[Bug c++/16924] New: dllexport attribute now causes some symbols _not_ to be exported

[Bug c++/16924] New: dllexport attribute now causes some symbols _not_ to be exported

[dannysmith at users dot sourceforge dot net]

Recent changes to dllexport handling in C++ frontend has broken
the use of dllexport attribute with multiple inheritance.

Now (gcc version 3.5.0 20040806 (experimental)) the dllexport attribute
causes some symbols *not* to be exported.

Here is a testcase:

// dll-mi.C 
#ifdef BUILDING_DLL
#define  DLL_IMPEXP __attribute__ ((dllexport))
#else
#define  DLL_IMPEXP
#endif

class DLL_IMPEXP MBase
{
public:
  virtual int vf() const = 0;
  virtual ~MBase();
};

class DLL_IMPEXP D1 : virtual public MBase
{
public:
  int vf() const;
};

MBase::~MBase(){}

int D1::vf() const { return 1; }



D:\develop\BUGS -shared -DBUILDING_DLL -o test.dll dll-mi.C 
D:\TEMP/ccueaaaa.o(.rdata$_ZTV2D1+0x18):dll-mi.C: undefined reference to 
`D1::~D1()'
D:\TEMP/ccueaaaa.o(.rdata$_ZTV2D1+0x1c):dll-mi.C: undefined reference to 
`D1::~D1()'

And looking at the assembler, the compiler puts those dtors into the
vtable for D1

.globl __ZTV2D1
	.section	.rdata$_ZTV2D1,"dr"
	.linkonce same_size
	.align 32
__ZTV2D1:
	.long	0
	.long	0
	.long	0
	.long	0
	.long	__ZTI2D1
	.long	__ZNK2D12vfEv
	.long	__ZN2D1D1Ev
	.long	__ZN2D1D0Ev
	.text


but doesn't actually emit the code for the two dtor's.

However if I build an object _without_ the dllexport, the dtor's
_ZN2D1D1Ev and _ZN2D1D0Ev (as well as thunks to these dtors) are
emitted. Here is the diff of two compiles without and with the dllexport
attribute enabled. The file dll-mi-no-export.s was built without the export
attribute, the other with:

