Canonicalize the type of .eh_frame.

GNU as can give it type SHT_PROGBITS or SHT_X86_64_UNWIND depending on
teh construct.

MC gives it type SHT_X86_64_UNWIND.

The linker has to canonicalize to one or the other so that there is only
one .eh_frame in the end.

llvm-svn: 252757

lld/ELF/Writer.cpp

@@ -489,8 +489,12 @@ template <class ELFT> void Writer<ELFT>::createSections() {
       // mapping from input to output.
       auto *IS = dyn_cast<InputSection<ELFT>>(C);
       uintX_t EntSize = IS ? 0 : H->sh_entsize;
+      uint32_t OutType = H->sh_type;
+      if (OutType == SHT_PROGBITS && C->getSectionName() == ".eh_frame" &&
+          Config->EMachine == EM_X86_64)
+        OutType = SHT_X86_64_UNWIND;
       SectionKey<ELFT::Is64Bits> Key{getOutputName(C->getSectionName()),
-                                     H->sh_type, OutFlags, EntSize};
+                                     OutType, OutFlags, EntSize};
       OutputSectionBase<ELFT> *&Sec = Map[Key];
       if (!Sec) {
         if (IS)

lld/test/elf2/eh-frame-type.test

@@ -0,0 +1,16 @@
+# RUN: yaml2obj -format elf %s -o %t.o
+# RUN: ld.lld2 %t.o -o %t -shared
+# RUN: llvm-readobj -s %t | FileCheck %s
+
+# CHECK:      Name: .eh_frame
+# CHECK-NEXT: Type: SHT_X86_64_UNWIND
+
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .eh_frame
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC ]