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llvm-project/lld/test/COFF/string-tail-merge.s

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COFF: Implement string tail merging. In COFF, duplicate string literals are merged by placing them in a comdat whose leader symbol name contains a specific prefix followed by the hash and partial contents of the string literal. This gives us an easy way to identify sections containing string literals in the linker: check for leader symbol names with the given prefix. Any sections that are identified in this way as containing string literals may be tail merged. We do so using the StringTableBuilder class, which is also used to tail merge string literals in the ELF linker. Tail merging is enabled only if ICF is enabled, as this provides a signal as to whether the user cares about binary size. Differential Revision: https://reviews.llvm.org/D44504 llvm-svn: 327668
2018-03-16 05:14:02 +08:00
# REQUIRES: x86
# RUN: llvm-mc -triple=x86_64-windows-msvc -filetype=obj -o %t.obj %s
# RUN: lld-link %t.obj /out:%t.exe /entry:main /subsystem:console
# RUN: llvm-objdump -s %t.exe | FileCheck %s
COFF: Add a flag for disabling string tail merging. We discovered (crbug.com/838449#c24) that string tail merging can negatively affect compressed binary size, so provide a flag to turn it off for users who care more about compressed size than uncompressed size. Differential Revision: https://reviews.llvm.org/D46780 llvm-svn: 332149
2018-05-12 06:21:36 +08:00
# RUN: lld-link %t.obj /out:%t.exe /entry:main /subsystem:console /opt:noicf /opt:lldtailmerge
# RUN: llvm-objdump -s %t.exe | FileCheck %s
# RUN: lld-link %t.obj /out:%t.exe /entry:main /subsystem:console /opt:noicf
# RUN: llvm-objdump -s %t.exe | FileCheck --check-prefix=NOSTM %s
# RUN: lld-link %t.obj /out:%t.exe /entry:main /subsystem:console /opt:nolldtailmerge
# RUN: llvm-objdump -s %t.exe | FileCheck --check-prefix=NOSTM %s
COFF: Implement string tail merging. In COFF, duplicate string literals are merged by placing them in a comdat whose leader symbol name contains a specific prefix followed by the hash and partial contents of the string literal. This gives us an easy way to identify sections containing string literals in the linker: check for leader symbol names with the given prefix. Any sections that are identified in this way as containing string literals may be tail merged. We do so using the StringTableBuilder class, which is also used to tail merge string literals in the ELF linker. Tail merging is enabled only if ICF is enabled, as this provides a signal as to whether the user cares about binary size. Differential Revision: https://reviews.llvm.org/D44504 llvm-svn: 327668
2018-03-16 05:14:02 +08:00
# CHECK: Contents of section .text:
COFF: Add a flag for disabling string tail merging. We discovered (crbug.com/838449#c24) that string tail merging can negatively affect compressed binary size, so provide a flag to turn it off for users who care more about compressed size than uncompressed size. Differential Revision: https://reviews.llvm.org/D46780 llvm-svn: 332149
2018-05-12 06:21:36 +08:00
# NOSTM: Contents of section .text:
COFF: Implement string tail merging. In COFF, duplicate string literals are merged by placing them in a comdat whose leader symbol name contains a specific prefix followed by the hash and partial contents of the string literal. This gives us an easy way to identify sections containing string literals in the linker: check for leader symbol names with the given prefix. Any sections that are identified in this way as containing string literals may be tail merged. We do so using the StringTableBuilder class, which is also used to tail merge string literals in the ELF linker. Tail merging is enabled only if ICF is enabled, as this provides a signal as to whether the user cares about binary size. Differential Revision: https://reviews.llvm.org/D44504 llvm-svn: 327668
2018-03-16 05:14:02 +08:00
.globl main
main:
