[PATCH] Don't look up a stub for an undefined symbol.

[PATCH] Don't look up a stub for an undefined symbol.

[Eric Christopher]

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Hi Cary, Han,

Here's a quick patch that:

a) Adds some gold_debug target debugging to look for mismatched cases
of having a stub and looking for a stub, and
b) Notices that we were trying to look up a stub to an undefined
symbol when we were explicitly not creating a stub for it earlier.

OK?

Thanks!

-eric

2017-06-07  Eric Christopher  <echristo@gmail.com>

        * aarch64.cc (maybe_apply_stub): Add debug logging for looking
        up stubs to undefined symbols and early return rather than
        fail to look them up.
(scan_reloc_for_stub): Add debug logging for no stub creation
        for undefined symbols.

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diff --git a/gold/aarch64.cc b/gold/aarch64.cc
index c9bb6b730d..dd6a7ddab3 100644
--- a/gold/aarch64.cc
+++ b/gold/aarch64.cc
@@ -3746,8 +3746,13 @@ Target_aarch64<size, big_endian>::scan_reloc_for_stub(
 	  psymval = &symval;
 	}
       else if (gsym->is_undefined())
-	// There is no need to generate a stub symbol is undefined.
-	return;
+	{
+	  // There is no need to generate a stub symbol is undefined.
+          gold_debug(DEBUG_TARGET,
+                     "stub: not creating a stub for undefined symbol %s in file %s",
+                     gsym->name(), aarch64_relobj->name().c_str());
+          return;
+	}
     }
 
   // Get the symbol value.
@@ -5403,6 +5408,14 @@ maybe_apply_stub(unsigned int r_type,
   if (stub_type == ST_NONE)
     return false;
 
+  // We don't create stubs for undefined symbols so don't look for one.
+  if (gsym && gsym->is_undefined()) {
+    gold_debug(DEBUG_TARGET,
+               "stub: looking for a stub for undefined symbol: %s",
+               gsym->name());
+    return false;
+  }
+
   const The_aarch64_relobj* aarch64_relobj =
       static_cast<const The_aarch64_relobj*>(object);
   The_stub_table* stub_table = aarch64_relobj->stub_table(relinfo->data_shndx);

Re: [PATCH] Don't look up a stub for an undefined symbol.

[Han Shen via binutils]

Hi Eric, thanks for fixing this. LGTM

BTW, instead of assertion failure in the middle, with this patch, link
proceeds and ends up with "undefined symbols", correct?

Han

On Wed, Jun 7, 2017 at 2:59 PM, Eric Christopher <echristo@gmail.com> wrote:
> Hi Cary, Han,
>
> Here's a quick patch that:
>
> a) Adds some gold_debug target debugging to look for mismatched cases
> of having a stub and looking for a stub, and
> b) Notices that we were trying to look up a stub to an undefined
> symbol when we were explicitly not creating a stub for it earlier.
>
> OK?
>
> Thanks!
>
> -eric
>
> 2017-06-07  Eric Christopher  <echristo@gmail.com>
>
>         * aarch64.cc (maybe_apply_stub): Add debug logging for looking
>         up stubs to undefined symbols and early return rather than
>         fail to look them up.
> (scan_reloc_for_stub): Add debug logging for no stub creation
>         for undefined symbols.



-- 
Han Shen |  Software Engineer |  shenhan@google.com |  +1-650-440-3330

Re: [PATCH] Don't look up a stub for an undefined symbol.

[Eric Christopher]

Yep. That's correct.

(Or at least it gets further now...)

-eric

On Wed, Jun 7, 2017 at 3:47 PM, Han Shen <shenhan@google.com> wrote:
> Hi Eric, thanks for fixing this. LGTM
>
> BTW, instead of assertion failure in the middle, with this patch, link
> proceeds and ends up with "undefined symbols", correct?
>
> Han
>
> On Wed, Jun 7, 2017 at 2:59 PM, Eric Christopher <echristo@gmail.com> wrote:
>> Hi Cary, Han,
>>
>> Here's a quick patch that:
>>
>> a) Adds some gold_debug target debugging to look for mismatched cases
>> of having a stub and looking for a stub, and
>> b) Notices that we were trying to look up a stub to an undefined
>> symbol when we were explicitly not creating a stub for it earlier.
>>
>> OK?
>>
>> Thanks!
>>
>> -eric
>>
>> 2017-06-07  Eric Christopher  <echristo@gmail.com>
>>
>>         * aarch64.cc (maybe_apply_stub): Add debug logging for looking
>>         up stubs to undefined symbols and early return rather than
>>         fail to look them up.
>> (scan_reloc_for_stub): Add debug logging for no stub creation
>>         for undefined symbols.
>
>
>
> --
> Han Shen |  Software Engineer |  shenhan@google.com |  +1-650-440-3330

Re: [PATCH] Don't look up a stub for an undefined symbol.

[Cary Coutant]

> 2017-06-07  Eric Christopher  <echristo@gmail.com>
>
>         * aarch64.cc (maybe_apply_stub): Add debug logging for looking
>         up stubs to undefined symbols and early return rather than
>         fail to look them up.
> (scan_reloc_for_stub): Add debug logging for no stub creation
>         for undefined symbols.

+  // We don't create stubs for undefined symbols so don't look for one.
+  if (gsym && gsym->is_undefined()) {
+    gold_debug(DEBUG_TARGET,
+               "stub: looking for a stub for undefined symbol: %s",
+               gsym->name());
+    return false;
+  }

The braces here aren't Gnu style. Fix that, and it's OK to apply. Thanks!

-cary

Re: [PATCH] Don't look up a stub for an undefined symbol.

[Eric Christopher]

On Wed, Jun 7, 2017 at 5:36 PM, Cary Coutant <ccoutant@gmail.com> wrote:
>> 2017-06-07  Eric Christopher  <echristo@gmail.com>
>>
>>         * aarch64.cc (maybe_apply_stub): Add debug logging for looking
>>         up stubs to undefined symbols and early return rather than
>>         fail to look them up.
>> (scan_reloc_for_stub): Add debug logging for no stub creation
>>         for undefined symbols.
>
> +  // We don't create stubs for undefined symbols so don't look for one.
> +  if (gsym && gsym->is_undefined()) {
> +    gold_debug(DEBUG_TARGET,
> +               "stub: looking for a stub for undefined symbol: %s",
> +               gsym->name());
> +    return false;
> +  }
>
> The braces here aren't Gnu style. Fix that, and it's OK to apply. Thanks!
>

Oops, thanks :)

Pushed thusly:

echristo@athyra ~/s/binutils-gdb> git push origin master
To ssh://sourceware.org/git/binutils-gdb.git
   3030551ec5..81b6fe3bf9  master -> master

-eric