Hi Richi,
Thanks for the review!
on 2021/9/17 下午6:04, Richard Biener wrote:
> On Fri, Sep 17, 2021 at 12:03 PM Richard Biener
> <richard.guent...@gmail.com> wrote:
>>
>> On Fri, Sep 17, 2021 at 11:43 AM Kewen.Lin <li...@linux.ibm.com> wrote:
>>>
>>> Hi,
>>>
>>> When changing target_info with bitfield, I happened to find this
>>> inconsistent streaming in and out. We have the streaming in:
>>>
>>> bp_pack_value (&bp, info->inlinable, 1);
>>> bp_pack_value (&bp, false, 1);
>>> bp_pack_value (&bp, info->fp_expressions, 1);
>>>
>>> while the streaming out:
>>>
>>> info->inlinable = bp_unpack_value (&bp, 1);
>>> info->fp_expressions = bp_unpack_value (&bp, 1)
>>>
>>> The cleanup of Cilk Plus support seemed to miss to remove the bit
>>> streaming out but change with streaming false.
>>>
>>> By hacking fp_expression_p to return true always, I can see it
>>> reads the wrong fp_expressions value (false) out in wpa dumping.
>>>
>>> Bootstrapped and regress-tested on powerpc64le-linux-gnu Power9.
>>>
>>> Is it ok for trunk?
>>
>> OK for trunk and all affected branches (note we need to bump the
>> LTO minor version there). The issue comes from the removal
>> of cilk+ in r8-4956 which removed the bp_unpack but replaced
>> the bp_pack ...
>>
>> It's a correctness issue as we'll read fp_expressions as always 'false'
>
> Btw, on branches we could also simply unpack a dummy bit to avoid
> changing the format.
>
Committed in r12-3721. Thanks!
As suggested, the patch for branches is listed below.
Is ok for branches 9, 10 and 11 after some trunk burn in time?
BR,
Kewen
-----
gcc/ChangeLog:
* ipa-fnsummary.c (inline_read_section): Unpack a dummy bit
to keep consistent with the side of streaming out.
---
diff --git a/gcc/ipa-fnsummary.c b/gcc/ipa-fnsummary.c
index 18bbae145b9..bf635c1f78a 100644
--- a/gcc/ipa-fnsummary.c
+++ b/gcc/ipa-fnsummary.c
@@ -4403,13 +4403,20 @@ inline_read_section (struct lto_file_decl_data
*file_data, const char *data,
bp = streamer_read_bitpack (&ib);
if (info)
{
- info->inlinable = bp_unpack_value (&bp, 1);
- info->fp_expressions = bp_unpack_value (&bp, 1);
+ info->inlinable = bp_unpack_value (&bp, 1);
+ /* On the side of streaming out, there is still one bit
+ streamed out between inlinable and fp_expressions bits,
+ which was used for cilk+ before but now always false.
+ To remove the bit packing need to bump LTO minor version,
+ so unpack a dummy bit here to keep consistent instead. */
+ bp_unpack_value (&bp, 1);
+ info->fp_expressions = bp_unpack_value (&bp, 1);
}
else
{
- bp_unpack_value (&bp, 1);
- bp_unpack_value (&bp, 1);
+ bp_unpack_value (&bp, 1);
+ bp_unpack_value (&bp, 1);
+ bp_unpack_value (&bp, 1);
}
count2 = streamer_read_uhwi (&ib);