COFF: Layout sections in the same order as link.exe One place where this seems to matter is to make sure the .rsrc section comes after .text. The Win32 UpdateResource() function can change the contents of .rsrc. It will move the sections that come after, but if .text gets moved, the entry point header will not get updated and the executable breaks. This was found by a test in Chromium. Differential Revision: https://reviews.llvm.org/D45260 llvm-svn: 329221
2018-04-05 03:15:55 +08:00
# CHECK-NEXT: 140001000 11200040 01000000 17200040 01000000
COFF: Add a flag for disabling string tail merging. We discovered (crbug.com/838449#c24) that string tail merging can negatively affect compressed binary size, so provide a flag to turn it off for users who care more about compressed size than uncompressed size. Differential Revision: https://reviews.llvm.org/D46780 llvm-svn: 332149
2018-05-12 06:21:36 +08:00
# NOSTM-NEXT: 140001000 00200040 01000000 0c200040 01000000
COFF: Implement string tail merging. In COFF, duplicate string literals are merged by placing them in a comdat whose leader symbol name contains a specific prefix followed by the hash and partial contents of the string literal. This gives us an easy way to identify sections containing string literals in the linker: check for leader symbol names with the given prefix. Any sections that are identified in this way as containing string literals may be tail merged. We do so using the StringTableBuilder class, which is also used to tail merge string literals in the ELF linker. Tail merging is enabled only if ICF is enabled, as this provides a signal as to whether the user cares about binary size. Differential Revision: https://reviews.llvm.org/D44504 llvm-svn: 327668
2018-03-16 05:14:02 +08:00
.8byte "??_C@_0M@LACCCNMM@hello?5world?$AA@"
.8byte "??_C@_05MCBCHHEJ@world?$AA@"
COFF: Layout sections in the same order as link.exe One place where this seems to matter is to make sure the .rsrc section comes after .text. The Win32 UpdateResource() function can change the contents of .rsrc. It will move the sections that come after, but if .text gets moved, the entry point header will not get updated and the executable breaks. This was found by a test in Chromium. Differential Revision: https://reviews.llvm.org/D45260 llvm-svn: 329221
2018-04-05 03:15:55 +08:00
# CHECK-NEXT: 140001010 2a200040 01000000 36200040 01000000
COFF: Add a flag for disabling string tail merging. We discovered (crbug.com/838449#c24) that string tail merging can negatively affect compressed binary size, so provide a flag to turn it off for users who care more about compressed size than uncompressed size. Differential Revision: https://reviews.llvm.org/D46780 llvm-svn: 332149
2018-05-12 06:21:36 +08:00
# NOSTM-NEXT: 140001010 12200040 01000000 2a200040 01000000
COFF: Implement string tail merging. In COFF, duplicate string literals are merged by placing them in a comdat whose leader symbol name contains a specific prefix followed by the hash and partial contents of the string literal. This gives us an easy way to identify sections containing string literals in the linker: check for leader symbol names with the given prefix. Any sections that are identified in this way as containing string literals may be tail merged. We do so using the StringTableBuilder class, which is also used to tail merge string literals in the ELF linker. Tail merging is enabled only if ICF is enabled, as this provides a signal as to whether the user cares about binary size. Differential Revision: https://reviews.llvm.org/D44504 llvm-svn: 327668
2018-03-16 05:14:02 +08:00
.8byte "??_C@_1BI@HHJHKLLN@?$AAh?$AAe?$AAl?$AAl?$AAo?$AA?5?$AAw?$AAo?$AAr?$AAl?$AAd?$AA?$AA@"
.8byte "??_C@_1M@NBBDDHIO@?$AAw?$AAo?$AAr?$AAl?$AAd?$AA?$AA@"
COFF: Layout sections in the same order as link.exe One place where this seems to matter is to make sure the .rsrc section comes after .text. The Win32 UpdateResource() function can change the contents of .rsrc. It will move the sections that come after, but if .text gets moved, the entry point header will not get updated and the executable breaks. This was found by a test in Chromium. Differential Revision: https://reviews.llvm.org/D45260 llvm-svn: 329221
2018-04-05 03:15:55 +08:00
# CHECK-NEXT: 140001020 00200040 01000000 0c200040 01000000
COFF: Add a flag for disabling string tail merging. We discovered (crbug.com/838449#c24) that string tail merging can negatively affect compressed binary size, so provide a flag to turn it off for users who care more about compressed size than uncompressed size. Differential Revision: https://reviews.llvm.org/D46780 llvm-svn: 332149
2018-05-12 06:21:36 +08:00
# NOSTM-NEXT: 140001020 36200040 01000000 42200040 01000000
COFF: Implement string tail merging. In COFF, duplicate string literals are merged by placing them in a comdat whose leader symbol name contains a specific prefix followed by the hash and partial contents of the string literal. This gives us an easy way to identify sections containing string literals in the linker: check for leader symbol names with the given prefix. Any sections that are identified in this way as containing string literals may be tail merged. We do so using the StringTableBuilder class, which is also used to tail merge string literals in the ELF linker. Tail merging is enabled only if ICF is enabled, as this provides a signal as to whether the user cares about binary size. Differential Revision: https://reviews.llvm.org/D44504 llvm-svn: 327668
2018-03-16 05:14:02 +08:00
.8byte "??_D@not_a_string_literal"
.8byte "??_C@string_literal_with_relocs"
COFF: Layout sections in the same order as link.exe One place where this seems to matter is to make sure the .rsrc section comes after .text. The Win32 UpdateResource() function can change the contents of .rsrc. It will move the sections that come after, but if .text gets moved, the entry point header will not get updated and the executable breaks. This was found by a test in Chromium. Differential Revision: https://reviews.llvm.org/D45260 llvm-svn: 329221
2018-04-05 03:15:55 +08:00
# CHECK-NEXT: 140001030 00300040 01000000 1e200040 01000000
COFF: Add a flag for disabling string tail merging. We discovered (crbug.com/838449#c24) that string tail merging can negatively affect compressed binary size, so provide a flag to turn it off for users who care more about compressed size than uncompressed size. Differential Revision: https://reviews.llvm.org/D46780 llvm-svn: 332149
2018-05-12 06:21:36 +08:00
# NOSTM-NEXT: 140001030 00300040 01000000 48200040 01000000
COFF: Implement string tail merging. In COFF, duplicate string literals are merged by placing them in a comdat whose leader symbol name contains a specific prefix followed by the hash and partial contents of the string literal. This gives us an easy way to identify sections containing string literals in the linker: check for leader symbol names with the given prefix. Any sections that are identified in this way as containing string literals may be tail merged. We do so using the StringTableBuilder class, which is also used to tail merge string literals in the ELF linker. Tail merging is enabled only if ICF is enabled, as this provides a signal as to whether the user cares about binary size. Differential Revision: https://reviews.llvm.org/D44504 llvm-svn: 327668
2018-03-16 05:14:02 +08:00
.8byte "??_C@string_literal_in_wrong_section"
.8byte "??_C@overaligned_string_literal"
COFF: Layout sections in the same order as link.exe One place where this seems to matter is to make sure the .rsrc section comes after .text. The Win32 UpdateResource() function can change the contents of .rsrc. It will move the sections that come after, but if .text gets moved, the entry point header will not get updated and the executable breaks. This was found by a test in Chromium. Differential Revision: https://reviews.llvm.org/D45260 llvm-svn: 329221
2018-04-05 03:15:55 +08:00
# CHECK: Contents of section .rdata:
# CHECK-NEXT: 140002000 68656c6c 6f20776f 726c6400 6f826ca4 hello world.o.l.
# CHECK-NEXT: 140002010 0068656c 6c6f2077 6f726c64 00006865 .hello world..he
# CHECK-NEXT: 140002020 6c6c6f20 776f726c 64006800 65006c00 llo world.h.e.l.
# CHECK-NEXT: 140002030 6c006f00 20007700 6f007200 6c006400 l.o. .w.o.r.l.d.
# CHECK-NEXT: 140002040 0000 ..
COFF: Add a flag for disabling string tail merging. We discovered (crbug.com/838449#c24) that string tail merging can negatively affect compressed binary size, so provide a flag to turn it off for users who care more about compressed size than uncompressed size. Differential Revision: https://reviews.llvm.org/D46780 llvm-svn: 332149
