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verify.cc (_Jv_BytecodeVerifier::type_val): Added unused_by_subroutine_type.

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* verify.cc (_Jv_BytecodeVerifier::type_val): Added
	unused_by_subroutine_type.
	(_Jv_BytecodeVerifier::type::merge): Handle
	unused_by_subroutine_type.
	(_Jv_BytecodeVerifier::state::state): Added `ret_semantics'
	argument.
	(_Jv_BytecodeVerifier::state::copy): Likewise.
	(_Jv_BytecodeVerifier::push_jump_merge): Pass `ret_semantics' to
	state constructor.
	(_Jv_BytecodeVerifier::state::is_unmerged_ret_state): New method.
	(_Jv_BytecodeVerifier::pop_jump): Don't accept a jump which is
	from an unmerged ret.
	(_Jv_BytecodeVerifier::verify_instructions_0): Don't let an
	unmerged ret state skip verification in the fall-through case.
	(debug_print): New function.
	(_Jv_BytecodeVerifier::type::print): New method.
	(_Jv_BytecodeVerifier::state::print): New method.
	(_Jv_BytecodeVerifier::push_jump_merge): Print state.
	(_Jv_BytecodeVerifier::verify_instructions_0): Likewise.
	(_Jv_BytecodeVerifier::get_variable): Don't call note_variable.
	(_Jv_BytecodeVerifier::_Jv_BytecodeVerifier): Print debug
	information.

From-SVN: r47734
This commit is contained in:
Tom Tromey 2001-12-06 23:06:11 +00:00 • committed by Tom Tromey
parent d06ba3c7e6
commit c1bf99a2ab
2 changed files with 207 additions and 19 deletions
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25
libjava/ChangeLog
View file

@ -1,3 +1,28 @@
2001-12-06 Tom Tromey <tromey@redhat.com>
* verify.cc (_Jv_BytecodeVerifier::type_val): Added
unused_by_subroutine_type.
(_Jv_BytecodeVerifier::type::merge): Handle
unused_by_subroutine_type.
(_Jv_BytecodeVerifier::state::state): Added `ret_semantics'
argument.
(_Jv_BytecodeVerifier::state::copy): Likewise.
(_Jv_BytecodeVerifier::push_jump_merge): Pass `ret_semantics' to
state constructor.
(_Jv_BytecodeVerifier::state::is_unmerged_ret_state): New method.
(_Jv_BytecodeVerifier::pop_jump): Don't accept a jump which is
from an unmerged ret.
(_Jv_BytecodeVerifier::verify_instructions_0): Don't let an
unmerged ret state skip verification in the fall-through case.
(debug_print): New function.
(_Jv_BytecodeVerifier::type::print): New method.
(_Jv_BytecodeVerifier::state::print): New method.
(_Jv_BytecodeVerifier::push_jump_merge): Print state.
(_Jv_BytecodeVerifier::verify_instructions_0): Likewise.
(_Jv_BytecodeVerifier::get_variable): Don't call note_variable.
(_Jv_BytecodeVerifier::_Jv_BytecodeVerifier): Print debug
information.
2001-12-05 Tom Tromey <tromey@redhat.com>
* defineclass.cc (character): Removed.

