llvm/test/Transforms/Util/split-bit-piece.ll
Adrian Prantl 460dd60c1a [DIExpression] Introduce a dedicated DW_OP_LLVM_fragment operation
so we can stop using DW_OP_bit_piece with the wrong semantics.

The entire back story can be found here:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20161114/405934.html

The gist is that in LLVM we've been misinterpreting DW_OP_bit_piece's
offset field to mean the offset into the source variable rather than
the offset into the location at the top the DWARF expression stack. In
order to be able to fix this in a subsequent patch, this patch
introduces a dedicated DW_OP_LLVM_fragment operation with the
semantics that we used to apply to DW_OP_bit_piece, which is what we
actually need while inside of LLVM. This patch is complete with a
bitcode upgrade for expressions using the old format. It does not yet
fix the DWARF backend to use DW_OP_bit_piece correctly.

Implementation note: We discussed several options for implementing
this, including reserving a dedicated field in DIExpression for the
fragment size and offset, but using an custom operator at the end of
the expression works just fine and is more efficient because we then
only pay for it when we need it.

Differential Revision: https://reviews.llvm.org/D27361
rdar://problem/29335809

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@288683 91177308-0d34-0410-b5e6-96231b3b80d8
2016-12-05 18:04:47 +00:00

46 lines
2.4 KiB
LLVM

; Checks that llvm.dbg.declare -> llvm.dbg.value conversion utility
; (here exposed through the SROA) pass, properly inserts bit_piece expressions
; if it only describes part of the variable.
; RUN: opt -S -sroa %s | FileCheck %s
; Function Attrs: nounwind readnone
declare void @llvm.dbg.declare(metadata, metadata, metadata) #0
; Function Attrs: nounwind uwtable
define hidden void @_ZN6__tsan9FastState14SetHistorySizeEi(i32 %hs) #1 align 2 {
entry:
%hs.addr = alloca i32, align 4
%v1 = alloca i64, align 8
%v2 = alloca i64, align 8
store i32 %hs, i32* %hs.addr, align 4
; CHECK: call void @llvm.dbg.value(metadata i32 %hs, i64 0, metadata !{{[0-9]+}}, metadata ![[EXPR:[0-9]+]])
; CHECK: ![[EXPR]] = !DIExpression(DW_OP_LLVM_fragment, 0
call void @llvm.dbg.declare(metadata i64* %v1, metadata !9, metadata !12), !dbg !13
%0 = load i32, i32* %hs.addr, align 4
%conv = sext i32 %0 to i64
store i64 %conv, i64* %v1, align 8
%1 = load i64, i64* %v2, align 8
unreachable
}
attributes #0 = { nounwind readnone }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!7}
!llvm.ident = !{!8}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 256979) (llvm/trunk 257107)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, retainedTypes: !2)
!1 = !DIFile(filename: "tsan_shadow_test.cc", directory: "/tmp")
!2 = !{!3, !5}
!3 = !DICompositeType(tag: DW_TAG_class_type, name: "FastState", file: !4, line: 91, size: 64, align: 64, identifier: "_ZTSN6__tsan9FastStateE")
!4 = !DIFile(filename: "/mnt/extra/llvm/projects/compiler-rt/lib/tsan/rtl/tsan_rtl.h", directory: "/tmp")
!5 = distinct !DIDerivedType(tag: DW_TAG_typedef, name: "u64", line: 78, baseType: !6)
!6 = !DIBasicType(name: "long long unsigned int", size: 64, align: 64, encoding: DW_ATE_unsigned)
!7 = !{i32 2, !"Debug Info Version", i32 3}
!8 = !{!"clang version 3.8.0 (trunk 256979) (llvm/trunk 257107)"}
!9 = !DILocalVariable(name: "v1", scope: !10, file: !4, line: 136, type: !5)
!10 = distinct !DILexicalBlock(scope: !11, file: !4, line: 136, column: 5)
!11 = distinct !DISubprogram(name: "SetHistorySize", linkageName: "_ZN6__tsan9FastState14SetHistorySizeEi", scope: !3, file: !4, line: 135, isLocal: false, isDefinition: true, scopeLine: 135, flags: DIFlagPrototyped, isOptimized: false, unit: !0)
!12 = !DIExpression()
!13 = !DILocation(line: 136, column: 5, scope: !10)