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[GCC/LTO,ping3] Fix PR69866: LTO with def for weak alias in regular object file

Message ID 530b495f-e3e8-8223-cda0-1fe0525ba46b@foss.arm.com
State New
Headers show

Commit Message

Thomas Preudhomme June 6, 2017, 10:12 a.m. UTC 
On 09/05/17 23:36, Jan Hubicka wrote:
>> Ping?
> Sorry for late reply

My turn to apologize now.

>>> Hi,
>>>
>>> This patch fixes an assert failure when linking one LTOed object file
>>> having a weak alias with a regular object file containing a strong
>>> definition for that same symbol. The patch is twofold:
>>>
>>> + do not add an alias to a partition if it is external
>>> + do not declare (.globl) an alias if it is external
>
> Adding external alises to partitions is important to keep the information
> that two symbols are the same.

So how about simply relaxing the assert then? Right now it trips for any 
external symbol, even external aliases.

How about the following:


ChangeLog entries are as follow:

*** gcc/lto/ChangeLog ***

2017-06-02  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* lto/lto-partition.c (add_symbol_to_partition_1): Change assert to
	allow external aliases to be added.

*** gcc/ChangeLog ***

2017-03-01  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* cgraphunit.c (cgraph_node::assemble_thunks_and_aliases): Do not
	declare external aliases.

*** gcc/testsuite/ChangeLog ***

2017-02-28  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* gcc.dg/lto/pr69866_0.c: New test.
	* gcc.dg/lto/pr69866_1.c: Likewise.

Bootstrapped with LTO on Aarch64 and ARM and testsuite on both of these 
architectures do not show any regression.

Is this ok for trunk?

Best regards,

Thomas


> The second part makes sense to me.  What breaks when you drop the first
> change?
>
> Honza
>>>
>>> ChangeLog entries are as follow:
>>>
>>> *** gcc/lto/ChangeLog ***
>>>
>>> 2017-03-01  Thomas Preud'homme  <thomas.preudhomme@arm.com>
>>>
>>>    PR lto/69866
>>>    * lto/lto-partition.c (add_symbol_to_partition_1): Do not add external
>>>    aliases to partition.
>>>
>>> *** gcc/ChangeLog ***
>>>
>>> 2017-03-01  Thomas Preud'homme  <thomas.preudhomme@arm.com>
>>>
>>>    PR lto/69866
>>>    * cgraphunit.c (cgraph_node::assemble_thunks_and_aliases): Do not
>>>    declare external aliases.
>>>
>>> *** gcc/testsuite/ChangeLog ***
>>>
>>> 2017-02-28  Thomas Preud'homme  <thomas.preudhomme@arm.com>
>>>
>>>    PR lto/69866
>>>    * gcc.dg/lto/pr69866_0.c: New test.
>>>    * gcc.dg/lto/pr69866_1.c: Likewise.
>>>
>>>
>>> Testing: Testsuite shows no regression when targeting Cortex-M3 with an
>>> arm-none-eabi GCC cross-compiler, neither does it show any regression with
>>> native LTO-bootstrapped x86-64_linux-gnu and aarch64-linux-gnu compilers.
>>>
>>> Is this ok for stage4?
>>>
>>> Best regards,
>>>
>>> Thomas
>>>
>>> On 31/03/17 18:07, Richard Biener wrote:
>>>> On March 31, 2017 5:23:03 PM GMT+02:00, Jeff Law <law@redhat.com> wrote:
>>>>> On 03/16/2017 08:05 AM, Thomas Preudhomme wrote:
>>>>>> Ping?
>>>>>>
>>>>>> Is this ok for stage4?
>>>>> Given the lack of response from Richi, I'd suggest deferring to stage1.
>>>>
>>>> Honza needs to review this, i habe too little knowledge here.
>>>>
>>>> Richard.
>>>>
>>>>> jeff
>>>>
>
>> diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
>> index c82a88a599ca61b068dd9783d2a6158163809b37..580500ff922b8546d33119261a2455235edbf16d 100644
>> --- a/gcc/cgraphunit.c
>> +++ b/gcc/cgraphunit.c
>> @@ -1972,7 +1972,7 @@ cgraph_node::assemble_thunks_and_aliases (void)
>>    FOR_EACH_ALIAS (this, ref)
>>      {
>>        cgraph_node *alias = dyn_cast <cgraph_node *> (ref->referring);
>> -      if (!alias->transparent_alias)
>> +      if (!alias->transparent_alias && !DECL_EXTERNAL (alias->decl))
>>  	{
>>  	  bool saved_written = TREE_ASM_WRITTEN (decl);
>>
>> diff --git a/gcc/lto/lto-partition.c b/gcc/lto/lto-partition.c
>> index e27d0d1690c1fcfb39e2fac03ce0f4154031fc7c..f44fd435ed075a27e373bdfdf0464eb06e1731ef 100644
>> --- a/gcc/lto/lto-partition.c
>> +++ b/gcc/lto/lto-partition.c
>> @@ -178,7 +178,8 @@ add_symbol_to_partition_1 (ltrans_partition part, symtab_node *node)
>>    /* Add all aliases associated with the symbol.  */
>>
>>    FOR_EACH_ALIAS (node, ref)
>> -    if (!ref->referring->transparent_alias)
>> +    if (!ref->referring->transparent_alias
>> +	&& ref->referring->get_partitioning_class () != SYMBOL_EXTERNAL)
>>        add_symbol_to_partition_1 (part, ref->referring);
>>      else
>>        {
>> @@ -189,7 +190,8 @@ add_symbol_to_partition_1 (ltrans_partition part, symtab_node *node)
>>  	  {
>>  	    /* Nested transparent aliases are not permitted.  */
>>  	    gcc_checking_assert (!ref2->referring->transparent_alias);
>> -	    add_symbol_to_partition_1 (part, ref2->referring);
>> +	    if (ref2->referring->get_partitioning_class () != SYMBOL_EXTERNAL)
>> +	      add_symbol_to_partition_1 (part, ref2->referring);
>>  	  }
>>        }
>>
>> diff --git a/gcc/testsuite/gcc.dg/lto/pr69866_0.c b/gcc/testsuite/gcc.dg/lto/pr69866_0.c
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..f49ef8d4c1da7a21d1bfb5409d647bd18141595b
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/lto/pr69866_0.c
>> @@ -0,0 +1,13 @@
>> +/* { dg-lto-do link } */
>> +
>> +int _umh(int i)
>> +{
>> +  return i+1;
>> +}
>> +
>> +int weaks(int i) __attribute__((weak, alias("_umh")));
>> +
>> +int main()
>> +{
>> +  return weaks(10);
>> +}
>> diff --git a/gcc/testsuite/gcc.dg/lto/pr69866_1.c b/gcc/testsuite/gcc.dg/lto/pr69866_1.c
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..3a14f850eefaffbf659ce4642adef7900330f4ed
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/lto/pr69866_1.c
>> @@ -0,0 +1,6 @@
>> +/* { dg-options { -fno-lto } } */
>> +
>> +int weaks(int i)
>> +{
>> +  return i+1;
>> +}
>
diff mbox

Patch

diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
index 7b4f47e6efb41e7c401e7347d86fffca6618c4e9..c2cc9df6419573bdc6223e1d2ee348f8af69ccca 100644
--- a/gcc/cgraphunit.c
+++ b/gcc/cgraphunit.c
@@ -1984,7 +1984,7 @@  cgraph_node::assemble_thunks_and_aliases (void)
   FOR_EACH_ALIAS (this, ref)
     {
       cgraph_node *alias = dyn_cast <cgraph_node *> (ref->referring);
-      if (!alias->transparent_alias)
+      if (!alias->transparent_alias && !DECL_EXTERNAL (alias->decl))
 	{
 	  bool saved_written = TREE_ASM_WRITTEN (decl);
 
diff --git a/gcc/lto/lto-partition.c b/gcc/lto/lto-partition.c
index 3600ab23bd9157aad76751912306abd498acae92..620deac090b7e718f05d3f37e6ef68e759de0008 100644
--- a/gcc/lto/lto-partition.c
+++ b/gcc/lto/lto-partition.c
@@ -132,7 +132,7 @@  add_symbol_to_partition_1 (ltrans_partition part, symtab_node *node)
 
   /* Be sure that we never try to duplicate partitioned symbol
      or add external symbol.  */
-  gcc_assert (c != SYMBOL_EXTERNAL
+  gcc_assert ((c != SYMBOL_EXTERNAL || node->alias)
 	      && (c == SYMBOL_DUPLICATE || !symbol_partitioned_p (node)));
 
   part->symbols++;
diff --git a/gcc/testsuite/gcc.dg/lto/pr69866_0.c b/gcc/testsuite/gcc.dg/lto/pr69866_0.c
new file mode 100644
index 0000000000000000000000000000000000000000..f49ef8d4c1da7a21d1bfb5409d647bd18141595b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/pr69866_0.c
@@ -0,0 +1,13 @@ 
+/* { dg-lto-do link } */
+
+int _umh(int i)
+{
+  return i+1;
+}
+
+int weaks(int i) __attribute__((weak, alias("_umh")));
+
+int main()
+{
+  return weaks(10);
+}
diff --git a/gcc/testsuite/gcc.dg/lto/pr69866_1.c b/gcc/testsuite/gcc.dg/lto/pr69866_1.c
new file mode 100644
index 0000000000000000000000000000000000000000..3a14f850eefaffbf659ce4642adef7900330f4ed
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/pr69866_1.c
@@ -0,0 +1,6 @@ 
+/* { dg-options { -fno-lto } } */
+
+int weaks(int i)
+{
+  return i+1;
+}