analyzer: handle strlen(INIT_VAL(STRING_REG)) [PR105899]

gcc/analyzer/ChangeLog:
	PR analyzer/105899
	* region-model.cc (fragment::has_null_terminator): Move STRING_CST
	handling to fragment::string_cst_has_null_terminator; also use it to
	handle INIT_VAL(STRING_REG).
	(fragment::string_cst_has_null_terminator): New, from above.

gcc/testsuite/ChangeLog:
	PR analyzer/105899
	* gcc.dg/analyzer/strcpy-3.c (test_2): New.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

2 files changed, 54 insertions, 21 deletions

diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc
index 00c306a..6574ec1 100644
--- a/gcc/analyzer/region-model.cc
+++ b/gcc/analyzer/region-model.cc
@@ -3310,27 +3310,10 @@ struct fragment
 	  switch (TREE_CODE (cst))
 	    {
 	    case STRING_CST:
-	      {
-		/* Look for the first 0 byte within STRING_CST
-		   from START_READ_OFFSET onwards.  */
-		const HOST_WIDE_INT num_bytes_to_search
-		  = std::min<HOST_WIDE_INT> ((TREE_STRING_LENGTH (cst)
-					      - rel_start_read_offset_hwi),
-					     available_bytes_hwi);
-		const char *start = (TREE_STRING_POINTER (cst)
-				     + rel_start_read_offset_hwi);
-		if (num_bytes_to_search >= 0)
-		  if (const void *p = memchr (start, 0,
-					      num_bytes_to_search))
-		    {
-		      *out_bytes_read = (const char *)p - start + 1;
-		      return tristate (true);
-		    }
-
-		*out_bytes_read = available_bytes;
-		return tristate (false);
-	      }
-	      break;
+	      return string_cst_has_null_terminator (cst,
+						     rel_start_read_offset_hwi,
+						     available_bytes_hwi,
+						     out_bytes_read);
 	    case INTEGER_CST:
 	      if (rel_start_read_offset_hwi == 0
 		  && integer_onep (TYPE_SIZE_UNIT (TREE_TYPE (cst))))
@@ -3357,12 +3340,55 @@ struct fragment
 	    }
 	}
 	break;
+
+      case SK_INITIAL:
+	{
+	  const initial_svalue *initial_sval = (const initial_svalue *)m_sval;
+	  const region *reg = initial_sval->get_region ();
+	  if (const string_region *string_reg = reg->dyn_cast_string_region ())
+	    {
+	      tree string_cst = string_reg->get_string_cst ();
+	      return string_cst_has_null_terminator (string_cst,
+						     rel_start_read_offset_hwi,
+						     available_bytes_hwi,
+						     out_bytes_read);
+	    }
+	  return tristate::TS_UNKNOWN;
+	}
+	break;
+
       default:
 	// TODO: it may be possible to handle other cases here.
 	return tristate::TS_UNKNOWN;
       }
   }
 
+  static tristate
+  string_cst_has_null_terminator (tree string_cst,
+				  HOST_WIDE_INT rel_start_read_offset_hwi,
+				  HOST_WIDE_INT available_bytes_hwi,
+				  byte_offset_t *out_bytes_read)
+  {
+    /* Look for the first 0 byte within STRING_CST
+       from START_READ_OFFSET onwards.  */
+    const HOST_WIDE_INT num_bytes_to_search
+      = std::min<HOST_WIDE_INT> ((TREE_STRING_LENGTH (string_cst)
+				  - rel_start_read_offset_hwi),
+				 available_bytes_hwi);
+    const char *start = (TREE_STRING_POINTER (string_cst)
+			 + rel_start_read_offset_hwi);
+    if (num_bytes_to_search >= 0)
+      if (const void *p = memchr (start, 0,
+				  num_bytes_to_search))
+	{
+	  *out_bytes_read = (const char *)p - start + 1;
+	  return tristate (true);
+	}
+
+    *out_bytes_read = available_bytes_hwi;
+    return tristate (false);
+  }
+
   byte_range m_byte_range;
   const svalue *m_sval;
 };
diff --git a/gcc/testsuite/gcc.dg/analyzer/strcpy-3.c b/gcc/testsuite/gcc.dg/analyzer/strcpy-3.c
index abb49bc..a7b324f 100644
--- a/gcc/testsuite/gcc.dg/analyzer/strcpy-3.c
+++ b/gcc/testsuite/gcc.dg/analyzer/strcpy-3.c
@@ -22,3 +22,10 @@ void test_1 (void)
   __analyzer_eval (result[5] == 0); /* { dg-warning "TRUE" } */
   __analyzer_eval (strlen (result) == 5); /* { dg-warning "TRUE" } */
 }
+
+void test_2 (void)
+{
+  char buf[16];
+  __builtin_strcpy (buf, "abc");
+  __analyzer_eval (strlen (buf) == 3); /* { dg-warning "TRUE" } */
+}