[lld] r338088 - ELF: Make --print-icf-sections output deterministic.
Ilya Biryukov via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 27 01:46:13 PDT 2018
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
>>
>>
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>
>
>
> --
> Regards,
> Ilya Biryukov
>
--
Regards,
Ilya Biryukov
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180727/40aac0f7/attachment.html>
More information about the llvm-commits
mailing list