[PATCH] Select new undefined atom rather than old one if other conditions are the same.

[Rui Ueyama]

Ping. Anyone?


On Tue, Nov 12, 2013 at 10:25 PM, Rui Ueyama <ruiu at google.com> wrote:

>
>
>> __lseek. When the linker tries to resolve _read, it supposed to read the
>> file
>>
>
> There's a typo in this line: s/_read/_lseek/
>
>
>> from OLDNAMES.LIB and use the new fallback from the file. Currently LLD
>> cannot
>> handle such case because duplicate undefined atoms with the same
>> attributes are
>> ignored.
>>
>> http://llvm-reviews.chandlerc.com/D2161
>>
>> Files:
>>   lib/Core/SymbolTable.cpp
>>   test/core/undef-weak-coalesce.objtxt
>>
>> Index: lib/Core/SymbolTable.cpp
>> ===================================================================
>> --- lib/Core/SymbolTable.cpp
>> +++ lib/Core/SymbolTable.cpp
>> @@ -178,20 +178,34 @@
>>              dyn_cast<UndefinedAtom>(&newAtom);
>>            assert(existingUndef != nullptr);
>>            assert(newUndef != nullptr);
>> -          if ( existingUndef->canBeNull() == newUndef->canBeNull() ) {
>> -            useNew = false;
>> +          if (existingUndef->canBeNull() != newUndef->canBeNull() &&
>> +              _context.warnIfCoalesableAtomsHaveDifferentCanBeNull()) {
>> +            // FIXME: need diagonstics interface for writing warning
>> messages
>> +            llvm::errs() << "lld warning: undefined symbol "
>> +                         << existingUndef->name()
>> +                         << " has different weakness in "
>> +                         << existingUndef->file().path()
>> +                         << " and in "
>> +                         << newUndef->file().path();
>>            }
>> -          else {
>> -            if (_context.warnIfCoalesableAtomsHaveDifferentCanBeNull()) {
>> -              // FIXME: need diagonstics interface for writing warning
>> messages
>> -              llvm::errs() << "lld warning: undefined symbol "
>> -                           << existingUndef->name()
>> -                           << " has different weakness in "
>> -                           << existingUndef->file().path()
>> -                           << " and in "
>> -                           << newUndef->file().path();
>> -            }
>> -            useNew = (newUndef->canBeNull() <
>> existingUndef->canBeNull());
>> +          useNew = (newUndef->canBeNull() <= existingUndef->canBeNull());
>> +
>> +          // Warn if the fallback atom is being overriden.
>> +          const UndefinedAtom *existingFallback =
>> existingUndef->fallback();
>> +          if (useNew && existingFallback) {
>> +            const UndefinedAtom *newFallback = newUndef->fallback();
>> +            if (!newFallback) {
>> +              llvm::errs() << "lld warning: new undefined atom removes
>> the "
>> +                           << "existing fallback atom "
>> +                           << existingUndef->name() << " ("
>> +                           << existingFallback->name() << ")";
>> +            } else if (existingFallback->name() != newFallback->name())
>> +              llvm::errs() << "lld warning: new undefined atom "
>> +                           << newUndef->name() << " ("
>> +                           << newFallback->name() << ")"
>> +                           << " shadows the existing fallback atom "
>> +                           << existingUndef->name() << " ("
>> +                           << existingFallback->name() << ")";
>>            }
>>          }
>>          break;
>> Index: test/core/undef-weak-coalesce.objtxt
>> ===================================================================
>> --- test/core/undef-weak-coalesce.objtxt
>> +++ test/core/undef-weak-coalesce.objtxt
>> @@ -8,86 +8,66 @@
>>  undefined-atoms:
>>      - name:              regular_func
>>        can-be-null:       never
>> -
>>      - name:              weak_import_func
>>        can-be-null:       at-runtime
>> -
>>      - name:              weak_func
>>        can-be-null:       at-buildtime
>> -
>>      - name:              bar1
>>        can-be-null:       never
>> -
>>      - name:              bar2
>>        can-be-null:       at-runtime
>> -
>>      - name:              bar3
>>        can-be-null:       at-buildtime
>> -
>>      - name:              bar4
>>        can-be-null:       never
>> -
>>      - name:              bar5
>>        can-be-null:       at-runtime
>> -
>>      - name:              bar6
>>        can-be-null:       at-buildtime
>> -
>>      - name:              bar7
>>        can-be-null:       never
>> -
>>      - name:              bar8
>>        can-be-null:       at-runtime
>> -
>>      - name:              bar9
>>        can-be-null:       at-buildtime
>> -
>>  ---
>>  undefined-atoms:
>>      - name:              bar1
>>        can-be-null:       never
>> -
>>      - name:              bar2
>>        can-be-null:       at-runtime
>> -
>>      - name:              bar3
>>        can-be-null:       at-buildtime
>> -
>>      - name:              bar4
>>        can-be-null:       at-runtime
>> -
>>      - name:              bar5
>>        can-be-null:       at-buildtime
>> -
>>      - name:              bar6
>>        can-be-null:       never
>> -
>>      - name:              bar7
>>        can-be-null:       at-buildtime
>> -
>>      - name:              bar8
>>        can-be-null:       never
>> -
>>      - name:              bar9
>>        can-be-null:       at-runtime
>>  ...
>>
>> -# CHECK:   - name:       regular_func
>> -# CHECK:   - name:       weak_import_func
>> -# CHECK:     can-be-null:  at-runtime
>> -# CHECK:   - name:       weak_func
>> -# CHECK:     can-be-null:  at-buildtime
>> -# CHECK:   - name:       bar1
>> -# CHECK:   - name:       bar2
>> -# CHECK:     can-be-null:  at-runtime
>> -# CHECK:   - name:       bar3
>> -# CHECK:     can-be-null:  at-buildtime
>> -# CHECK:   - name:       bar4
>> -# CHECK:   - name:       bar5
>> -# CHECK:     can-be-null:  at-runtime
>> -# CHECK:   - name:       bar7
>> -# CHECK:   - name:       bar6
>> -# CHECK:   - name:       bar8
>> -# CHECK:   - name:       bar9
>> -# CHECK:     can-be-null:  at-runtime
>> -# CHECK:       ...
>> +# CHECK:        - name:       regular_func
>> +# CHECK-NEXT:   - name:       weak_import_func
>> +# CHECK-NEXT:     can-be-null:  at-runtime
>> +# CHECK-NEXT:   - name:       weak_func
>> +# CHECK-NEXT:     can-be-null:  at-buildtime
>> +# CHECK-NEXT:   - name:       bar4
>> +# CHECK-NEXT:   - name:       bar5
>> +# CHECK-NEXT:     can-be-null:  at-runtime
>> +# CHECK-NEXT:   - name:       bar7
>> +# CHECK-NEXT:   - name:       bar1
>> +# CHECK-NEXT:   - name:       bar2
>> +# CHECK-NEXT:     can-be-null:  at-runtime
>> +# CHECK-NEXT:   - name:       bar3
>> +# CHECK-NEXT:     can-be-null:  at-buildtime
>> +# CHECK-NEXT:   - name:       bar6
>> +# CHECK-NEXT:   - name:       bar8
>> +# CHECK-NEXT:   - name:       bar9
>> +# CHECK-NEXT:     can-be-null:  at-runtime
>> +# CHECK-NEXT:       ...
>>
>
>
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