> diff -up dll-mi-no-export.s dll-mi-export.s

D:\develop\BUGS>diff -up dll-mi-no-export.s dll-mi-export.s 
--- dll-mi-no-export.s	Mon Aug 09 08:30:35 2004
+++ dll-mi-export.s	Mon Aug 09 08:30:41 2004
@@ -165,124 +165,15 @@ LCFI13:
 	leave
 	ret
 LFE6:
-	.section	.text$_ZTv0_n16_N2D1D1Ev,"x"
-	.linkonce discard
-	.align 2
-.globl __ZTv0_n16_N2D1D1Ev
-	.def	__ZTv0_n16_N2D1D1Ev;	.scl	2;	.type	32;	.endef
-__ZTv0_n16_N2D1D1Ev:
-	movl	4(%esp), %eax
-	movl	(%eax), %ecx
-	addl	-16(%ecx), %eax
-	movl	%eax, 4(%esp)
-	jmp	__ZN2D1D1Ev
-	.section	.text$_ZN2D1D1Ev,"x"
-	.linkonce discard
-	.align 2
-.globl __ZN2D1D1Ev
-	.def	__ZN2D1D1Ev;	.scl	2;	.type	32;	.endef
-__ZN2D1D1Ev:
-LFB9:
-	pushl	%ebp
-LCFI14:
-	movl	%esp, %ebp
-LCFI15:
-	subl	$8, %esp
-LCFI16:
-	movl	$__ZTV2D1+20, %eax
-	movl	8(%ebp), %edx
-	movl	%eax, (%edx)
-	movl	8(%ebp), %eax
-	movl	%eax, -4(%ebp)
-	movl	$0, %eax
-	movl	-4(%ebp), %edx
-	addl	%eax, %edx
-	movl	$__ZTV2D1+20, %eax
-	movl	%eax, (%edx)
-	movl	$2, %eax
-	shrl	%eax
-	andl	$1, %eax
-	testb	%al, %al
-	je	L15
-	movl	8(%ebp), %edx
-	movl	%edx, -4(%ebp)
-	subl	$12, %esp
-	pushl	-4(%ebp)
-LCFI17:
-	call	__ZN5MBaseD2Ev
-	addl	$16, %esp
-L15:
-	movl	$0, %eax
-	testb	%al, %al
-	je	L14
-	subl	$12, %esp
-	pushl	8(%ebp)
-	call	__ZdlPv
-	addl	$16, %esp
-L14:
-	leave
-	ret
-LFE9:
-	.section	.text$_ZTv0_n16_N2D1D0Ev,"x"
-	.linkonce discard
-	.align 2
-.globl __ZTv0_n16_N2D1D0Ev
-	.def	__ZTv0_n16_N2D1D0Ev;	.scl	2;	.type	32;	.endef
-__ZTv0_n16_N2D1D0Ev:
-	movl	4(%esp), %eax
-	movl	(%eax), %ecx
-	addl	-16(%ecx), %eax
-	movl	%eax, 4(%esp)
-	jmp	__ZN2D1D0Ev
-	.section	.text$_ZN2D1D0Ev,"x"
-	.linkonce discard
-	.align 2
-.globl __ZN2D1D0Ev
-	.def	__ZN2D1D0Ev;	.scl	2;	.type	32;	.endef
-__ZN2D1D0Ev:
-LFB10:
-	pushl	%ebp
-LCFI18:
-	movl	%esp, %ebp
-LCFI19:
-	subl	$8, %esp
-LCFI20:
-	movl	$__ZTV2D1+20, %eax
-	movl	8(%ebp), %edx
-	movl	%eax, (%edx)
-	movl	8(%ebp), %eax
-	movl	%eax, -4(%ebp)
-	movl	$0, %eax
-	movl	-4(%ebp), %edx
-	addl	%eax, %edx
-	movl	$__ZTV2D1+20, %eax
-	movl	%eax, (%edx)
-	movl	$3, %eax
-	shrl	%eax
-	andl	$1, %eax
-	testb	%al, %al
-	je	L20
-	movl	8(%ebp), %edx
-	movl	%edx, -4(%ebp)
-	subl	$12, %esp
-	pushl	-4(%ebp)
-LCFI21:
-	call	__ZN5MBaseD2Ev
-	addl	$16, %esp
-L20:
-	movl	$1, %eax
-	testb	%al, %al
-	je	L19
-	subl	$12, %esp
-	pushl	8(%ebp)
-	call	__ZdlPv
-	addl	$16, %esp
-L19:
-	leave
-	ret
-LFE10:
-	.def	__ZTv0_n16_N2D1D0Ev;	.scl	3;	.type	32;	.endef
-	.def	__ZTv0_n16_N2D1D1Ev;	.scl	3;	.type	32;	.endef
-	.def	__ZTv0_n12_NK2D12vfEv;	.scl	3;	.type	32;	.endef
 	.def	___cxa_pure_virtual;	.scl	3;	.type	32;	.endef
 	.def	__ZdlPv;	.scl	3;	.type	32;	.endef
+	.section .drectve
+
+	.ascii " -export:_ZNK2D12vfEv"
+	.ascii " -export:_ZTv0_n12_NK2D12vfEv"
+	.ascii " -export:_ZN5MBaseD0Ev"
+	.ascii " -export:_ZN5MBaseD1Ev"
+	.ascii " -export:_ZN5MBaseD2Ev"
+	.ascii " -export:_ZTV2D1,data"
+	.ascii " -export:_ZTT2D1,data"
+	.ascii " -export:_ZTV5MBase,data"

-- 
           Summary: dllexport attribute now causes some symbols _not_ to be
                    exported
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dannysmith at users dot sourceforge dot net
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-mingw32
  GCC host triplet: i686-pc-mingw32
GCC target triplet: i686-pc-mingw32


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16924

[Bug c++/16924] [3.5 Regression] dllexport attribute now causes some symbols _not_ to be exported

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mmitchel at gcc dot gnu dot
                   |                            |org
           Severity|normal                      |critical
           Keywords|                            |wrong-code
            Summary|dllexport attribute now     |[3.5 Regression] dllexport
                   |causes some symbols _not_ to|attribute now causes some
                   |be exported                 |symbols _not_ to be exported
   Target Milestone|---                         |3.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16924

[Bug c++/16924] [3.5 Regression] dllexport attribute now causes some symbols _not_ to be exported

[mmitchel at gcc dot gnu dot org]

------- Additional Comments From mmitchel at gcc dot gnu dot org  2004-08-11 17:30 -------
Created an attachment (id=6916)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=6916&action=view)
Patch to winnt.c

Danny --

The problem is that winnt.c is creating SYMBOL_REFs that do not have
SYMBOL_REF_DECL set correctly. That's been a latent bug since SYMBOL_REF_DECL
went in, but some of my changes have made it manifest in your test case.  Would
you please test my patch?  If it works out, I'll commit it.

