[lld-macho][nfc] Fix test to reflect that symbol attributes don't matter within an archive

[int3]

Summary

We had a comment that claimed that defined symbols had priority
over common symbols if they occurred in the same archive. In fact, they
appear to have equal precedence. Our implementation already does this,
so I'm just updating the test comment. Also added a few other test
comments along the way for readability.

[thakis]

Ah right, dblaikie wants me to also say "lg" or similar when accepting :)

lld/test/MachO/common-symbol-resolution.s

 # REQUIRES: x86
 # RUN: rm -rf %t; split-file %s %t
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/common.s -o %t/common.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/weak-common.s -o %t/weak-common.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/defined.s -o %t/defined.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/weak-defined.s -o %t/weak-defined.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/libfoo.s -o %t/libfoo.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/test.s -o %t/test.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/calls-foo.s -o %t/calls-foo.o
 
 # RUN: %lld -lSystem -order_file %t/order -dylib %t/libfoo.o -o %t/libfoo.dylib
 
 # RUN: llvm-ar rcs %t/defined.a %t/defined.o
 # RUN: llvm-ar rcs %t/weak-defined-and-common.a %t/weak-defined.o %t/common.o
+# RUN: llvm-ar rcs %t/common-and-weak-defined.a %t/common.o %t/weak-defined.o
 
 ## The weak attribute appears to have no effect on common symbols. Given two
 ## common symbols of the same name, we always pick the one with the larger size,
 ## regardless of whether it is weak. Moreover, the resolved symbol in the output
 ## file will always be non-weak, even if the winning input symbol definition was
 ## weak.
 # RUN: %lld -lSystem -order_file %t/order %t/common.o %t/weak-common.o %t/test.o -o %t/test
 # RUN: llvm-objdump --syms %t/test | FileCheck %s --check-prefix=LARGER-COMMON

 # RUN: llvm-objdump --syms %t/test | FileCheck %s --check-prefix=WEAK-DEFINED
 
 ## Common symbols take precedence over archive symbols.
 # RUN: %lld -lSystem -order_file %t/order %t/defined.a %t/weak-common.o %t/test.o -o %t/test
 # RUN: llvm-objdump --syms %t/test | FileCheck %s --check-prefix=LARGER-COMMON
 # RUN: %lld -lSystem -order_file %t/order %t/weak-common.o %t/defined.a %t/test.o -o %t/test
 # RUN: llvm-objdump --syms %t/test | FileCheck %s --check-prefix=LARGER-COMMON
 
-## If an archive has both a common and a defined symbol, the defined one should
-## win.
+## Defined symbols have the same precedence as common symbols within an archive.
 # RUN: %lld -lSystem -order_file %t/order %t/weak-defined-and-common.a %t/calls-foo.o -o %t/calls-foo
 # RUN: llvm-objdump --syms %t/calls-foo | FileCheck %s --check-prefix=WEAK-DEFINED
-# RUN: %lld -lSystem -order_file %t/order %t/calls-foo.o %t/weak-defined-and-common.a -o %t/calls-foo
-# RUN: llvm-objdump --syms %t/calls-foo | FileCheck %s --check-prefix=WEAK-DEFINED
+# RUN: %lld -lSystem -order_file %t/order %t/calls-foo.o %t/common-and-weak-defined.a -o %t/calls-foo
+# RUN: llvm-objdump --syms %t/calls-foo | FileCheck %s --check-prefix=COMMON
 
 ## Common symbols take precedence over dylib symbols.
 # RUN: %lld -lSystem -order_file %t/order %t/libfoo.dylib %t/weak-common.o %t/test.o -o %t/test
 # RUN: llvm-objdump --syms %t/test | FileCheck %s --check-prefix=LARGER-COMMON
 # RUN: %lld -lSystem -order_file %t/order %t/weak-common.o %t/libfoo.dylib %t/test.o -o %t/test
 # RUN: llvm-objdump --syms %t/test | FileCheck %s --check-prefix=LARGER-COMMON
 
-# LARGER-COMMON-LABEL: SYMBOL TABLE:
 # LARGER-COMMON-DAG:   [[#%x, FOO_ADDR:]] g     O __DATA,__common _foo
 # LARGER-COMMON-DAG:   [[#FOO_ADDR + 2]]  g     O __DATA,__common _foo_end
 