201
libjava/verify.cc
View file

@ -10,6 +10,8 @@ details. */
// Written by Tom Tromey <tromey@redhat.com>
// Define VERIFY_DEBUG to enable debugging output.
#include <config.h>
#include <jvm.h>
@ -25,6 +27,9 @@ details. */
#include <java/lang/reflect/Modifier.h>
#include <java/lang/StringBuffer.h>
#ifdef VERIFY_DEBUG
#include <stdio.h>
#endif /* VERIFY_DEBUG */
// TO DO
// * read more about when classes must be loaded
@ -39,6 +44,20 @@ details. */
static void verify_fail (char *msg, jint pc = -1)
__attribute__ ((__noreturn__));
static void debug_print (const char *fmt, ...)
__attribute__ ((format (printf, 1, 2)));
static inline void
debug_print (const char *fmt, ...)
{
#ifdef VERIFY_DEBUG
va_list ap;
va_start (ap, fmt);
vfprintf (stderr, fmt, ap);
va_end (ap);
#endif /* VERIFY_DEBUG */
}
class _Jv_BytecodeVerifier
{
private:
@ -147,6 +166,11 @@ private:
return_address_type,
continuation_type,
// There is an obscure special case which requires us to note when
// a local variable has not been used by a subroutine. See
// push_jump_merge for more information.
unused_by_subroutine_type,
// Everything after `reference_type' must be a reference type.
reference_type,
null_type,
@ -661,9 +685,20 @@ private:
{
if (local_semantics)
{
// If we're merging into an "unused" slot, then we
// simply accept whatever we're merging from.
if (key == unused_by_subroutine_type)
{
*this = old_type;
changed = true;
}
else if (old_type.key == unused_by_subroutine_type)
{
// Do nothing.
}
// If we already have an `unsuitable' type, then we
// don't need to change again.
if (key != unsuitable_type)
else if (key != unsuitable_type)
{
key = unsuitable_type;
changed = true;
@ -674,6 +709,35 @@ private:
}
return changed;
}
#ifdef VERIFY_DEBUG
void print (void) const
{
char c = '?';
switch (key)
{
case boolean_type: c = 'Z'; break;
case byte_type: c = 'B'; break;
case char_type: c = 'C'; break;
case short_type: c = 'S'; break;
case int_type: c = 'I'; break;
case long_type: c = 'J'; break;
case float_type: c = 'F'; break;
case double_type: c = 'D'; break;
case void_type: c = 'V'; break;
case unsuitable_type: c = '-'; break;
case return_address_type: c = 'r'; break;
case continuation_type: c = '+'; break;
case unused_by_subroutine_type: c = '_'; break;
case reference_type: c = 'L'; break;
case null_type: c = '@'; break;
case unresolved_reference_type: c = 'l'; break;
case uninitialized_reference_type: c = 'U'; break;
case uninitialized_unresolved_reference_type: c = 'u'; break;
}
debug_print ("%c", c);
}
#endif /* VERIFY_DEBUG */
};
// This class holds all the state information we need for a given
@ -731,12 +795,13 @@ private:
subroutine = 0;
}
state (const state *orig, int max_stack, int max_locals)
state (const state *orig, int max_stack, int max_locals,
bool ret_semantics = false)
{
stack = new type[max_stack];
locals = new type[max_locals];
local_changed = (bool *) _Jv_Malloc (sizeof (bool) * max_locals);
copy (orig, max_stack, max_locals);
copy (orig, max_stack, max_locals, ret_semantics);
next = INVALID;
}
@ -770,7 +835,8 @@ private:
_Jv_Free (mem);
}
void copy (const state *copy, int max_stack, int max_locals)
void copy (const state *copy, int max_stack, int max_locals,
bool ret_semantics = false)
{
stacktop = copy->stacktop;
stackdepth = copy->stackdepth;
@ -779,7 +845,13 @@ private:
stack[i] = copy->stack[i];
for (int i = 0; i < max_locals; ++i)
{
locals[i] = copy->locals[i];
// See push_jump_merge to understand this case.
if (ret_semantics)
locals[i] = type (copy->local_changed[i]
? unsuitable_type
: unused_by_subroutine_type);
else
locals[i] = copy->locals[i];
local_changed[i] = copy->local_changed[i];
}
// Don't modify `next'.
@ -869,7 +941,7 @@ private:
verify_fail ("uninitialized object in local variable");
}
// Note that a local variable was accessed or modified.
// Note that a local variable was modified.
void note_variable (int index)
{
if (subroutine > 0)
@ -885,6 +957,38 @@ private:
for (int i = 0; i < max_locals; ++i)
locals[i].set_initialized (pc);
}
// Return true if this state is the unmerged result of a `ret'.
bool is_unmerged_ret_state (int max_locals) const
{
for (int i = 0; i < max_locals; ++i)
{
if (locals[i].key == unused_by_subroutine_type)
return true;
}
return false;
}
#ifdef VERIFY_DEBUG
void print (const char *leader, int pc,
int max_stack, int max_locals) const
{
debug_print ("%s [%4d]: [stack] ", leader, pc);
int i;
for (i = 0; i < stacktop; ++i)
stack[i].print ();
for (; i < max_stack; ++i)
debug_print (".");
debug_print (" [local] ");
for (i = 0; i < max_locals; ++i)
