit_range::falls_short_of_p): Likewise.

gcc/testsuite/ChangeLog:
	* c-c++-common/analyzer/out-of-bounds-pr114472.c: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>
---
 gcc/analyzer/access-diagram.cc                |  4 ++++
 gcc/analyzer/region.cc                        |  2 +-
 gcc/analyzer/store.cc                         | 20 +++++++++++++++----
 .../analyzer/out-of-bounds-pr114472.c         | 17 ++++++++++++++++
 4 files changed, 38 insertions(+), 5 deletions(-)
 create mode 100644 gcc/testsuite/c-c++-common/analyzer/out-of-bounds-pr114472.c

diff --git a/gcc/analyzer/access-diagram.cc b/gcc/analyzer/access-diagram.cc
index 4cb6570e90b9..873205c46499 100644
--- a/gcc/analyzer/access-diagram.cc
+++ b/gcc/analyzer/access-diagram.cc
@@ -373,6 +373,8 @@ bit_size_expr::maybe_get_formatted_str (text_art::style_manager &sm,
       if (tree cst = num_bytes->maybe_get_constant ())
 	{
 	  byte_size_t concrete_num_bytes = wi::to_offset (cst);
+	  if (!wi::fits_uhwi_p (concrete_num_bytes))
+	    return nullptr;
 	  if (concrete_num_bytes == 1)
 	    return ::make_unique <text_art::styled_string>
 	      (fmt_styled_string (sm, concrete_single_byte_fmt,
@@ -396,6 +398,8 @@ bit_size_expr::maybe_get_formatted_str (text_art::style_manager &sm,
   else if (tree cst = m_num_bits.maybe_get_constant ())
     {
       bit_size_t concrete_num_bits = wi::to_offset (cst);
+      if (!wi::fits_uhwi_p (concrete_num_bits))
+	return nullptr;
       if (concrete_num_bits == 1)
 	return ::make_unique <text_art::styled_string>
 	  (fmt_styled_string (sm, concrete_single_bit_fmt,
diff --git a/gcc/analyzer/region.cc b/gcc/analyzer/region.cc
index 705816b62454..7d79b45563fd 100644
--- a/gcc/analyzer/region.cc
+++ b/gcc/analyzer/region.cc
@@ -89,7 +89,7 @@ region_offset::calc_symbolic_bit_offset (region_model_manager *mgr) const
 					m_sym_offset, bits_per_byte);
     }
   else
-    return *mgr->get_or_create_int_cst (size_type_node, m_offset);
+    return *mgr->get_or_create_int_cst (NULL_TREE, m_offset);
 }
 
 const svalue *
diff --git a/gcc/analyzer/store.cc b/gcc/analyzer/store.cc
index e85a19647f7e..a36de13c1743 100644
--- a/gcc/analyzer/store.cc
+++ b/gcc/analyzer/store.cc
@@ -290,7 +290,10 @@ bit_range::intersects_p (const bit_range &other,
       bit_offset_t overlap_next
 	= MIN (get_next_bit_offset (),
 	       other.get_next_bit_offset ());
-      gcc_assert (overlap_next > overlap_start);
+      if (overlap_next <= overlap_start)
+	/* If this has happened, some kind of overflow has happened in
+	   our arithmetic.  For now, reject such cases.  */
+	return false;
       bit_range abs_overlap_bits (overlap_start, overlap_next - overlap_start);
       *out_this = abs_overlap_bits - get_start_bit_offset ();
       *out_other = abs_overlap_bits - other.get_start_bit_offset ();
@@ -316,7 +319,10 @@ bit_range::intersects_p (const bit_range &other,
 					 other.get_start_bit_offset ());
       bit_offset_t overlap_next = MIN (get_next_bit_offset (),
 					other.get_next_bit_offset ());
-      gcc_assert (overlap_next > overlap_start);
+      if (overlap_next <= overlap_start)
+	/* If this has happened, some kind of overflow has happened in
+	   our arithmetic.  For now, reject such cases.  */
+	return false;
       *out_num_overlap_bits = overlap_next - overlap_start;
       return true;
     }
@@ -339,7 +345,10 @@ bit_range::exceeds_p (const bit_range &other,
       bit_offset_t start = MAX (get_start_bit_offset (),
 				 other.get_next_bit_offset ());
       bit_offset_t size = get_next_bit_offset () - start;
-      gcc_assert (size > 0);
+      if (size <= 0)
+	/* If this has happened, some kind of overflow has happened in
+	   our arithmetic.  For now, reject such cases.  */
+	return false;
       out_overhanging_bit_range->m_start_bit_offset = start;
       out_overhanging_bit_range->m_size_in_bits = size;
       return true;
@@ -362,7 +371,10 @@ bit_range::falls_short_of_p (bit_offset_t offset,
       /* THIS falls short of OFFSET.  */
       bit_offset_t start = get_start_bit_offset ();
       bit_offset_t size = MIN (offset, get_next_bit_offset ()) - start;
-      gcc_assert (size > 0);
+      if (size <= 0)
+	/* If this has happened, some kind of overflow has happened in
+	   our arithmetic.  For now, reject such cases.  */
+	return false;
       out_fall_short_bits->m_start_bit_offset = start;
       out_fall_short_bits->m_size_in_bits = size;
       return true;
diff --git a/gcc/testsuite/c-c++-common/analyzer/out-of-bounds-pr114472.c b/gcc/testsuite/c-c++-common/analyzer/out-of-bounds-pr114472.c
new file mode 100644
index 000000000000..ef9e7711a2e4
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/analyzer/out-of-bounds-pr114472.c
@@ -0,0 +1,17 @@
+/* Verify we don't ICE on cases involving very large values for size.  */
+
+char s, d;
+
+void
+foo(void)
+{
+  __builtin_strncpy(&d, &s + 3, -1); /* { dg-warning "Wstringop-overflow" } */
+  __builtin_strncpy(&d + 3, &s, -1); /* { dg-warning "Wstringop-overflow" } */
+}
+
+void
+bar(void)
+{
+  __builtin_strncpy(&d, &s - 3, -1); /* { dg-warning "Wstringop-overflow" } */
+  __builtin_strncpy(&d - 3, &s, -1); /* { dg-warning "Wstringop-overflow" } */
+}
-- 
2.26.3