[lld] r338088 - ELF: Make --print-icf-sections output deterministic.
Ilya Biryukov via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 27 02:01:24 PDT 2018
Reverted in r338110 to unbreak the integrate.
On Fri, Jul 27, 2018 at 10:46 AM Ilya Biryukov <ibiryukov at google.com> wrote:
> The results depend on the compiler flags, specifically setting
> '-funsigned-char' produces different results.
>
> On Fri, Jul 27, 2018 at 9:46 AM Ilya Biryukov <ibiryukov at google.com>
> wrote:
>
>> This seems to break our integrate, the order of sections in the test
>> seems different. Any ideas what could cause this?
>>
>> On Fri, Jul 27, 2018 at 1:34 AM Peter Collingbourne via llvm-commits <
>> llvm-commits at lists.llvm.org> wrote:
>>
>>> Author: pcc
>>> Date: Thu Jul 26 16:34:35 2018
>>> New Revision: 338088
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=338088&view=rev
>>> Log:
>>> ELF: Make --print-icf-sections output deterministic.
>>>
>>> The icf-safe.s test currently fails on 32-bit platforms because it uses
>>> the --print-icf-sections flag and depends on the output appearing in
>>> a specific order. However, this flag causes the output to depend on
>>> the order of the sections in the Sections array, which depends on the
>>> hash values returned from hash_combine, which happen to be different
>>> for that test between 32-bit and 64-bit platforms.
>>>
>>> This change makes the output deterministic by using xxHash64 instead of
>>> hash_combine.
>>>
>>> Differential Revision: https://reviews.llvm.org/D49877
>>>
>>> Modified:
>>> lld/trunk/ELF/ICF.cpp
>>> lld/trunk/test/ELF/icf-safe.s
>>>
>>> Modified: lld/trunk/ELF/ICF.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/ICF.cpp?rev=338088&r1=338087&r2=338088&view=diff
>>>
>>> ==============================================================================
>>> --- lld/trunk/ELF/ICF.cpp (original)
>>> +++ lld/trunk/ELF/ICF.cpp Thu Jul 26 16:34:35 2018
>>> @@ -80,9 +80,10 @@
>>> #include "SyntheticSections.h"
>>> #include "Writer.h"
>>> #include "lld/Common/Threads.h"
>>> -#include "llvm/ADT/Hashing.h"
>>> +#include "llvm/ADT/StringExtras.h"
>>> #include "llvm/BinaryFormat/ELF.h"
>>> #include "llvm/Object/ELF.h"
>>> +#include "llvm/Support/xxhash.h"
>>> #include <algorithm>
>>> #include <atomic>
>>>
>>> @@ -155,12 +156,6 @@ private:
>>> };
>>> }
>>>
>>> -// Returns a hash value for S. Note that the information about
>>> -// relocation targets is not included in the hash value.
>>> -template <class ELFT> static uint32_t getHash(InputSection *S) {
>>> - return hash_combine(S->Flags, S->getSize(), S->NumRelocations,
>>> S->Data);
>>> -}
>>> -
>>> // Returns true if section S is subject of ICF.
>>> static bool isEligible(InputSection *S) {
>>> if (!S->Live || S->KeepUnique || !(S->Flags & SHF_ALLOC))
>>> @@ -441,7 +436,7 @@ template <class ELFT> void ICF<ELFT>::ru
>>> // Initially, we use hash values to partition sections.
>>> parallelForEach(Sections, [&](InputSection *S) {
>>> // Set MSB to 1 to avoid collisions with non-hash IDs.
>>> - S->Class[0] = getHash<ELFT>(S) | (1U << 31);
>>> + S->Class[0] = xxHash64(toStringRef(S->Data)) | (1U << 31);
>>> });
>>>
>>> // From now on, sections in Sections vector are ordered so that
>>> sections
>>>
>>> Modified: lld/trunk/test/ELF/icf-safe.s
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/icf-safe.s?rev=338088&r1=338087&r2=338088&view=diff
>>>
>>> ==============================================================================
>>> --- lld/trunk/test/ELF/icf-safe.s (original)
>>> +++ lld/trunk/test/ELF/icf-safe.s Thu Jul 26 16:34:35 2018
>>> @@ -10,10 +10,6 @@
>>> # RUN: ld.lld %t1.o %t2.o -o %t2 --icf=all --print-icf-sections
>>> --export-dynamic | FileCheck --check-prefix=ALL-EXPORT %s
>>> # RUN: ld.lld %t1copy.o -o %t4 --icf=safe 2>&1 | FileCheck
>>> --check-prefix=OBJCOPY %s
>>>
>>> -# CHECK-NOT: selected section {{.*}}:(.rodata.l1)
>>> -# CHECK: selected section {{.*}}:(.rodata.l3)
>>> -# CHECK: removing identical section {{.*}}:(.rodata.l4)
>>> -
>>> # CHECK-NOT: selected section {{.*}}:(.text.f1)
>>> # CHECK: selected section {{.*}}:(.text.f3)
>>> # CHECK: removing identical section {{.*}}:(.text.f4)
>>> @@ -22,6 +18,10 @@
>>> # CHECK: selected section {{.*}}:(.rodata.h3)
>>> # CHECK: removing identical section {{.*}}:(.rodata.h4)
>>>
>>> +# CHECK-NOT: selected section {{.*}}:(.rodata.l1)
>>> +# CHECK: selected section {{.*}}:(.rodata.l3)
>>> +# CHECK: removing identical section {{.*}}:(.rodata.l4)
>>> +
>>> # CHECK-NOT: selected section {{.*}}:(.rodata.g1)
>>> # CHECK: selected section {{.*}}:(.rodata.g3)
>>> # CHECK: removing identical section {{.*}}:(.rodata.g4)
>>> @@ -30,21 +30,21 @@
>>>
>>> # With --icf=all address-significance implies keep-unique only for
>>> rodata, not
>>> # text.