2018-05-12 06:21:36 +08:00
# NOSTM: Contents of section .rdata:
# NOSTM-NEXT: 140002000 68656c6c 6f20776f 726c6400 776f726c hello world.worl
# NOSTM-NEXT: 140002010 64006800 65006c00 6c006f00 20007700 d.h.e.l.l.o. .w.
# NOSTM-NEXT: 140002020 6f007200 6c006400 00007700 6f007200 o.r.l.d...w.o.r.
# NOSTM-NEXT: 140002030 6c006400 00006865 6c6c6f20 776f726c l.d...hello worl
# NOSTM-NEXT: 140002040 64006f82 6ca40000 68656c6c 6f20776f d.o.l...hello wo
# NOSTM-NEXT: 140002050 726c6400 rld.
COFF: Layout sections in the same order as link.exe One place where this seems to matter is to make sure the .rsrc section comes after .text. The Win32 UpdateResource() function can change the contents of .rsrc. It will move the sections that come after, but if .text gets moved, the entry point header will not get updated and the executable breaks. This was found by a test in Chromium. Differential Revision: https://reviews.llvm.org/D45260 llvm-svn: 329221
2018-04-05 03:15:55 +08:00
COFF: Implement string tail merging. In COFF, duplicate string literals are merged by placing them in a comdat whose leader symbol name contains a specific prefix followed by the hash and partial contents of the string literal. This gives us an easy way to identify sections containing string literals in the linker: check for leader symbol names with the given prefix. Any sections that are identified in this way as containing string literals may be tail merged. We do so using the StringTableBuilder class, which is also used to tail merge string literals in the ELF linker. Tail merging is enabled only if ICF is enabled, as this provides a signal as to whether the user cares about binary size. Differential Revision: https://reviews.llvm.org/D44504 llvm-svn: 327668
2018-03-16 05:14:02 +08:00
.section .rdata,"dr",discard,"??_C@_0M@LACCCNMM@hello?5world?$AA@"
.globl "??_C@_0M@LACCCNMM@hello?5world?$AA@"
"??_C@_0M@LACCCNMM@hello?5world?$AA@":
.asciz "hello world"
.section .rdata,"dr",discard,"??_C@_05MCBCHHEJ@world?$AA@"
.globl "??_C@_05MCBCHHEJ@world?$AA@"
"??_C@_05MCBCHHEJ@world?$AA@":
.asciz "world"
.section .rdata,"dr",discard,"??_C@_1BI@HHJHKLLN@?$AAh?$AAe?$AAl?$AAl?$AAo?$AA?5?$AAw?$AAo?$AAr?$AAl?$AAd?$AA?$AA@"
.globl "??_C@_1BI@HHJHKLLN@?$AAh?$AAe?$AAl?$AAl?$AAo?$AA?5?$AAw?$AAo?$AAr?$AAl?$AAd?$AA?$AA@"
.p2align 1
"??_C@_1BI@HHJHKLLN@?$AAh?$AAe?$AAl?$AAl?$AAo?$AA?5?$AAw?$AAo?$AAr?$AAl?$AAd?$AA?$AA@":
.short 104
.short 101
.short 108
.short 108
.short 111
.short 32
.short 119
.short 111
.short 114
.short 108
.short 100
.short 0
.section .rdata,"dr",discard,"??_C@_1M@NBBDDHIO@?$AAw?$AAo?$AAr?$AAl?$AAd?$AA?$AA@"
.globl "??_C@_1M@NBBDDHIO@?$AAw?$AAo?$AAr?$AAl?$AAd?$AA?$AA@"
.p2align 1
"??_C@_1M@NBBDDHIO@?$AAw?$AAo?$AAr?$AAl?$AAd?$AA?$AA@":
.short 119
.short 111
.short 114
.short 108
.short 100
.short 0
.section .data,"drw",discard,"??_C@string_literal_in_wrong_section"
.globl "??_C@string_literal_in_wrong_section"
"??_C@string_literal_in_wrong_section":
.asciz "hello world"
.section .rdata,"dr",discard,"??_D@not_a_string_literal"
.globl "??_D@not_a_string_literal"
"??_D@not_a_string_literal":
.asciz "hello world"
.section .rdata,"dr",discard,"??_C@string_literal_with_relocs"
.globl "??_C@string_literal_with_relocs"
"??_C@string_literal_with_relocs":
.4byte main + 111 + (114 << 8) + (108 << 16) + (100 << 24) # main + "orld"
.byte 0
.section .rdata,"dr",discard,"??_C@overaligned_string_literal"
.globl "??_C@overaligned_string_literal"
.p2align 1
"??_C@overaligned_string_literal":
.asciz "hello world"