[llvm-objdump] Warn if no user specified sections (-j) are not found.

Match GNU objdump.

https://bugs.llvm.org/show_bug.cgi?id=41898

Reviewers: jhenderson, grimar, MaskRay, rupprecht

Reviewed by: jhenderson, grimar, MaskRay

Differential Revision: https://reviews.llvm.org/D63779

llvm-svn: 364955

1 files changed, 26 insertions, 3 deletions

diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index f45559b5497..8045b942402 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -336,6 +336,7 @@ static cl::extrahelp
     HelpResponse("\nPass @FILE as argument to read options from FILE.\n");
 
 static StringSet<> DisasmFuncsSet;
+static StringSet<> FoundSectionSet;
 static StringRef ToolName;
 
 typedef std::vector<std::tuple<uint64_t, StringRef, uint8_t>> SectionSymbolsTy;
@@ -343,11 +344,15 @@ typedef std::vector<std::tuple<uint64_t, StringRef, uint8_t>> SectionSymbolsTy;
 static bool shouldKeep(object::SectionRef S) {
   if (FilterSections.empty())
     return true;
-  StringRef String;
-  std::error_code error = S.getName(String);
+  StringRef SecName;
+  std::error_code error = S.getName(SecName);
   if (error)
     return false;
-  return is_contained(FilterSections, String);
+  // StringSet does not allow empty key so avoid adding sections with
+  // no name (such as the section with index 0) here.
+  if (!SecName.empty())
+    FoundSectionSet.insert(SecName);
+  return is_contained(FilterSections, SecName);
 }
 
 SectionFilter ToolSectionFilter(object::ObjectFile const &O) {
@@ -434,6 +439,22 @@ LLVM_ATTRIBUTE_NORETURN void report_error(Error E, StringRef ArchiveName,
     report_error(std::move(E), ArchiveName, NameOrErr.get(), ArchitectureName);
 }
 
+static void warnOnNoMatchForSections() {
+  SetVector<StringRef> MissingSections;
+  for (StringRef S : FilterSections) {
+    if (FoundSectionSet.count(S))
+      return;
+    // User may specify a unnamed section. Don't warn for it.
+    if (!S.empty())
+      MissingSections.insert(S);
+  }
+
+  // Warn only if no section in FilterSections is matched.
+  for (StringRef S : MissingSections)
+    warn("section '" + S + "' mentioned in a -j/--section option, but not "
+         "found in any input file");
+}
+
 static const Target *getTarget(const ObjectFile *Obj = nullptr) {
   // Figure out the target triple.
   Triple TheTriple("unknown-unknown-unknown");
@@ -2157,5 +2178,7 @@ int main(int argc, char **argv) {
 
   llvm::for_each(InputFilenames, dumpInput);
 
+  warnOnNoMatchForSections();
+
   return EXIT_SUCCESS;
 }