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Re: [PATCH][debug] Reuse debug exprs generated in remap_ssa_name


On 07/09/2018 02:43 PM, Richard Biener wrote:
> On Sun, Jul 8, 2018 at 11:27 AM Tom de Vries <tdevries@suse.de> wrote:
>>
>> On Sun, Jul 08, 2018 at 11:22:41AM +0200, Tom de Vries wrote:
>>> On Fri, Jul 06, 2018 at 04:38:50PM +0200, Richard Biener wrote:
>>>> On Fri, Jul 6, 2018 at 12:47 PM Tom de Vries <tdevries@suse.de> wrote:
>>>>> On 07/05/2018 01:39 PM, Richard Biener wrote:
>>>
>>> <SNIP>
>>>
>>>> I now also spotted the code in remap_ssa_name that is supposed to handle
>>>> this it seems and for the testcase we only give up because the PARM_DECL is
>>>> remapped to a VAR_DECL.  So I suppose it is to be handled via the
>>>> debug-args stuff
>>>> which probably lacks in the area of versioning.
>>>>
>>>> Your patch feels like it adds stuff ontop of existing mechanisms that
>>>> should "just work"
>>>> with the correct setup at the correct places...
>>>>
>>>
>>> Hmm, I realized that I may be complicating things, by trying to do an
>>> optimal fix in a single patch, so I decided to write two patches, one
>>> with a fix, and then one improving the fix to be more optimal.
>>>
>>> Also, I suspect that the "just work" approach is this:
>>> ...
>>>        # DEBUG D#8 s=> iD.1900
>>>        # DEBUG iD.1949 => D#8
>>>        # DEBUG D#6 s=> iD.1949
>>> ...
>>> whereas previously I tried to map 'D#6' on iD.1900 directly.
>>>
>>
>> Second patch OK for trunk?
> 
> OK, though I wonder how it doesn't fail with that testcase with
> the mismatching type where the removed param-decl is mapped
> to a local var-decl.

Previously I mapped the default def ssa-name onto the debug expression,
which meant I had to add special handling at the start of
remap_ssa_name, where already mapped ssa-names are handled, for the
mismatched argument/parameter type case.

Now I map the local var-decl onto the debug expression, and the code
that is added to look it up is already guarded with processing_debug_stmt.

Thanks,
- Tom

>> diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
>> index 6fbd8c3ca61..164c7fff710 100644
>> --- a/gcc/tree-inline.c
>> +++ b/gcc/tree-inline.c
>> @@ -215,12 +215,16 @@ remap_ssa_name (tree name, copy_body_data *id)
>>               processing_debug_stmt = -1;
>>               return name;
>>             }
>> +         n = id->decl_map->get (val);
>> +         if (n && TREE_CODE (*n) == DEBUG_EXPR_DECL)
>> +           return *n;
>>           def_temp = gimple_build_debug_source_bind (vexpr, val, NULL);
>>           DECL_ARTIFICIAL (vexpr) = 1;
>>           TREE_TYPE (vexpr) = TREE_TYPE (name);
>>           SET_DECL_MODE (vexpr, DECL_MODE (SSA_NAME_VAR (name)));
>>           gsi = gsi_after_labels (single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
>>           gsi_insert_before (&gsi, def_temp, GSI_SAME_STMT);
>> +         insert_decl_map (id, val, vexpr);
>>           return vexpr;
>>         }
>>
>>


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