llvm-objdump: Print x64 unwind info in executable.

The original code does not work correctly on executable files because the
code is written in such a way that only object files are assumed to be given
to llvm-objdump.

Contents of RuntimeFunction are different between executables and objects. In
executables, fields in RuntimeFunction have actual addresses to unwind info
structures. On the other hand, in object files, the fields have zero value,
but instead there are relocations pointing to the fields, so that Linker will
fill them at link-time.

So, when we are reading an object file, we need to use relocation info to
find the location of unwind info. When executable, we should just look at the
values in RuntimeFunction.

llvm-svn: 202785

1 files changed, 33 insertions, 4 deletions

diff --git a/llvm/tools/llvm-objdump/COFFDump.cpp b/llvm/tools/llvm-objdump/COFFDump.cpp
index ba5de46b9f6..53cedbbdbd4 100644
--- a/llvm/tools/llvm-objdump/COFFDump.cpp
+++ b/llvm/tools/llvm-objdump/COFFDump.cpp
@@ -453,10 +453,32 @@ static void printWin64EHUnwindInfo(const Win64EH::UnwindInfo *UI) {
   outs().flush();
 }
 
+/// Prints out the given RuntumeFunction struct for x64, assuming that Obj is
+/// pointing to an executable file.
 static void printRuntimeFunction(const COFFObjectFile *Obj,
-                                 const RuntimeFunction &RF,
-                                 uint64_t SectionOffset,
-                                 const std::vector<RelocationRef> &Rels) {
+                                 const RuntimeFunction &RF) {
+  if (!RF.StartAddress)
+    return;
+  outs() << "Function Table:\n"
+         << format("  Start Address: 0x%04x\n", RF.StartAddress)
+         << format("  End Address: 0x%04x\n", RF.EndAddress)
+         << format("  Unwind Info Address: : 0x%04x\n\n", RF.UnwindInfoOffset);
+  uintptr_t addr;
+  if (Obj->getRvaPtr(RF.UnwindInfoOffset, addr))
+    return;
+  printWin64EHUnwindInfo(reinterpret_cast<const Win64EH::UnwindInfo *>(addr));
+}
+
+/// Prints out the given RuntumeFunction struct for x64, assuming that Obj is
+/// pointing to an object file. Unlike executable, fields in RuntumeFunction
+/// struct are filled with zeros, but instead there are relocations pointing to
+/// them so that the linker will fill targets' RVAs to the fields at link
+/// time. This function interprets the relocations to find the data to be used
+/// in the resulting executable.
+static void printRuntimeFunctionRels(const COFFObjectFile *Obj,
+                                     const RuntimeFunction &RF,
+                                     uint64_t SectionOffset,
+                                     const std::vector<RelocationRef> &Rels) {
   outs() << "Function Table:\n";
   outs() << "  Start Address: ";
   printCOFFSymbolAddress(outs(), Rels,
@@ -516,10 +538,17 @@ void llvm::printCOFFUnwindInfo(const COFFObjectFile *Obj) {
     return;
   ArrayRef<RuntimeFunction> RFs(RFStart, NumRFs);
 
+  bool IsExecutable = Rels.empty();
+  if (IsExecutable) {
+    for (const RuntimeFunction &RF : RFs)
+      printRuntimeFunction(Obj, RF);
+    return;
+  }
+
   for (const RuntimeFunction &RF : RFs) {
     uint64_t SectionOffset =
         std::distance(RFs.begin(), &RF) * sizeof(RuntimeFunction);
-    printRuntimeFunction(Obj, RF, SectionOffset, Rels);
+    printRuntimeFunctionRels(Obj, RF, SectionOffset, Rels);
   }
 }