d449fc8671
dynamic symbol table populating and DT_NEEDED tag creation. The `isDynSymEntryRequired` function returns true if the specified shared library atom requires a dynamic symbol table entry. The `isNeededTagRequired` function returns true if we need to create DT_NEEDED tag for the shared library defined specified shared atom. By default the both functions return true. So there is no functional changes for all targets except MIPS. Probably we need to spread the same modifications on other ELF targets but I want to implement and fully tested complete set of changes for MIPS target first. For MIPS we create a dynamic symbol table entry for a shared library atom iif this atom is referenced by a regular defined atom. For example, if library L1 defines symbol T1, library L2 defines symbol T2 and uses symbol T1 and executable file E1 uses symbol T2 but does not use symbol T1 we create an entry in the E1 dynamic symbol table for symbol T2 and do not create an entry for T1. The patch creates DT_NEEDED tags for shared libraries contain shared library atoms which a) referenced by regular defined atoms; b) have corresponding copy dynamic relocations (R_MIPS_COPY). Now the patch does not take in account --as-needed / --no-as-needed command line options. So it is too restrictive and create DT_NEEDED tags for really needed shared libraries only. I plan to fix that by subsequent patches. llvm-svn: 211674
102 lines
2.8 KiB
Plaintext
102 lines
2.8 KiB
Plaintext
# Check that LLD does not populate a shared library dynamic symbol table
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# by unnecessary symbols.
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# 1. bar.so defines T2 and T3
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# 2. foo.so defines T1 and references T2
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# 4. foo.so dynamic table should contain T1 and T2 entries only
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# RUN: yaml2obj -format=elf -docnum 1 %s > %t-bar.o
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# RUN: yaml2obj -format=elf -docnum 2 %s > %t-foo.o
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# RUN: lld -flavor gnu -target mipsel -shared -o %t-bar.so %t-bar.o
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# RUN: lld -flavor gnu -target mipsel -shared -o %t-foo.so %t-foo.o %t-bar.so
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# RUN: llvm-readobj -dt -dynamic-table %t-foo.so | FileCheck %s
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# CHECK: DynamicSymbols [
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# CHECK-NEXT: Symbol {
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# CHECK-NEXT: Name: @ (0)
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# CHECK-NEXT: Value: 0x0
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# CHECK-NEXT: Size: 0
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# CHECK-NEXT: Binding: Local (0x0)
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# CHECK-NEXT: Type: None (0x0)
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# CHECK-NEXT: Other: 0
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# CHECK-NEXT: Section: Undefined (0x0)
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# CHECK-NEXT: }
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# CHECK-NEXT: Symbol {
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# CHECK-NEXT: Name: T1@ ({{.*}})
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# CHECK-NEXT: Value: {{.*}}
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# CHECK-NEXT: Size: 8
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# CHECK-NEXT: Binding: Global (0x1)
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# CHECK-NEXT: Type: Function (0x2)
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# CHECK-NEXT: Other: 0
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# CHECK-NEXT: Section: .text (0x4)
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# CHECK-NEXT: }
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# CHECK-NEXT: Symbol {
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# CHECK-NEXT: Name: T2@ ({{.*}})
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# CHECK-NEXT: Value: 0x0
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# CHECK-NEXT: Size: 0
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# CHECK-NEXT: Binding: Global (0x1)
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# CHECK-NEXT: Type: Function (0x2)
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# CHECK-NEXT: Other: 0
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# CHECK-NEXT: Section: Undefined (0x0)
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# CHECK-NEXT: }
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# CHECK-NEXT: ]
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# CHECK: 0x00000003 PLTGOT 0x1000
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# CHECK-NEXT: 0x00000001 NEEDED SharedLibrary (dynsym-table-2.test.tmp-bar.so)
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# CHECK-NEXT: 0x00000000 NULL 0x0
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# bar.o
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---
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FileHeader:
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Class: ELFCLASS32
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Data: ELFDATA2LSB
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Type: ET_REL
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Machine: EM_MIPS
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Sections:
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- Name: .text
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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AddressAlign: 0x04
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Size: 0x08
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Symbols:
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Global:
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- Name: T2
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Type: STT_FUNC
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Section: .text
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Size: 0x04
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- Name: T3
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Type: STT_FUNC
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Section: .text
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Value: 0x04
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Size: 0x04
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# foo.o
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---
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FileHeader:
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Class: ELFCLASS32
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Data: ELFDATA2LSB
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Type: ET_REL
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Machine: EM_MIPS
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Sections:
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- Name: .text
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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AddressAlign: 0x04
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Size: 0x08
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- Name: .rel.text
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Type: SHT_REL
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Link: .symtab
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AddressAlign: 0x08
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Info: .text
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Relocations:
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- Offset: 0
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Symbol: T2
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Type: R_MIPS_CALL16
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Symbols:
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Global:
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- Name: T1
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Type: STT_FUNC
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Section: .text
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Size: 0x08
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- Name: T2
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...
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