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llvm-project/llvm/test/DebugInfo/X86/range_reloc.ll
David Blaikie bb279116f2 DebugInfo: Add a CU metadata attribute for use of DWARF ranges base address specifiers 
Summary:
Ranges base address specifiers can save a lot of object size in
relocation records especially in optimized builds.

For an optimized self-host build of Clang with split DWARF and debug
info compression in object files, but uncompressed debug info in the
executable, this change produces about 18% smaller object files and 6%
larger executable.

While it would've been nice to turn this on by default, gold's 32 bit
gdb-index support crashes on this input & I don't think there's any
perfect heuristic to implement solely in LLVM that would suffice - so
we'll need a flag one way or another (also possible people might want to
aggressively optimized for executable size that contains debug info
(even with compression this would still come at some cost to executable
size)) - so let's plumb it through.

Differential Revision: https://reviews.llvm.org/D54242

llvm-svn: 346788
2018-11-13 20:08:10 +00:00

168 lines
8.6 KiB
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; RUN: llc -filetype=asm -mtriple=x86_64-pc-linux-gnu %s -o - | FileCheck %s
; RUN: llc -filetype=asm -mtriple=x86_64-pc-linux-gnu %s -o - -dwarf-version 5 | FileCheck --check-prefix=DWARF5 %s
; Group ranges in a range list that apply to the same section and use a base
; address selection entry to reduce the number of relocations to one reloc per
; section per range list. DWARF5 debug_rnglist (with *x variants) are more
; efficient than this in terms of relocations, but it's still better than one
; reloc per entry in a range list.
; This is an object/executable size tradeoff - shrinking objects, but growing
; the linked executable. In one large binary tested, total object size (not just
; debug info) shrank by 16%, entirely relocation entries. Linked executable
; grew by 4%. This was with compressed debug info in the objects, uncompressed
; in the linked executable. Without compression in the objects, the win would be
; smaller (the growth of debug_ranges itself would be more significant).
; This is a merged module containing two CUs, one that uses range base address
; specifiers and exercises different cases there, and another that does not
; ranges.cpp
; Single range entry
; __attribute__((section("a"))) void f1() {}
; Single address with two ranges due to the whole caused by f3
; __attribute__((section("b"))) void f2() {}
; __attribute__((section("b"))) __attribute__((nodebug)) void f3() {}
; __attribute__((section("b"))) void f4() {}
; Reset the base address & emit a couple more single range entries
; __attribute__((section("c"))) void f5() {}
; __attribute__((section("d"))) void f6() {}
; ranges_no_base.cpp:
; Include enough complexity to cause ranges to be emitted, so it can be checked
; that those ranges don't use base address specifiers
; __attribute__((section("e"))) void f7() {}
; __attribute__((section("f"))) void f8() {}
; CHECK: {{^.Ldebug_ranges0}}
; CHECK-NEXT: .quad -1
; CHECK-NEXT: .quad .Lfunc_begin0
; CHECK-NEXT: .quad .Lfunc_begin0-.Lfunc_begin0
; CHECK-NEXT: .quad .Lfunc_end0-.Lfunc_begin0
; CHECK-NEXT: .quad -1
; CHECK-NEXT: .quad .Lfunc_begin1
; CHECK-NEXT: .quad .Lfunc_begin1-.Lfunc_begin1
; CHECK-NEXT: .quad .Lfunc_end1-.Lfunc_begin1
; CHECK-NEXT: .quad .Lfunc_begin3-.Lfunc_begin1
; CHECK-NEXT: .quad .Lfunc_end3-.Lfunc_begin1
; CHECK-NEXT: .quad -1
; CHECK-NEXT: .quad .Lfunc_begin4
; CHECK-NEXT: .quad .Lfunc_begin4-.Lfunc_begin4
; CHECK-NEXT: .quad .Lfunc_end4-.Lfunc_begin4
; CHECK-NEXT: .quad -1
; CHECK-NEXT: .quad .Lfunc_begin5
; CHECK-NEXT: .quad .Lfunc_begin5-.Lfunc_begin5
; CHECK-NEXT: .quad .Lfunc_end5-.Lfunc_begin5
; CHECK-NEXT: .quad 0
; CHECK-NEXT: .quad 0
; CHECK-NEXT: {{^.Ldebug_ranges1}}
; CHECK-NEXT: .quad .Lfunc_begin6
; CHECK-NEXT: .quad .Lfunc_end6
; CHECK-NEXT: .quad .Lfunc_begin7
; CHECK-NEXT: .quad .Lfunc_end7
; DWARF5: {{^.Ldebug_ranges0}}
; DWARF5-NEXT: # DW_RLE_startx_length
; DWARF5-NEXT: .byte 0 # start index
; DWARF5-NEXT: .uleb128 .Lfunc_end0-.Lfunc_begin0 # length
; DWARF5-NEXT: # DW_RLE_base_addressx
; DWARF5-NEXT: .byte 1 # base address index
; DWARF5-NEXT: # DW_RLE_offset_pair
; DWARF5-NEXT: .uleb128 .Lfunc_begin1-.Lfunc_begin1 # starting offset
; DWARF5-NEXT: .uleb128 .Lfunc_end1-.Lfunc_begin1 # ending offset
