[ELF] Improve canBeOmittedFromSymbolTable tests

A linkonce_odr definition can be omitted in LTO compilation if
`canBeOmittedFromSymbolTable()` is true in all bitcode files.
Test more linkage merge scenarios.

The lo_and_wo symbol tests #111341.

Author: MaskRay

lld/test/ELF/lto/Inputs/internalize-exportdyn.ll

@@ -1,6 +1,31 @@
 target triple = "x86_64-unknown-linux-gnu"
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 
+$ext_and_ext = comdat any
+$lo_and_ext = comdat any
+$lo_and_wo = comdat any
+$wo_and_lo = comdat any
+
+declare void @foo(i64)
+
 define weak_odr void @bah() {
   ret void
 }
+
+define void @ext_and_ext() local_unnamed_addr comdat {
+  call void @foo(i64 2)
+  ret void
+}
+
+define linkonce_odr void @lo_and_ext() local_unnamed_addr comdat {
+  call void @foo(i64 2)
+  ret void
+}
+
+define weak_odr void @lo_and_wo() local_unnamed_addr comdat {
+  ret void
+}
+
+define linkonce_odr void @wo_and_lo() local_unnamed_addr comdat {
+  ret void
+}

lld/test/ELF/lto/internalize-exportdyn.ll

@@ -1,21 +1,31 @@
 ; REQUIRES: x86
-; RUN: llvm-as %s -o %t.o
-; RUN: llvm-as %p/Inputs/internalize-exportdyn.ll -o %t2.o
-; RUN: ld.lld %t.o %t2.o -o %t2 --export-dynamic -save-temps
-; RUN: llvm-dis < %t2.0.2.internalize.bc | FileCheck %s
-; RUN: ld.lld %t.o %t2.o -o %t3 -shared -save-temps
-; RUN: llvm-dis < %t3.0.2.internalize.bc | FileCheck %s --check-prefix=DSO
+; RUN: rm -rf %t && split-file %s %t && cd %t
+; RUN: llvm-as a.ll -o a.bc
+; RUN: llvm-as %p/Inputs/internalize-exportdyn.ll -o b.bc
+; RUN: llvm-mc -filetype=obj -triple=x86_64 lib.s -o lib.o
+; RUN: ld.lld a.bc b.bc lib.o -o out --export-dynamic -save-temps
+; RUN: llvm-dis < out.0.2.internalize.bc | FileCheck %s
+; RUN: ld.lld a.bc b.bc lib.o -o out2 -shared -save-temps
+; RUN: llvm-dis < out2.0.2.internalize.bc | FileCheck %s --check-prefix=DSO
 
+;--- a.ll
 target triple = "x86_64-unknown-linux-gnu"
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 
+$ext_and_ext = comdat any
+$lo_and_ext = comdat any
+$lo_and_wo = comdat any
+$wo_and_lo = comdat any
+
 @c = linkonce_odr constant i32 1
 @g = linkonce_odr global i32 1
 @u_c = linkonce_odr unnamed_addr constant i32 1
 @u_g = linkonce_odr unnamed_addr global i32 1
 @lu_c = linkonce_odr local_unnamed_addr constant i32 1
 @lu_g = linkonce_odr local_unnamed_addr global i32 1
 
+declare void @lib(i64)
+
 define void @_start() {
   ret void
 }
@@ -46,6 +56,24 @@ define linkonce_odr void @baz() {
 
 @use_baz = global ptr @baz
 
+define void @ext_and_ext() local_unnamed_addr comdat {
+  call void @foo(i64 1)
+  ret void
+}
+
+define linkonce_odr void @lo_and_ext() local_unnamed_addr comdat {
+  call void @foo(i64 1)
+  ret void
+}
+
+define linkonce_odr void @lo_and_wo() local_unnamed_addr comdat {
+  ret void
+}
+
+define weak_odr void @wo_and_lo() local_unnamed_addr comdat {
+  ret void
+}
+
 ; Check what gets internalized.
 ; CHECK: @c = weak_odr dso_local constant i32 1
 ; CHECK: @g = weak_odr dso_local global i32 1
@@ -60,6 +88,12 @@ define linkonce_odr void @baz() {
 ; CHECK: define internal void @zed2()
 ; CHECK: define weak_odr dso_local void @bah()
 ; CHECK: define weak_odr dso_local void @baz()
+; CHECK: define dso_local void @ext_and_ext() comdat
+; CHECK-NEXT: call void @foo(i64 1)
+; CHECK: define internal void @lo_and_ext() comdat
+; CHECK-NEXT: call void @foo(i64 1)
+; CHECK: define internal void @lo_and_wo() comdat
+; CHECK: define weak_odr dso_local void @wo_and_lo() comdat
 
 ; DSO: @c = weak_odr constant i32 1
 ; DSO: @g = weak_odr global i32 1
@@ -74,3 +108,11 @@ define linkonce_odr void @baz() {
 ; DSO: define internal void @zed2()
 ; DSO: define weak_odr void @bah()
 ; DSO: define weak_odr void @baz()
+; DSO: define void @ext_and_ext() comdat
+; DSO: define internal void @lo_and_ext() comdat
+; DSO: define internal void @lo_and_wo() comdat
+; DSO: define weak_odr void @wo_and_lo() comdat
+
+;--- lib.s
+.globl lib
+lib: