diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp --- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp +++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp @@ -3042,13 +3042,18 @@ for (const ArangeSpan &Span : List) { Asm->emitLabelReference(Span.Start, PtrSize); - // Calculate the size as being from the span start to it's end. - if (Span.End) { + // Calculate the size as being from the span start to its end. + // + // If the size is zero, then round it up to one byte. The DWARF + // specification requires that entries in this table have nonzero + // lengths. + auto SizeRef = SymSize.find(Span.Start); + if ((SizeRef == SymSize.end() || SizeRef->second != 0) && Span.End) { Asm->emitLabelDifference(Span.End, Span.Start, PtrSize); } else { // For symbols without an end marker (e.g. common), we // write a single arange entry containing just that one symbol. - uint64_t Size = SymSize[Span.Start]; + uint64_t Size = SizeRef->second; if (Size == 0) Size = 1; diff --git a/llvm/test/CodeGen/X86/dwarf-aranges-zero-size.ll b/llvm/test/CodeGen/X86/dwarf-aranges-zero-size.ll new file mode 100644 --- /dev/null +++ b/llvm/test/CodeGen/X86/dwarf-aranges-zero-size.ll @@ -0,0 +1,39 @@ +; Ensures that the AsmPrinter rounds up zero-sized symbols in `.debug_aranges` to one byte. + +; Generated from the following Rust source: +; +; pub static EXAMPLE: () = (); +; +; Compiled with: +; +; $ rustc --crate-type=lib --target=x86_64-unknown-linux-gnu --emit=llvm-ir -g dwarf-aranges-zero-size.rs + +; RUN: llc --generate-arange-section < %s | FileCheck %s +; CHECK: .section .debug_aranges +; CHECK: .quad _ZN23dwarf_aranges_zero_size7EXAMPLE17h8ab19f2b0c3b238dE +; CHECK-NEXT: .quad 1 +; CHECK: .section + +; ModuleID = 'dwarf_aranges_zero_size.fbc28187-cgu.0' +source_filename = "dwarf_aranges_zero_size.fbc28187-cgu.0" +target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-unknown-linux-gnu" + +@_ZN23dwarf_aranges_zero_size7EXAMPLE17h8ab19f2b0c3b238dE = constant <{ [0 x i8] }> zeroinitializer, align 1, !dbg !0 +@__rustc_debug_gdb_scripts_section__ = linkonce_odr unnamed_addr constant [34 x i8] c"\01gdb_load_rust_pretty_printers.py\00", section ".debug_gdb_scripts", align 1 + +!llvm.module.flags = !{!5, !6, !7} +!llvm.dbg.cu = !{!8} + +!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression()) +!1 = distinct !DIGlobalVariable(name: "EXAMPLE", linkageName: "_ZN23dwarf_aranges_zero_size7EXAMPLE17h8ab19f2b0c3b238dE", scope: !2, file: !3, line: 1, type: !4, isLocal: false, isDefinition: true, align: 8) +!2 = !DINamespace(name: "dwarf_aranges_zero_size", scope: null) +!3 = !DIFile(filename: "dwarf-aranges-zero-size.rs", directory: "/Users/pcwalton/Desktop", checksumkind: CSK_MD5, checksum: "c2d51547bfaf5562b9c9061311fe4140") +!4 = !DIBasicType(name: "()", encoding: DW_ATE_unsigned) +!5 = !{i32 7, !"PIC Level", i32 2} +!6 = !{i32 2, !"RtLibUseGOT", i32 1} +!7 = !{i32 2, !"Debug Info Version", i32 3} +!8 = distinct !DICompileUnit(language: DW_LANG_Rust, file: !9, producer: "clang LLVM (rustc version 1.60.0-nightly (0c292c966 2022-02-08))", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !10, globals: !11) +!9 = !DIFile(filename: "dwarf-aranges-zero-size.rs/@/dwarf_aranges_zero_size.fbc28187-cgu.0", directory: "/Users/pcwalton/Desktop") +!10 = !{} +!11 = !{!0}