Link .ARM.exidx with corresponding text section.

The sh_link in the ELF section header of .ARM.exidx should
be filled with the section index of the corresponding text
section.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174372 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 65 insertions, 0 deletions

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index 8805773a3e..d65f22709e 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -1332,6 +1332,24 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm,
     break;
   }
 
+  if (TargetObjectWriter->getEMachine() == ELF::EM_ARM &&
+      Section.getType() == ELF::SHT_ARM_EXIDX) {
+    StringRef SecName(Section.getSectionName());
+    if (SecName == ".ARM.exidx") {
+      sh_link = SectionIndexMap.lookup(
+        Asm.getContext().getELFSection(".text",
+                                       ELF::SHT_PROGBITS,
+                                       ELF::SHF_EXECINSTR | ELF::SHF_ALLOC,
+                                       SectionKind::getText()));
+    } else if (SecName.startswith(".ARM.exidx")) {
+      sh_link = SectionIndexMap.lookup(
+        Asm.getContext().getELFSection(SecName.substr(sizeof(".ARM.exidx") - 1),
+                                       ELF::SHT_PROGBITS,
+                                       ELF::SHF_EXECINSTR | ELF::SHF_ALLOC,
+                                       SectionKind::getText()));
+    }
+  }
+
   WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(),
                    Section.getFlags(), 0, Offset, Size, sh_link, sh_info,
                    Alignment, Section.getEntrySize());
diff --git a/test/CodeGen/ARM/ehabi-mc-sh_link.ll b/test/CodeGen/ARM/ehabi-mc-sh_link.ll
new file mode 100644
index 0000000000..f90e5f384c
--- /dev/null
+++ b/test/CodeGen/ARM/ehabi-mc-sh_link.ll
@@ -0,0 +1,47 @@
+; Test the sh_link in Elf32_Shdr.
+
+; The .ARM.exidx section should be linked with corresponding text section.
+; The sh_link in Elf32_Shdr should be filled with the section index of
+; the text section.
+
+; RUN: llc -mtriple arm-unknown-linux-gnueabi \
+; RUN:     -arm-enable-ehabi -arm-enable-ehabi-descriptors \
+; RUN:     -filetype=obj -o - %s \
+; RUN:   | elf-dump --dump-section-data \
+; RUN:   | FileCheck %s
+
+define void @test1() nounwind {
+entry:
+  ret void
+}
+
+define void @test2() nounwind section ".test_section" {
+entry:
+  ret void
+}
+
+; CHECK: # Section 1
+; CHECK-NEXT: (('sh_name', 0x00000010) # '.text'
+
+; CHECK:      (('sh_name', 0x00000005) # '.ARM.exidx'
+; CHECK-NEXT:  ('sh_type', 0x70000001)
+; CHECK-NEXT:  ('sh_flags', 0x00000082)
+; CHECK-NEXT:  ('sh_addr', 0x00000000)
+; CHECK-NEXT:  ('sh_offset', 0x0000005c)
+; CHECK-NEXT:  ('sh_size', 0x00000008)
+; CHECK-NEXT:  ('sh_link',  0x00000001)
+; CHECK-NEXT:  ('sh_info',  0x00000000)
+; CHECK-NEXT:  ('sh_addralign',  0x00000004)
+
+; CHECK: # Section 7
+; CHECK-NEXT: (('sh_name', 0x00000039) # '.test_section'
+
+; CHECK:      (('sh_name', 0x0000002f) # '.ARM.exidx.test_section'
+; CHECK-NEXT:  ('sh_type', 0x70000001)
+; CHECK-NEXT:  ('sh_flags', 0x00000082)
+; CHECK-NEXT:  ('sh_addr', 0x00000000)
+; CHECK-NEXT:  ('sh_offset', 0x00000068)
+; CHECK-NEXT:  ('sh_size', 0x00000008)
+; CHECK-NEXT:  ('sh_link',  0x00000007)
+; CHECK-NEXT:  ('sh_info',  0x00000000)
+; CHECK-NEXT:  ('sh_addralign',  0x00000004)