[PATCH v2][lld] ELF: Handle sh_addralign being set to zero

[Shankar Easwaran]

LGTM.

On 1/20/2015 4:39 AM, Will Newton wrote:
> On 13 January 2015 at 16:57, Will Newton <will.newton at linaro.org> wrote:
>> sh_addralign of zero is equivalent to sh_addralign of one, meaning
>> no alignment specified. Avoid calculating Log2 or modulus when
>> sh_addralign is zero as the results will not be useful.
>> ---
>>   lib/ReaderWriter/ELF/Atoms.h |  3 +++
>>   test/elf/sh_addralign.test   | 38 ++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 41 insertions(+)
>>   create mode 100644 test/elf/sh_addralign.test
>>
>> Changes in v2:
>>   - Added a test
> Ping - is the test ok?
>
>> diff --git a/lib/ReaderWriter/ELF/Atoms.h b/lib/ReaderWriter/ELF/Atoms.h
>> index 23fa3f8..1aed346 100644
>> --- a/lib/ReaderWriter/ELF/Atoms.h
>> +++ b/lib/ReaderWriter/ELF/Atoms.h
>> @@ -286,6 +286,9 @@ public:
>>       if ((_symbol->getType() == llvm::ELF::STT_COMMON) ||
>>           _symbol->st_shndx == llvm::ELF::SHN_COMMON) {
>>         return Alignment(llvm::Log2_64(_symbol->st_value));
>> +    } else if (_section->sh_addralign == 0) {
>> +      // sh_addralign of 0 means no alignment
>> +      return Alignment(0, _symbol->st_value);
>>       }
>>       return Alignment(llvm::Log2_64(_section->sh_addralign),
>>                        _symbol->st_value % _section->sh_addralign);
>> diff --git a/test/elf/sh_addralign.test b/test/elf/sh_addralign.test
>> new file mode 100644
>> index 0000000..404c676
>> --- /dev/null
>> +++ b/test/elf/sh_addralign.test
>> @@ -0,0 +1,38 @@
>> +# Check handling of section alignment.
>> +# RUN: yaml2obj -format=elf %s > %t-obj
>> +# RUN: lld -flavor gnu -target arm64 -o %t-exe %t-obj
>> +# RUN: llvm-objdump -h %t-exe | FileCheck %s
>> +
>> +# CHECK: 8 .data         00000000 0000000000402000 DATA
>> +
>> +!ELF
>> +FileHeader: !FileHeader
>> +  Class: ELFCLASS64
>> +  Data: ELFDATA2LSB
>> +  Type: ET_REL
>> +  Machine: EM_AARCH64
>> +
>> +Sections:
>> +- Name: .text
>> +  Type: SHT_PROGBITS
>> +  Content: ''
>> +  AddressAlign: 0
>> +  Flags: [SHF_ALLOC, SHF_EXECINSTR]
>> +- Name:            .bss
>> +  Type:            SHT_NOBITS
>> +  Flags:           [ SHF_WRITE, SHF_ALLOC ]
>> +  AddressAlign:    1
>> +  Content:         ''
>> +  Size:            0x80000000
>> +- Name: .data
>> +  Type: SHT_PROGBITS
>> +  Content: ''
>> +  AddressAlign: 4096
>> +  Flags: [SHF_ALLOC, SHF_WRITE]
>> +
>> +Symbols:
>> +  Global:
>> +    - Name: _start
>> +      Section: .text
>> +      Value: 0x0
>> +      Size: 4
>> --
>> 2.1.0
>>
>
>


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