[lld] r338088 - ELF: Make --print-icf-sections output deterministic.
Ilya Biryukov via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 27 00:46:24 PDT 2018
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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--
Regards,
Ilya Biryukov
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