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llvm-mirror/test/DebugInfo/X86/debug-loc-offset.ll
David Blaikie 8572946bd5 DebugInfo: Do not emit empty CUs
Consistent with GCC and addresses a shortcoming with ThinLTO where many
imported CUs may end up being empty (because the functions imported from
them either ended up not being used (and were then discarded, since
they're imported as available_externally) or optimized away entirely).

Test cases previously testing empty CUs (either intentionally, or
because they didn't need anything more complicated) had a trivial 'int'
or similar basic type added to their retained types list.

This is a first order approximation - a deeper implementation could do
things like:

1) Be more lazy about construction of the CU - for example if two CUs
containing a single identical retained type are linked together, with
this change one of the two CUs will be produced but empty (since a
duplicate type won't be produced).

2) Go further and invert all the CU links the same way the subprogram
link is inverted - keep named CU lists of retained types, macros, etc,
and have those link back to the CU. Then if they're emitted, the CU is
emitted, but never otherwise - this would allow the metadata itself to
be dropped earlier too, though it seems unlikely that's an important
optimization as there shouldn't be many CUs relative to the number of
other entities.

llvm-svn: 304020
2017-05-26 18:52:56 +00:00

152 lines
6.5 KiB
LLVM

; RUN: llc %s -filetype=obj -O0 -mtriple=i386-unknown-linux-gnu -dwarf-version=4 -o %t
; RUN: llvm-dwarfdump %t | FileCheck %s
; From the code:
; debug-loc-offset1.cc
; int bar (int b) {
; return b+4;
; }
; debug-loc-offset2.cc
; struct A {
; int var;
; virtual char foo();
; };
; void baz(struct A a) {
; int z = 2;
; if (a.var > 2)
; z++;
; if (a.foo() == 'a')
; z++;
; }
; Compiled separately for i386-pc-linux-gnu and linked together.
; This ensures that we have multiple compile units so that we can verify that
; debug_loc entries are relative to the low_pc of the CU. The loc entry for
; the byval argument in foo.cpp is in the second CU and so should have
; an offset relative to that CU rather than from the beginning of the text
; section.
; Checking that we have two compile units with two sets of high/lo_pc.
; CHECK: .debug_info contents
; CHECK: DW_TAG_compile_unit
; CHECK: DW_AT_low_pc
; CHECK: DW_AT_high_pc
; CHECK: DW_TAG_subprogram
; CHECK-NOT: DW_TAG
; CHECK: DW_AT_linkage_name [DW_FORM_strp]{{.*}}"_Z3baz1A"
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_formal_parameter
; CHECK-NOT: DW_TAG
; CHECK: DW_AT_location [DW_FORM_sec_offset] (0x00000000)
; CHECK-NOT: DW_TAG
; CHECK: DW_AT_name [DW_FORM_strp]{{.*}}"a"
; CHECK: DW_TAG_variable
; CHECK: DW_AT_location [DW_FORM_exprloc]
; CHECK-NOT: DW_AT_location
; CHECK: DW_TAG_compile_unit
; CHECK: DW_AT_low_pc
; CHECK: DW_AT_high_pc
; CHECK: .debug_loc contents:
; CHECK: 0x00000000: Beginning address offset: 0x0000000000000000
; CHECK: Ending address offset: 0x0000000000000017
%struct.A = type { i32 (...)**, i32 }
; Function Attrs: nounwind
define i32 @_Z3bari(i32 %b) #0 !dbg !4 {
entry:
%b.addr = alloca i32, align 4
store i32 %b, i32* %b.addr, align 4
call void @llvm.dbg.declare(metadata i32* %b.addr, metadata !21, metadata !DIExpression()), !dbg !22
%0 = load i32, i32* %b.addr, align 4, !dbg !23
%add = add nsw i32 %0, 4, !dbg !23
ret i32 %add, !dbg !23
}
; Function Attrs: nounwind readnone
declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
define void @_Z3baz1A(%struct.A* %a) #2 !dbg !14 {
