[PATCH]: Fix PR debug/19191 and dwarf-die-7.c

[Daniel Berlin <dberlin at dberlin dot org>]

This fixes both PR debug/19191 (a 4.0 regression) and the failure in 
dwarf-die-7.c

What happens is that when we fix up the block tree in lower_bind_expr, we 
don't mark the block as used, only as asm_written.

Thus, we end up with the following situation (AFAICT):

before fixup


block 1 (marked used)
    |
    v
block 2 (marked used), block 3 (marked used), etc

after fixup

block 1 (marked used)
    |
    v
block 4 (*NOT* marked used)
    |
    v
block 2 (marked used), block 3 (marked used), etc

The debug info output generator won't bother walking the subblocks if the 
parent block isn't marked used, so we never generate info for block 2 or 
block 3, which is where the inlined info is.

The attached patch marks the block used if the block that is now it's 
"parent" (in the case of block 4, this would be block 1), is marked used,

This is done on assumption that the parent was marked used because either 
it has something in it used, or one of it's subblocks was marked used in 
the first place.  In the first case, it may be true that none of the 
subblocks are marked used.  When this happens, i believe we will just do a 
little extra walking, but not output any extraneous info.
I can't see a way around this without walking the subblocks anyway, though 
i'm happy to insert the walk there if someone wants it done there.

This fixes both the PR, and the dwarf-die failure.

Bootstrapped and regtested on i686-pc-linux-gnu.

Okay for mainline?

Attachment: 19191.diff
Description: Text document