[lld] [lld-macho] Fix erasing category names for ObjC categories (PR #98417)

via llvm-commits llvm-commits at lists.llvm.org
Wed Jul 10 18:18:00 PDT 2024


https://github.com/alx32 updated https://github.com/llvm/llvm-project/pull/98417

>From 7efaeb576752e8864cfd126d99cdf0d56ec51a66 Mon Sep 17 00:00:00 2001
From: Alex B <alexborcan at meta.com>
Date: Wed, 10 Jul 2024 16:42:39 -0700
Subject: [PATCH] [lld-macho] Fix erasing category names for ObjC categories

---
 lld/MachO/ObjC.cpp                            |  16 +-
 ...jc-category-merging-erase-objc-name-test.s | 306 ++++++++++++++++++
 2 files changed, 317 insertions(+), 5 deletions(-)
 create mode 100644 lld/test/MachO/objc-category-merging-erase-objc-name-test.s

diff --git a/lld/MachO/ObjC.cpp b/lld/MachO/ObjC.cpp
index 740ebaf7e0403..c0216117efc7c 100644
--- a/lld/MachO/ObjC.cpp
+++ b/lld/MachO/ObjC.cpp
@@ -1308,12 +1308,18 @@ void ObjcCategoryMerger::eraseMergedCategories() {
         continue;
 
       eraseISec(catInfo.catBodyIsec);
-      // We can't erase 'catLayout.nameOffset' for Swift categories because the
-      // name will be referenced for generating relative offsets
-      // See usages of 'l_.str.11.SimpleClass' in objc-category-merging-swift.s
+
+      // We can't erase 'catLayout.nameOffset' for either Swift or ObjC
+      //   categories because the name will sometimes also be used for other
+      //   purposes.
+      // For Swift, see  usages of 'l_.str.11.SimpleClass' in
+      //   objc-category-merging-swift.s
+      // For ObjC, see usages of 'l_OBJC_CLASS_NAME_.1' in
+      //   objc-category-merging-erase-objc-name-test.s
       // TODO: handle the above in a smarter way
-      if (catInfo.sourceLanguage != SourceLanguage::Swift)
-        tryEraseDefinedAtIsecOffset(catInfo.catBodyIsec, catLayout.nameOffset);
+
+      // tryEraseDefinedAtIsecOffset(catInfo.catBodyIsec, catLayout.nameOffset);
+
       tryEraseDefinedAtIsecOffset(catInfo.catBodyIsec,
                                   catLayout.instanceMethodsOffset);
       tryEraseDefinedAtIsecOffset(catInfo.catBodyIsec,
diff --git a/lld/test/MachO/objc-category-merging-erase-objc-name-test.s b/lld/test/MachO/objc-category-merging-erase-objc-name-test.s
new file mode 100644
index 0000000000000..7f5753705c30d
--- /dev/null
+++ b/lld/test/MachO/objc-category-merging-erase-objc-name-test.s
@@ -0,0 +1,306 @@
+# REQUIRES: aarch64
+
+
+### Here we test that if we defined a protocl MyTestProtocol and also a category MyTestProtocol
+### then when merging the category into the base class (and deleting the category), we don't
+### delete the 'MyTestProtocol' name
+
+# RUN: llvm-mc -filetype=obj -triple=arm64-apple-macos -o erase-objc-name.o %s
+# RUN: %lld -arch arm64 -dylib -o erase-objc-name.dylib erase-objc-name.o -objc_category_merging
+# RUN: llvm-objdump --objc-meta-data --macho erase-objc-name.dylib | FileCheck %s --check-prefixes=MERGE_CATS
+
+#### Check merge categories enabled ###