entry:
%z = alloca i32, align 4
call void @llvm.dbg.declare(metadata %struct.A* %a, metadata !24, metadata !DIExpression(DW_OP_deref)), !dbg !25
call void @llvm.dbg.declare(metadata i32* %z, metadata !26, metadata !DIExpression()), !dbg !27
store i32 2, i32* %z, align 4, !dbg !27
%var = getelementptr inbounds %struct.A, %struct.A* %a, i32 0, i32 1, !dbg !28
%0 = load i32, i32* %var, align 4, !dbg !28
%cmp = icmp sgt i32 %0, 2, !dbg !28
br i1 %cmp, label %if.then, label %if.end, !dbg !28
if.then: ; preds = %entry
%1 = load i32, i32* %z, align 4, !dbg !30
%inc = add nsw i32 %1, 1, !dbg !30
store i32 %inc, i32* %z, align 4, !dbg !30
br label %if.end, !dbg !30
if.end: ; preds = %if.then, %entry
%call = call signext i8 @_ZN1A3fooEv(%struct.A* %a), !dbg !31
%conv = sext i8 %call to i32, !dbg !31
%cmp1 = icmp eq i32 %conv, 97, !dbg !31
br i1 %cmp1, label %if.then2, label %if.end4, !dbg !31
if.then2: ; preds = %if.end
%2 = load i32, i32* %z, align 4, !dbg !33
%inc3 = add nsw i32 %2, 1, !dbg !33
store i32 %inc3, i32* %z, align 4, !dbg !33
br label %if.end4, !dbg !33
if.end4: ; preds = %if.then2, %if.end
ret void, !dbg !34
}
declare signext i8 @_ZN1A3fooEv(%struct.A*) #2
attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { nounwind readnone }
attributes #2 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
!llvm.dbg.cu = !{!0, !9}
!llvm.module.flags = !{!18, !19}
!llvm.ident = !{!20, !20}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.5.0 (210479)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
!1 = !DIFile(filename: "debug-loc-offset1.cc", directory: "/llvm_cmake_gcc")
!2 = !{}
!4 = distinct !DISubprogram(name: "bar", linkageName: "_Z3bari", line: 1, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 1, file: !1, scope: !5, type: !6, variables: !2)
!5 = !DIFile(filename: "debug-loc-offset1.cc", directory: "/llvm_cmake_gcc")
!6 = !DISubroutineType(types: !7)
!7 = !{!8, !8}
!8 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
!9 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.5.0 (210479)", isOptimized: false, emissionKind: FullDebug, file: !10, enums: !2, retainedTypes: !11, globals: !2, imports: !2)
!10 = !DIFile(filename: "debug-loc-offset2.cc", directory: "/llvm_cmake_gcc")
!11 = !{!12}
!12 = !DICompositeType(tag: DW_TAG_structure_type, name: "A", line: 1, flags: DIFlagFwdDecl, file: !10, identifier: "_ZTS1A")
!14 = distinct !DISubprogram(name: "baz", linkageName: "_Z3baz1A", line: 6, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !9, scopeLine: 6, file: !10, scope: !15, type: !16, variables: !2)
!15 = !DIFile(filename: "debug-loc-offset2.cc", directory: "/llvm_cmake_gcc")
!16 = !DISubroutineType(types: !17)
!17 = !{null, !12}
!18 = !{i32 2, !"Dwarf Version", i32 4}
!19 = !{i32 2, !"Debug Info Version", i32 3}
!20 = !{!"clang version 3.5.0 (210479)"}
!21 = !DILocalVariable(name: "b", line: 1, arg: 1, scope: !4, file: !5, type: !8)
!22 = !DILocation(line: 1, scope: !4)
!23 = !DILocation(line: 2, scope: !4)
!24 = !DILocalVariable(name: "a", line: 6, arg: 1, scope: !14, file: !15, type: !12)
!25 = !DILocation(line: 6, scope: !14)
!26 = !DILocalVariable(name: "z", line: 7, scope: !14, file: !15, type: !8)
!27 = !DILocation(line: 7, scope: !14)
!28 = !DILocation(line: 8, scope: !29)
!29 = distinct !DILexicalBlock(line: 8, column: 0, file: !10, scope: !14)
!30 = !DILocation(line: 9, scope: !29)
!31 = !DILocation(line: 10, scope: !32)
!32 = distinct !DILexicalBlock(line: 10, column: 0, file: !10, scope: !14)
!33 = !DILocation(line: 11, scope: !32)
!34 = !DILocation(line: 12, scope: !14)