fix 364058 - clarify in manual limitations of array overruns detections

Further try to clarify again with more words the way sgcheck works
and the implied limitations

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15897

diff --git a/NEWS b/NEWS
index 3520e3b906d8855fae0381577abeab5662a1c897..0df38cb6cb86423acc6532a96a53a951a174eb9f 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -107,6 +107,7 @@ where XXXXXX is the bug number as listed below.
 363680  add renameat2() support
 363705  arm64 missing syscall name_to_handle_at and open_by_handle_at
 363714  ppc64 missing syscalls sync, waitid and name_to/open_by_handle_at
+364058  clarify in manual limitations of array overruns detections
 364413  pselect sycallwrapper mishandles NULL sigmask
 364728  Power PC, missing support for several HW registrs in
         get_otrack_shadow_offset_wrk()

diff --git a/exp-sgcheck/docs/sg-manual.xml b/exp-sgcheck/docs/sg-manual.xml
index a8ee31380e2ba6bc82ca56ae18a7f6f4f3e9cee6..c03e77811d51eff6350ba1f8e810564d7235a1e3 100644 (file)
--- a/exp-sgcheck/docs/sg-manual.xml
+++ b/exp-sgcheck/docs/sg-manual.xml
@@ -100,11 +100,19 @@ does not carry any restriction from one call to the next.  Indeed,
 multiple threads may make multiple simultaneous calls to
 (e.g.) <function>memcpy</function> without mutual interference.</para>
 
+<para>It is important to note that the association is done between
+  a <emphasis>binary instruction</emphasis> and an array, the
+  <emphasis>first time</emphasis> this binary instruction accesses an
+  array during a function call.  When the same instruction is executed
+  again during the same function call, then SGCheck might report a
+  problem, if these further executions are not accessing the same
+  array. This technique causes several limitations in SGCheck, see
+  <xref linkend="sg-manual.limitations"/>.
+</para>
 </sect1>
 
 
 
-
 <sect1 id="sg-manual.cmp-w-memcheck"
        xreflabel="Comparison with Memcheck">
 <title>Comparison with Memcheck</title>
@@ -146,6 +154,9 @@ of.</para>
    function instantiation) is not checked for overrun, since SGCheck
    uses that as the "example" of how subsequent accesses should
    behave.</para>
+   <para>It also means that errors will not be found in an instruction
+     executed only once (e.g. because this instruction is not in a loop,
+     or the loop is executed only once).</para>
   </listitem>
 
   <listitem>