-# DEFINED-LABEL:       SYMBOL TABLE:
+# COMMON:              g     O __DATA,__common _foo
 # DEFINED:             g     F __TEXT,__text _foo
-
-# WEAK-DEFINED-LABEL:  SYMBOL TABLE:
 # WEAK-DEFINED:        w     F __TEXT,__text _foo
 
 #--- order
 ## %t/order is important as we determine the size of a given symbol via the
 ## address of the next symbol.
 _foo
 _foo_end
 

lld/test/MachO/weak-definition-direct-fetch.s

 
 # RUN: %lld -lSystem -o %t/weak-nonweak-archives %t/weakfoo.a %t/foo.a %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/weak-nonweak-archives | FileCheck %s --check-prefix=PREFER-WEAK-OBJECT
 # RUN: %lld -lSystem -o %t/nonweak-weak-archives %t/foo.a %t/weakfoo.a %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/nonweak-weak-archives | FileCheck %s --check-prefix=PREFER-NONWEAK-OBJECT
 
 ## The remaining lines test symbol pairs of different types.
 
+## (Weak) archive symbols take precedence over weak dylib symbols.
 # RUN: %lld -lSystem -o %t/weak-dylib-weak-ar -L%t -lweakfoo %t/weakfoo.a %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/weak-dylib-weak-ar | FileCheck %s --check-prefix=PREFER-WEAK-OBJECT
 # RUN: %lld -lSystem -o %t/weak-ar-weak-dylib -L%t %t/weakfoo.a -lweakfoo %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/weak-ar-weak-dylib | FileCheck %s --check-prefix=PREFER-WEAK-OBJECT
 
+## (Weak) archive symbols have the same precedence as dylib symbols.
 # RUN: %lld -lSystem -o %t/weak-ar-nonweak-dylib -L%t %t/weakfoo.a -lfoo %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/weak-ar-nonweak-dylib | FileCheck %s --check-prefix=PREFER-WEAK-OBJECT
 # RUN: %lld -lSystem -o %t/nonweak-dylib-weak-ar -L%t -lfoo %t/weakfoo.a %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/nonweak-dylib-weak-ar | FileCheck %s --check-prefix=PREFER-NONWEAK-DYLIB
 
+## Weak defined symbols take precedence over weak dylib symbols.
 # RUN: %lld -lSystem -o %t/weak-dylib-weak-obj -L%t -lweakfoo %t/weakfoo.o %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/weak-dylib-weak-obj | FileCheck %s --check-prefix=PREFER-WEAK-OBJECT
 # RUN: %lld -lSystem -o %t/weak-obj-weak-dylib -L%t %t/weakfoo.o -lweakfoo %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/weak-obj-weak-dylib | FileCheck %s --check-prefix=PREFER-WEAK-OBJECT
 
+## Weak defined symbols take precedence over dylib symbols.
 # RUN: %lld -lSystem -o %t/weak-obj-nonweak-dylib -L%t %t/weakfoo.o -lfoo %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/weak-obj-nonweak-dylib | FileCheck %s --check-prefix=PREFER-WEAK-OBJECT
 # RUN: %lld -lSystem -o %t/nonweak-dylib-weak-obj -L%t -lfoo %t/weakfoo.o %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/nonweak-dylib-weak-obj | FileCheck %s --check-prefix=PREFER-WEAK-OBJECT
 
+## Weak defined symbols take precedence over archive symbols.
 # RUN: %lld -lSystem -o %t/weak-obj-nonweak-ar %t/weakfoo.o %t/foo.a %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/weak-obj-nonweak-ar | FileCheck %s --check-prefix=PREFER-WEAK-OBJECT
 # RUN: %lld -lSystem -o %t/nonweak-ar-weak-obj %t/foo.a %t/weakfoo.o %t/test.o
 # RUN: llvm-objdump --macho --lazy-bind --syms %t/nonweak-ar-weak-obj | FileCheck %s --check-prefix=PREFER-WEAK-OBJECT
 
 #--- foo.s
 .globl _foo
 .section __TEXT,nonweak