+# Check that the original categories are not there
+# MERGE_CATS-NOT: __OBJC_$_CATEGORY_MyBaseClass_$_Category01
+# MERGE_CATS-NOT: __OBJC_$_CATEGORY_MyBaseClass_$_Category02
+
+# Check that we get the expected output - most importantly that the protocol is named `MyTestProtocol`
+; MERGE_CATS:        Contents of (__DATA_CONST,__objc_classlist) section
+; MERGE_CATS-NEXT:   _OBJC_CLASS_$_MyBaseClass
+; MERGE_CATS-NEXT:            isa {{.*}} _OBJC_METACLASS_$_MyBaseClass
+; MERGE_CATS-NEXT:     superclass {{.*}}
+; MERGE_CATS-NEXT:          cache {{.*}}
+; MERGE_CATS-NEXT:         vtable {{.*}}
+; MERGE_CATS-NEXT:           data {{.*}} (struct class_ro_t *)
+; MERGE_CATS-NEXT:                     flags {{.*}} RO_ROOT
+; MERGE_CATS-NEXT:             instanceStart 0
+; MERGE_CATS-NEXT:              instanceSize 0
+; MERGE_CATS-NEXT:                  reserved {{.*}}
+; MERGE_CATS-NEXT:                ivarLayout {{.*}}
+; MERGE_CATS-NEXT:                      name {{.*}} MyBaseClass
+; MERGE_CATS-NEXT:               baseMethods {{.*}} (struct method_list_t *)
+; MERGE_CATS-NEXT: 		   entsize 24
+; MERGE_CATS-NEXT: 		     count 2
+; MERGE_CATS-NEXT: 		      name {{.*}} getValue
+; MERGE_CATS-NEXT: 		     types {{.*}} i16 at 0:8
+; MERGE_CATS-NEXT: 		       imp -[MyBaseClass(MyTestProtocol) getValue]
+; MERGE_CATS-NEXT: 		      name {{.*}} baseInstanceMethod
+; MERGE_CATS-NEXT: 		     types {{.*}} v16 at 0:8
+; MERGE_CATS-NEXT: 		       imp -[MyBaseClass baseInstanceMethod]
+; MERGE_CATS-NEXT:             baseProtocols {{.*}}
+; MERGE_CATS-NEXT:                       count 1
+; MERGE_CATS-NEXT: 		      list[0] {{.*}} (struct protocol_t *)
+; MERGE_CATS-NEXT: 			      isa {{.*}}
+; MERGE_CATS-NEXT: 			     name {{.*}} MyTestProtocol
+; MERGE_CATS-NEXT: 			protocols {{.*}}
+; MERGE_CATS-NEXT: 		  instanceMethods {{.*}} (struct method_list_t *)
+; MERGE_CATS-NEXT: 			   entsize 24
+; MERGE_CATS-NEXT: 			     count 1
+; MERGE_CATS-NEXT: 			      name {{.*}} getValue
+; MERGE_CATS-NEXT: 			     types {{.*}} i16 at 0:8
+; MERGE_CATS-NEXT: 			       imp {{.*}}
+; MERGE_CATS-NEXT: 		     classMethods {{.*}} (struct method_list_t *)
+; MERGE_CATS-NEXT: 	  optionalInstanceMethods {{.*}}
+; MERGE_CATS-NEXT: 	     optionalClassMethods {{.*}}
+; MERGE_CATS-NEXT: 	       instanceProperties {{.*}}
+; MERGE_CATS-NEXT:                     ivars {{.*}}
+; MERGE_CATS-NEXT:            weakIvarLayout {{.*}}
+; MERGE_CATS-NEXT:            baseProperties {{.*}}
+; MERGE_CATS-NEXT: Meta Class
+; MERGE_CATS-NEXT:            isa {{.*}} _OBJC_METACLASS_$_MyBaseClass
+; MERGE_CATS-NEXT:     superclass {{.*}} _OBJC_CLASS_$_MyBaseClass
+; MERGE_CATS-NEXT:          cache {{.*}}
+; MERGE_CATS-NEXT:         vtable {{.*}}
+; MERGE_CATS-NEXT:           data {{.*}} (struct class_ro_t *)
+; MERGE_CATS-NEXT:                     flags {{.*}} RO_META RO_ROOT
+; MERGE_CATS-NEXT:             instanceStart 40
+; MERGE_CATS-NEXT:              instanceSize 40
