[lld-macho] Don't attempt to emit rebase opcodes for debug sections
This was causing a crash as we were attempting to look up the
nonexistent parent OutputSection of the debug sections. We didn't detect
it earlier because there was no test for PIEs with debug info (PIEs
require us to emit rebases for X86_64_RELOC_UNSIGNED).
This diff filters out the debug sections while loading the ObjFiles. In
addition to fixing the above problem, it also lets us avoid doing
redundant work -- we no longer parse / apply relocations / attempt to
emit dyld opcodes for these sections that we don't emit.
Fixes llvm.org/PR48392.
Reviewed By: thakis
Differential Revision: https://reviews.llvm.org/D92904
diff --git a/lld/MachO/Dwarf.cpp b/lld/MachO/Dwarf.cpp
index 121f54f..3e79492 100644
--- a/lld/MachO/Dwarf.cpp
+++ b/lld/MachO/Dwarf.cpp
@@ -20,26 +20,19 @@
std::unique_ptr<DwarfObject> DwarfObject::create(ObjFile *obj) {
auto dObj = std::make_unique<DwarfObject>();
bool hasDwarfInfo = false;
- for (SubsectionMap subsecMap : obj->subsections) {
- for (auto it : subsecMap) {
- InputSection *isec = it.second;
- if (!(isDebugSection(isec->flags) &&
- isec->segname == segment_names::dwarf))
- continue;
-
- if (isec->name == "__debug_info") {
- dObj->infoSection.Data = toStringRef(isec->data);
- hasDwarfInfo = true;
- continue;
- }
-
- if (StringRef *s = StringSwitch<StringRef *>(isec->name)
- .Case("__debug_abbrev", &dObj->abbrevSection)
- .Case("__debug_str", &dObj->strSection)
- .Default(nullptr)) {
- *s = toStringRef(isec->data);
- hasDwarfInfo = true;
- }
+ // LLD only needs to extract the source file path from the debug info, so we
+ // initialize DwarfObject with just the sections necessary to get that path.
+ // The debugger will locate the debug info via the object file paths that we
+ // emit in our STABS symbols, so we don't need to process & emit them
+ // ourselves.
+ for (InputSection *isec : obj->debugSections) {
+ if (StringRef *s = StringSwitch<StringRef *>(isec->name)
+ .Case("__debug_info", &dObj->infoSection.Data)
+ .Case("__debug_abbrev", &dObj->abbrevSection)
+ .Case("__debug_str", &dObj->strSection)
+ .Default(nullptr)) {
+ *s = toStringRef(isec->data);
+ hasDwarfInfo = true;
}
}
