[ORC][MachOPlatform] Don't add InitSectionSymbols for __objc_imageinfo.

The __objc_imageinfo section may be deleted (leaving dangling references to any
symbols that it contains), and shouldn't have any dependencies anyway. This
patch verifies that the section has no dependencies and then skips the section.

rdar://108469243

Author: lhames

compiler-rt/test/orc/TestCases/Darwin/arm64/Inputs/objc-Foo-foo-class-method.S

@@ -0,0 +1,88 @@
+	.section	__TEXT,__text,regular,pure_instructions
+	.build_version macos, 14, 0	sdk_version 14, 0
+	.p2align	2
+"+[Foo foo]":
+	mov	w0, wzr
+	ret
+
+	.section	__TEXT,__objc_classname,cstring_literals
+l_OBJC_CLASS_NAME_:
+	.asciz	"Foo"
+
+	.section	__TEXT,__objc_methname,cstring_literals
+l_OBJC_METH_VAR_NAME_:
+	.asciz	"foo"
+
+	.section	__TEXT,__objc_methtype,cstring_literals
+l_OBJC_METH_VAR_TYPE_:
+	.asciz	"i16@0:8"
+
+	.section	__DATA,__objc_const
+	.p2align	3
+__OBJC_$_CLASS_METHODS_Foo:
+	.long	24
+	.long	1
+	.quad	l_OBJC_METH_VAR_NAME_
+	.quad	l_OBJC_METH_VAR_TYPE_
+	.quad	"+[Foo foo]"
+
+	.p2align	3
+__OBJC_METACLASS_RO_$_Foo:
+	.long	1
+	.long	40
+	.long	40
+	.space	4
+	.quad	0
+	.quad	l_OBJC_CLASS_NAME_
+	.quad	__OBJC_$_CLASS_METHODS_Foo
+	.quad	0
+	.quad	0
+	.quad	0
+	.quad	0
+
+	.section	__DATA,__objc_data
+	.globl	_OBJC_METACLASS_$_Foo
+	.p2align	3
+_OBJC_METACLASS_$_Foo:
+	.quad	_OBJC_METACLASS_$_NSObject
+	.quad	_OBJC_METACLASS_$_NSObject
+	.quad	__objc_empty_cache
+	.quad	0
+	.quad	__OBJC_METACLASS_RO_$_Foo
+
+	.section	__DATA,__objc_const
+	.p2align	3
+__OBJC_CLASS_RO_$_Foo:
+	.long	0
+	.long	8
+	.long	8
+	.space	4
+	.quad	0
+	.quad	l_OBJC_CLASS_NAME_
+	.quad	0
+	.quad	0
+	.quad	0
+	.quad	0
+	.quad	0
+
+	.section	__DATA,__objc_data
+	.globl	_OBJC_CLASS_$_Foo
+	.p2align	3
+_OBJC_CLASS_$_Foo:
+	.quad	_OBJC_METACLASS_$_Foo
+	.quad	_OBJC_CLASS_$_NSObject
+	.quad	__objc_empty_cache
+	.quad	0
+	.quad	__OBJC_CLASS_RO_$_Foo
+
+	.section	__DATA,__objc_classlist,regular,no_dead_strip
+	.p2align	3
+l_OBJC_LABEL_CLASS_$:
+	.quad	_OBJC_CLASS_$_Foo
+
+	.section	__DATA,__objc_imageinfo,regular,no_dead_strip
+L_OBJC_IMAGE_INFO:
+	.long	0
+	.long	64
+
+.subsections_via_symbols

compiler-rt/test/orc/TestCases/Darwin/arm64/objc-cross-file-method-call.S

@@ -0,0 +1,37 @@
+// Test that calls to Objective-C methods in other files work.
+//
+// RUN: %clang -c -o %t.o %s
+// RUN: %clang -c -o %t.aux.o %S/Inputs/objc-Foo-foo-class-method.S
+// RUN: %llvm_jitlink -preload libobjc.A.dylib %t.o %t.aux.o
+
+        .section	__TEXT,__text,regular,pure_instructions
+	.build_version macos, 14, 0	sdk_version 14, 0
+	.globl	_main
+	.p2align	2
+_main:
+	adrp	x8, _OBJC_CLASSLIST_REFERENCES_$_@PAGE
+	ldr	x0, [x8, _OBJC_CLASSLIST_REFERENCES_$_@PAGEOFF]
+	adrp	x8, _OBJC_SELECTOR_REFERENCES_@PAGE
+	ldr	x1, [x8, _OBJC_SELECTOR_REFERENCES_@PAGEOFF]
+	b	_objc_msgSend
+
+	.section	__DATA,__objc_classrefs,regular,no_dead_strip
+	.p2align	3, 0x0
+_OBJC_CLASSLIST_REFERENCES_$_:
+	.quad	_OBJC_CLASS_$_Foo
+
+	.section	__TEXT,__objc_methname,cstring_literals
+l_OBJC_METH_VAR_NAME_:
+	.asciz	"foo"
+
+	.section	__DATA,__objc_selrefs,literal_pointers,no_dead_strip
+	.p2align	3, 0x0
+_OBJC_SELECTOR_REFERENCES_:
+	.quad	l_OBJC_METH_VAR_NAME_
+
+	.section	__DATA,__objc_imageinfo,regular,no_dead_strip
+L_OBJC_IMAGE_INFO:
+	.long	0
+	.long	64
+
+.subsections_via_symbols

llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp

@@ -908,21 +908,34 @@ Error MachOPlatform::MachOPlatformPlugin::preserveImportantSections(
   // address in the first graph that it appears in, then verify and discard it
   // in all subsequent graphs. In this pass we preserve unconditionally -- we'll
   // manually throw it away in the processObjCImageInfo pass.
-  if (auto *ObjCImageInfoSec = G.findSectionByName("__DATA,__objc_imageinfo")) {
+  if (auto *ObjCImageInfoSec =
+          G.findSectionByName(MachOObjCImageInfoSectionName)) {
     if (ObjCImageInfoSec->blocks_size() != 1)
       return make_error<StringError>(
           "In " + G.getName() +
               "__DATA,__objc_imageinfo contains multiple blocks",
           inconvertibleErrorCode());
     G.addAnonymousSymbol(**ObjCImageInfoSec->blocks().begin(), 0, 0, false,
                          true);
+
+    for (auto *B : ObjCImageInfoSec->blocks())
+      if (!B->edges_empty())
+        return make_error<StringError>("In " + G.getName() + ", " +
+                                           MachOObjCImageInfoSectionName +
+                                           " contains references to symbols",
+                                       inconvertibleErrorCode());
   }
 
   // Init sections are important: We need to preserve them and so that their
   // addresses can be captured and reported to the ORC runtime in
   // registerObjectPlatformSections.
   JITLinkSymbolSet InitSectionSymbols;
   for (auto &InitSectionName : MachOInitSectionNames) {
+    // Skip ObjCImageInfo -- this shouldn't have any dependencies, and we may
+    // remove it later.
+    if (InitSectionName == MachOObjCImageInfoSectionName)
+      continue;
+
     // Skip non-init sections.
     auto *InitSection = G.findSectionByName(InitSectionName);
     if (!InitSection)