Force @{init,fini}_array if section name starts with ".{init,fini}_array.".

[ruiu]

Summary

Fixes https://bugs.llvm.org/show_bug.cgi?id=32307.

[ruiu]

• Do not use template.

[gsmolarczyk]

lld/ELF/InputSection.cpp

78 ↗

(On Diff #92691)

SHT_INIT_ARRAY

88 ↗

(On Diff #92691)

How about folding if (Type == SHT_PROGBITS) into outer if instruction?

[ruiu]

lld/ELF/InputSection.cpp

78 ↗

(On Diff #92691)

Fixed.

88 ↗

(On Diff #92691)

I originally did this that way, but I changed that as I think this new code is slightly easier to read.

[ruiu]

• Fix typo.

[gsmolarczyk]

lld/ELF/InputSection.cpp

88 ↗

(On Diff #92691)

You might be right. Ok with me either way.

lld/trunk/ELF/InputSection.cpp

InputSectionBase::InputSectionBase(InputFile *File, uint64_t Flags,
   // The ELF spec states that a value of 0 means the section has
   // no alignment constraits.
   uint32_t V = std::max<uint64_t>(Alignment, 1);
   if (!isPowerOf2_64(V))
     fatal(toString(File) + ": section sh_addralign is not a power of 2");
   this->Alignment = V;
 }
 
+// GNU assembler 2.24 and LLVM 4.0.0's MC (the newest release as of
+// March 2017) fail to infer section types for sections starting with
+// ".init_array." or ".fini_array.". They set SHT_PROGBITS instead of
+// SHF_INIT_ARRAY. As a result, the following assembler directive
+// creates ".init_array.100" with SHT_PROGBITS, for example.
+//
+//   .section .init_array.100, "aw"
+//
+// This function forces SHT_{INIT,FINI}_ARRAY so that we can handle
+// incorrect inputs as if they were correct from the beginning.
+static uint64_t getType(uint64_t Type, StringRef Name) {
+  if (Type == SHT_PROGBITS && Name.startswith(".init_array."))
+    return SHT_INIT_ARRAY;
+  if (Type == SHT_PROGBITS && Name.startswith(".fini_array."))
+    return SHT_FINI_ARRAY;
+  return Type;
+}
+
 template <class ELFT>
 InputSectionBase::InputSectionBase(elf::ObjectFile<ELFT> *File,
                                    const typename ELFT::Shdr *Hdr,
                                    StringRef Name, Kind SectionKind)
-    : InputSectionBase(File, Hdr->sh_flags & ~SHF_INFO_LINK, Hdr->sh_type,
-                       Hdr->sh_entsize, Hdr->sh_link, Hdr->sh_info,
-                       Hdr->sh_addralign, getSectionContents(File, Hdr), Name,
-                       SectionKind) {
+    : InputSectionBase(File, Hdr->sh_flags & ~SHF_INFO_LINK,
+                       getType(Hdr->sh_type, Name), Hdr->sh_entsize,
+                       Hdr->sh_link, Hdr->sh_info, Hdr->sh_addralign,
+                       getSectionContents(File, Hdr), Name, SectionKind) {
   // We reject object files having insanely large alignments even though
   // they are allowed by the spec. I think 4GB is a reasonable limitation.
   // We might want to relax this in the future.
   if (Hdr->sh_addralign > UINT32_MAX)
     fatal(toString(File) + ": section sh_addralign is too large");
 }
 
 size_t InputSectionBase::getSize() const {

lld/trunk/test/ELF/init-fini-progbits.s

+// REQUIRES: x86
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+// RUN: ld.lld %t -o %t.exe
+// RUN: llvm-readobj -sections %t.exe | FileCheck %s
+
+// CHECK:      Name: .init_array
+// CHECK-NEXT: Type: SHT_INIT_ARRAY
+// CHECK:      Name: .fini_array
+// CHECK-NEXT: Type: SHT_FINI_ARRAY
+
+.globl _start
+_start:
+  nop
+
+.section .init_array.100, "aw", @progbits
+  .byte 0
+.section .fini_array.100, "aw", @progbits
+  .byte 0