; DWARF5-NEXT: # DW_RLE_offset_pair
; DWARF5-NEXT: .uleb128 .Lfunc_begin3-.Lfunc_begin1 # starting offset
; DWARF5-NEXT: .uleb128 .Lfunc_end3-.Lfunc_begin1 # ending offset
; DWARF5-NEXT: # DW_RLE_startx_length
; DWARF5-NEXT: .byte 3 # start index
; DWARF5-NEXT: .uleb128 .Lfunc_end4-.Lfunc_begin4 # length
; DWARF5-NEXT: # DW_RLE_startx_length
; DWARF5-NEXT: .byte 4 # start index
; DWARF5-NEXT: .uleb128 .Lfunc_end5-.Lfunc_begin5 # length
; DWARF5-NEXT: # DW_RLE_end_of_list
; DWARF5-NEXT: {{^.Ldebug_ranges1}}
; DWARF5-NEXT: # DW_RLE_startx_length
; DWARF5-NEXT: .byte 5 # start index
; DWARF5-NEXT: .uleb128 .Lfunc_end6-.Lfunc_begin6 # length
; DWARF5-NEXT: # DW_RLE_startx_length
; DWARF5-NEXT: .byte 6 # start index
; DWARF5-NEXT: .uleb128 .Lfunc_end7-.Lfunc_begin7 # length
; DWARF5-NEXT: # DW_RLE_end_of_list
; Function Attrs: noinline nounwind optnone uwtable
define dso_local void @_Z2f1v() section "a" !dbg !9 {
entry:
ret void, !dbg !12
}
; Function Attrs: noinline nounwind optnone uwtable
define dso_local void @_Z2f2v() section "b" !dbg !13 {
entry:
ret void, !dbg !14
}
; Function Attrs: noinline nounwind optnone uwtable
define dso_local void @_Z2f3v() section "b" {
entry:
ret void
}
; Function Attrs: noinline nounwind optnone uwtable
define dso_local void @_Z2f4v() section "b" !dbg !15 {
entry:
ret void, !dbg !16
}
; Function Attrs: noinline nounwind optnone uwtable
define dso_local void @_Z2f5v() section "c" !dbg !17 {
entry:
ret void, !dbg !18
}
; Function Attrs: noinline nounwind optnone uwtable
define dso_local void @_Z2f6v() section "d" !dbg !19 {
entry:
ret void, !dbg !20
}
; Function Attrs: noinline nounwind optnone uwtable
define dso_local void @_Z2f7v() section "e" !dbg !21 {
entry:
ret void, !dbg !22
}
; Function Attrs: noinline nounwind optnone uwtable
define dso_local void @_Z2f8v() section "f" !dbg !23 {
entry:
ret void, !dbg !24
}
!llvm.dbg.cu = !{!0, !3}
!llvm.ident = !{!5, !5}
!llvm.module.flags = !{!6, !7, !8}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 8.0.0 (trunk 346343) (llvm/trunk 346350)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None, debugBaseAddress: true)
!1 = !DIFile(filename: "ranges.cpp", directory: "/usr/local/google/home/blaikie/dev/scratch")
!2 = !{}
!3 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !4, producer: "clang version 8.0.0 (trunk 346343) (llvm/trunk 346350)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
!4 = !DIFile(filename: "ranges_no_base.cpp", directory: "/usr/local/google/home/blaikie/dev/scratch")
!5 = !{!"clang version 8.0.0 (trunk 346343) (llvm/trunk 346350)"}
!6 = !{i32 2, !"Dwarf Version", i32 4}
!7 = !{i32 2, !"Debug Info Version", i32 3}
!8 = !{i32 1, !"wchar_size", i32 4}
!9 = distinct !DISubprogram(name: "f1", linkageName: "_Z2f1v", scope: !1, file: !1, line: 1, type: !10, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
!10 = !DISubroutineType(types: !11)
!11 = !{null}
!12 = !DILocation(line: 1, column: 42, scope: !9)
!13 = distinct !DISubprogram(name: "f2", linkageName: "_Z2f2v", scope: !1, file: !1, line: 2, type: !10, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
!14 = !DILocation(line: 2, column: 42, scope: !13)
!15 = distinct !DISubprogram(name: "f4", linkageName: "_Z2f4v", scope: !1, file: !1, line: 4, type: !10, isLocal: false, isDefinition: true, scopeLine: 4, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
!16 = !DILocation(line: 4, column: 42, scope: !15)
!17 = distinct !DISubprogram(name: "f5", linkageName: "_Z2f5v", scope: !1, file: !1, line: 5, type: !10, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
!18 = !DILocation(line: 5, column: 42, scope: !17)
!19 = distinct !DISubprogram(name: "f6", linkageName: "_Z2f6v", scope: !1, file: !1, line: 6, type: !10, isLocal: false, isDefinition: true, scopeLine: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
!20 = !DILocation(line: 6, column: 42, scope: !19)
!21 = distinct !DISubprogram(name: "f7", linkageName: "_Z2f7v", scope: !4, file: !4, line: 1, type: !10, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, unit: !3, retainedNodes: !2)
!22 = !DILocation(line: 1, column: 42, scope: !21)
!23 = distinct !DISubprogram(name: "f8", linkageName: "_Z2f8v", scope: !4, file: !4, line: 2, type: !10, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: false, unit: !3, retainedNodes: !2)
!24 = !DILocation(line: 2, column: 42, scope: !23)
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