>>> -# ALL-NOT: selected section {{.*}}:(.rodata.l1)
>>> -# ALL: selected section {{.*}}:(.rodata.l3)
>>> -# ALL: removing identical section {{.*}}:(.rodata.l4)
>>> -
>>> # ALL: selected section {{.*}}:(.text.f3)
>>> # ALL: removing identical section {{.*}}:(.text.f4)
>>>
>>> +# ALL-NOT: selected section {{.*}}:(.rodata.h1)
>>> +# ALL: selected section {{.*}}:(.rodata.h3)
>>> +# ALL: removing identical section {{.*}}:(.rodata.h4)
>>> +
>>> # ALL: selected section {{.*}}:(.text.f1)
>>> # ALL: removing identical section {{.*}}:(.text.f2)
>>> # ALL: removing identical section {{.*}}:(.text.non_addrsig1)
>>> # ALL: removing identical section {{.*}}:(.text.non_addrsig2)
>>>
>>> -# ALL-NOT: selected section {{.*}}:(.rodata.h1)
>>> -# ALL: selected section {{.*}}:(.rodata.h3)
>>> -# ALL: removing identical section {{.*}}:(.rodata.h4)
>>> +# ALL-NOT: selected section {{.*}}:(.rodata.l1)
>>> +# ALL: selected section {{.*}}:(.rodata.l3)
>>> +# ALL: removing identical section {{.*}}:(.rodata.l4)
>>>
>>> # ALL-NOT: selected section {{.*}}:(.rodata.g1)
>>> # ALL: selected section {{.*}}:(.rodata.g3)
>>> @@ -58,36 +58,36 @@
>>> # STB_LOCAL or STV_HIDDEN symbols. The dynsym entries should have
>>> prevented
>>> # anything else from being merged.
>>> # EXPORT-NOT: selected section
>>> -# EXPORT: selected section {{.*}}:(.rodata.l3)
>>> -# EXPORT: removing identical section {{.*}}:(.rodata.l4)
>>> -# EXPORT-NOT: selected section
>>> # EXPORT: selected section {{.*}}:(.rodata.h3)
>>> # EXPORT: removing identical section {{.*}}:(.rodata.h4)
>>> # EXPORT-NOT: selected section
>>> # EXPORT: selected section {{.*}}:(.text)
>>> # EXPORT: removing identical section {{.*}}:(.text)
>>> # EXPORT-NOT: selected section
>>> +# EXPORT: selected section {{.*}}:(.rodata.l3)
>>> +# EXPORT: removing identical section {{.*}}:(.rodata.l4)
>>> +# EXPORT-NOT: selected section
>>>
>>> # If --icf=all is specified when exporting we can also merge the
>>> exported text
>>> # sections, but not the exported rodata.
>>> # ALL-EXPORT-NOT: selected section
>>> -# ALL-EXPORT: selected section {{.*}}:(.rodata.l3)
>>> -# ALL-EXPORT: removing identical section {{.*}}:(.rodata.l4)
>>> -# ALL-EXPORT-NOT: selected section
>>> # ALL-EXPORT: selected section {{.*}}:(.text.f3)
>>> # ALL-EXPORT: removing identical section {{.*}}:(.text.f4)
>>> # ALL-EXPORT-NOT: selected section
>>> +# ALL-EXPORT: selected section {{.*}}:(.rodata.h3)
>>> +# ALL-EXPORT: removing identical section {{.*}}:(.rodata.h4)
>>> +# ALL-EXPORT-NOT: selected section
>>> # ALL-EXPORT: selected section {{.*}}:(.text.f1)
>>> # ALL-EXPORT: removing identical section {{.*}}:(.text.f2)
>>> # ALL-EXPORT: removing identical section {{.*}}:(.text.non_addrsig1)
>>> # ALL-EXPORT: removing identical section {{.*}}:(.text.non_addrsig2)
>>> # ALL-EXPORT-NOT: selected section
>>> -# ALL-EXPORT: selected section {{.*}}:(.rodata.h3)
>>> -# ALL-EXPORT: removing identical section {{.*}}:(.rodata.h4)
>>> -# ALL-EXPORT-NOT: selected section
>>> # ALL-EXPORT: selected section {{.*}}:(.text)
>>> # ALL-EXPORT: removing identical section {{.*}}:(.text)
>>> # ALL-EXPORT-NOT: selected section
>>> +# ALL-EXPORT: selected section {{.*}}:(.rodata.l3)
>>> +# ALL-EXPORT: removing identical section {{.*}}:(.rodata.l4)
>>> +# ALL-EXPORT-NOT: selected section
>>>
>>> # OBJCOPY: --icf=safe is incompatible with object files created using
>>> objcopy or ld -r
>>>
>>>
>>>
>>> _______________________________________________
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>>> llvm-commits at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>>
>>
>>
>> --
>> Regards,
>> Ilya Biryukov
>>
>
>
> --
> Regards,
> Ilya Biryukov
>
--
Regards,
Ilya Biryukov
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