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clang-p2996/llvm/test/tools/yaml2obj/ELF/section-headers-exclude.yaml
Alexander Yermolovich a224c5199b [LLD][LLVM] CG Graph profile using relocations 
Currently when .llvm.call-graph-profile is created by llvm it explicitly encodes the symbol indices. This section is basically a black box for post processing tools. For example, if we run strip -s on the object files the symbol table changes, but indices in that section do not. In non-visible behavior indices point to wrong symbols. The visible behavior indices point outside of Symbol table: "invalid symbol index".

This patch changes the format by using R_*_NONE relocations to indicate the from/to symbols. The Frequency (Weight) will still be in the .llvm.call-graph-profile, but symbol information will be in relocation section. In LLD information from both sections is used to reconstruct call graph profile. Relocations themselves will never be applied.

With this approach post processing tools that handle relocations correctly work for this section also. Tools can add/remove symbols and as long as they handle relocation sections with this approach information stays correct.

Doing a quick experiment with clang-13.
The size went up from 107KB to 322KB, aggregate of all the input sections. Size of clang-13 binary is ~118MB. For users of -fprofile-use/-fprofile-sample-use the size of object files will go up slightly, it will not impact final binary size.

Reviewed By: jhenderson, MaskRay

Differential Revision: https://reviews.llvm.org/D104080
2021-06-24 09:09:33 -07:00

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## Check how we can use the "Excluded" key of the "SectionHeaderTable" tag to exclude
## entries from the section header table.
## Check we can use the "Excluded" key to omit a section from the section header table.
## Check we do not include the name of the excluded section in the string table.
# RUN: yaml2obj %s -DINCLUDED=.foo -DEXCLUDED=.bar --docnum=1 -o %t1
# RUN: llvm-readelf --section-headers -p .shstrtab %t1 | \
# RUN: FileCheck %s -DSEC=.foo --check-prefixes=INCLUDE-SEC,INCLUDE-FOO
# RUN: yaml2obj %s -DINCLUDED=.bar -DEXCLUDED=.foo --docnum=1 -o %t2
# RUN: llvm-readelf --section-headers -p .shstrtab %t2 | \
# RUN: FileCheck %s -DSEC=.bar --check-prefixes=INCLUDE-SEC,INCLUDE-BAR
# INCLUDE-SEC: [Nr] Name
# INCLUDE-SEC: [ 1] [[SEC]]
# INCLUDE-SEC-NEXT: [ 2] .strtab
# INCLUDE-SEC-NEXT: [ 3] .shstrtab
# INCLUDE-SEC: String dump of section '.shstrtab':
# INCLUDE-FOO-NEXT: [ 1] .foo
# INCLUDE-BAR-NEXT: [ 1] .bar
# INCLUDE-SEC-NEXT: [ 6] .shstrtab
# INCLUDE-SEC-NEXT: [ 10] .strtab
# INCLUDE-SEC-NOT: {{.}}
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Name: .foo
Type: SHT_PROGBITS
- Name: .bar
Type: SHT_PROGBITS
- Type: SectionHeaderTable
Sections:
- Name: [[INCLUDED]]
- Name: .strtab
- Name: .shstrtab
Excluded:
- Name: [[EXCLUDED]]
