llvm-objdump: Handle BSS sections larger than the object file

The size of the uninitialized sections, like BSS, can exceed the size of
the object file.

Do not attempt to grab the contents of such sections.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212953 91177308-0d34-0410-b5e6-96231b3b80d8

test/tools/llvm-objdump/coff-large-bss.test

@@ -0,0 +1,6 @@
+RUN: llvm-objdump -s %p/Inputs/large-bss.obj.coff-i386 | FileCheck %s
+
+; CHECK:      Contents of section .text:
+: CHECK-NEXT: Contents of section .data:
+: CHECK-NEXT: Contents of section .bss:
+: CHECK-NEXT: <skipping contents of bss section at [0000, 010f)>

tools/llvm-objdump/llvm-objdump.cpp

@@ -628,8 +628,6 @@ static void PrintSectionContents(const ObjectFile *Obj) {
     bool BSS;
     if (error(Section.getName(Name)))
       continue;
-    if (error(Section.getContents(Contents)))
-      continue;
     if (error(Section.getAddress(BaseAddr)))
       continue;
     if (error(Section.isBSS(BSS)))
@@ -637,12 +635,18 @@ static void PrintSectionContents(const ObjectFile *Obj) {
 
     outs() << "Contents of section " << Name << ":\n";
     if (BSS) {
+      uint64_t Size;
+      if (error(Section.getSize(Size)))
+        continue;
       outs() << format("<skipping contents of bss section at [%04" PRIx64
-                       ", %04" PRIx64 ")>\n", BaseAddr,
-                       BaseAddr + Contents.size());
+                       ", %04" PRIx64 ")>\n",
+                       BaseAddr, BaseAddr + Size);
       continue;
     }
 
+    if (error(Section.getContents(Contents)))
+      continue;
+
     // Dump out the content as hex and printable ascii characters.
     for (std::size_t addr = 0, end = Contents.size(); addr < end; addr += 16) {
       outs() << format(" %04" PRIx64 " ", BaseAddr + addr);