76c0063eeb
String tables in unstripped executable files are fairly large in size. For example, lld's executable file is about 34.4 MB in my environment, and of which 3.5 MB is the string table. Efficiency of string table construction matters. Previously, the string table was built in an inefficient way. We used StringTableBuilder to build that and enabled string tail merging, although tail merging is not effective for the symbol table (you can only make the string table 0.3% smaller for lld.) Tail merging is computation intensive task and slow. This patch eliminates string tail merging. I changed the way of adding strings to the string table in this patch too. Previously, strings were added using add() and the same strings were then passed to getOffset() to get their offsets in the string table. In this way, getOffset() needs to look up a hash table to get offsets for given strings. This is a violation of "we look up the symbol table (or a hash table) only once for each symbol" dogma of the new LLD's design. Hash table lookup for long C++ mangled names is slow. I eliminated that lookup in this patch. In total, this patch improves link time of lld itself about 12% (3.50 seconds -> 3.08 seconds.) llvm-svn: 257017
82 lines
2.3 KiB
ArmAsm
82 lines
2.3 KiB
ArmAsm
// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
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// RUN: ld.lld %t -o %t2
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// RUN: llvm-readobj -sections -section-data %t2 | FileCheck %s
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// REQUIRES: x86
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.global _start
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_start:
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.section foobar,"",@progbits,unique,1
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.section foobar,"T",@progbits,unique,2
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.section foobar,"",@nobits,unique,3
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.section foobar,"",@nobits,unique,4
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.section bar, "a"
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// Both sections are in the output and that the alloc section is first:
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// CHECK: Name: bar
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// CHECK-NEXT: Type: SHT_PROGBITS
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// CHECK-NEXT: Flags [
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// CHECK-NEXT: SHF_ALLOC
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// CHECK-NEXT: ]
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// CHECK-NEXT: Address: 0x10120
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// CHECK: Name: foobar
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// CHECK-NEXT: Type: SHT_PROGBITS
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// CHECK-NEXT: Flags [
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// CHECK-NEXT: ]
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// CHECK-NEXT: Address: 0x0
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// CHECK: Name: foobar
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// CHECK-NEXT: Type: SHT_PROGBITS
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// CHECK-NEXT: Flags [
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// CHECK-NEXT: SHF_TLS
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// CHECK-NEXT: ]
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// CHECK-NEXT: Address: 0x0
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// CHECK: Name: foobar
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// CHECK-NEXT: Type: SHT_NOBITS
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// CHECK-NEXT: Flags [
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// CHECK-NEXT: ]
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// CHECK-NEXT: Address: 0x0
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// CHECK-NOT: Name: foobar
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// Test that the string "bar" is merged into "foobar".
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// CHECK: Section {
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// CHECK: Index:
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// CHECK: Name: .shstrtab
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// CHECK-NEXT: Type: SHT_STRTAB
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// CHECK-NEXT: Flags [
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// CHECK-NEXT: ]
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// CHECK-NEXT: Address: 0x0
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// CHECK-NEXT: Offset:
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// CHECK-NEXT: Size:
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// CHECK-NEXT: Link: 0
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// CHECK-NEXT: Info: 0
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// CHECK-NEXT: AddressAlignment: 1
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// CHECK-NEXT: EntrySize: 0
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// CHECK-NEXT: SectionData (
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// CHECK-NEXT: 0000: 00626172 002E7465 78740066 6F6F6261 |.bar..text.fooba|
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// CHECK-NEXT: 0010: 7200666F 6F626172 00666F6F 62617200 |r.foobar.foobar.|
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// CHECK-NEXT: 0020: 2E73796D 74616200 2E736873 74727461 |.symtab..shstrta|
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// CHECK-NEXT: 0030: 62002E73 74727461 6200 |b..strtab.|
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// CHECK-NEXT: )
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// CHECK-NEXT:}
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// CHECK: Name: .strtab
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// CHECK-NEXT: Type: SHT_STRTAB (0x3)
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// CHECK-NEXT: Flags [ (0x0)
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// CHECK-NEXT: ]
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// CHECK-NEXT: Address: 0x0
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// CHECK-NEXT: Offset:
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// CHECK-NEXT: Size: 15
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// CHECK-NEXT: Link: 0
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// CHECK-NEXT: Info: 0
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// CHECK-NEXT: AddressAlignment: 1
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// CHECK-NEXT: EntrySize: 0
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// CHECK-NEXT: SectionData (
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// CHECK-NEXT: 0000: 00666F6F 62617200 5F737461 727400 |.foobar._start.|
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// CHECK-NEXT: )
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// CHECK-NEXT: }
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