+; MERGE_CATS-NEXT:                  reserved {{.*}}
+; MERGE_CATS-NEXT:                ivarLayout {{.*}}
+; MERGE_CATS-NEXT:                      name {{.*}} MyBaseClass
+; MERGE_CATS-NEXT:               baseMethods {{.*}} (struct method_list_t *)
+; MERGE_CATS-NEXT:             baseProtocols {{.*}}
+; MERGE_CATS-NEXT:                       count 1
+; MERGE_CATS-NEXT: 		      list[0] {{.*}} (struct protocol_t *)
+; MERGE_CATS-NEXT: 			      isa {{.*}}
+; MERGE_CATS-NEXT: 			     name {{.*}} MyTestProtocol
+; MERGE_CATS-NEXT: 			protocols {{.*}}
+; MERGE_CATS-NEXT: 		  instanceMethods {{.*}} (struct method_list_t *)
+; MERGE_CATS-NEXT: 			   entsize 24
+; MERGE_CATS-NEXT: 			     count 1
+; MERGE_CATS-NEXT: 			      name {{.*}} getValue
+; MERGE_CATS-NEXT: 			     types {{.*}} i16 at 0:8
+; MERGE_CATS-NEXT: 			       imp {{.*}}
+; MERGE_CATS-NEXT: 		     classMethods {{.*}} (struct method_list_t *)
+; MERGE_CATS-NEXT: 	  optionalInstanceMethods {{.*}}
+; MERGE_CATS-NEXT: 	     optionalClassMethods {{.*}}
+; MERGE_CATS-NEXT: 	       instanceProperties {{.*}}
+; MERGE_CATS-NEXT:                     ivars {{.*}}
+; MERGE_CATS-NEXT:            weakIvarLayout {{.*}}
+; MERGE_CATS-NEXT:            baseProperties {{.*}}
+; MERGE_CATS-NEXT: Contents of (__DATA_CONST,__objc_protolist) section
+; MERGE_CATS-NEXT: {{.*}} {{.*}} __OBJC_PROTOCOL_$_MyTestProtocol
+; MERGE_CATS-NEXT: Contents of (__DATA_CONST,__objc_imageinfo) section
+; MERGE_CATS-NEXT:   version 0
+; MERGE_CATS-NEXT:     flags {{.*}} OBJC_IMAGE_HAS_CATEGORY_CLASS_PROPERTIES
+
+
+; ================== repro.sh ====================
+; # Write the Objective-C code to a file
+; cat << EOF > MyClass.m
+; @protocol MyTestProtocol
+; - (int)getValue;
+; @end
+;
+; __attribute__((objc_root_class))
+; @interface MyBaseClass
+; - (void)baseInstanceMethod;
+; @end
+;
+; @implementation MyBaseClass
+; - (void)baseInstanceMethod {}
+; @end
+;
+; @interface MyBaseClass (MyTestProtocol) <MyTestProtocol>
+; @end
+;
+; @implementation MyBaseClass (MyTestProtocol)
+;
+; - (int)getValue {
+;     return 0x30;
+; }
+;
+; @end
+; EOF
+;
+; # Compile the Objective-C file to assembly
+; xcrun clang -S -arch arm64 MyClass.m -o MyClass.s
+
+
+	.section	__TEXT,__text,regular,pure_instructions
+	.p2align	2                               ; -- Begin function -[MyBaseClass baseInstanceMethod]
+"-[MyBaseClass baseInstanceMethod]":    ; @"\01-[MyBaseClass baseInstanceMethod]"
+	.cfi_startproc
+; %bb.0:
+	sub	sp, sp, #16
+	.cfi_def_cfa_offset 16
+	str	x0, [sp, #8]
+	str	x1, [sp]
+	add	sp, sp, #16
+	ret
+	.cfi_endproc
+                                        ; -- End function
+	.p2align	2                               ; -- Begin function -[MyBaseClass(MyTestProtocol) getValue]
+"-[MyBaseClass(MyTestProtocol) getValue]": ; @"\01-[MyBaseClass(MyTestProtocol) getValue]"
+	.cfi_startproc
+; %bb.0:
+	sub	sp, sp, #16
+	.cfi_def_cfa_offset 16
+	str	x0, [sp, #8]
+	str	x1, [sp]
