[ELF] Handle .init_array prefix consistently

[nikic]

Summary

Currently, the code in TargetLoweringObjectFile only assigns @init_array section type to plain .init_array sections, but not prioritized sections like .init_array.00001.

This is inconsistent with the interpretation in the AsmParser (see https://github.com/llvm/llvm-project/blob/791523bae6153b13bb41ba05c9fc89e502cc4a1a/llvm/lib/MC/MCParser/ELFAsmParser.cpp#L621-L632) and upcoming expectations in LLD (see https://github.com/rust-lang/rust/issues/92181 for context).

This patch assigns @init_array section type to all sections with an .init_array prefix. The same is done for .fini_array and .preinit_array as well. With that, the logic matches the AsmParser.

[MaskRay]

Thanks!

llvm/test/CodeGen/X86/attribute-sections.ll

10

.globl can appear anywhere. The position of label definition is what matters.

[MaskRay]

llvm/test/CodeGen/X86/attribute-sections.ll

9–14

-LABEL is even better. A regression will lead to a better FileCheck. diagnostic.

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

if (Name == ".tbss" ||
       Name.startswith(".tbss.") ||
       Name.startswith(".gnu.linkonce.tb.") ||
       Name.startswith(".llvm.linkonce.tb."))
     return SectionKind::getThreadBSS();
 
   return K;
 }
 
+static bool hasPrefix(StringRef SectionName, StringRef Prefix) {
+  return SectionName.consume_front(Prefix) &&
+         (SectionName.empty() || SectionName[0] == '.');
+}
+
 static unsigned getELFSectionType(StringRef Name, SectionKind K) {
   // Use SHT_NOTE for section whose name starts with ".note" to allow
   // emitting ELF notes from C variable declaration.
   // See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77609
   if (Name.startswith(".note"))
     return ELF::SHT_NOTE;
 
-  if (Name == ".init_array")
+  if (hasPrefix(Name, ".init_array"))
     return ELF::SHT_INIT_ARRAY;
 
-  if (Name == ".fini_array")
+  if (hasPrefix(Name, ".fini_array"))
     return ELF::SHT_FINI_ARRAY;
 
-  if (Name == ".preinit_array")
+  if (hasPrefix(Name, ".preinit_array"))
     return ELF::SHT_PREINIT_ARRAY;
 
   if (K.isBSS() || K.isThreadBSS())
     return ELF::SHT_NOBITS;
 
   return ELF::SHT_PROGBITS;
 }
 

llvm/test/CodeGen/X86/attribute-sections.ll

-; RUN: llc < %s -mtriple=i386-unknown-linux-gnu | FileCheck %s -check-prefix=LINUX
+; RUN: llc < %s -mtriple=i386-unknown-linux-gnu | FileCheck %s
 
 declare i32 @foo()
-@G0 = global i32 ()* @foo, section ".init_array"
-
-; LINUX:  .section  .init_array,"aw"
-; LINUX:  .globl G0
-
-@G1 = global i32 ()* @foo, section ".fini_array"
-
-; LINUX:  .section  .fini_array,"aw"
-; LINUX:  .globl G1
-
-@G2 = global i32 ()* @foo, section ".preinit_array"
-
-; LINUX:  .section .preinit_array,"aw"
-; LINUX:  .globl G2
 
+@init_array1 = global i32 ()* @foo, section ".init_array"
+@init_array2 = global i32 ()* @foo, section ".init_array.00001"
+@init_array3 = global i32 ()* @foo, section ".init_arrayfoo"
+
+; CHECK-LABEL: .section  .init_array,"aw",@init_array
+; CHECK: init_array1:
+; CHECK-LABEL: .section  .init_array.00001,"aw",@init_array
+; CHECK: init_array2:
+; CHECK-LABEL: .section  .init_arrayfoo,"aw",@progbits
+; CHECK: init_array3:
+
+@fini_array1 = global i32 ()* @foo, section ".fini_array"
+@fini_array2 = global i32 ()* @foo, section ".fini_array.00001"
+@fini_array3 = global i32 ()* @foo, section ".fini_arrayfoo"
+
+; CHECK-LABEL: .section  .fini_array,"aw",@fini_array
+; CHECK: fini_array1:
+; CHECK-LABEL: .section  .fini_array.00001,"aw",@fini_array
+; CHECK: fini_array2:
+; CHECK-LABEL: .section  .fini_arrayfoo,"aw",@progbits
+; CHECK: fini_array3:
+
+@preinit_array1 = global i32 ()* @foo, section ".preinit_array"
+@preinit_array2 = global i32 ()* @foo, section ".preinit_array.00001"
+@preinit_array3 = global i32 ()* @foo, section ".preinit_arrayfoo"
+
+; CHECK-LABEL: .section  .preinit_array,"aw",@preinit_array
+; CHECK: preinit_array1:
+; CHECK-LABEL: .section  .preinit_array.00001,"aw",@preinit_array
+; CHECK: preinit_array2:
+; CHECK-LABEL: .section  .preinit_arrayfoo,"aw",@progbits
+; CHECK: preinit_array3: