[llvm] [llvm-objcopy] Handle SHF_ALLOC relocation sections in relocatable files (PR #227204)

[James Henderson via llvm-commits]

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@@ -0,0 +1,42 @@
+## In a relocatable file, an SHF_ALLOC relocation section (e.g. .klp.rela.* in
+## Linux livepatch modules) is a static relocation section: its symbol indexes
+## are updated and the symbols it references are kept.
+
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-strip --strip-unneeded %t -o %t1
+# RUN: llvm-readelf -Sr -s %t1 | FileCheck %s
+# RUN: yaml2obj -DTYPE=SHT_CREL %s -o %t.crel
+# RUN: llvm-strip --strip-unneeded %t.crel -o %t1.crel
+# RUN: llvm-readelf -Sr -s %t1.crel | FileCheck %s
+
+# CHECK:      [ 2] .klp.rela.vmlinux.text {{RELA|CREL}} {{.*}} AI  3   1
+# CHECK-NEXT: [ 3] .symtab
+# CHECK:      R_X86_64_PC32 {{.*}} b + 0
+# CHECK:      Symbol table '.symtab' contains 2 entries:
+# CHECK:      1: {{.*}} UND b
+
+!ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+  - Name:    .text
+    Type:    SHT_PROGBITS
+    Flags:   [ SHF_ALLOC, SHF_EXECINSTR ]
+    Content: "e800000000"
+  - Name:    .klp.rela.vmlinux.text
+    Type:    [[TYPE=SHT_RELA]]
+    Flags:   [ SHF_ALLOC, SHF_INFO_LINK ]
+    Link:    .symtab
+    Info:    .text
+    Relocations:
+      - Offset: 1
+        Symbol: b
+        Type:   R_X86_64_PC32
+Symbols:
+  - Name:    l
+    Section: .text
+  - Name:    b
----------------
jh7370 wrote:

Nit: could you change the names to be a bit more specific, e.g. "referenced" and "unreferenced" or similar, please? I think that would help a little with the test input readability.

https://github.com/llvm/llvm-project/pull/227204