[ELF] --orphan-handling=: don't warn/error for input SHT_REL[A] retained by --emit-relocs

[MaskRay]

Summary

They are purposefully skipped by input section descriptions (rL295324).
Similarly, --orphan-handling= should not warn/error for them.
This behavior matches GNU ld.

[MaskRay]

Use -o /dev/null (the output file is not significant)

[kees]

Awesome! With this and D75149 my defconfig kernel build now only shows:

ld.lld: warning: <internal>:(.symtab) is being placed in '.symtab'
ld.lld: warning: <internal>:(.shstrtab) is being placed in '.shstrtab'
ld.lld: warning: <internal>:(.strtab) is being placed in '.strtab'

Nice :)

[grimar]

LGTM

lld/ELF/LinkerScript.cpp

void LinkerScript::addOrphanSections() {
   if (hasSectionsCommand)
     sectionCommands.insert(sectionCommands.end(), v.begin(), v.end());
   else
     sectionCommands.insert(sectionCommands.begin(), v.begin(), v.end());
 }
 
 void LinkerScript::diagnoseOrphanHandling() const {
   for (const InputSectionBase *sec : orphanSections) {
+    // Input SHT_REL[A] retained by --emit-relocs are ignored by
+    // computeInputSections(). Don't warn/error.
+    if (isa<InputSection>(sec) &&
+        cast<InputSection>(sec)->getRelocatedSection())
+      continue;
+
     StringRef name = getOutputSectionName(sec);
     if (config->orphanHandling == OrphanHandlingPolicy::Error)
       error(toString(sec) + " is being placed in '" + name + "'");
     else if (config->orphanHandling == OrphanHandlingPolicy::Warn)
       warn(toString(sec) + " is being placed in '" + name + "'");
   }
 }
 

lld/test/ELF/linkerscript/emit-reloc.s

 # REQUIRES: x86
+## Test that input SHT_REL[A] retained by --emit-relocs are not matched by input section descriptions.
+
 # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
 # RUN: echo "SECTIONS { .rela.dyn : { *(.rela.data) } }" > %t.script
 # RUN: ld.lld --hash-style=sysv -T %t.script --emit-relocs %t.o -o %t.so -shared
 # RUN: llvm-readobj -r %t.so | FileCheck %s
 
+## .rela.data is not listed, but don't error.
+# RUN: echo 'SECTIONS { \
+# RUN:   .dynsym : { *(.dynsym) } \
+# RUN:   .gnu.hash : { *(.gnu.hash) } \
+# RUN:   .hash : { *(.hash) } \
+# RUN:   .dynstr : { *(.dynstr) } \
+# RUN:   .dynamic : { *(.dynamic) } \
+# RUN:   .rela.dyn : { *(.rela.dyn) } \
+# RUN:   .text : { *(.text) } \
+# RUN:   .data : { *(.data) } \
+# RUN:   .comment : { *(.comment) } \
+# RUN:   .symtab : { *(.symtab) } \
+# RUN:   .shstrtab : { *(.shstrtab) } \
+# RUN:   .strtab : { *(.strtab) } \
+# RUN:  }' > %t1.script
+# RUN: ld.lld -T %t1.script -shared --emit-relocs %t.o --orphan-handling=error -o /dev/null
+
 .data
 .quad .foo
 
 # CHECK:      Relocations [
 # CHECK-NEXT:   Section ({{.*}}) .rela.dyn {
 # CHECK-NEXT:     0xF8 R_X86_64_64 .foo 0x0
 # CHECK-NEXT:   }
 # CHECK-NEXT:   Section ({{.*}}) .rela.data {
 # CHECK-NEXT:     0xF8 R_X86_64_64 .foo 0x0
 # CHECK-NEXT:   }
 # CHECK-NEXT: ]