The second part of support for generating dwarf for assembly source files. This
generates the dwarf Compile Unit DIE and a dwarf subprogram DIE for each
non-temporary label.
The next part will be to get the clang driver to enable this when assembling
a .s file. rdar://9275556
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146262 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index 8157b41..46ab65f 100644
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -19,9 +19,12 @@
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/SourceMgr.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Twine.h"
+#include "llvm/Config/config.h"
using namespace llvm;
// Given a special op, return the address skip amount (in units of
@@ -423,6 +426,342 @@
print(dbgs());
}
+// Utility function to write a tuple for .debug_abbrev.
+static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
+ MCOS->EmitULEB128IntValue(Name);
+ MCOS->EmitULEB128IntValue(Form);
+}
+
+// When generating dwarf for assembly source files this emits
+// the data for .debug_abbrev section which contains three DIEs.
+static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
+ MCContext &context = MCOS->getContext();
+ MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
+
+ // DW_TAG_compile_unit DIE abbrev (1).
+ MCOS->EmitULEB128IntValue(1);
+ MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
+ MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
+ EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4);
+ EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
+ EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
+ EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
+ EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
+ StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
+ if (!DwarfDebugFlags.empty())
+ EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
+ EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
+ EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
+ EmitAbbrev(MCOS, 0, 0);
+
+ // DW_TAG_subprogram DIE abbrev (2).
+ MCOS->EmitULEB128IntValue(2);
+ MCOS->EmitULEB128IntValue(dwarf::DW_TAG_subprogram);
+ MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
+ EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
+ EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
+ EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
+ EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
+ EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
+ EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
+ EmitAbbrev(MCOS, 0, 0);
+
+ // DW_TAG_unspecified_parameters DIE abbrev (3).
+ MCOS->EmitULEB128IntValue(3);
+ MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
+ MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
+ EmitAbbrev(MCOS, 0, 0);
+
+ // Terminate the abbreviations for this compilation unit.
+ MCOS->EmitIntValue(0, 1);
+}
+
+// When generating dwarf for assembly source files this emits the data for
+// .debug_aranges section. Which contains a header and a table of pairs of
+// PointerSize'ed values for the address and size of section(s) with line table
+// entries (just the default .text in our case) and a terminating pair of zeros.
+static void EmitGenDwarfAranges(MCStreamer *MCOS) {
+ MCContext &context = MCOS->getContext();
+
+ // Create a symbol at the end of the section that we are creating the dwarf
+ // debugging info to use later in here as part of the expression to calculate
+ // the size of the section for the table.
+ MCOS->SwitchSection(context.getGenDwarfSection());
+ MCSymbol *SectionEndSym = context.CreateTempSymbol();
+ MCOS->EmitLabel(SectionEndSym);
+ context.setGenDwarfSectionEndSym(SectionEndSym);
+
+ MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
+
+ // This will be the length of the .debug_aranges section, first account for
+ // the size of each item in the header (see below where we emit these items).
+ int Length = 4 + 2 + 4 + 1 + 1;
+
+ // Figure the padding after the header before the table of address and size
+ // pairs who's values are PointerSize'ed.
+ const MCAsmInfo &asmInfo = context.getAsmInfo();
+ int AddrSize = asmInfo.getPointerSize();
+ int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
+ if (Pad == 2 * AddrSize)
+ Pad = 0;
+ Length += Pad;
+
+ // Add the size of the pair of PointerSize'ed values for the address and size
+ // of the one default .text section we have in the table.
+ Length += 2 * AddrSize;
+ // And the pair of terminating zeros.
+ Length += 2 * AddrSize;
+
+
+ // Emit the header for this section.
+ // The 4 byte length not including the 4 byte value for the length.
+ MCOS->EmitIntValue(Length - 4, 4);
+ // The 2 byte version, which is 2.
+ MCOS->EmitIntValue(2, 2);
+ // The 4 byte offset to the compile unit in the .debug_info from the start
+ // of the .debug_info, it is at the start of that section so this is zero.
+ MCOS->EmitIntValue(0, 4);
+ // The 1 byte size of an address.
+ MCOS->EmitIntValue(AddrSize, 1);
+ // The 1 byte size of a segment descriptor, we use a value of zero.
+ MCOS->EmitIntValue(0, 1);
+ // Align the header with the padding if needed, before we put out the table.
+ for(int i = 0; i < Pad; i++)
+ MCOS->EmitIntValue(0, 1);
+
+ // Now emit the table of pairs of PointerSize'ed values for the section(s)
+ // address and size, in our case just the one default .text section.
