gc sections and .eh_frame

[Jonathan Larmour]

Alan Modra wrote:
> On Tue, Jun 07, 2005 at 06:49:00PM +0100, Jonathan Larmour wrote:
> 
>>But now I'm using the powerpc architecture where the stuff usually in 
>>.gcc_except_table is placed in .rodata instead. If the object file has 
>>nothing else in .rodata, then that section is also being GC'd in the final 
>>link. And Bad Things Happen.
> 
> 
> Which powerpc target?  What compiler version?

powerpc-eabi, gcc 3.4.4.

 From a brief foray into the GCC sources, I believe the use of 
gcc_except_table depends on the existence of TARGET_ASM_NAMED_SECTION, 
which is not defined for any powerpc other than rs6000-xcoff.

There are probably other targets than powerpc that don't have 
TARGET_ASM_NAMED_SECTION too. From a glance, SuperH doesn't either at least.

I still don't have an understanding as to why sections referenced (by 
reloc) from .eh_frame shouldn't be kept safe from GC. Marking them as KEEP 
in the linker script just means that you've got one bit of code trying to 
stop such sections being included, and another bit in the linker script 
forcing them to be. It seems pointless and breaks existing working linker 
scripts, nevermind the powerpc issue.

Jifl
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