Patch: FYI: libgcj verifier fix
Tom Tromey
tromey@redhat.com
Thu Feb 13 23:43:00 GMT 2003
I'm checking this in to 3.3 and 3.4.
This fixes a verifier bug that manifested as an infinite loop. There
is a test case for this in the Mauve `verify' module; it is
"subr.pass.nonret". Some compilers (including the current gcj) can
generate code that cause this problem.
Tested against the Mauve verify tests.
Tom
Index: ChangeLog
from Tom Tromey <tromey@redhat.com>
* verify.cc (state::seen_subrs): New field.
(state::state): Initialize it.
(state::clean_subrs): New method.
(state::~state): Call it.
(state::copy): Copy subroutine list.
(state::add_subr): New method.
(state::merge): Only register a change if the current subroutine
hasn't yet been noted.
Index: verify.cc
===================================================================
RCS file: /cvs/gcc/gcc/libjava/verify.cc,v
retrieving revision 1.48
diff -u -r1.48 verify.cc
--- verify.cc 5 Dec 2002 02:23:57 -0000 1.48
+++ verify.cc 13 Feb 2003 23:37:35 -0000
@@ -1,6 +1,6 @@
// defineclass.cc - defining a class from .class format.
-/* Copyright (C) 2001, 2002 Free Software Foundation
+/* Copyright (C) 2001, 2002, 2003 Free Software Foundation
This file is part of libgcj.
@@ -128,6 +128,34 @@
return r;
}
+ __attribute__ ((__noreturn__)) void verify_fail (char *s, jint pc = -1)
+ {
+ using namespace java::lang;
+ StringBuffer *buf = new StringBuffer ();
+
+ buf->append (JvNewStringLatin1 ("verification failed"));
+ if (pc == -1)
+ pc = start_PC;
+ if (pc != -1)
+ {
+ buf->append (JvNewStringLatin1 (" at PC "));
+ buf->append (pc);
+ }
+
+ _Jv_InterpMethod *method = current_method;
+ buf->append (JvNewStringLatin1 (" in "));
+ buf->append (current_class->getName());
+ buf->append ((jchar) ':');
+ buf->append (JvNewStringUTF (method->get_method()->name->data));
+ buf->append ((jchar) '(');
+ buf->append (JvNewStringUTF (method->get_method()->signature->data));
+ buf->append ((jchar) ')');
+
+ buf->append (JvNewStringLatin1 (": "));
+ buf->append (JvNewStringLatin1 (s));
+ throw new java::lang::VerifyError (buf->toString ());
+ }
+
// This enum holds a list of tags for all the different types we
// need to handle. Reference types are treated specially by the
// type class.
@@ -793,6 +821,12 @@
// assigns to locals[0] (overwriting `this') and then returns
// without really initializing.
type this_type;
+ // This is a list of all subroutines that have been seen at this
+ // point. Ordinarily this is NULL; it is only allocated and used
+ // in relatively weird situations involving non-ret exit from a
+ // subroutine. We have to keep track of this in this way to avoid
+ // endless recursion in these cases.
+ subr_info *seen_subrs;
// INVALID marks a state which is not on the linked list of states
// requiring reverification.
@@ -811,6 +845,7 @@
stack = NULL;
locals = NULL;
local_changed = NULL;
+ seen_subrs = NULL;
}
state (int max_stack, int max_locals)
@@ -823,6 +858,7 @@
stack[i] = unsuitable_type;
locals = new type[max_locals];
local_changed = (bool *) _Jv_Malloc (sizeof (bool) * max_locals);
+ seen_subrs = NULL;
for (int i = 0; i < max_locals; ++i)
{
locals[i] = unsuitable_type;
@@ -838,6 +874,7 @@
stack = new type[max_stack];
locals = new type[max_locals];
local_changed = (bool *) _Jv_Malloc (sizeof (bool) * max_locals);
+ seen_subrs = NULL;
copy (orig, max_stack, max_locals, ret_semantics);
next = INVALID;
}
@@ -850,6 +887,7 @@
delete[] locals;
if (local_changed)
_Jv_Free (local_changed);
+ clean_subrs ();
}
void *operator new[] (size_t bytes)
@@ -872,6 +910,17 @@
_Jv_Free (mem);
}
+ void clean_subrs ()
+ {
+ subr_info *info = seen_subrs;
+ while (info != NULL)
+ {
+ subr_info *next = info->next;
+ _Jv_Free (info);
+ info = next;
+ }
+ }
+
void copy (const state *copy, int max_stack, int max_locals,
bool ret_semantics = false)
{
@@ -891,6 +940,16 @@
locals[i] = copy->locals[i];
local_changed[i] = copy->local_changed[i];
}
+
+ clean_subrs ();
+ if (copy->seen_subrs)
+ {
+ for (subr_info *info = seen_subrs; info != NULL; info = info->next)
+ add_subr (info->pc);
+ }
+ else
+ seen_subrs = NULL;
+
this_type = copy->this_type;
// Don't modify `next'.
}
@@ -917,6 +976,15 @@
local_changed[i] = false;
}
+ // Indicate that we've been in this this subroutine.
+ void add_subr (int pc)
+ {
+ subr_info *n = (subr_info *) _Jv_Malloc (sizeof (subr_info));
+ n->pc = pc;
+ n->next = seen_subrs;
+ seen_subrs = n;
+ }
+
// Merge STATE_OLD into this state. Destructively modifies this
// state. Returns true if the new state was in fact changed.
// Will throw an exception if the states are not mergeable.
@@ -944,10 +1012,23 @@
}
else
{
- // If the subroutines differ, indicate that the state
- // changed. This is needed to detect when subroutines have
- // merged.
- changed = true;
+ // If the subroutines differ, and we haven't seen this
+ // subroutine before, indicate that the state changed. This
+ // is needed to detect when subroutines have merged.
+ bool found = false;
+ for (subr_info *info = seen_subrs; info != NULL; info = info->next)
+ {
+ if (info->pc == state_old->subroutine)
+ {
+ found = true;
+ break;
+ }
+ }
+ if (! found)
+ {
+ add_subr (state_old->subroutine);
+ changed = true;
+ }
}
// Merge stacks. Special handling for NO_STACK case.
@@ -3062,34 +3143,6 @@
start_PC);
}
}
- }
-
- __attribute__ ((__noreturn__)) void verify_fail (char *s, jint pc = -1)
- {
- using namespace java::lang;
- StringBuffer *buf = new StringBuffer ();
-
- buf->append (JvNewStringLatin1 ("verification failed"));
- if (pc == -1)
- pc = start_PC;
- if (pc != -1)
- {
- buf->append (JvNewStringLatin1 (" at PC "));
- buf->append (pc);
- }
-
- _Jv_InterpMethod *method = current_method;
- buf->append (JvNewStringLatin1 (" in "));
- buf->append (current_class->getName());
- buf->append ((jchar) ':');
- buf->append (JvNewStringUTF (method->get_method()->name->data));
- buf->append ((jchar) '(');
- buf->append (JvNewStringUTF (method->get_method()->signature->data));
- buf->append ((jchar) ')');
-
- buf->append (JvNewStringLatin1 (": "));
- buf->append (JvNewStringLatin1 (s));
- throw new java::lang::VerifyError (buf->toString ());
}
public:
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