+ const MCExpr *Addr = MCSymbolRefExpr::Create(
+ context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
+ const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
+ *context.getGenDwarfSectionStartSym(), *SectionEndSym, 0);
+ MCOS->EmitAbsValue(Addr, AddrSize);
+ MCOS->EmitAbsValue(Size, AddrSize);
+
+ // And finally the pair of terminating zeros.
+ MCOS->EmitIntValue(0, AddrSize);
+ MCOS->EmitIntValue(0, AddrSize);
+}
+
+// When generating dwarf for assembly source files this emits the data for
+// .debug_info section which contains three parts. The header, the compile_unit
+// DIE and a list of subprogram DIEs.
+static void EmitGenDwarfInfo(MCStreamer *MCOS) {
+ MCContext &context = MCOS->getContext();
+
+ MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
+
+ // Create a symbol at the start and end of this section used in here for the
+ // expression to calculate the length in the header.
+ MCSymbol *InfoStart = context.CreateTempSymbol();
+ MCOS->EmitLabel(InfoStart);
+ MCSymbol *InfoEnd = context.CreateTempSymbol();
+
+ // First part: the header.
+
+ // The 4 byte total length of the information for this compilation unit, not
+ // including these 4 bytes.
+ const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
+ MCOS->EmitAbsValue(Length, 4);
+
+ // The 2 byte DWARF version, which is 2.
+ MCOS->EmitIntValue(2, 2);
+
+ // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
+ // it is at the start of that section so this is zero.
+ MCOS->EmitIntValue(0, 4);
+
+ const MCAsmInfo &asmInfo = context.getAsmInfo();
+ int AddrSize = asmInfo.getPointerSize();
+ // The 1 byte size of an address.
+ MCOS->EmitIntValue(AddrSize, 1);
+
+ // Second part: the compile_unit DIE.
+
+ // The DW_TAG_compile_unit DIE abbrev (1).
+ MCOS->EmitULEB128IntValue(1);
+
+ // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
+ // which is at the start of that section so this is zero.
+ MCOS->EmitIntValue(0, 4);
+
+ // AT_low_pc, the first address of the default .text section.
+ const MCExpr *Start = MCSymbolRefExpr::Create(
+ context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
+ MCOS->EmitAbsValue(Start, AddrSize);
+
+ // AT_high_pc, the last address of the default .text section.
+ const MCExpr *End = MCSymbolRefExpr::Create(
+ context.getGenDwarfSectionEndSym(), MCSymbolRefExpr::VK_None, context);
+ MCOS->EmitAbsValue(End, AddrSize);
+
+ // AT_name, the name of the source file. Reconstruct from the first directory
+ // and file table entries.
+ const std::vector<StringRef> &MCDwarfDirs =
+ context.getMCDwarfDirs();
+ if (MCDwarfDirs.size() > 0) {
+ MCOS->EmitBytes(MCDwarfDirs[0], 0);
+ MCOS->EmitBytes("/", 0);
+ }
+ const std::vector<MCDwarfFile *> &MCDwarfFiles =
+ MCOS->getContext().getMCDwarfFiles();
+ MCOS->EmitBytes(MCDwarfFiles[1]->getName(), 0);
+ MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
+
+ // AT_comp_dir, the working directory the assembly was done in.
+ llvm::sys::Path CWD = llvm::sys::Path::GetCurrentDirectory();
+ MCOS->EmitBytes(StringRef(CWD.c_str()), 0);
+ MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
+
+ // AT_APPLE_flags, the command line arguments of the assembler tool.
+ StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
+ if (!DwarfDebugFlags.empty()){
+ MCOS->EmitBytes(DwarfDebugFlags, 0);
+ MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
+ }
+
+ // AT_producer, the version of the assembler tool.
+ MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM "), 0);
+ MCOS->EmitBytes(StringRef(PACKAGE_VERSION), 0);
+ MCOS->EmitBytes(StringRef(")"), 0);
+ MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
+
+ // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
+ // draft has no standard code for assembler.
+ MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
+
+ // Third part: the list of subprogram DIEs.
+
+ // Loop on saved info for dwarf subprograms and create the DIEs for them.
+ const std::vector<const MCGenDwarfSubprogramEntry *> &Entries =
+ MCOS->getContext().getMCGenDwarfSubprogramEntries();
+ for (std::vector<const MCGenDwarfSubprogramEntry *>::const_iterator it =
+ Entries.begin(), ie = Entries.end(); it != ie;
+ ++it) {
+ const MCGenDwarfSubprogramEntry *Entry = *it;
+
+ // The DW_TAG_subprogram DIE abbrev (2).
+ MCOS->EmitULEB128IntValue(2);
+
+ // AT_name, of the label without any leading underbar.
+ MCOS->EmitBytes(Entry->getName(), 0);
+ MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
+
+ // AT_decl_file, index into the file table.
