llvm-objdump: Don't print contents of BSS sections: it makes no sense…

… and crashes llvm-objdump on relocated objects with large bss

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179589 91177308-0d34-0410-b5e6-96231b3b80d8

test/Object/objdump-section-content.test

@@ -1,6 +1,8 @@
 RUN: yaml2obj %p/Inputs/COFF/i386.yaml | llvm-objdump -s - | FileCheck %s -check-prefix COFF-i386
 RUN: llvm-objdump -s %p/Inputs/trivial-object-test.elf-i386 \
 RUN:              | FileCheck %s -check-prefix ELF-i386
+RUN: llvm-objdump -s %p/Inputs/shared-object-test.elf-i386 \
+RUN:              | FileCheck %s -check-prefix BSS
 
 COFF-i386: file format
 COFF-i386: Contents of section .text:
@@ -17,3 +19,6 @@ ELF-i386:  0010 0000e8fc ffffffe8 fcffffff 8b442408  .............D$.
 ELF-i386:  0020 83c40cc3                             ....
 ELF-i386: Contents of section .rodata.str1.1:
 ELF-i386:  0024 48656c6c 6f20576f 726c6421 00        Hello World!.
+
+BSS: Contents of section .bss:
+BSS-NEXT: <skipping contents of bss section at [12c8, 12cc)>

tools/llvm-objdump/llvm-objdump.cpp

@@ -468,11 +468,19 @@ static void PrintSectionContents(const ObjectFile *o) {
     StringRef Name;
     StringRef Contents;
     uint64_t BaseAddr;
+    bool BSS;
     if (error(si->getName(Name))) continue;
     if (error(si->getContents(Contents))) continue;
     if (error(si->getAddress(BaseAddr))) continue;
+    if (error(si->isBSS(BSS))) continue;
 
     outs() << "Contents of section " << Name << ":\n";
+    if (BSS) {
+      outs() << format("<skipping contents of bss section at [%04" PRIx64
+                       ", %04" PRIx64 ")>\n", BaseAddr,
+                       BaseAddr + Contents.size());
+      continue;
+    }
 
     // Dump out the content as hex and printable ascii characters.
     for (std::size_t addr = 0, end = Contents.size(); addr < end; addr += 16) {