From f76a0cd97aa2ee52dd7e0fccb0a6a33d3af2af77 Mon Sep 17 00:00:00 2001 From: Igor Kudrin Date: Fri, 17 Jul 2020 12:46:47 +0700 Subject: [PATCH] [DebugInfo] Fix a misleading usage of DWARF forms with DIEExpr. NFCI. For now, DIEExpr is used only in two places: 1) in the debug info library unit test suite to emit a DW_AT_str_offsets_base attribute with the DW_FORM_sec_offset form, see dwarfgen::DIE::addStrOffsetsBaseAttribute(); 2) in DwarfCompileUnit::addLocationAttribute() to generate the location attribute for a TLS variable. The later case used an incorrect DWARF form of DW_FORM_udata, which implies storing an uleb128 value, not a 4/8 byte constant. The generated result was as expected because DIEExpr::SizeOf() did not handle the used form, but returned the size of the code pointer by default. The patch fixes the issue by using more appropriate DWARF forms for the problematic case and making DIEExpr::SizeOf() more straightforward. Differential Revision: https://reviews.llvm.org/D83958 --- llvm/lib/CodeGen/AsmPrinter/DIE.cpp | 15 +++++++++++---- llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp | 4 +++- 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp index edf82fb..713a15d 100644 --- a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp +++ b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp @@ -472,10 +472,17 @@ void DIEExpr::emitValue(const AsmPrinter *AP, dwarf::Form Form) const { /// SizeOf - Determine size of expression value in bytes. /// unsigned DIEExpr::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const { - if (Form == dwarf::DW_FORM_data4) return 4; - if (Form == dwarf::DW_FORM_sec_offset) return 4; - if (Form == dwarf::DW_FORM_strp) return 4; - return AP->getPointerSize(); + switch (Form) { + case dwarf::DW_FORM_data4: + return 4; + case dwarf::DW_FORM_data8: + return 8; + case dwarf::DW_FORM_sec_offset: + // FIXME: add support for DWARF64 + return 4; + default: + llvm_unreachable("DIE Value form not supported yet"); + } } LLVM_DUMP_METHOD diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp index 296c380..d90e49c 100644 --- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp +++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp @@ -260,7 +260,9 @@ void DwarfCompileUnit::addLocationAttribute( : dwarf::DW_OP_const8u); // 2) containing the (relocated) offset of the TLS variable // within the module's TLS block. - addExpr(*Loc, dwarf::DW_FORM_udata, + addExpr(*Loc, + PointerSize == 4 ? dwarf::DW_FORM_data4 + : dwarf::DW_FORM_data8, Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym)); } else { addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_const_index); -- 2.7.4