## Check we report an error when a section is in both the "Sections" and "Excluded" lists at the same time.
## Also check that we report an error if a section is missing from the lists.
# RUN: not yaml2obj %s -DINCLUDED=.bar -DEXCLUDED=.strtab --docnum=1 -o /dev/null 2>&1 | \
# RUN: FileCheck %s --check-prefix=EXCLUDE-INCLUDED
# EXCLUDE-INCLUDED: error: repeated section name: '.strtab' in the section header description
# EXCLUDE-INCLUDED: error: section '.foo' should be present in the 'Sections' or 'Excluded' lists
## Check we report an error when the `Excluded` key mentions an unknown section.
# RUN: not yaml2obj %s -DINCLUDED=.bar -DEXCLUDED=.unknown --docnum=1 -o /dev/null 2>&1 | \
# RUN: FileCheck %s --check-prefix=EXCLUDE-UNKNOWN
# EXCLUDE-UNKNOWN: error: section '.foo' should be present in the 'Sections' or 'Excluded' lists
# EXCLUDE-UNKNOWN: error: section header contains undefined section '.unknown'
## Check we report an error when the `Excluded` key mentions a section more than once.
# RUN: not yaml2obj %s --docnum=2 -o /dev/null 2>&1 | FileCheck %s --check-prefix=EXCLUDE-TWICE
# EXCLUDE-TWICE: error: repeated section name: '.strtab' in the section header description
# EXCLUDE-TWICE: error: repeated section name: '.strtab' in the section header description
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Type: SectionHeaderTable
Sections:
- Name: .strtab
- Name: .shstrtab
Excluded:
- Name: .strtab
- Name: .strtab
## Check that we are able to exclude all sections, except the implicit
## null section, with the use of the "Excluded" key.
## Case A: the "Sections" key is present, but empty.
# RUN: yaml2obj %s --docnum=3 -o %t3
# RUN: llvm-readelf --section-headers %t3 | FileCheck %s --check-prefix=NO-SECTIONS
# NO-SECTIONS: There are 1 section headers, starting at offset 0x48:
# NO-SECTIONS: Section Headers:
# NO-SECTIONS-NEXT: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
# NO-SECTIONS-NEXT: [ 0] <no-strings> NULL 0000000000000000 000000 000000 00 0 0 0
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Type: SectionHeaderTable
Sections: []
Excluded:
- Name: .strtab
- Name: .shstrtab
## Case B: the "Sections" key is not present.
# RUN: yaml2obj %s --docnum=4 -o %t4
# RUN: llvm-readelf --section-headers %t4 | FileCheck %s --check-prefix=NO-SECTIONS
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Type: SectionHeaderTable
Excluded:
- Name: .strtab
- Name: .shstrtab
## Check how we handle cases when a section is excluded, but its section index is needed.
## The general rule is: when a section is explicitly linked with another section, which is
## excluded, then we report an error. In the case when it is linked implicitly with an excluded
## section, we use 0 as index value.
## Case A: check we report an error when a regular section has a Link field which
## points to an excluded section.
# RUN: not yaml2obj %s --docnum=5 -o /dev/null 2>&1 | \
# RUN: FileCheck %s --check-prefix=LINK -DSEC=.foo -DTARGET=.bar
# LINK: error: unable to link '[[SEC]]' to excluded section '[[TARGET]]'
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Name: .foo
Type: SHT_PROGBITS
Link: .bar
- Name: .bar
Type: SHT_PROGBITS
- Type: SectionHeaderTable
Sections:
- Name: .foo
- Name: .strtab
- Name: .shstrtab
Excluded:
- Name: .bar
## Case B.1: check we report an error when a symbol table section has a Link field which
## points to an excluded section.
# RUN: not yaml2obj %s --docnum=6 -DNAME=.symtab -DTYPE=SHT_SYMTAB -o /dev/null 2>&1 | \
# RUN: FileCheck %s --check-prefix=LINK -DSEC=.symtab -DTARGET=.foo
# RUN: not yaml2obj %s --docnum=6 -DNAME=.dynsym -DTYPE=SHT_DYNSYM -o /dev/null 2>&1 | \
# RUN: FileCheck %s --check-prefix=LINK -DSEC=.dynsym -DTARGET=.foo
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Sections:
- Name: [[NAME]]
Type: [[TYPE]]
Link: .foo
- Name: .foo
Type: SHT_PROGBITS
- Type: SectionHeaderTable
Sections:
- Name: [[NAME]]
- Name: .strtab
- Name: .shstrtab
Excluded:
- Name: .foo
## Case B.2: check we do not link .dynsym with .dynstr implicitly when the latter is excluded.
# RUN: yaml2obj %s --docnum=7 -o %t5
# RUN: llvm-readelf %t5 --section-headers | FileCheck %s --check-prefix=LINK-DYNSYM
# LINK-DYNSYM: [Nr] Name Type Address Off Size ES Flg Lk
# LINK-DYNSYM: [ 1] .dynsym DYNSYM 0000000000000000 000040 000018 18 A 0
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Sections:
- Name: .dynsym
Type: SHT_DYNSYM
- Name: .dynstr
Type: SHT_PROGBITS
- Type: SectionHeaderTable
Sections:
- Name: .dynsym
- Name: .strtab
- Name: .shstrtab
Excluded:
- Name: .dynstr
## Case B.3: check we do not link .symtab with .strtab implicitly when the latter is excluded.
# RUN: yaml2obj %s --docnum=8 -o %t6
# RUN: llvm-readelf %t6 --section-headers | FileCheck %s --check-prefix=LINK-SYMTAB
# LINK-SYMTAB: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
# LINK-SYMTAB: [ 1] .symtab SYMTAB 0000000000000000 000040 000018 18 0 1 0
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Sections:
- Name: .symtab
Type: SHT_SYMTAB
- Name: .strtab
Type: SHT_PROGBITS
- Type: SectionHeaderTable
Sections:
- Name: .symtab
- Name: .shstrtab
Excluded:
- Name: .strtab
## Case C: check we report an error when a debug section has a Link field which
## points to an excluded section.
# RUN: not yaml2obj %s --docnum=9 -o /dev/null 2>&1 | \
# RUN: FileCheck %s --check-prefix=LINK -DSEC=.debug_unknown -DTARGET=.strtab
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_EXEC
Sections:
- Name: .debug_unknown
Type: SHT_PROGBITS
Link: .strtab
- Type: SectionHeaderTable
Sections:
- Name: .debug_unknown
- Name: .shstrtab
Excluded:
- Name: .strtab
## Case D.1: check we report an error when a relocatable section has an Info field which
## points to an excluded section.
# RUN: not yaml2obj %s --docnum=10 -o /dev/null 2>&1 | \
# RUN: FileCheck %s --check-prefix=LINK -DSEC=.rela -DTARGET=.strtab
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Sections:
- Name: .rela
Type: SHT_RELA
Info: .strtab
Relocations: []
- Type: SectionHeaderTable
Sections:
- Name: .rela
- Name: .shstrtab
Excluded:
- Name: .strtab
## Case D.2: check we report an error when the SHT_REL[A] section is linked
## with an excluded section explicitly.
# RUN: not yaml2obj %s --docnum=11 -o /dev/null 2>&1 | \
# RUN: FileCheck %s --check-prefix=LINK -DSEC=.rela -DTARGET=.symtab
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Sections:
- Name: .rela
Type: SHT_RELA
Link: .symtab
Relocations: []
- Name: .symtab
Type: SHT_PROGBITS
- Type: SectionHeaderTable
Sections:
- Name: .rela
- Name: .strtab
- Name: .shstrtab
Excluded:
- Name: .symtab
## Case E: check we report an error when a symbol references an excluded section.
# RUN: not yaml2obj %s --docnum=12 -o /dev/null 2>&1 | \
# RUN: FileCheck %s --check-prefix=SYMBOL-SECTION
# SYMBOL-SECTION: error: excluded section referenced: '.foo' by symbol 'foo'
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Sections:
- Name: .foo
Type: SHT_PROGBITS
- Type: SectionHeaderTable
Sections:
- Name: .symtab
- Name: .strtab
- Name: .shstrtab
Excluded:
- Name: .foo
Symbols:
- Name: foo
Type: STT_OBJECT
Section: .foo
## Case F.1: check we report an error when a group section
## contains an excluded section member.
# RUN: not yaml2obj %s --docnum=13 -o /dev/null 2>&1 | \
# RUN: FileCheck %s --check-prefix=LINK -DSEC=.group -DTARGET=.strtab
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Name: .group
Type: SHT_GROUP
Members:
- SectionOrType: .strtab
- Type: SectionHeaderTable
Sections:
- Name: .group
- Name: .shstrtab
Excluded:
- Name: .strtab
## Case F.2: check we report an error when the group section is linked
## to an excluded section explicitly.
# RUN: not yaml2obj %s --docnum=14 -o /dev/null 2>&1 | \
# RUN: FileCheck %s --check-prefix=LINK -DSEC=.group -DTARGET=.symtab
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Name: .group
Type: SHT_GROUP
Link: .symtab
Members: []
- Name: .symtab
Type: SHT_SYMTAB
- Type: SectionHeaderTable
Sections:
- Name: .group
- Name: .strtab
- Name: .shstrtab
Excluded:
