[lld] [ELF] Fix unnecessary inclusion of unreferenced provide symbols (PR #84512)

[via llvm-commits]

================
@@ -0,0 +1,51 @@
+# REQUIRES: x86
+
+# This test verifies that garbage-collection is correctly garbage collecting
+# unused sections when the symbol of the unused section is only referred by
+# an unused PROVIDE symbol.
+
+# RUN: rm -rf %t && split-file %s %t && cd %t
+# RUN: llvm-mc -filetype=obj -triple=x86_64 a.s -o a.o
+# RUN: ld.lld -o a_nogc a.o -T script.t
+# RUN: llvm-readobj --sections --symbols a_nogc | FileCheck -check-prefix=NOGC %s
+# RUN: ld.lld -o a_gc a.o --gc-sections --print-gc-sections -T script.t | FileCheck --check-prefix=GC_LINK %s
+# RUN: llvm-readobj --sections --symbols a_gc | FileCheck -check-prefix=GC %s
+
+NOGC: Name: foo
+NOGC: Name: used
+NOGC: Name: bar
+NOGC: Name: baz
+NOGC-NOT: unused
+
+GC_LINK: removing unused section a.o:(.text.bar)
+
+GC: Name: foo
+GC: Name: used
+GC: Name: baz
+GC-NOT: bar
+GC-NOT: unused
+
+#--- a.s
+.global _start
+_start:
+ call foo
+ call used
+
+.section .text.foo,"ax", at progbits
+foo:
+ nop
+
+.section .text.bar,"ax", at progbits
+.global bar
+bar:
+ nop
+
+.section .text.baz,"ax", at progbits
+.global baz
+baz:
+ nop
+
+
+#--- script.t
+PROVIDE(unused = bar);
+PROVIDE(used = baz);
----------------
partaror wrote:

Done.

https://github.com/llvm/llvm-project/pull/84512