[llvm-objdump] Implement --prefix option

The prefix given to --prefix will be added to GNU absolute paths when
used with --source option (source interleaved with the disassembly).

This matches GNU's objdump behavior.

GNU and C++17 rules for absolute paths are different.

Differential Revision: https://reviews.llvm.org/D85024

Fixes PR46368.

Differential Revision: https://reviews.llvm.org/D85024

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index d57ea8e..bc13b26 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -353,6 +353,10 @@ static cl::opt<bool>
          cl::cat(ObjdumpCat));
 static cl::alias WideShort("w", cl::Grouping, cl::aliasopt(Wide));
 
+cl::opt<std::string> objdump::Prefix("prefix",
+                                     cl::desc("Add prefix to absolute paths"),
+                                     cl::cat(ObjdumpCat));
+
 enum DebugVarsFormat {
   DVDisabled,
   DVUnicode,
@@ -1031,6 +1035,13 @@ void SourcePrinter::printSourceLine(formatted_raw_ostream &OS,
     }
   }
 
+  if (!Prefix.empty() && sys::path::is_absolute_gnu(LineInfo.FileName)) {
+    SmallString<128> FilePath;
+    sys::path::append(FilePath, Prefix, LineInfo.FileName);
+
+    LineInfo.FileName = std::string(FilePath);
+  }
+
   if (PrintLines)
     printLines(OS, LineInfo, Delimiter, LVP);
   if (PrintSource)
@@ -2961,6 +2972,10 @@ int main(int argc, char **argv) {
   if (InputFilenames.empty())
     InputFilenames.push_back("a.out");
 
+  // Removes trailing separators from prefix.
+  while (!Prefix.empty() && sys::path::is_separator(Prefix.back()))
+    Prefix.pop_back();
+
   if (AllHeaders)
     ArchiveHeaders = FileHeaders = PrivateHeaders = Relocations =
         SectionHeaders = SymbolTable = true;