diff --git a/lib/CodeGen/AsmPrinter/CMakeLists.txt b/lib/CodeGen/AsmPrinter/CMakeLists.txt index f2da8557a52..ba2f61a4482 100644 --- a/lib/CodeGen/AsmPrinter/CMakeLists.txt +++ b/lib/CodeGen/AsmPrinter/CMakeLists.txt @@ -5,6 +5,7 @@ add_llvm_library(LLVMAsmPrinter AsmPrinterDwarf.cpp AsmPrinterInlineAsm.cpp DbgValueHistoryCalculator.cpp + DebugLocStream.cpp DIE.cpp DIEHash.cpp DwarfAccelTable.cpp diff --git a/lib/CodeGen/AsmPrinter/DebugLocEntry.h b/lib/CodeGen/AsmPrinter/DebugLocEntry.h index 083228b8fd4..3235929bba5 100644 --- a/lib/CodeGen/AsmPrinter/DebugLocEntry.h +++ b/lib/CodeGen/AsmPrinter/DebugLocEntry.h @@ -142,7 +142,7 @@ public: } /// \brief Lower this entry into a DWARF expression. - void finalize(const AsmPrinter &AP, DebugLocStream &Locs, + void finalize(const AsmPrinter &AP, DebugLocStream::ListBuilder &List, const DIBasicType *BT); }; diff --git a/lib/CodeGen/AsmPrinter/DebugLocStream.cpp b/lib/CodeGen/AsmPrinter/DebugLocStream.cpp new file mode 100644 index 00000000000..7e8ed7104af --- /dev/null +++ b/lib/CodeGen/AsmPrinter/DebugLocStream.cpp @@ -0,0 +1,46 @@ +//===- DebugLocStream.cpp - DWARF debug_loc stream --------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include "DebugLocStream.h" +#include "DwarfDebug.h" +#include "llvm/CodeGen/AsmPrinter.h" + +using namespace llvm; + +bool DebugLocStream::finalizeList(AsmPrinter &Asm) { + if (Lists.back().EntryOffset == Entries.size()) { + // Empty list. Delete it. + Lists.pop_back(); + return false; + } + + // Real list. Generate a label for it. + Lists.back().Label = Asm.createTempSymbol("debug_loc"); + return true; +} + +void DebugLocStream::finalizeEntry() { + if (Entries.back().ByteOffset != DWARFBytes.size()) + return; + + // The last entry was empty. Delete it. + Comments.erase(Comments.begin() + Entries.back().CommentOffset, + Comments.end()); + Entries.pop_back(); + + assert(Lists.back().EntryOffset <= Entries.size() && + "Popped off more entries than are in the list"); +} + +DebugLocStream::ListBuilder::~ListBuilder() { + if (!Locs.finalizeList(Asm)) + return; + V.initializeDbgValue(&MI); + V.setDebugLocListIndex(ListIndex); +} diff --git a/lib/CodeGen/AsmPrinter/DebugLocStream.h b/lib/CodeGen/AsmPrinter/DebugLocStream.h index 1ae385db4a5..3656e9d9509 100644 --- a/lib/CodeGen/AsmPrinter/DebugLocStream.h +++ b/lib/CodeGen/AsmPrinter/DebugLocStream.h @@ -15,7 +15,11 @@ #include "ByteStreamer.h" namespace llvm { + +class AsmPrinter; +class DbgVariable; class DwarfCompileUnit; +class MachineInstr; class MCSymbol; /// \brief Byte stream of .debug_loc entries. @@ -29,10 +33,10 @@ class DebugLocStream { public: struct List { DwarfCompileUnit *CU; - MCSymbol *Label; + MCSymbol *Label = nullptr; size_t EntryOffset; - List(DwarfCompileUnit *CU, MCSymbol *Label, size_t EntryOffset) - : CU(CU), Label(Label), EntryOffset(EntryOffset) {} + List(DwarfCompileUnit *CU, size_t EntryOffset) + : CU(CU), EntryOffset(EntryOffset) {} }; struct Entry { const MCSymbol *BeginSym; @@ -61,18 +65,30 @@ public: const List &getList(size_t LI) const { return Lists[LI]; } ArrayRef getLists() const { return Lists; } + class ListBuilder; + class EntryBuilder; + +private: /// \brief Start a new .debug_loc entry list. /// /// Start a new .debug_loc entry list. Return the new list's index so it can /// be retrieved later via \a getList(). /// /// Until the next call, \a startEntry() will add entries to this list. - size_t startList(DwarfCompileUnit *CU, MCSymbol *Label) { + size_t startList(DwarfCompileUnit *CU) { size_t LI = Lists.size(); - Lists.emplace_back(CU, Label, Entries.size()); + Lists.emplace_back(CU, Entries.size()); return LI; } + /// Finalize a .debug_loc entry list. + /// + /// If there are no entries in this list, delete it outright. Otherwise, + /// create a label with \a Asm. + /// + /// \return false iff the list is deleted. + bool finalizeList(AsmPrinter &Asm); + /// \brief Start a new .debug_loc entry. /// /// Until the next call, bytes added to the stream will be added to this @@ -81,6 +97,10 @@ public: Entries.emplace_back(BeginSym, EndSym, DWARFBytes.size(), Comments.size()); } + /// Finalize a .debug_loc entry, deleting if it's empty. + void finalizeEntry(); + +public: BufferByteStreamer getStreamer() { return BufferByteStreamer(DWARFBytes, Comments, GenerateComments); } @@ -129,5 +149,45 @@ private: return Entries[EI + 1].CommentOffset - Entries[EI].CommentOffset; } }; + +/// Builder for DebugLocStream lists. +class DebugLocStream::ListBuilder { + DebugLocStream &Locs; + AsmPrinter &Asm; + DbgVariable &V; + const MachineInstr &MI; + size_t ListIndex; + +public: + ListBuilder(DebugLocStream &Locs, DwarfCompileUnit &CU, AsmPrinter &Asm, + DbgVariable &V, const MachineInstr &MI) + : Locs(Locs), Asm(Asm), V(V), MI(MI), ListIndex(Locs.startList(&CU)) {} + + /// Finalize the list. + /// + /// If the list is empty, delete it. Otherwise, finalize it by creating a + /// temp symbol in \a Asm and setting up the \a DbgVariable. + ~ListBuilder(); + + DebugLocStream &getLocs() { return Locs; } +}; + +/// Builder for DebugLocStream entries. +class DebugLocStream::EntryBuilder { + DebugLocStream &Locs; + +public: + EntryBuilder(ListBuilder &List, const MCSymbol *Begin, const MCSymbol *End) + : Locs(List.getLocs()) { + Locs.startEntry(Begin, End); + } + + /// Finalize the entry, deleting it if it's empty. + ~EntryBuilder() { Locs.finalizeEntry(); } + + BufferByteStreamer getStreamer() { return Locs.getStreamer(); } +}; + } // namespace llvm + #endif diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp index bd54de7c1b9..7d03a3930d7 100644 --- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp +++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp @@ -908,15 +908,15 @@ void DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU, const MachineInstr *MInsn = Ranges.front().first; assert(MInsn->isDebugValue() && "History must begin with debug value"); - RegVar->initializeDbgValue(MInsn); // Check if the first DBG_VALUE is valid for the rest of the function. - if (Ranges.size() == 1 && Ranges.front().second == nullptr) + if (Ranges.size() == 1 && Ranges.front().second == nullptr) { + RegVar->initializeDbgValue(MInsn); continue; + } // Handle multiple DBG_VALUE instructions describing one variable. - RegVar->setDebugLocListIndex( - DebugLocs.startList(&TheCU, Asm->createTempSymbol("debug_loc"))); + DebugLocStream::ListBuilder List(DebugLocs, TheCU, *Asm, *RegVar, *MInsn); // Build the location list for this variable. SmallVector Entries; @@ -930,7 +930,7 @@ void DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU, // Finalize the entry by lowering it into a DWARF bytestream. for (auto &Entry : Entries) - Entry.finalize(*Asm, DebugLocs, BT); + Entry.finalize(*Asm, List, BT); } // Collect info for variables that were optimized out. @@ -1504,10 +1504,11 @@ static void emitDebugLocValue(const AsmPrinter &AP, const DIBasicType *BT, // FIXME: ^ } -void DebugLocEntry::finalize(const AsmPrinter &AP, DebugLocStream &Locs, +void DebugLocEntry::finalize(const AsmPrinter &AP, + DebugLocStream::ListBuilder &List, const DIBasicType *BT) { - Locs.startEntry(Begin, End); - BufferByteStreamer Streamer = Locs.getStreamer(); + DebugLocStream::EntryBuilder Entry(List, Begin, End); + BufferByteStreamer Streamer = Entry.getStreamer(); const DebugLocEntry::Value &Value = Values[0]; if (Value.isBitPiece()) { // Emit all pieces that belong to the same variable and range. diff --git a/test/DebugInfo/X86/debug-loc-empty-entries.ll b/test/DebugInfo/X86/debug-loc-empty-entries.ll new file mode 100644 index 00000000000..3b997fd35e0 --- /dev/null +++ b/test/DebugInfo/X86/debug-loc-empty-entries.ll @@ -0,0 +1,66 @@ +; RUN: llc -mtriple=x86_64-apple-macosx <%s | FileCheck %s +; Test that we don't generate empty .debug_loc entries. Originally, there were +; two empty .debug_loc entries for 'a' in an otherwise empty .debug_loc list. +; +; CHECK: .section __DWARF,__debug_loc,regular,debug +; CHECK-NEXT: Lsection_debug_loc: +; CHECK-NEXT: .section __DWARF,__debug_abbrev,regular,debug +; +; Test that the variable stuck around. +; CHECK: .section __DWARF,__debug_info,regular,debug +; CHECK: DW_TAG_variable +; CHECK-NOT: DW_AT_location + +; Generated using clang -cc1 with the following args: +; +; -triple x86_64-apple-macosx -emit-llvm -gdwarf-4 -O1 +; +; From this testcase: +; +;; void fn1() { +;; float a = 1; +;; for (;;) +;; a = 0; +;; } + +; Function Attrs: noreturn nounwind readnone +define void @_Z3fn1v() #0 { +entry: + tail call void @llvm.dbg.value(metadata float 1.000000e+00, i64 0, metadata !9, metadata !14), !dbg !15 + br label %for.cond, !dbg !16 + +for.cond: ; preds = %for.cond, %entry + tail call void @llvm.dbg.value(metadata float 0.000000e+00, i64 0, metadata !9, metadata !14), !dbg !15 + br label %for.cond, !dbg !17 +} + +; Function Attrs: nounwind readnone +declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #1 + +attributes #0 = { noreturn nounwind readnone "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-realign-stack" "stack-protector-buffer-size"="8" "target-features"="+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" } +attributes #1 = { nounwind readnone } + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!11, !12} +!llvm.ident = !{!13} + +!0 = !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.7.0 (trunk 238517) (llvm/trunk 238524)", isOptimized: true, runtimeVersion: 0, emissionKind: 1, enums: !2, retainedTypes: !2, subprograms: !3, globals: !2, imports: !2) +!1 = !DIFile(filename: "", directory: "/Users/dexonsmith/data/llvm/bootstrap/play/delta2/testcase") +!2 = !{} +!3 = !{!4} +!4 = !DISubprogram(name: "fn1", linkageName: "_Z3fn1v", scope: !5, file: !5, line: 1, type: !6, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, function: void ()* @_Z3fn1v, variables: !8) +!5 = !DIFile(filename: "t.cpp", directory: "/Users/dexonsmith/data/llvm/bootstrap/play/delta2/testcase") +!6 = !DISubroutineType(types: !7) +!7 = !{null} +!8 = !{!9} +!9 = !DILocalVariable(tag: DW_TAG_auto_variable, name: "a", scope: !4, file: !5, line: 2, type: !10) +!10 = !DIBasicType(name: "float", size: 32, align: 32, encoding: DW_ATE_float) +!11 = !{i32 2, !"Dwarf Version", i32 4} +!12 = !{i32 2, !"Debug Info Version", i32 3} +!13 = !{!"clang version 3.7.0 (trunk 238517) (llvm/trunk 238524)"} +!14 = !DIExpression() +!15 = !DILocation(line: 2, scope: !4) +!16 = !DILocation(line: 3, scope: !4) +!17 = !DILocation(line: 3, scope: !18) +!18 = distinct !DILexicalBlock(scope: !19, file: !5, line: 3) +!19 = distinct !DILexicalBlock(scope: !4, file: !5, line: 3)