llvm-6502/test/DebugInfo/X86/dbg-value-range.ll
Duncan P. N. Exon Smith 7838051bda DwarfDebug: Emit number of bytes in .debug_loc entry directly
Emit the number of bytes in a `.debug_loc` entry directly.  The old code
created temp labels (expensive), emitted the difference between them,
and then emitted one on each side of the relevant bytes.

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`
(the optimized version of ld64's `-save-temps` when linking the
`verify-uselistorder` executable in an LTO bootstrap).  I've hacked
`MCContext::Allocate()` to just call `malloc()` instead of using the
`BumpPtrAllocator` so that the heap profile is easier to read.  As far
as peak memory is concerned, `MCContext::Allocate()` is equivalent to a
leak, since it only gets freed at process teardown.

In my heap profile, this patch drops memory usage of
`DwarfDebug::emitDebugLoc()` from 132.56 MB (11.4%) down to 29.86 MB
(2.7%) at peak memory.  Some of that must be noise from `SmallVector`
(or other) allocations -- peak memory only dropped from 1160 MB down to
1100 MB -- but this nevertheless shaves 5% off the top.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236629 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-06 19:11:20 +00:00

63 lines
2.9 KiB
LLVM

; RUN: llc -mtriple=x86_64-apple-darwin10 < %s | FileCheck %s
%struct.a = type { i32 }
define i32 @bar(%struct.a* nocapture %b) nounwind ssp {
entry:
tail call void @llvm.dbg.value(metadata %struct.a* %b, i64 0, metadata !6, metadata !DIExpression()), !dbg !13
%tmp1 = getelementptr inbounds %struct.a, %struct.a* %b, i64 0, i32 0, !dbg !14
%tmp2 = load i32, i32* %tmp1, align 4, !dbg !14
tail call void @llvm.dbg.value(metadata i32 %tmp2, i64 0, metadata !11, metadata !DIExpression()), !dbg !14
%call = tail call i32 (...) @foo(i32 %tmp2) nounwind , !dbg !18
%add = add nsw i32 %tmp2, 1, !dbg !19
ret i32 %add, !dbg !19
}
declare i32 @foo(...)
declare void @llvm.dbg.value(metadata, i64, metadata, metadata) nounwind readnone
!llvm.dbg.cu = !{!2}
!llvm.module.flags = !{!24}
!0 = !DISubprogram(name: "bar", line: 5, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, file: !22, scope: !1, type: !3, function: i32 (%struct.a*)* @bar, variables: !21)
!1 = !DIFile(filename: "bar.c", directory: "/private/tmp")
!2 = !DICompileUnit(language: DW_LANG_C99, producer: "clang version 2.9 (trunk 122997)", isOptimized: true, emissionKind: 1, file: !22, enums: !23, retainedTypes: !23, subprograms: !20, imports: null)
!3 = !DISubroutineType(types: !4)
!4 = !{!5}
!5 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
!6 = !DILocalVariable(tag: DW_TAG_arg_variable, name: "b", line: 5, arg: 0, scope: !0, file: !1, type: !7)
!7 = !DIDerivedType(tag: DW_TAG_pointer_type, size: 64, align: 64, scope: !2, baseType: !8)
!8 = !DICompositeType(tag: DW_TAG_structure_type, name: "a", line: 1, size: 32, align: 32, file: !22, scope: !2, elements: !9)
!9 = !{!10}
!10 = !DIDerivedType(tag: DW_TAG_member, name: "c", line: 2, size: 32, align: 32, file: !22, scope: !1, baseType: !5)
!11 = !DILocalVariable(tag: DW_TAG_auto_variable, name: "x", line: 6, scope: !12, file: !1, type: !5)
!12 = distinct !DILexicalBlock(line: 5, column: 22, file: !22, scope: !0)
!13 = !DILocation(line: 5, column: 19, scope: !0)
!14 = !DILocation(line: 6, column: 14, scope: !12)
!18 = !DILocation(line: 7, column: 2, scope: !12)
!19 = !DILocation(line: 8, column: 2, scope: !12)
!20 = !{!0}
!21 = !{!6, !11}
!22 = !DIFile(filename: "bar.c", directory: "/private/tmp")
!23 = !{}
; Check that variable bar:b value range is appropriately truncated in debug info.
; The variable is in %rdi which is clobbered by 'movl %ebx, %edi'
; Here Ltmp7 is the end of the location range.
;CHECK: .loc 1 7 2
;CHECK: movl
;CHECK-NEXT: [[CLOBBER:Ltmp[0-9]*]]
;CHECK:Ldebug_loc0:
;CHECK-NEXT: Lset{{.*}} =
;CHECK-NEXT: .quad
;CHECK-NEXT: [[CLOBBER_OFF:Lset.*]] = [[CLOBBER]]-{{.*}}
;CHECK-NEXT: .quad [[CLOBBER_OFF]]
;CHECK-NEXT: .short 1 ## Loc expr size
;CHECK-NEXT: .byte 85 ## DW_OP_reg
;CHECK-NEXT: .quad 0
;CHECK-NEXT: .quad 0
!24 = !{i32 1, !"Debug Info Version", i32 3}