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llvm-mirror/test/DebugInfo/ARM/PR26163.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

110 lines
4.5 KiB
LLVM

; RUN: llc -filetype=obj -o - < %s | llvm-dwarfdump -debug-info - | FileCheck %s
;
; Checks that we're omitting the first range, as it is empty, and that we're
; emitting one that spans the rest of the function. In this case, the first
; range, which we omit, describes 8 bytes of the variable using DW_OP_litX,
; whereas the second one only describes 4 bytes, so clobbering the whole 8 byte
; fragment with the 4 bytes fragment isn't necessarily best thing to do here,
; but it is what is currently being emitted. Any change here needs to be
; intentional, so the test is very specific.
;
; The variable is given a single location instead of a location list entry
; because the function validThroughout has a special code path for single
; locations with a constant value that start in the prologue.
;
; CHECK: DW_TAG_inlined_subroutine
; CHECK: DW_TAG_variable
; CHECK-NEXT: DW_AT_location (DW_OP_lit0, DW_OP_stack_value, DW_OP_piece 0x4)
; CHECK-NEXT DW_AT_name ("i4")
; Created form the following test case (PR26163) with
; clang -cc1 -triple armv4t--freebsd11.0-gnueabi -emit-obj -debug-info-kind=standalone -O2 -x c test.c
;
; typedef unsigned int size_t;
; struct timeval {
; long long tv_sec;
; int tv_usec;
; };
;
; void *memset(void *, int, size_t);
; void foo(void);
;
; static void
; bar(int value)
; {
; struct timeval lifetime;
;
; memset(&lifetime, 0, sizeof(struct timeval));
; lifetime.tv_sec = value;
;
; foo();
; }
;
; int
; parse_config_file(void)
; {
; int value;
;
; bar(value);
; return (0);
; }
target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "armv4t--freebsd11.0-gnueabi"
%struct.timeval = type { i64, i32 }
declare void @llvm.dbg.declare(metadata, metadata, metadata)
declare void @llvm.dbg.value(metadata, metadata, metadata)
declare void @foo()
define i32 @parse_config_file() !dbg !4 {
entry:
tail call void @llvm.dbg.value(metadata i32 0, metadata !15, metadata !26), !dbg !27
tail call void @llvm.dbg.declare(metadata %struct.timeval* undef, metadata !16, metadata !26), !dbg !29
tail call void @llvm.dbg.value(metadata i64 0, metadata !16, metadata !30), !dbg !29
tail call void @llvm.dbg.value(metadata i32 0, metadata !16, metadata !31), !dbg !29
tail call void @foo() #3, !dbg !32
ret i32 0, !dbg !33
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!22, !23, !24}
!llvm.ident = !{!25}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.9.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "<stdin>", directory: "/home/ubuntu/bugs")
!2 = !{}
!4 = distinct !DISubprogram(name: "parse_config_file", scope: !5, file: !5, line: 22, type: !6, isLocal: false, isDefinition: true, scopeLine: 23, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !9)
!5 = !DIFile(filename: "test.c", directory: "/home/ubuntu/bugs")
!6 = !DISubroutineType(types: !7)
!7 = !{!8}
!8 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
!9 = !{!10}
!10 = !DILocalVariable(name: "value", scope: !4, file: !5, line: 24, type: !8)
!11 = distinct !DISubprogram(name: "bar", scope: !5, file: !5, line: 11, type: !12, isLocal: true, isDefinition: true, scopeLine: 12, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !14)
!12 = !DISubroutineType(types: !13)
!13 = !{null, !8}
!14 = !{!15, !16}
!15 = !DILocalVariable(name: "value", arg: 1, scope: !11, file: !5, line: 11, type: !8)
!16 = !DILocalVariable(name: "lifetime", scope: !11, file: !5, line: 13, type: !17)
!17 = !DICompositeType(tag: DW_TAG_structure_type, name: "timeval", file: !5, line: 2, size: 128, align: 64, elements: !18)
!18 = !{!19, !21}
!19 = !DIDerivedType(tag: DW_TAG_member, name: "tv_sec", scope: !17, file: !5, line: 3, baseType: !20, size: 64, align: 64)
!20 = !DIBasicType(name: "long long int", size: 64, align: 64, encoding: DW_ATE_signed)
!21 = !DIDerivedType(tag: DW_TAG_member, name: "tv_usec", scope: !17, file: !5, line: 4, baseType: !8, size: 32, align: 32, offset: 64)
!22 = !{i32 2, !"Debug Info Version", i32 3}
!23 = !{i32 1, !"wchar_size", i32 4}
!24 = !{i32 1, !"min_enum_size", i32 4}
!25 = !{!"clang version 3.9.0"}
!26 = !DIExpression()
!27 = !DILocation(line: 11, scope: !11, inlinedAt: !28)
!28 = distinct !DILocation(line: 26, scope: !4)
!29 = !DILocation(line: 13, scope: !11, inlinedAt: !28)
!30 = !DIExpression(DW_OP_LLVM_fragment, 0, 64)
!31 = !DIExpression(DW_OP_LLVM_fragment, 0, 32)
!32 = !DILocation(line: 18, scope: !11, inlinedAt: !28)
!33 = !DILocation(line: 27, scope: !4)