[lld-macho] Fix crash: ObjC category merge + relative method lists (#104081)
A crash was happening when both ObjC Category Merging and Relative
method lists were enabled.
ObjC Category Merging creates new data sections and adds them by calling
`addInputSection`. `addInputSection` uses the symbols within the added
section to determine which container to actually add the section to.
The issue is that ObjC Category merging is calling `addInputSection`
before actually adding the relevant symbols the the added section. This
causes `addInputSection` to add the `InputSection` to the wrong
container, eventually resulting in a crash.
To fix this, we ensure that ObjC Category Merging calls
`addInputSection` only after the symbols have been added to the
`InputSection`.
diff --git a/lld/MachO/ObjC.cpp b/lld/MachO/ObjC.cpp
index 18b7521..b9f7592 100644
--- a/lld/MachO/ObjC.cpp
+++ b/lld/MachO/ObjC.cpp
@@ -851,7 +851,6 @@
infoCategoryWriter.catPtrListInfo.align);
listSec->parent = infoCategoryWriter.catPtrListInfo.outputSection;
listSec->live = true;
- addInputSection(listSec);
listSec->parent = infoCategoryWriter.catPtrListInfo.outputSection;
@@ -867,6 +866,7 @@
ptrListSym->used = true;
parentSym->getObjectFile()->symbols.push_back(ptrListSym);
+ addInputSection(listSec);
createSymbolReference(parentSym, ptrListSym, linkAtOffset,
infoCategoryWriter.catBodyInfo.relocTemplate);
@@ -911,7 +911,6 @@
infoCategoryWriter.catPtrListInfo.align);
listSec->parent = infoCategoryWriter.catPtrListInfo.outputSection;
listSec->live = true;
- addInputSection(listSec);
listSec->parent = infoCategoryWriter.catPtrListInfo.outputSection;
@@ -927,6 +926,7 @@
ptrListSym->used = true;
parentSym->getObjectFile()->symbols.push_back(ptrListSym);
+ addInputSection(listSec);
createSymbolReference(parentSym, ptrListSym, linkAtOffset,
infoCategoryWriter.catBodyInfo.relocTemplate);
@@ -952,7 +952,6 @@
bodyData, infoCategoryWriter.catListInfo.align);
newCatList->parent = infoCategoryWriter.catListInfo.outputSection;
newCatList->live = true;
- addInputSection(newCatList);
newCatList->parent = infoCategoryWriter.catListInfo.outputSection;
@@ -968,6 +967,7 @@
catListSym->used = true;
objFile->symbols.push_back(catListSym);
+ addInputSection(newCatList);
return catListSym;
}
@@ -990,7 +990,6 @@
bodyData, infoCategoryWriter.catBodyInfo.align);
newBodySec->parent = infoCategoryWriter.catBodyInfo.outputSection;
newBodySec->live = true;
- addInputSection(newBodySec);
std::string symName =
objc::symbol_names::category + baseClassName + "(" + name + ")";
@@ -1003,6 +1002,7 @@
catBodySym->used = true;
objFile->symbols.push_back(catBodySym);
+ addInputSection(newBodySec);
createSymbolReference(catBodySym, nameSym, catLayout.nameOffset,
infoCategoryWriter.catBodyInfo.relocTemplate);
@@ -1223,7 +1223,6 @@
infoCategoryWriter.catListInfo.align);
listSec->parent = infoCategoryWriter.catListInfo.outputSection;
listSec->live = true;
- addInputSection(listSec);
std::string slotSymName = "<__objc_catlist slot for category ";
slotSymName += nonErasedCatBody->getName();
@@ -1238,6 +1237,7 @@
catListSlotSym->used = true;
objFile->symbols.push_back(catListSlotSym);
+ addInputSection(listSec);
// Now link the category body into the newly created slot
createSymbolReference(catListSlotSym, nonErasedCatBody, 0,
diff --git a/lld/test/MachO/objc-category-merging-minimal.s b/lld/test/MachO/objc-category-merging-minimal.s
index 5274933..b94799a5 100644
--- a/lld/test/MachO/objc-category-merging-minimal.s
+++ b/lld/test/MachO/objc-category-merging-minimal.s
