[llvm-objdump] - Implement the --adjust-vma option.
GNU objdump's help says: "--adjust-vma: Add OFFSET to all displayed section addresses"
In real life what it does is a bit more complicated
(and IMO not always reasonable. For example, GNU objdump prints not only VMA, but also LMA
for sections. And with --adjust-vma it adjusts LMA, but only when a section has relocations.
llvm-objsump does not seem to support printing LMAs yet, but GNU's logic anyways does not
make sense for me here).
This patch tries to adjust VMA. I tried to implement a reasonable approach.
I am not adjusting sections that are not allocatable. As, for example, adjusting debug sections
VA's and rel[a] sections VA's should not make sense. This behavior seems to be GNU compatible.
Differential revision: https://reviews.llvm.org/D57051
llvm-svn: 352347
diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 9ac5266..8241765 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -70,6 +70,11 @@
using namespace llvm;
using namespace object;
+cl::opt<unsigned long long> AdjustVMA(
+ "adjust-vma",
+ cl::desc("Increase the displayed address by the specified offset"),
+ cl::value_desc("offset"), cl::init(0));
+
cl::opt<bool>
llvm::AllHeaders("all-headers",
cl::desc("Display all available header information"));
@@ -890,6 +895,18 @@
return Ret;
}
+// Used for --adjust-vma to check if address should be adjusted by the
+// specified value for a given section.
+// For ELF we do not adjust non-allocatable sections like debug ones,
+// because they are not loadable.
+// TODO: implement for other file formats.
+static bool shouldAdjustVA(const SectionRef &Section) {
+ const ObjectFile *Obj = Section.getObject();
+ if (isa<object::ELFObjectFileBase>(Obj))
+ return ELFSectionRef(Section).getFlags() & ELF::SHF_ALLOC;
+ return false;
+}
+
static void disassembleObject(const Target *TheTarget, const ObjectFile *Obj,
MCContext &Ctx, MCDisassembler *DisAsm,
const MCInstrAnalysis *MIA, MCInstPrinter *IP,
@@ -1046,6 +1063,10 @@
ArrayRef<uint8_t> Bytes(reinterpret_cast<const uint8_t *>(BytesStr.data()),
BytesStr.size());
+ uint64_t VMAAdjustment = 0;
+ if (shouldAdjustVA(Section))
+ VMAAdjustment = AdjustVMA;
+
uint64_t Size;
uint64_t Index;
bool PrintedSection = false;
@@ -1110,7 +1131,8 @@
outs() << '\n';
if (!NoLeadingAddr)
- outs() << format("%016" PRIx64 " ", SectionAddr + Start);
+ outs() << format("%016" PRIx64 " ",
+ SectionAddr + Start + VMAAdjustment);
StringRef SymbolName = std::get<1>(Symbols[SI]);
if (Demangle)
@@ -1271,9 +1293,9 @@
if (Size == 0)
Size = 1;
- PIP.printInst(*IP, Disassembled ? &Inst : nullptr,
- Bytes.slice(Index, Size), SectionAddr + Index, outs(), "",
- *STI, &SP, &Rels);
+ PIP.printInst(
+ *IP, Disassembled ? &Inst : nullptr, Bytes.slice(Index, Size),
+ SectionAddr + Index + VMAAdjustment, outs(), "", *STI, &SP, &Rels);
outs() << CommentStream.str();
Comments.clear();
@@ -1353,6 +1375,15 @@
if (Offset >= Index + Size)
break;
+ // When --adjust-vma is used, update the address printed.
+ if (RelCur->getSymbol() != Obj->symbol_end()) {
+ Expected<section_iterator> SymSI =
+ RelCur->getSymbol()->getSection();
+ if (SymSI && *SymSI != Obj->section_end() &&
+ (shouldAdjustVA(**SymSI)))
+ Offset += AdjustVMA;
+ }
+
printRelocation(*RelCur, SectionAddr + Offset,
Obj->getBytesInAddress());
++RelCur;
@@ -1493,6 +1524,9 @@
StringRef Name;
error(Section.getName(Name));
uint64_t Address = Section.getAddress();
+ if (shouldAdjustVA(Section))
+ Address += AdjustVMA;
+
uint64_t Size = Section.getSize();
bool Text = Section.isText();
bool Data = Section.isData();