+	mov	w0, #48                         ; =0x30
+	add	sp, sp, #16
+	ret
+	.cfi_endproc
+                                        ; -- End function
+	.section	__DATA,__objc_data
+	.globl	_OBJC_CLASS_$_MyBaseClass       ; @"OBJC_CLASS_$_MyBaseClass"
+	.p2align	3, 0x0
+_OBJC_CLASS_$_MyBaseClass:
+	.quad	_OBJC_METACLASS_$_MyBaseClass
+	.quad	0
+	.quad	__objc_empty_cache
+	.quad	0
+	.quad	__OBJC_CLASS_RO_$_MyBaseClass
+	.globl	_OBJC_METACLASS_$_MyBaseClass   ; @"OBJC_METACLASS_$_MyBaseClass"
+	.p2align	3, 0x0
+_OBJC_METACLASS_$_MyBaseClass:
+	.quad	_OBJC_METACLASS_$_MyBaseClass
+	.quad	_OBJC_CLASS_$_MyBaseClass
+	.quad	__objc_empty_cache
+	.quad	0
+	.quad	__OBJC_METACLASS_RO_$_MyBaseClass
+	.section	__TEXT,__objc_classname,cstring_literals
+l_OBJC_CLASS_NAME_:                     ; @OBJC_CLASS_NAME_
+	.asciz	"MyBaseClass"
+	.section	__DATA,__objc_const
+	.p2align	3, 0x0                          ; @"_OBJC_METACLASS_RO_$_MyBaseClass"
+__OBJC_METACLASS_RO_$_MyBaseClass:
+	.long	131                             ; 0x83
+	.long	40                              ; 0x28
+	.long	40                              ; 0x28
+	.space	4
+	.quad	0
+	.quad	l_OBJC_CLASS_NAME_
+	.quad	0
+	.quad	0
+	.quad	0
+	.quad	0
+	.quad	0
+	.section	__TEXT,__objc_methname,cstring_literals
+l_OBJC_METH_VAR_NAME_:                  ; @OBJC_METH_VAR_NAME_
+	.asciz	"baseInstanceMethod"
+	.section	__TEXT,__objc_methtype,cstring_literals
+l_OBJC_METH_VAR_TYPE_:                  ; @OBJC_METH_VAR_TYPE_
+	.asciz	"v16 at 0:8"
+	.section	__DATA,__objc_const
+	.p2align	3, 0x0                          ; @"_OBJC_$_INSTANCE_METHODS_MyBaseClass"
+__OBJC_$_INSTANCE_METHODS_MyBaseClass:
+	.long	24                              ; 0x18
+	.long	1                               ; 0x1
+	.quad	l_OBJC_METH_VAR_NAME_
+	.quad	l_OBJC_METH_VAR_TYPE_
+	.quad	"-[MyBaseClass baseInstanceMethod]"
+	.p2align	3, 0x0                          ; @"_OBJC_CLASS_RO_$_MyBaseClass"
+__OBJC_CLASS_RO_$_MyBaseClass:
+	.long	130                             ; 0x82
+	.long	0                               ; 0x0
+	.long	0                               ; 0x0
+	.space	4
+	.quad	0
+	.quad	l_OBJC_CLASS_NAME_
+	.quad	__OBJC_$_INSTANCE_METHODS_MyBaseClass
+	.quad	0
+	.quad	0
+	.quad	0
+	.quad	0
+	.section	__TEXT,__objc_classname,cstring_literals
+l_OBJC_CLASS_NAME_.1:                   ; @OBJC_CLASS_NAME_.1
+	.asciz	"MyTestProtocol"
+	.section	__TEXT,__objc_methname,cstring_literals
+l_OBJC_METH_VAR_NAME_.2:                ; @OBJC_METH_VAR_NAME_.2
+	.asciz	"getValue"
+	.section	__TEXT,__objc_methtype,cstring_literals
+l_OBJC_METH_VAR_TYPE_.3:                ; @OBJC_METH_VAR_TYPE_.3
+	.asciz	"i16 at 0:8"
+	.section	__DATA,__objc_const
+	.p2align	3, 0x0                          ; @"_OBJC_$_CATEGORY_INSTANCE_METHODS_MyBaseClass_$_MyTestProtocol"
+__OBJC_$_CATEGORY_INSTANCE_METHODS_MyBaseClass_$_MyTestProtocol:
+	.long	24                              ; 0x18
+	.long	1                               ; 0x1
+	.quad	l_OBJC_METH_VAR_NAME_.2