Thanks,

-- Mark

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |mmitchel at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16924

[Bug c++/16924] [3.5 Regression] dllexport attribute now causes some symbols _not_ to be exported

[dannysmith at users dot sourceforge dot net]

------- Additional Comments From dannysmith at users dot sourceforge dot net  2004-08-11 22:55 -------
Thanks, Mark.

It does fix the regression, and cause no new failures.

config/sh/symbian.c  and mcore/mcore.c also need similar patch

Should, the SYMBOL_REF_DECL also be set when encode_section_info
overrides a prior dllimport declaration with a new declaration without
the attribute, like so?



*** winnt.c.mm	Thu Aug 12 07:36:01 2004
--- winnt.c	Thu Aug 12 09:13:41 2004
*************** i386_pe_encode_section_info (tree decl, 
*** 453,459 ****
  
        /* Remove DLL_IMPORT_PREFIX.  */
        tree idp = get_identifier (oldname + strlen (DLL_IMPORT_PREFIX));
!       rtx newrtl = gen_rtx_SYMBOL_REF (Pmode, IDENTIFIER_POINTER (idp));
  
        if (DECL_INITIAL (decl) || !DECL_EXTERNAL (decl))
  	warning ("%J'%D' defined locally after being "
--- 453,465 ----
  
        /* Remove DLL_IMPORT_PREFIX.  */
        tree idp = get_identifier (oldname + strlen (DLL_IMPORT_PREFIX));
!       rtx symref = gen_rtx_SYMBOL_REF (Pmode, IDENTIFIER_POINTER (idp));
!       SYMBOL_REF_DECL (symref) = decl;
!       XEXP (DECL_RTL (decl), 0) = symref;
!       DECL_NON_ADDR_CONST_P (decl) = 0;
! 
!       /* We previously set TREE_PUBLIC and DECL_EXTERNAL.
! 	 We leave these alone for now.  */
  
        if (DECL_INITIAL (decl) || !DECL_EXTERNAL (decl))
  	warning ("%J'%D' defined locally after being "
*************** i386_pe_encode_section_info (tree decl, 
*** 461,473 ****
        else
  	warning ("%J'%D' redeclared without dllimport attribute "
  		 "after being referenced with dllimport linkage", decl, decl);
- 
-       XEXP (DECL_RTL (decl), 0) = newrtl;
- 
-       DECL_NON_ADDR_CONST_P (decl) = 0;
- 
-       /* We previously set TREE_PUBLIC and DECL_EXTERNAL.
- 	 We leave these alone for now.  */
      }
  }
  
--- 467,472 ----

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16924

[Bug c++/16924] [3.5 Regression] dllexport attribute now causes some symbols _not_ to be exported

[mark at codesourcery dot com]

------- Additional Comments From mark at codesourcery dot com  2004-08-12 16:15 -------
Subject: Re:  [3.5 Regression] dllexport attribute now causes
 some symbols _not_ to be exported

dannysmith at users dot sourceforge dot net wrote:

>------- Additional Comments From dannysmith at users dot sourceforge dot net  2004-08-11 22:55 -------
>Thanks, Mark.
>
>It does fix the regression, and cause no new failures.
>  
>
Good.

>config/sh/symbian.c  and mcore/mcore.c also need similar patch
>  
>
Probably so.

>Should, the SYMBOL_REF_DECL also be set when encode_section_info
>overrides a prior dllimport declaration with a new declaration without
>the attribute, like so?
>  
>
Yes. 

I'm sorta suspicious of the NT port for needing to do this; I kinda 
think that some other approach (involving SYMBOL_REF_FLAGS and overring 
ASM_OUT_*) would be more reliable.

Will you please check in your patch together with mine?

Thanks,



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16924

[Bug c++/16924] [3.5 Regression] dllexport attribute now causes some symbols _not_ to be exported

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-08-13 01:24 -------
Subject: Bug 16924

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	dannysmith@gcc.gnu.org	2004-08-13 01:24:28

Modified files:
	gcc            : ChangeLog 
	gcc/config/i386: winnt.c 

Log message:
	PR c++/16924
	* config/i386/winnt.c (i386_pe_mark_dllexport): Set
	SYMBOL_REF_DECL.
	(i386_pe_mark_dllimport): Likewise.
	(i386_pe_encode_section_info): Likewise, when overriding
	dllimport attribute.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.4890&r2=2.4891
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/config/i386/winnt.c.diff?cvsroot=gcc&r1=1.69&r2=1.70



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16924

[Bug c++/16924] [3.5 Regression] dllexport attribute now causes some symbols _not_ to be exported

[dannysmith at users dot sourceforge dot net]

------- Additional Comments From dannysmith at users dot sourceforge dot net  2004-08-13 01:29 -------
Fixed by Mark's patch.
Danny

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16924