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llvm-project/lld/test/ELF/global-offset-table-position.s

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[ELF] Move `// REQUIRES:` line to the top llvm-svn: 335676
2018-06-27 06:20:04 +08:00
// REQUIRES: x86
[ELF] Define _GLOBAL_OFFSET_TABLE_ symbol relative to .got On many architectures gcc and clang will recognize _GLOBAL_OFFSET_TABLE_ - . and produce a relocation that can be processed without needing to know the value of _GLOBAL_OFFSET_TABLE_. This is not always the case; for example ARM gcc produces R_ARM_BASE_PREL but clang produces the more general R_ARM_REL32 to _GLOBAL_OFFSET_TABLE_. To evaluate this relocation correctly _GLOBAL_OFFSET_TABLE_ must be defined to be the either the base of the GOT or end of the GOT dependent on architecture.. If/when llvm-mc is changed to recognize _GLOBAL_OFFSET_TABLE_ - . this change will not be necessary for new objects. However there may still be old objects and versions of clang. Differential Revision: https://reviews.llvm.org/D34355 llvm-svn: 306282
2017-06-26 18:22:17 +08:00
// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t
[ELF] - Do --hash-style=both by default. Its PR34712, GNU linkers recently changed default values to "both" of "sysv". Patch do the same for all targets except MIPS, where .gnu.hash section is not yet supported. Code suggested by Rui Ueyama. Differential revision: https://reviews.llvm.org/D38407 llvm-svn: 315051
2017-10-06 17:37:44 +08:00
// RUN: ld.lld --hash-style=sysv -shared %t -o %t2
[test] Change llvm-readobj -long-option to --long-option or well-known short options. NFC Also change some options that have different semantics (cause confusion) in llvm-readelf mode: -s => -S -t => --symbols -sd => --section-data llvm-svn: 359651
2019-05-01 13:49:01 +08:00
// RUN: llvm-readobj --symbols %t2 | FileCheck %s
[ELF] Define _GLOBAL_OFFSET_TABLE_ symbol relative to .got On many architectures gcc and clang will recognize _GLOBAL_OFFSET_TABLE_ - . and produce a relocation that can be processed without needing to know the value of _GLOBAL_OFFSET_TABLE_. This is not always the case; for example ARM gcc produces R_ARM_BASE_PREL but clang produces the more general R_ARM_REL32 to _GLOBAL_OFFSET_TABLE_. To evaluate this relocation correctly _GLOBAL_OFFSET_TABLE_ must be defined to be the either the base of the GOT or end of the GOT dependent on architecture.. If/when llvm-mc is changed to recognize _GLOBAL_OFFSET_TABLE_ - . this change will not be necessary for new objects. However there may still be old objects and versions of clang. Differential Revision: https://reviews.llvm.org/D34355 llvm-svn: 306282
2017-06-26 18:22:17 +08:00
[ELF] Recommit 327248 with Arm using the .got for _GLOBAL_OFFSET_TABLE_ This is the same as 327248 except Arm defining _GLOBAL_OFFSET_TABLE_ to be the base of the .got section as some existing code is relying upon it. For most Targets the _GLOBAL_OFFSET_TABLE_ symbol is expected to be at the start of the .got.plt section so that _GLOBAL_OFFSET_TABLE_[0] = reserved value that is by convention the address of the dynamic section. Previously we had defined _GLOBAL_OFFSET_TABLE_ as either the start or end of the .got section with the intention that the .got.plt section would follow the .got. However this does not always hold with the current default section ordering so _GLOBAL_OFFSET_TABLE_[0] may not be consistent with the reserved first entry of the .got.plt. X86, X86_64 and AArch64 will use the .got.plt. Arm, Mips and Power use .got Fixes PR36555 Differential Revision: https://reviews.llvm.org/D44259 llvm-svn: 327823
2018-03-19 14:52:51 +08:00
// The X86_64 _GLOBAL_OFFSET_TABLE_ is defined at the start of the .got.plt
// section.
