[dsymutil] Add preliminary support for DWARF 5.
Currently dsymutil will silently fail when processing binaries with
Dwarf 5 debug info. This patch adds rudimentary support for Dwarf 5 in
dsymutil.
- Recognize relocations in the debug_addr section.
- Recognize (a subset of) Dwarf 5 form values.
- Emits valid Dwarf 5 compile unit header chains.
To simplify things (and avoid having to emit indexed sections) I decided
to emit the relocated addresses directly in the debug info section.
- DW_FORM_strx gets relocated and rewritten to DW_FORM_strp
- DW_FORM_addrx gets relocated and rewritten to DW_FORM_addr
Obviously there's a lot of work left, but this should be a step in the
right direction.
rdar://62345491
Differential revision: https://reviews.llvm.org/D94323
GitOrigin-RevId: f1d5cbbdee5526bc86eac0a5652b115d9bc158e5
diff --git a/lib/DWARFLinker/DWARFStreamer.cpp b/lib/DWARFLinker/DWARFStreamer.cpp
index e900335..c0043ae 100644
--- a/lib/DWARFLinker/DWARFStreamer.cpp
+++ b/lib/DWARFLinker/DWARFStreamer.cpp
@@ -121,16 +121,23 @@
/// Emit the compilation unit header for \p Unit in the debug_info section.
///
-/// A Dwarf section header is encoded as:
+/// A Dwarf 4 section header is encoded as:
/// uint32_t Unit length (omitting this field)
/// uint16_t Version
/// uint32_t Abbreviation table offset
/// uint8_t Address size
-///
/// Leading to a total of 11 bytes.
-void DwarfStreamer::emitCompileUnitHeader(CompileUnit &Unit) {
- unsigned Version = Unit.getOrigUnit().getVersion();
- switchToDebugInfoSection(Version);
+///
+/// A Dwarf 5 section header is encoded as:
+/// uint32_t Unit length (omitting this field)
+/// uint16_t Version
+/// uint8_t Unit type
+/// uint8_t Address size
+/// uint32_t Abbreviation table offset
+/// Leading to a total of 12 bytes.
+void DwarfStreamer::emitCompileUnitHeader(CompileUnit &Unit,
+ unsigned DwarfVersion) {
+ switchToDebugInfoSection(DwarfVersion);
/// The start of the unit within its section.
Unit.setLabelBegin(Asm->createTempSymbol("cu_begin"));
@@ -140,13 +147,22 @@
// been computed in CompileUnit::computeOffsets(). Subtract 4 to that size to
// account for the length field.
Asm->emitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset() - 4);
- Asm->emitInt16(Version);
+ Asm->emitInt16(DwarfVersion);
- // We share one abbreviations table across all units so it's always at the
- // start of the section.
- Asm->emitInt32(0);
- Asm->emitInt8(Unit.getOrigUnit().getAddressByteSize());
- DebugInfoSectionSize += 11;
+ if (DwarfVersion >= 5) {
+ Asm->emitInt8(dwarf::DW_UT_compile);
+ Asm->emitInt8(Unit.getOrigUnit().getAddressByteSize());
+ // We share one abbreviations table across all units so it's always at the
+ // start of the section.
+ Asm->emitInt32(0);
+ DebugInfoSectionSize += 12;
+ } else {
+ // We share one abbreviations table across all units so it's always at the
+ // start of the section.
+ Asm->emitInt32(0);
+ Asm->emitInt8(Unit.getOrigUnit().getAddressByteSize());
+ DebugInfoSectionSize += 11;
+ }
// Remember this CU.
EmittedUnits.push_back({Unit.getUniqueID(), Unit.getLabelBegin()});
@@ -211,6 +227,16 @@
// Emit a null terminator.
Asm->emitInt8(0);
}
+
+#if 0
+ if (DwarfVersion >= 5) {
+ // Emit an empty string offset section.
+ Asm->OutStreamer->SwitchSection(MOFI->getDwarfStrOffSection());
+ Asm->emitDwarfUnitLength(4, "Length of String Offsets Set");
+ Asm->emitInt16(DwarfVersion);
+ Asm->emitInt16(0);
+ }
+#endif
}
void DwarfStreamer::emitDebugNames(
