[lld][ELF][test] test LTO-removed symbols are not in symtab

[edd]

Summary

Test that symbols eliminated by LTO do not appear in
the final .symtab section.

Added with the intention of moving coverage out of an internal
testsuite.

[MaskRay]

Instead of keeping adding new tests for some specific properties, I find many times reusing the existing tests is more appropriate. (People studying the behavior can read one file instead of several files with the same structure which just tests different properties). For this case the test can be added into lto/internalize-basic.ll

[edd]

I have moved the checks to the suggested location - thanks.

[MaskRay]

LGTM.

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

 ; REQUIRES: x86
 ; RUN: llvm-as %s -o %t.o
 ; RUN: ld.lld %t.o -o %t2 -save-temps
 ; RUN: llvm-dis < %t2.0.2.internalize.bc | FileCheck %s
+; RUN: llvm-readelf --syms %t2 | FileCheck --check-prefix=SYMTAB %s
 
 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"
 
 define void @_start() {
   call void @bar()
   ret void
 }
 
 define void @bar() {
   ret void
 }
 
 define hidden void @foo() {
   ret void
 }
 
 ; Check that _start is not internalized.
 ; CHECK: define dso_local void @_start()
 
 ; Check that the foo and bar functions are correctly internalized.
 ; CHECK: define internal void @bar()
 ; CHECK: define internal void @foo()
+
+; Check foo and bar are not emitted to the .symtab
+; SYMTAB:      Symbol table '.symtab' contains 3 entries:
+; SYMTAB-NEXT: Num: Value  Size Type   Bind   Vis     Ndx    Name
+; SYMTAB-NEXT: 0:   {{.+}} 0    NOTYPE
+; SYMTAB-NEXT: 1:   {{.+}} 0    FILE
+; SYMTAB-NEXT: 2:   {{.+}} 1    FUNC   GLOBAL DEFAULT {{.+}} _start