+	.quad	l_OBJC_METH_VAR_TYPE_.3
+	.quad	"-[MyBaseClass(MyTestProtocol) getValue]"
+	.p2align	3, 0x0                          ; @"_OBJC_$_PROTOCOL_INSTANCE_METHODS_MyTestProtocol"
+__OBJC_$_PROTOCOL_INSTANCE_METHODS_MyTestProtocol:
+	.long	24                              ; 0x18
+	.long	1                               ; 0x1
+	.quad	l_OBJC_METH_VAR_NAME_.2
+	.quad	l_OBJC_METH_VAR_TYPE_.3
+	.quad	0
+	.p2align	3, 0x0                          ; @"_OBJC_$_PROTOCOL_METHOD_TYPES_MyTestProtocol"
+__OBJC_$_PROTOCOL_METHOD_TYPES_MyTestProtocol:
+	.quad	l_OBJC_METH_VAR_TYPE_.3
+	.private_extern	__OBJC_PROTOCOL_$_MyTestProtocol ; @"_OBJC_PROTOCOL_$_MyTestProtocol"
+	.section	__DATA,__data
+	.globl	__OBJC_PROTOCOL_$_MyTestProtocol
+	.weak_definition	__OBJC_PROTOCOL_$_MyTestProtocol
+	.p2align	3, 0x0
+__OBJC_PROTOCOL_$_MyTestProtocol:
+	.quad	0
+	.quad	l_OBJC_CLASS_NAME_.1
+	.quad	0
+	.quad	__OBJC_$_PROTOCOL_INSTANCE_METHODS_MyTestProtocol
+	.quad	0
+	.quad	0
+	.quad	0
+	.quad	0
+	.long	96                              ; 0x60
+	.long	0                               ; 0x0
+	.quad	__OBJC_$_PROTOCOL_METHOD_TYPES_MyTestProtocol
+	.quad	0
+	.quad	0
+	.private_extern	__OBJC_LABEL_PROTOCOL_$_MyTestProtocol ; @"_OBJC_LABEL_PROTOCOL_$_MyTestProtocol"
+	.section	__DATA,__objc_protolist,coalesced,no_dead_strip
+	.globl	__OBJC_LABEL_PROTOCOL_$_MyTestProtocol
+	.weak_definition	__OBJC_LABEL_PROTOCOL_$_MyTestProtocol
+	.p2align	3, 0x0
+__OBJC_LABEL_PROTOCOL_$_MyTestProtocol:
+	.quad	__OBJC_PROTOCOL_$_MyTestProtocol
+	.section	__DATA,__objc_const
+	.p2align	3, 0x0                          ; @"_OBJC_CATEGORY_PROTOCOLS_$_MyBaseClass_$_MyTestProtocol"
+__OBJC_CATEGORY_PROTOCOLS_$_MyBaseClass_$_MyTestProtocol:
+	.quad	1                               ; 0x1
+	.quad	__OBJC_PROTOCOL_$_MyTestProtocol
+	.quad	0
+	.p2align	3, 0x0                          ; @"_OBJC_$_CATEGORY_MyBaseClass_$_MyTestProtocol"
+__OBJC_$_CATEGORY_MyBaseClass_$_MyTestProtocol:
+	.quad	l_OBJC_CLASS_NAME_.1
+	.quad	_OBJC_CLASS_$_MyBaseClass
+	.quad	__OBJC_$_CATEGORY_INSTANCE_METHODS_MyBaseClass_$_MyTestProtocol
+	.quad	0
+	.quad	__OBJC_CATEGORY_PROTOCOLS_$_MyBaseClass_$_MyTestProtocol
+	.quad	0
+	.quad	0
+	.long	64                              ; 0x40
+	.space	4
+	.section	__DATA,__objc_classlist,regular,no_dead_strip
+	.p2align	3, 0x0                          ; @"OBJC_LABEL_CLASS_$"
+l_OBJC_LABEL_CLASS_$:
+	.quad	_OBJC_CLASS_$_MyBaseClass
+	.section	__DATA,__objc_catlist,regular,no_dead_strip
+	.p2align	3, 0x0                          ; @"OBJC_LABEL_CATEGORY_$"
+l_OBJC_LABEL_CATEGORY_$:
+	.quad	__OBJC_$_CATEGORY_MyBaseClass_$_MyTestProtocol
+	.no_dead_strip	__OBJC_PROTOCOL_$_MyTestProtocol
+	.no_dead_strip	__OBJC_LABEL_PROTOCOL_$_MyTestProtocol
+	.section	__DATA,__objc_imageinfo,regular,no_dead_strip
+L_OBJC_IMAGE_INFO:
+	.long	0
+	.long	64
+
+__objc_empty_cache:
+_$sBOWV:
+  .quad 0
+
+.subsections_via_symbols



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