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llvm-mirror/test/DebugInfo/X86/live-debug-variables.ll
OCHyams 9d1808f4ad [DebugInfo] Drop location ranges for variables which exist entirely outside the variable's scope
Summary:
This patch reduces file size in debug builds by dropping variable locations a
debugger user will not see.

After building the debug entity history map we loop through it. For each
variable we look at each entry. If the entry opens a location range which does
not intersect any of the variable's scope's ranges then we mark it for removal.
After visiting the entries for each variable we also mark any clobbering
entries which will no longer be referenced for removal, and then finally erase
the marked entries. This all requires the ability to query the order of
instructions, so before this runs we number them.

Tests:
Added llvm/test/DebugInfo/X86/trim-var-locs.mir

Modified llvm/test/DebugInfo/COFF/register-variables.ll
  Branch folding merges the tails of if.then and if.else into if.else. Each
  blocks' debug-locations point to different scopes so when they're merged we
  can't use either. Because of this the variable 'c' ends up with a location
  range which doesn't cover any instructions in its scope; with the patch
  applied the location range is dropped and its flag changes to IsOptimizedOut.

Modified llvm/test/DebugInfo/X86/live-debug-variables.ll
Modified llvm/test/DebugInfo/ARM/PR26163.ll
  In both tests an out of scope location is now removed. The remaining location
  covers the entire scope of the variable allowing us to emit it as a single
  location.

Reviewed By: aprantl

Differential Revision: https://reviews.llvm.org/D82129
2020-07-22 12:45:21 +01:00

84 lines
3.8 KiB
LLVM

; RUN: llc -mtriple=x86_64-linux-gnu -filetype=obj -o - %s | llvm-dwarfdump -name i4 - \
; RUN: | FileCheck %s
; The test inlines the function F four times, with each inlined variable for
; "i4" sharing the same virtual register. This means the live interval of the
; register spans all of the inlined callsites, extending beyond the lexical
; scope of each. Later during register allocation the live interval is split
; into multiple intervals. Check that this does not generate multiple entries
; within the debug location (see PR33730).
;
; Generated from:
;
; extern int foobar(int, int, int, int, int);
;
; int F(int i1, int i2, int i3, int i4, int i5) {
; return foobar(i1, i2, i3, i4, i5);
; }
;
; int foo(int a, int b, int c, int d, int e) {
; return F(a,b,c,d,e) +
; F(a,b,c,d,e) +
; F(a,b,c,d,e) +
; F(a,b,c,d,e);
; }
; Ignore the abstract entry.
; CHECK: DW_TAG_formal_parameter
; Check concrete entry has a single location.
; CHECK: DW_TAG_formal_parameter
; CHECK-NEXT: DW_AT_location (DW_OP_reg3 RBX)
; CHECK-NEXT: DW_AT_abstract_origin
; CHECK-NOT: DW_TAG_formal_parameter
declare i32 @foobar(i32, i32, i32, i32, i32)
define i32 @foo(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) !dbg !25 {
entry:
tail call void @llvm.dbg.value(metadata i32 %d, i64 0, metadata !15, metadata !17) #3, !dbg !41
%call.i = tail call i32 @foobar(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) #3, !dbg !43
%call.i21 = tail call i32 @foobar(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) #3, !dbg !50
%add = add nsw i32 %call.i21, %call.i, !dbg !51
%call.i22 = tail call i32 @foobar(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) #3, !dbg !58
%add3 = add nsw i32 %add, %call.i22, !dbg !59
%call.i23 = tail call i32 @foobar(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) #3, !dbg !66
%add5 = add nsw i32 %add3, %call.i23, !dbg !67
ret i32 %add5, !dbg !68
}
declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5}
!llvm.ident = !{!6}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 6.0.0 (trunk 308976)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "foo.c", directory: "")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{!"clang version 6.0.0 (trunk 308976)"}
!7 = distinct !DISubprogram(name: "F", scope: !1, file: !1, line: 3, type: !8, isLocal: false, isDefinition: true, scopeLine: 3, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !11)
!8 = !DISubroutineType(types: !9)
!9 = !{!10, !10, !10, !10, !10, !10}
!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!11 = !{!15}
!15 = !DILocalVariable(name: "i4", arg: 4, scope: !7, file: !1, line: 3, type: !10)
!17 = !DIExpression()
!25 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 7, type: !8, isLocal: false, isDefinition: true, scopeLine: 7, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !26)
!26 = !{}
!38 = distinct !DILocation(line: 8, column: 10, scope: !25)
!41 = !DILocation(line: 3, column: 35, scope: !7, inlinedAt: !38)
!43 = !DILocation(line: 4, column: 10, scope: !7, inlinedAt: !38)
!45 = distinct !DILocation(line: 9, column: 10, scope: !25)
!50 = !DILocation(line: 4, column: 10, scope: !7, inlinedAt: !45)
!51 = !DILocation(line: 8, column: 23, scope: !25)
!53 = distinct !DILocation(line: 10, column: 10, scope: !25)
!58 = !DILocation(line: 4, column: 10, scope: !7, inlinedAt: !53)
!59 = !DILocation(line: 9, column: 23, scope: !25)
!61 = distinct !DILocation(line: 11, column: 10, scope: !25)
!66 = !DILocation(line: 4, column: 10, scope: !7, inlinedAt: !61)
!67 = !DILocation(line: 10, column: 23, scope: !25)
!68 = !DILocation(line: 8, column: 3, scope: !25)