still invalid relocations generated for debug info (C++)

[Ulrich Drepper]

I've reported this already on 10/7 but it's still not fixed.  So I
looked a bit closer at the problem.  The source code in question can
be downloaded at

	http://www.cygnus.com/~drepper/nsTableFrame.ii.bz2

The problem is with the generation of debug information (stabs).  At
some point the numbers for the labels generated in the code and those
used in the debug information diverge.  This leads to expressions
where two symbols from different sections are substracted.  Here are a
few excerpts:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi:
.LFB160:
	.stabn 68,0,5524,.LM3914-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
.LM3914:
	pushl	%ebp
[...]
.LBB1430:
	.stabn 68,0,5534,.LM3918-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
.LM3918:
	cmpl	$0, 88(%esi)
	je	.L5130
.LBB1431:
	.stabn 68,0,5536,.LM3919-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
.LM3919:
	subl	$4, %esp
	leal	-4(%ebp), %eax
	pushl	%eax
	pushl	%ebx
	pushl	88(%esi)
.LCFI1047:
	call	SizeOf__C15ColumnInfoCacheP16nsISizeOfHandlerPUi
	.stabn 68,0,5537,.LM3920-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
.LM3920:
	subl	$4, %esp
	movl	(%ebx), %eax
	pushl	-4(%ebp)
	pushl	_13nsLayoutAtoms.tableColCache
	pushl	%ebx
	movl	28(%eax), %eax
	call	*%eax
.LBE1431:
	addl	$32, %esp
.L5130:
.LBE1430:
	.stabn 68,0,5542,.LM3921-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
[...]
.stabn 192,0,0,.LBB1430-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
.stabn 192,0,0,.LBB1431-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
.stabs "colCacheSize:(5,5)",128,0,5535,-4
.stabn 192,0,0,.LBB1432-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
.stabn 224,0,0,.LBE1432-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
.stabn 224,0,0,.LBE1431-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
.stabn 224,0,0,.LBE1430-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
[...]
assign_with_QueryInterface__t8nsCOMPtr1Z11nsISupportsP11nsISupportsRC4nsIDPUi:
.LFB161:
.LBB1432:
	.stabn 68,0,640,.LM3929-assign_with_QueryInterface__t8nsCOMPtr1Z11nsISupportsP11nsISupportsRC4nsIDPUi
[...]
.LM3936:
	movl	%ebx, (%edi)
.LBE1432:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Short summary:

- function SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi contains three
  labelled blocks .LBB1429/.LBE1429, .LBB1430/.LBE1430, .LBB1431/.LBE1431

- function assign_with_QueryInterface__t8nsCOMPtr1Z11nsISupportsP11nsISupportsRC4nsIDPUi
  contains among others block .LBB1432/.LBE1433

- the stabs generated for function
  SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi correctly use the block
  *1430 and *1431 but also use *1432

=> but *1432 is in the other function and therefore the lines

   .stabn 192,0,0,.LBB1432-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi
   .stabn 224,0,0,.LBE1432-SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi

   cause problems.


I don't know whether it's important but the function

 assign_with_QueryInterface__t8nsCOMPtr1Z11nsISupportsP11nsISupportsRC4nsIDPUi

is a template which gets instantiated at the end of the compilation and

 SizeOf__C12nsTableFrameP16nsISizeOfHandlerPUi

is the last function in the file.

-- 
---------------.      drepper at gnu.org  ,-.   1325 Chesapeake Terrace
Ulrich Drepper  \    ,-------------------'   \  Sunnyvale, CA 94089 USA
Cygnus Solutions `--' drepper at cygnus.com   `------------------------