[Bug target/16665] New: [3.4.1] SH: wrong thunk

["sugioka at itonet dot co dot jp" <gcc-bugzilla at gcc dot gnu dot org>]

On sh*-linux, thunk code generated by g++-3.4.1 seems incorrect.

Attached code generates following thunk code.
In this case, '_ZThn4_N7Derived1vEv' is an entry point of virtual function
v() and exported from shared library through vtable.
When this function is called from main(), r12 has invalid value,
and jumps to wrong place.

------------------------------------
	.set	.LTHUNK1,_ZN7Derived1vEv
	.section	.gnu.linkonce.t._ZThn4_N7Derived1vEv,"ax",@progbits
	.align 1
	.weak	_ZThn4_N7Derived1vEv
	.type	_ZThn4_N7Derived1vEv, @function
_ZThn4_N7Derived1vEv:
.LFB6:
	.loc 2 13 0
	add	#-4,r4
	mov.l	.L5,r3
	add	r12,r3           <==== r12 has invalid value
	jmp	@r3              <==== jump to wrong place
	nop
.L6:
	.align 2
.L5:
	.long	.LTHUNK1@GOTOFF
.LFE6:
	.size	_ZThn4_N7Derived1vEv, .-_ZThn4_N7Derived1vEv
------------------------------------


////////////////////////////////////////////////////////////
build and execute as follows.
 $ g++ -O -g -fPIC -c lib.cxx
 $ g++ -shared -o libApp.so lib.o
 $ g++ -O -g -o main -L. main.cxx -lApp
 $ LD_LIBRARY_PATH=. ./main
 Segmentation fault

////////////////////////////////////////////////////////////
// lib.h
class Base {
public: virtual void v() = 0;
};

class Base2 {
public: virtual void v2();
};

class Intermediate : public Base2, public Base {
public: virtual void v();
};

class Derived : public Intermediate {
public: virtual void v();
};

////////////////////////////////////////////////////////////
// lib.cxx
#include "lib.h"
void Base2::v2() {}
void Intermediate::v() {}
void Derived::v() {}

////////////////////////////////////////////////////////////
// main.cxx
#include "lib.h"

int main()
{
	Derived obj;
	Base *p = &obj;

	p->v();
}

-- 
           Summary: [3.4.1] SH: wrong thunk
           Product: gcc
           Version: 3.4.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: sugioka at itonet dot co dot jp
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: sh4-unknown-linux-gnu
  GCC host triplet: sh4-unknown-linux-gnu
GCC target triplet: sh4-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16665