+ MCOS->EmitIntValue(Entry->getFileNumber(), 4);
+
+ // AT_decl_line, source line number.
+ MCOS->EmitIntValue(Entry->getLineNumber(), 4);
+
+ // AT_low_pc, start address of the label.
+ const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry->getLabel(),
+ MCSymbolRefExpr::VK_None, context);
+ MCOS->EmitAbsValue(AT_low_pc, AddrSize);
+
+ // AT_high_pc, end address which is the next label or end of the section.
+ std::vector<const MCGenDwarfSubprogramEntry *>::const_iterator next = it+1;
+ if (next != Entries.end()){
+ const MCGenDwarfSubprogramEntry *NextEntry = *next;
+ const MCExpr *AT_high_pc = MCSymbolRefExpr::Create(NextEntry->getLabel(),
+ MCSymbolRefExpr::VK_None, context);
+ MCOS->EmitAbsValue(AT_high_pc, AddrSize);
+ } else {
+ MCOS->EmitAbsValue(End, AddrSize);
+ }
+
+ // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
+ MCOS->EmitIntValue(0, 1);
+
+ // The DW_TAG_unspecified_parameters DIE abbrev (3).
+ MCOS->EmitULEB128IntValue(3);
+
+ // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
+ MCOS->EmitIntValue(0, 1);
+ }
+ // Deallocate the MCGenDwarfSubprogramEntry classes that saved away the info
+ // for the dwarf subprograms.
+ for (std::vector<const MCGenDwarfSubprogramEntry *>::const_iterator it =
+ Entries.begin(), ie = Entries.end(); it != ie;
+ ++it) {
+ const MCGenDwarfSubprogramEntry *Entry = *it;
+ delete Entry;
+ }
+
+ // Add the NULL DIE terminating the Compile Unit DIE's.
+ MCOS->EmitIntValue(0, 1);
+
+ // Now set the value of the symbol at the end of the info section.
+ MCOS->EmitLabel(InfoEnd);
+}
+
+//
+// When generating dwarf for assembly source files this emits the Dwarf
+// sections.
+//
+void MCGenDwarfInfo::Emit(MCStreamer *MCOS) {
+ // Create the dwarf sections in this order (.debug_line already created).
+ MCContext &context = MCOS->getContext();
+ MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
+ MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
+ MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
+
+ // If there are no line table entries then do not emit any section contents.
+ if (context.getMCLineSections().empty())
+ return;
+
+ // Output the data for .debug_aranges section.
+ EmitGenDwarfAranges(MCOS);
+
+ // Output the data for .debug_abbrev section.
+ EmitGenDwarfAbbrev(MCOS);
+
+ // Output the data for .debug_info section.
+ EmitGenDwarfInfo(MCOS);
+}
+
+//
+// When generating dwarf for assembly source files this is called when symbol
+// for a label is created. If this symbol is not a temporary and is in the
+// section that dwarf is being generated for, save the needed info to create
+// a dwarf subprogram.
+//
+void MCGenDwarfSubprogramEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
+ SourceMgr &SrcMgr, SMLoc &Loc) {
+ // We won't create dwarf subprogram's for temporary symbols or symbols not in
+ // the default text.
+ if (Symbol->isTemporary())
+ return;
+ MCContext &context = MCOS->getContext();
+ if (context.getGenDwarfSection() != MCOS->getCurrentSection())
+ return;
+
+ // The dwarf subprogram's name does not have the symbol name's leading
+ // underbar if any.
+ StringRef Name = Symbol->getName();
+ if (Name.startswith("_"))
+ Name = Name.substr(1, Name.size()-1);
+
+ // Get the dwarf file number to be used for the dwarf subprogram.
+ unsigned FileNumber = context.getGenDwarfFileNumber();
+
+ // Finding the line number is the expensive part which is why we just don't
+ // pass it in as for some symbols we won't create a dwarf subprogram.
+ int CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
+ unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
+
+ // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
+ // values so that they don't have things like an ARM thumb bit from the
+ // original symbol. So when used they won't get a low bit set after
+ // relocation.
+ MCSymbol *Label = context.CreateTempSymbol();
+ MCOS->EmitLabel(Label);
+
+ // Create and entry for the info and add it to the other entries.
+ MCGenDwarfSubprogramEntry *Entry =
+ new MCGenDwarfSubprogramEntry(Name, FileNumber, LineNumber, Label);
+ MCOS->getContext().addMCGenDwarfSubprogramEntry(Entry);
+}
+
static int getDataAlignmentFactor(MCStreamer &streamer) {
MCContext &context = streamer.getContext();
const MCAsmInfo &asmInfo = context.getAsmInfo();