llvm-6502/test/MC/ELF/comdat-reloc.s

// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | llvm-readobj -s -sd | FileCheck %s

  .text
  .globl  hello
  .type  hello,@function
hello:
  call  world
  ret

  .section  .text.world,"axG",@progbits,world,comdat
  .type  world,@function
world:
  call  doctor
  ret

// CHECK:  Name: .group
// CHECK-NOT: SectionData
// CHECK: SectionData
// CHECK-NEXT: 0000: 01000000 05000000 07000000

// CHECK: Index: 5
// CHECK-NEXT: Name: .text.world
// CHECK-NOT: Section {
// CHECK: SHF_GROUP

// CHECK: Index: 7
// CHECK-NEXT: Name: .rela.text.world
// CHECK-NOT: Section {
// CHECK: SHF_GROUP
Put ELF COMDAT relocations into the relevant COMDAT group. Patch from Игорь Пашев (I do hope we support utf-8 commit messages; I also hope he'll forgive me for transliterating it as Igor Pashev in case things go horribly wrong). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186034 91177308-0d34-0410-b5e6-96231b3b80d8 2013-07-10 20:58:17 +00:00			`// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - \| llvm-readobj -s -sd \| FileCheck %s`

			`.text`
			`.globl hello`
			`.type hello,@function`
			`hello:`
			`call world`
			`ret`

			`.section .text.world,"axG",@progbits,world,comdat`
			`.type world,@function`
			`world:`
			`call doctor`
			`ret`

			`// CHECK: Name: .group`
			`// CHECK-NOT: SectionData`
			`// CHECK: SectionData`
Write relocation sections contiguously. Linkers normally read all the relocations upfront to compute the references between sections. Putting them together is a bit more cache friendly. I benchmarked linking a Release+Asserts clang with gold on a vm. I tried all 4 combinations of --gc-sections/no --gc-section hot and cold cache. I cleared the cache with echo 3 > /proc/sys/vm/drop_caches and warmed it up by running the link once before timing the subsequent ones. With cold cache and --gc-sections the time goes from 1.86130781665 +- 0.01713126697463843 seconds to 1.82370735105 +- 0.014127522318814516 seconds With cold cache and no --gc-sections the time goes from 1.6087245435500002 +- 0.012999066825178644 seconds to 1.5687122041500001 +- 0.013145850126026619 seconds With hot cache and no --gc-sections the time goes from 0.926200939 ( +- 0.33% ) seconds to 0.907200079 ( +- 0.31% ) seconds With hot cache and gc sections the time goes from 1.183038049 ( +- 0.34% ) seconds to 1.147355862 ( +- 0.39% ) seconds git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235165 91177308-0d34-0410-b5e6-96231b3b80d8 2015-04-17 08:11:38 +00:00			`// CHECK-NEXT: 0000: 01000000 05000000 07000000`
Put ELF COMDAT relocations into the relevant COMDAT group. Patch from Игорь Пашев (I do hope we support utf-8 commit messages; I also hope he'll forgive me for transliterating it as Igor Pashev in case things go horribly wrong). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186034 91177308-0d34-0410-b5e6-96231b3b80d8 2013-07-10 20:58:17 +00:00
Write relocation sections contiguously. Linkers normally read all the relocations upfront to compute the references between sections. Putting them together is a bit more cache friendly. I benchmarked linking a Release+Asserts clang with gold on a vm. I tried all 4 combinations of --gc-sections/no --gc-section hot and cold cache. I cleared the cache with echo 3 > /proc/sys/vm/drop_caches and warmed it up by running the link once before timing the subsequent ones. With cold cache and --gc-sections the time goes from 1.86130781665 +- 0.01713126697463843 seconds to 1.82370735105 +- 0.014127522318814516 seconds With cold cache and no --gc-sections the time goes from 1.6087245435500002 +- 0.012999066825178644 seconds to 1.5687122041500001 +- 0.013145850126026619 seconds With hot cache and no --gc-sections the time goes from 0.926200939 ( +- 0.33% ) seconds to 0.907200079 ( +- 0.31% ) seconds With hot cache and gc sections the time goes from 1.183038049 ( +- 0.34% ) seconds to 1.147355862 ( +- 0.39% ) seconds git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235165 91177308-0d34-0410-b5e6-96231b3b80d8 2015-04-17 08:11:38 +00:00			`// CHECK: Index: 5`
Put ELF COMDAT relocations into the relevant COMDAT group. Patch from Игорь Пашев (I do hope we support utf-8 commit messages; I also hope he'll forgive me for transliterating it as Igor Pashev in case things go horribly wrong). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186034 91177308-0d34-0410-b5e6-96231b3b80d8 2013-07-10 20:58:17 +00:00			`// CHECK-NEXT: Name: .text.world`
			`// CHECK-NOT: Section {`
			`// CHECK: SHF_GROUP`

			`// CHECK: Index: 7`
			`// CHECK-NEXT: Name: .rela.text.world`
			`// CHECK-NOT: Section {`
			`// CHECK: SHF_GROUP`