The following testcase taken from testsuite (and many others):
// PR 14535
// { dg-do run }
// { dg-options "-O -finline" }
//
// Original test case failure required that Raiser constructor be inlined.
extern "C" void abort();
bool destructor_called = false;
struct B {
virtual void Run(){};
};
struct D : public B {
virtual void Run()
{
struct O {
~O() { destructor_called = true; };
} o;
struct Raiser {
Raiser() throw( int ) {throw 1;};
} raiser;
};
};
int main() {
try {
D d;
static_cast<B&>(d).Run();
} catch (...) {}
if (!destructor_called)
abort ();
}
leads to following in .optimized dump:
<bb 2>:
MEM[(struct B *)&d]._vptr.B = &_ZTV1B[2];
d.D.2108._vptr.B = &_ZTV1D[2];
D.2210_2 = _ZTV1D[2];
OBJ_TYPE_REF(D.2210_2;&d.D.2108->0) (&d.D.2108);
Obviously OBJ_TYPE_REF can be optimized here since we know the
virtual table. Why it is missed?
I run into it because my new folding code is actually smart enough to lead to:
int (*__vtbl_ptr_type) (void)
void D::<T400> (struct D *)
D.2210_2 = Run;
The error comes because we pick from initializer of VTBL the following
ADDR_EXPR:
<addr_expr 0x7ffff7ec8b10
type <pointer_type 0x7ffff6b7db28 __vtbl_ptr_type
type <function_type 0x7ffff6b7da80 type <integer_type 0x7ffff7edb498
int>
type_6 QI
size <integer_cst 0x7ffff7ec54d8 constant 8>
unit size <integer_cst 0x7ffff7ec5500 constant 1>
align 8 symtab 0 alias set -1 canonical type 0x7ffff6b7da80
pointer_to_this <pointer_type 0x7ffff6b7db28 __vtbl_ptr_type>>
unsigned type_6 DI
size <integer_cst 0x7ffff7ec57d0 constant 64>
unit size <integer_cst 0x7ffff7ec57f8 constant 8>
align 64 symtab 0 alias set -1 canonical type 0x7ffff6b7db28
pointer_to_this <pointer_type 0x7ffff6b7dc78>>
constant
arg 0 <function_decl 0x7ffff6b8e500 Run
type <method_type 0x7ffff6b9b9d8 type <void_type 0x7ffff7edbe70 void>
type_6 QI size <integer_cst 0x7ffff7ec54d8 8> unit size
<integer_cst 0x7ffff7ec5500 1>
align 8 symtab 0 alias set -1 canonical type 0x7ffff6b9b9d8 method
basetype <record_type 0x7ffff6b9b7e0 D>
arg-types <tree_list 0x7ffff6b80af0 value <pointer_type
0x7ffff6b9ba80>
chain <tree_list 0x7ffff7eed398 value <void_type 0x7ffff7edbe70
void>>>
pointer_to_this <pointer_type 0x7ffff6bab150>>
addressable volatile asm_written used public static weak autoinline
virtual decl_5 QI file /home/jh/a.C line 15 col 18 align 16 context
<record_type 0x7ffff6b9b7e0 D> initial <error_mark 0x7ffff7ecdb28>
arguments <parm_decl 0x7ffff7ece990 this type <pointer_type
0x7ffff6b9bb28>
readonly unsigned DI file /home/jh/a.C line 15 col 22 size
<integer_cst 0x7ffff7ec57d0 64> unit size <integer_cst 0x7ffff7ec57f8 8>
align 64 context <function_decl 0x7ffff6b8e500 Run>
(reg/f:DI 62 [ this ]) arg-type <pointer_type 0x7ffff6b9bb28>
incoming-rtl (reg:DI 5 di [ this ])>
result <result_decl 0x7ffff7ed0380 D.2112 type <void_type
0x7ffff7edbe70 void>
ignored VOID file /home/jh/a.C line 16 col 7
align 8 context <function_decl 0x7ffff6b8e500 Run>>
full-name "virtual void D::Run()"
pending-inline-info 0x7ffff6ba42a0
(mem:QI (symbol_ref/i:DI ("_ZN1D3RunEv") [flags 0x1] <function_decl
0x7ffff6b8e500 Run>) [0 S1 A8])>>
Note the differece in between type of address and the method RUN. This is what
makes verifier unhappy. How to fix this? Should FE put there some NOP_EXPR
somewhere? Still devirtualizing should realize this case a lot earlier.
Honza
--
Summary: Missed devirtualization
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: hubicka at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45605