locals[i].print ();
debug_print (" | %p\n", this);
}
#else
inline void print (const char *, int, int, int) const
{
}
#endif /* VERIFY_DEBUG */
};
type pop_raw ()
@ -980,7 +1084,6 @@ private:
if (! current_state->locals[index + 1].compatible (t))
verify_fail ("invalid local variable", start_PC);
}
current_state->note_variable (index);
return current_state->locals[index];
}
@ -1059,14 +1162,31 @@ private:
bool changed = true;
if (states[npc] == NULL)
{
// FIXME: what if we reach this code from a `ret'?
// There's a weird situation here. If are examining the
// branch that results from a `ret', and there is not yet a
// state available at the branch target (the instruction just
// after the `jsr'), then we have to construct a special kind
// of state at that point for future merging. This special
// state has the type `unused_by_subroutine_type' in each slot
// which was not modified by the subroutine.
states[npc] = new state (nstate, current_method->max_stack,
current_method->max_locals);
current_method->max_locals, ret_semantics);
debug_print ("== New state in push_jump_merge\n");
states[npc]->print ("New", npc, current_method->max_stack,
current_method->max_locals);
}
else
changed = states[npc]->merge (nstate, ret_semantics,
current_method->max_locals);
{
debug_print ("== Merge states in push_jump_merge\n");
nstate->print ("Frm", start_PC, current_method->max_stack,
current_method->max_locals);
states[npc]->print (" To", npc, current_method->max_stack,
current_method->max_locals);
changed = states[npc]->merge (nstate, ret_semantics,
current_method->max_locals);
states[npc]->print ("New", npc, current_method->max_stack,
current_method->max_locals);
}
if (changed && states[npc]->next == state::INVALID)
{
@ -1097,13 +1217,35 @@ private:
int pop_jump ()
{
int *prev_loc = &next_verify_pc;
int npc = next_verify_pc;
if (npc != state::NO_NEXT)
bool skipped = false;
while (npc != state::NO_NEXT)
{
next_verify_pc = states[npc]->next;
states[npc]->next = state::INVALID;
// If the next available PC is an unmerged `ret' state, then
// we aren't yet ready to handle it. That's because we would
// need all kind of special cases to do so. So instead we
// defer this jump until after we've processed it via a
// fall-through. This has to happen because the instruction
// before this one must be a `jsr'.
if (! states[npc]->is_unmerged_ret_state (current_method->max_locals))
{
*prev_loc = states[npc]->next;
states[npc]->next = state::INVALID;
return npc;
}
skipped = true;
prev_loc = &states[npc]->next;
npc = states[npc]->next;
}
return npc;
// If we've skipped states and there is nothing else, that's a
// bug.
if (skipped)
verify_fail ("pop_jump: can't happen");
return state::NO_NEXT;
}
void invalidate_pc ()
@ -1795,16 +1937,27 @@ private:
{
// We've already visited this instruction. So merge
// the states together. If this yields no change then
// we don't have to re-verify.
// we don't have to re-verify. However, if the new
// state is an the result of an unmerged `ret', we
// must continue through it.
debug_print ("== Fall through merge\n");
states[PC]->print ("Old", PC, current_method->max_stack,
current_method->max_locals);
current_state->print ("Cur", PC, current_method->max_stack,
current_method->max_locals);
if (! current_state->merge (states[PC], false,
current_method->max_locals))
current_method->max_locals)
&& ! states[PC]->is_unmerged_ret_state (current_method->max_locals))
{
debug_print ("== Fall through optimization\n");
invalidate_pc ();
continue;
}
// Save a copy of it for later.
states[PC]->copy (current_state, current_method->max_stack,
current_method->max_locals);
current_state->print ("New", PC, current_method->max_stack,
current_method->max_locals);
}
}
@ -1817,6 +1970,10 @@ private:
current_method->max_locals);
}
// Set this before handling exceptions so that debug output is
// sane.
start_PC = PC;
// Update states for all active exception handlers. Ordinarily
// there are not many exception handlers. So we simply run
// through them all.
@ -1831,7 +1988,8 @@ private:
}
}
start_PC = PC;
current_state->print (" ", PC, current_method->max_stack,
current_method->max_locals);
java_opcode opcode = (java_opcode) bytecode[PC++];
switch (opcode)
{
@ -2629,6 +2787,11 @@ public:
_Jv_BytecodeVerifier (_Jv_InterpMethod *m)
{
// We just print the text as utf-8. This is just for debugging
// anyway.
debug_print ("--------------------------------\n");
debug_print ("-- Verifying method `%s'\n", m->self->name->data);
current_method = m;
bytecode = m->bytecode ();
exception = m->exceptions ();