[llvm-readobj] Unwrap the value first to avoid the error

This addresses the issue introduced in r369169, we need to unwrap
the value first before we can check whether it's empty. This also
swaps the two branches to put the common path first which should
be NFC.

llvm-svn: 369177

llvm/test/tools/llvm-readobj/gnu-notes.test

@@ -24,7 +24,7 @@
 
 # LLVM:      Notes [
 # LLVM-NEXT:   NoteSection {
-# LLVM-NEXT:     Offset: 0x200
+# LLVM-NEXT:     Offset: 0x238
 # LLVM-NEXT:     Size: 0x20
 # LLVM-NEXT:     Note {
 # LLVM-NEXT:       Owner: GNU
@@ -35,7 +35,7 @@
 # LLVM-NEXT:     }
 # LLVM-NEXT:   }
 # LLVM-NEXT:   NoteSection {
-# LLVM-NEXT:     Offset: 0x220
+# LLVM-NEXT:     Offset: 0x258
 # LLVM-NEXT:     Size: 0x20
 # LLVM-NEXT:     Note {
 # LLVM-NEXT:       Owner: GNU
@@ -45,7 +45,7 @@
 # LLVM-NEXT:     }
 # LLVM-NEXT:   }
 # LLVM-NEXT:   NoteSection {
-# LLVM-NEXT:     Offset: 0x240
+# LLVM-NEXT:     Offset: 0x278
 # LLVM-NEXT:     Size: 0x1C
 # LLVM-NEXT:     Note {
 # LLVM-NEXT:       Owner: GNU
@@ -58,7 +58,7 @@
 
 # LLVM-STRIPPED:      Notes [
 # LLVM-STRIPPED-NEXT:   NoteSection {
-# LLVM-STRIPPED-NEXT:     Offset: 0x40
+# LLVM-STRIPPED-NEXT:     Offset: 0x78
 # LLVM-STRIPPED-NEXT:     Size: 0x20
 # LLVM-STRIPPED-NEXT:     Note {
 # LLVM-STRIPPED-NEXT:       Owner: GNU
@@ -69,7 +69,7 @@
 # LLVM-STRIPPED-NEXT:   }
 # LLVM-STRIPPED-NEXT: ]
 
-#      GNU-STRIPPED:Displaying notes found at file offset 0x00000040 with length 0x00000020:
+#      GNU-STRIPPED:Displaying notes found at file offset 0x00000078 with length 0x00000020:
 # GNU-STRIPPED-NEXT:  Owner                Data size 	Description
 # GNU-STRIPPED-NEXT:  GNU                  0x00000010	NT_GNU_BUILD_ID (unique build ID bitstring)
 # GNU-STRIPPED-NEXT:    Build ID: 4fcb712aa6387724a9f465a32cd8c14b

llvm/tools/llvm-readobj/ELFDumper.cpp

@@ -4502,26 +4502,26 @@ void GNUStyle<ELFT>::printNotes(const ELFFile<ELFT> *Obj) {
     }
   };
 
-  if (Obj->getHeader()->e_type == ELF::ET_CORE || Obj->sections()->empty()) {
-    for (const auto &P :
-         unwrapOrError(this->FileName, Obj->program_headers())) {
-      if (P.p_type != PT_NOTE)
+  ArrayRef<Elf_Shdr> Sections = unwrapOrError(this->FileName, Obj->sections());
+  if (Obj->getHeader()->e_type != ELF::ET_CORE && !Sections.empty()) {
+    for (const auto &S : Sections) {
+      if (S.sh_type != SHT_NOTE)
         continue;
-      PrintHeader(P.p_offset, P.p_filesz);
+      PrintHeader(S.sh_offset, S.sh_size);
       Error Err = Error::success();
-      for (const auto &Note : Obj->notes(P, Err))
+      for (const auto &Note : Obj->notes(S, Err))
         ProcessNote(Note);
       if (Err)
         reportError(std::move(Err), this->FileName);
     }
   } else {
-    for (const auto &S :
-         unwrapOrError(this->FileName, Obj->sections())) {
-      if (S.sh_type != SHT_NOTE)
+    for (const auto &P :
+         unwrapOrError(this->FileName, Obj->program_headers())) {
+      if (P.p_type != PT_NOTE)
         continue;
-      PrintHeader(S.sh_offset, S.sh_size);
+      PrintHeader(P.p_offset, P.p_filesz);
       Error Err = Error::success();
-      for (const auto &Note : Obj->notes(S, Err))
+      for (const auto &Note : Obj->notes(P, Err))
         ProcessNote(Note);
       if (Err)
         reportError(std::move(Err), this->FileName);
@@ -5703,27 +5703,28 @@ void LLVMStyle<ELFT>::printNotes(const ELFFile<ELFT> *Obj) {
     }
   };
 
-  if (Obj->getHeader()->e_type == ELF::ET_CORE || Obj->sections()->empty()) {
-    for (const auto &P :
-         unwrapOrError(this->FileName, Obj->program_headers())) {
-      if (P.p_type != PT_NOTE)
+  ArrayRef<Elf_Shdr> Sections = unwrapOrError(this->FileName, Obj->sections());
+  if (Obj->getHeader()->e_type != ELF::ET_CORE && !Sections.empty()) {
+    for (const auto &S : Sections) {
+      if (S.sh_type != SHT_NOTE)
         continue;
       DictScope D(W, "NoteSection");
-      PrintHeader(P.p_offset, P.p_filesz);
+      PrintHeader(S.sh_offset, S.sh_size);
       Error Err = Error::success();
-      for (const auto &Note : Obj->notes(P, Err))
+      for (const auto &Note : Obj->notes(S, Err))
         ProcessNote(Note);
       if (Err)
         reportError(std::move(Err), this->FileName);
     }
   } else {
-    for (const auto &S : unwrapOrError(this->FileName, Obj->sections())) {
-      if (S.sh_type != SHT_NOTE)
+    for (const auto &P :
+         unwrapOrError(this->FileName, Obj->program_headers())) {
+      if (P.p_type != PT_NOTE)
         continue;
       DictScope D(W, "NoteSection");
-      PrintHeader(S.sh_offset, S.sh_size);
+      PrintHeader(P.p_offset, P.p_filesz);
       Error Err = Error::success();
-      for (const auto &Note : Obj->notes(S, Err))
+      for (const auto &Note : Obj->notes(P, Err))
         ProcessNote(Note);
       if (Err)
         reportError(std::move(Err), this->FileName);