forked from OSchip/llvm-project
[ELF] - Dedupliсate FDEs when sections are ICFed.
When LLD do ICF for 2 identical sections it leaves 2 duplicate entries in .eh_frame pointing to the same address. After that it fixes .eh_frame_header's header, so that it says it contains single FDE, though section itself contains 2 (it contains garbage data at tail). As a result excessive entries in .eh_frame and excessive dummy data in .eh_frame_header emited to output. Patch fixes that. This is PR34518. Differential revision: https://reviews.llvm.org/D38998 llvm-svn: 316648
This commit is contained in:
George Rimar
parent
b72b1fb0de
commit
d605f414db
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@ -449,9 +449,11 @@ bool EhFrameSection<ELFT>::isFdeLive(EhSectionPiece &Fde,
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const RelTy &Rel = Rels[FirstRelI];
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SymbolBody &B = Sec->template getFile<ELFT>()->getRelocTargetSym(Rel);
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// FDEs for garbage-collected or merged-by-ICF sections are dead.
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if (auto *D = dyn_cast<DefinedRegular>(&B))
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if (D->Section)
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return cast<InputSectionBase>(D->Section)->Repl->Live;
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if (auto *Sec = cast_or_null<InputSectionBase>(D->Section))
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return Sec->Live && (Sec == Sec->Repl);
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return false;
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}
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@ -0,0 +1,95 @@
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# REQUIRES: x86
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## Testcase checks that we correctly deduplicate FDEs when ICF
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## merges two sections.
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# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
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# RUN: ld.lld %t -o %t2 --icf=all --eh-frame-hdr
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# RUN: llvm-readobj -r %t | FileCheck %s --check-prefix=OBJ
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# RUN: llvm-readobj -s -section-data %t2 | FileCheck %s
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# OBJ: Relocations [
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# OBJ-NEXT: Section {{.*}} .rela.eh_frame {
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# OBJ-NEXT: 0x20 R_X86_64_PC32 .text.f1 0x0
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# OBJ-NEXT: 0x34 R_X86_64_PC32 .text.f1 0x2
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# OBJ-NEXT: 0x48 R_X86_64_PC32 .text.f2 0x0
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# OBJ-NEXT: 0x5C R_X86_64_PC32 .text.f2 0x2
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# OBJ-NEXT: }
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# OBJ-NEXT: ]
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# CHECK: Section {
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# CHECK: Index: 1
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# CHECK: Name: .eh_frame_hdr
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# CHECK-NEXT: Type: SHT_PROGBITS
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# CHECK-NEXT: Flags [
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# CHECK-NEXT: SHF_ALLOC
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# CHECK-NEXT: ]
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# CHECK-NEXT: Address: 0x200158
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# CHECK-NEXT: Offset: 0x158
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# CHECK-NEXT: Size: 28
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# CHECK-NEXT: Link: 0
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# CHECK-NEXT: Info: 0
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# CHECK-NEXT: AddressAlignment:
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# CHECK-NEXT: EntrySize: 0
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# CHECK-NEXT: SectionData (
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# CHECK-NEXT: 0000: 011B033B 1C000000 02000000 A80E0000
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## ^ ^-- FDE(1) PC
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## ^-- Number of FDEs
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# CHECK-NEXT: 0010: 38000000 AA0E0000 50000000
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## ^-- FDE(2) PC
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# CHECK-NEXT: )
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# CHECK-NEXT: }
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## FDE(1) == 0x201000 - .eh_frame_hdr(0x200158) = 0xEA8
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## FDE(2) == 0x201000 - .eh_frame_hdr(0x200158) + 2(relocation addend) = 0xEAA
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## Check .eh_frame contains CIE and two FDEs remaining after ICF.
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# CHECK-NEXT: Section {
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# CHECK-NEXT: Index: 2
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# CHECK-NEXT: Name: .eh_frame
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# CHECK-NEXT: Type: SHT_PROGBITS
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# CHECK-NEXT: Flags [
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# CHECK-NEXT: SHF_ALLOC
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# CHECK-NEXT: ]
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# CHECK-NEXT: Address: 0x200178
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# CHECK-NEXT: Offset: 0x178
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# CHECK-NEXT: Size: 72
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# CHECK-NEXT: Link: 0
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# CHECK-NEXT: Info: 0
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# CHECK-NEXT: AddressAlignment: 8
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# CHECK-NEXT: EntrySize: 0
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# CHECK-NEXT: SectionData (
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# CHECK-NEXT: 0000: 14000000 00000000 017A5200 01781001
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# CHECK-NEXT: 0010: 1B0C0708 90010000 14000000 1C000000
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# CHECK-NEXT: 0020: 680E0000 01000000 00000000 00000000
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# CHECK-NEXT: 0030: 14000000 34000000 520E0000 01000000
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# CHECK-NEXT: 0040: 00000000 00000000
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# CHECK-NEXT: )
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# CHECK-NEXT: }
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# CHECK: Section {
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# CHECK: Index:
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# CHECK: Name: .text
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# CHECK-NEXT: Type: SHT_PROGBITS
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# CHECK-NEXT: Flags [
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# CHECK-NEXT: SHF_ALLOC
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# CHECK-NEXT: SHF_EXECINSTR
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# CHECK-NEXT: ]
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# CHECK-NEXT: Address: 0x201000
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.section .text.f1, "ax"
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.cfi_startproc
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nop
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.cfi_endproc
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nop
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.cfi_startproc
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ret
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.cfi_endproc
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.section .text.f2, "ax"
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.cfi_startproc
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nop
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.cfi_endproc
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nop
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.cfi_startproc
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ret
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.cfi_endproc
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@ -2,17 +2,18 @@
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# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
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# RUN: ld.lld %t -o %t2 --icf=all --eh-frame-hdr
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# RUN: llvm-objdump -s %t2 | FileCheck %s
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# RUN: llvm-objdump -s -section-headers %t2 | FileCheck %s
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## Check .eh_frame_hdr contains single FDE and no garbage data at tail.
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# CHECK: Sections:
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# CHECK: Idx Name Size
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# CHECK: .eh_frame_hdr 00000014
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# CHECK: Contents of section .eh_frame_hdr:
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# CHECK-NEXT: 200158 011b033b 1c000000 01000000 a80e0000
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# CHECK-NEXT: 200158 011b033b 14000000 01000000
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# ^ FDE count
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# CHECK-NEXT: 200168 38000000 00000000 00000000
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# ^ FDE for f2
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.globl _start, f1, f2
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_start:
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ret
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.globl f1, f2
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.section .text.f1, "ax"
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f1:
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