[ELF] Define _GLOBAL_OFFSET_TABLE_ symbol relative to .got On many architectures gcc and clang will recognize _GLOBAL_OFFSET_TABLE_ - . and produce a relocation that can be processed without needing to know the value of _GLOBAL_OFFSET_TABLE_. This is not always the case; for example ARM gcc produces R_ARM_BASE_PREL but clang produces the more general R_ARM_REL32 to _GLOBAL_OFFSET_TABLE_. To evaluate this relocation correctly _GLOBAL_OFFSET_TABLE_ must be defined to be the either the base of the GOT or end of the GOT dependent on architecture.. If/when llvm-mc is changed to recognize _GLOBAL_OFFSET_TABLE_ - . this change will not be necessary for new objects. However there may still be old objects and versions of clang. Differential Revision: https://reviews.llvm.org/D34355 llvm-svn: 306282
2017-06-26 18:22:17 +08:00
.globl a
.type a,@object
.comm a,4,4
.globl f
.type f,@function
f:
movq a@GOTPCREL(%rip), %rax
.global _start
.type _start,@function
_start:
callq f@PLT
.data
.long _GLOBAL_OFFSET_TABLE_ - .
// CHECK: Name: _GLOBAL_OFFSET_TABLE_
[ELF] Simplify RelRo, TLS, NOBITS section ranks and make RW PT_LOAD start with RelRo Old: PT_LOAD(.data | PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .bss) New: PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .data .bss) The placement of | indicates page alignment caused by PT_GNU_RELRO. The new layout has simpler rules and saves space for many cases. Old size: roundup(.data) + roundup(.data.rel.ro) New size: roundup(.data.rel.ro + .bss.rel.ro) + .data Other advantages: * At runtime the 3 memory mappings decrease to 2. * start(PT_TLS) = start(PT_GNU_RELRO) = start(RW PT_LOAD). This simplifies binary manipulation tools. GNU strip before 2.31 discards PT_GNU_RELRO if its address is not equal to the start of its associated PT_LOAD. This has been fixed by https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f2731e0c374e5323ce4cdae2bcc7b7fe22da1a6f But with this change, we will be compatible with GNU strip before 2.31 * Before, .got.plt (non-relro by default) was placed before .got (relro by default), which made it impossible to have _GLOBAL_OFFSET_TABLE_ (start of .got.plt on x86-64) equal to the end of .got (R_GOT*_FROM_END) (https://bugs.llvm.org/show_bug.cgi?id=36555). With the new ordering, we can improve on this regard if we'd like to. Reviewers: ruiu, espindola, pcc Subscribers: emaste, arichardson, llvm-commits, joerg, jdoerfert Differential Revision: https://reviews.llvm.org/D56828 llvm-svn: 356117
2019-03-14 11:47:45 +08:00
// CHECK-NEXT: Value: 0x3008
[ELF] Define _GLOBAL_OFFSET_TABLE_ symbol relative to .got On many architectures gcc and clang will recognize _GLOBAL_OFFSET_TABLE_ - . and produce a relocation that can be processed without needing to know the value of _GLOBAL_OFFSET_TABLE_. This is not always the case; for example ARM gcc produces R_ARM_BASE_PREL but clang produces the more general R_ARM_REL32 to _GLOBAL_OFFSET_TABLE_. To evaluate this relocation correctly _GLOBAL_OFFSET_TABLE_ must be defined to be the either the base of the GOT or end of the GOT dependent on architecture.. If/when llvm-mc is changed to recognize _GLOBAL_OFFSET_TABLE_ - . this change will not be necessary for new objects. However there may still be old objects and versions of clang. Differential Revision: https://reviews.llvm.org/D34355 llvm-svn: 306282
2017-06-26 18:22:17 +08:00
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Local
// CHECK-NEXT: Type: None (0x0)
// CHECK-NEXT: Other [
// CHECK-NEXT: STV_HIDDEN
// CHECK-NEXT: ]
[ELF] Recommit 327248 with Arm using the .got for _GLOBAL_OFFSET_TABLE_ This is the same as 327248 except Arm defining _GLOBAL_OFFSET_TABLE_ to be the base of the .got section as some existing code is relying upon it. For most Targets the _GLOBAL_OFFSET_TABLE_ symbol is expected to be at the start of the .got.plt section so that _GLOBAL_OFFSET_TABLE_[0] = reserved value that is by convention the address of the dynamic section. Previously we had defined _GLOBAL_OFFSET_TABLE_ as either the start or end of the .got section with the intention that the .got.plt section would follow the .got. However this does not always hold with the current default section ordering so _GLOBAL_OFFSET_TABLE_[0] may not be consistent with the reserved first entry of the .got.plt. X86, X86_64 and AArch64 will use the .got.plt. Arm, Mips and Power use .got Fixes PR36555 Differential Revision: https://reviews.llvm.org/D44259 llvm-svn: 327823
2018-03-19 14:52:51 +08:00
// CHECK-NEXT: Section: .got.plt