Re: [PATCH dwarves v3 0/3] permit merging all dwarf cu's for clang lto built binary

[Yonghong Song <yhs@fb.com>]

On 3/30/21 8:10 AM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Mar 29, 2021 at 02:40:05PM -0300, Arnaldo Carvalho de Melo escreveu:
>> [acme@five pahole]$ ulimit -c 10000000
>> [acme@five pahole]$
>> [acme@five pahole]$ file tcp_bbr.o
>> tcp_bbr.o: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), with debug_info, not stripped
>> [acme@five pahole]$ readelf -wi tcp_bbr.o | grep DW_AT_producer
>>      <d>   DW_AT_producer    : (indirect string, offset: 0x4a97): GNU C89 10.2.1 20200723 (Red Hat 10.2.1-1) -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -m64 -mno-80387 -mno-fp-ret-in-387 -mpreferred-stack-boundary=3 -mskip-rax-setup -mtune=generic -mno-red-zone -mcmodel=kernel -mindirect-branch=thunk-extern -mindirect-branch-register -mrecord-mcount -mfentry -march=x86-64 -g -O2 -std=gnu90 -p -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -falign-jumps=1 -falign-loops=1 -fno-asynchronous-unwind-tables -fno-jump-tables -fno-delete-null-pointer-checks -fno-allow-store-data-races -fstack-protector-strong -fno-var-tracking-assignments -fno-strict-overflow -fno-merge-all-constants -fmerge-constants -fstack-check=no -fconserve-stack -fcf-protection=none
>> [acme@five pahole]$ fullcircle tcp_bbr.o
>> /home/acme/bin/fullcircle: line 38: 3969006 Segmentation fault      (core dumped) ${pfunct_bin} --compile $file > $c_output
>> /tmp/fullcircle.4XujnI.c:1435:2: error: unterminated comment
>>   1435 |  /* si
>>        |  ^
>> /tmp/fullcircle.4XujnI.c:1433:2: error: expected specifier-qualifier-list at end of input
>>   1433 |  u32 *                      saved_syn;            /*  2184     8 */
>>        |  ^~~
>> codiff: couldn't load debugging info from /tmp/fullcircle.ZOVXGv.o
>> /home/acme/bin/fullcircle: line 40: 3969019 Segmentation fault      (core dumped) ${codiff_bin} -q -s $file $o_output
>> [acme@five pahole]$
>>
>> Both seem unrelated to what you've done here, I'm investigating it now.
> 
> The fullcircle one, that crashes at the 'codiff' utility is related to
> the patch that makes dwarf_cu to allocate space for the hash tables, as
> you introduced a destructor for the dwarf_cu hashtables and the dwarf_cu
> that was assigned to cu->priv was a local variable, which wasn't much of
> a problem because we were not freeing it, as it went away at each loop
> iteration, the following patch to that first patch in the series seems
> to cure it, I'm folding it into your patch + a commiter note.

Thanks for the fix!

> 
> - Arnaldo
> 
> diff --git a/dwarf_loader.c b/dwarf_loader.c
> index 5a1e860da079e04c..3e7875d4ab577f1b 100644
> --- a/dwarf_loader.c
> +++ b/dwarf_loader.c
> @@ -150,6 +150,18 @@ static int dwarf_cu__init(struct dwarf_cu *dcu)
>   	return 0;
>   }
>   
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