@@ -9,7 +9,7 @@
## Create our main testing dylib - linking against the fake dylib above
# RUN: llvm-mc -filetype=obj -triple=arm64-apple-macos -o merge_cat_minimal.o merge_cat_minimal.s
# RUN: %lld -arch arm64 -dylib -o merge_cat_minimal_no_merge.dylib a64_fakedylib.dylib merge_cat_minimal.o
-# RUN: %lld -arch arm64 -dylib -o merge_cat_minimal_merge.dylib -objc_category_merging a64_fakedylib.dylib merge_cat_minimal.o
+# RUN: %lld -objc_relative_method_lists -arch arm64 -dylib -o merge_cat_minimal_merge.dylib -objc_category_merging a64_fakedylib.dylib merge_cat_minimal.o
## Now verify that the flag caused category merging to happen appropriatelly
# RUN: llvm-objdump --objc-meta-data --macho merge_cat_minimal_no_merge.dylib | FileCheck %s --check-prefixes=NO_MERGE_CATS
@@ -17,7 +17,7 @@
############ Test merging multiple categories into the base class ############
# RUN: llvm-mc -filetype=obj -triple=arm64-apple-macos -o merge_base_class_minimal.o merge_base_class_minimal.s
-# RUN: %lld -arch arm64 -dylib -o merge_base_class_minimal_yes_merge.dylib -objc_category_merging merge_base_class_minimal.o merge_cat_minimal.o
+# RUN: %lld -arch arm64 -dylib -objc_relative_method_lists -o merge_base_class_minimal_yes_merge.dylib -objc_category_merging merge_base_class_minimal.o merge_cat_minimal.o
# RUN: %lld -arch arm64 -dylib -o merge_base_class_minimal_no_merge.dylib merge_base_class_minimal.o merge_cat_minimal.o
# RUN: llvm-objdump --objc-meta-data --macho merge_base_class_minimal_no_merge.dylib | FileCheck %s --check-prefixes=NO_MERGE_INTO_BASE
@@ -37,14 +37,14 @@
MERGE_CATS: __OBJC_$_CATEGORY_MyBaseClass(Category01|Category02)
MERGE_CATS-NEXT: name {{.*}} Category01|Category02
MERGE_CATS: instanceMethods
-MERGE_CATS-NEXT: 24
-MERGE_CATS-NEXT: 2
+MERGE_CATS-NEXT: entsize 12 (relative)
+MERGE_CATS-NEXT: count 2
MERGE_CATS-NEXT: name {{.*}} cat01_InstanceMethod
MERGE_CATS-NEXT: types {{.*}} v16@0:8
-MERGE_CATS-NEXT: imp -[MyBaseClass(Category01) cat01_InstanceMethod]
+MERGE_CATS-NEXT: imp {{.*}} -[MyBaseClass(Category01) cat01_InstanceMethod]
MERGE_CATS-NEXT: name {{.*}} cat02_InstanceMethod
MERGE_CATS-NEXT: types {{.*}} v16@0:8
-MERGE_CATS-NEXT: imp -[MyBaseClass(Category02) cat02_InstanceMethod]
+MERGE_CATS-NEXT: imp {{.*}} -[MyBaseClass(Category02) cat02_InstanceMethod]
MERGE_CATS-NEXT: classMethods 0x0
MERGE_CATS-NEXT: protocols 0x0
MERGE_CATS-NEXT: instanceProperties 0x0
@@ -69,17 +69,17 @@
YES_MERGE_INTO_BASE: _OBJC_CLASS_$_MyBaseClass
YES_MERGE_INTO_BASE-NEXT: _OBJC_METACLASS_$_MyBaseClass
YES_MERGE_INTO_BASE: baseMethods
-YES_MERGE_INTO_BASE-NEXT: entsize 24
+YES_MERGE_INTO_BASE-NEXT: entsize 12 (relative)
YES_MERGE_INTO_BASE-NEXT: count 3
YES_MERGE_INTO_BASE-NEXT: name {{.*}} cat01_InstanceMethod
YES_MERGE_INTO_BASE-NEXT: types {{.*}} v16@0:8
-YES_MERGE_INTO_BASE-NEXT: imp -[MyBaseClass(Category01) cat01_InstanceMethod]
+YES_MERGE_INTO_BASE-NEXT: imp {{.*}} -[MyBaseClass(Category01) cat01_InstanceMethod]
YES_MERGE_INTO_BASE-NEXT: name {{.*}} cat02_InstanceMethod
YES_MERGE_INTO_BASE-NEXT: types {{.*}} v16@0:8
-YES_MERGE_INTO_BASE-NEXT: imp -[MyBaseClass(Category02) cat02_InstanceMethod]
+YES_MERGE_INTO_BASE-NEXT: imp {{.*}} -[MyBaseClass(Category02) cat02_InstanceMethod]
YES_MERGE_INTO_BASE-NEXT: name {{.*}} baseInstanceMethod
YES_MERGE_INTO_BASE-NEXT: types {{.*}} v16@0:8
-YES_MERGE_INTO_BASE-NEXT: imp -[MyBaseClass baseInstanceMethod]
+YES_MERGE_INTO_BASE-NEXT: imp {{.*}} -[MyBaseClass baseInstanceMethod]
#### Check merge swift category into base class ###