- Name: .symtab
## Case G: check we do not link SHT_LLVM_CALL_GRAPH_PROFILE/SHT_LLVM_ADDRSIG/SHT_GROUP/SHT_REL[A] sections
## with .symtab implicitly when the latter is excluded.
# RUN: yaml2obj %s --docnum=15 -o %t7
# RUN: llvm-readelf %t7 --section-headers | FileCheck %s --check-prefix=LINK-IMPLICIT
# LINK-IMPLICIT: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
# LINK-IMPLICIT: [ 1] .cgp LLVM_CALL_GRAPH_PROFILE 0000000000000000 000040 000000 08 0 0 0
# LINK-IMPLICIT-NEXT: [ 2] .llvm_addrsig LLVM_ADDRSIG 0000000000000000 000040 000000 00 0 0 0
# LINK-IMPLICIT-NEXT: [ 3] .group GROUP 0000000000000000 000040 000000 04 0 0 0
# LINK-IMPLICIT-NEXT: [ 4] .rela RELA 0000000000000000 000040 000000 18 0 0 0
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Sections:
- Name: .cgp
Type: SHT_LLVM_CALL_GRAPH_PROFILE
Content: ""
- Name: .llvm_addrsig
Type: SHT_LLVM_ADDRSIG
Content: ""
- Name: .group
Type: SHT_GROUP
Members: []
- Name: .rela
Type: SHT_RELA
Relocations: []
- Name: .symtab
Type: SHT_SYMTAB
- Type: SectionHeaderTable
Sections:
- Name: .cgp
- Name: .llvm_addrsig
- Name: .group
- Name: .rela
- Name: .strtab
- Name: .shstrtab
Excluded:
- Name: .symtab
## Case H: check we do not link SHT_HASH/SHT_GNU_HASH sections with .dynsym
## implicitly when the latter is excluded.
# RUN: yaml2obj %s --docnum=16 -o %t8
# RUN: llvm-readelf %t8 --section-headers | FileCheck %s --check-prefix=LINK-HASH
# LINK-HASH: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
# LINK-HASH: [ 1] .hash HASH 0000000000000000 000040 000000 04 0 0 0
# LINK-HASH-NEXT: [ 2] .gnu_hash GNU_HASH 0000000000000000 000040 000000 00 0 0 0
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Sections:
- Name: .hash
Type: SHT_HASH
Content: ""
- Name: .gnu_hash
Type: SHT_GNU_HASH
Content: ""
- Name: .dynsym
Type: SHT_DYNSYM
- Type: SectionHeaderTable
Sections:
- Name: .hash
- Name: .gnu_hash
- Name: .strtab
- Name: .shstrtab
Excluded:
- Name: .dynsym
## Case I: document the case when an excluded section is explicitly linked to another excluded section.
## We report an error in this case, because:
## 1) It is a reasonable behavior, as it is perhaps usually a result of a mistake
## in a YAML description.
## 2) Helps to keep the code simpler.
# RUN: not yaml2obj %s --docnum=17 -o /dev/null 2>&1 | FileCheck %s --check-prefix=CROSS-LINK
# CROSS-LINK: error: unable to link '.foo' to excluded section '.bar'
# CROSS-LINK-NEXT: error: unable to link '.bar' to excluded section '.foo'
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Name: .foo
Type: SHT_PROGBITS
Link: .bar
- Name: .bar
Type: SHT_PROGBITS
Link: .foo
- Type: SectionHeaderTable
Sections:
- Name: .strtab
- Name: .shstrtab
Excluded:
- Name: .foo
- Name: .bar
## Check we set e_shstrndx field to 0 when the section header string table is excluded.
## Check that the e_shnum field is adjusted properly when a section is removed.
# RUN: yaml2obj --docnum=18 %s -o %t9
# RUN: llvm-readelf --file-headers %t9 | FileCheck %s --check-prefix=SHSTRTAB
# SHSTRTAB: Number of section headers: 2
# SHSTRTAB: Section header string table index: 0
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Type: SectionHeaderTable
Sections:
- Name: .strtab
Excluded:
- Name: .shstrtab
## Check we do not allow using "Excluded" together with "NoHeaders".
# RUN: not yaml2obj %s --docnum=19 -DNOHEADERS=true -o /dev/null 2>&1 | FileCheck %s --check-prefix=NOHEADERS
# RUN: not yaml2obj %s --docnum=19 -DNOHEADERS=false -o /dev/null 2>&1 | FileCheck %s --check-prefix=NOHEADERS
# NOHEADERS: NoHeaders can't be used together with Offset/Sections/Excluded
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Type: SectionHeaderTable
NoHeaders: [[NOHEADERS]]
Excluded: []
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