Modify llvm-objdump to print disassembly failures inline

[colinl]

Summary

Two major problems exist with the current way failed disassembly is printed. Warnings are printed to stderr which is not synchronized with stdout, leading to confusing output and if someone is trying to pipe output to a file, warnings are still printed out to the command line.

This patch prints the text "<unknown>" where the instruction text would have been, had disassembly succeeded.

[rnk]

lgtm

[colinl]

Committed in r263793

test/MC/X86/invalid_opcode.s

+# RUN: llvm-mc -triple=x86_64 -filetype=obj %s -o - | llvm-objdump -d - | FileCheck %s
+
+# CHECK: 0:       ff ff  <unknown>
+.word 0xffff
 No newline at end of file

tools/llvm-objdump/llvm-objdump.cpp

                          ArrayRef<uint8_t> Bytes, uint64_t Address,
                          raw_ostream &OS, StringRef Annot,
                          MCSubtargetInfo const &STI) {
-    outs() << format("%8" PRIx64 ":", Address);
+    OS << format("%8" PRIx64 ":", Address);
     if (!NoShowRawInsn) {
-      outs() << "\t";
-      dumpBytes(Bytes, outs());
+      OS << "\t";
+      dumpBytes(Bytes, OS);
     }
-    IP.printInst(MI, outs(), "", STI);
+    if (MI)
+      IP.printInst(MI, OS, "", STI);
+    else
+      OS << " <unknown>";
   }
 };
 PrettyPrinter PrettyPrinterInst;

                  ArrayRef<uint8_t> Bytes, uint64_t Address,
                  raw_ostream &OS, StringRef Annot,
                  MCSubtargetInfo const &STI) override {
+    if (!MI) {
+      printLead(Bytes, Address, OS);
+      OS << " <unknown>";
+      return;
+    }
     std::string Buffer;
     {
       raw_string_ostream TempStream(Buffer);

         if (Index >= End)
           break;
 
-        if (DisAsm->getInstruction(Inst, Size, Bytes.slice(Index),
+        bool Disassembled = DisAsm->getInstruction(Inst, Size, Bytes.slice(Index),
                                                    SectionAddr + Index, DebugOut,
-                                   CommentStream)) {
-          PIP.printInst(*IP, &Inst,
-                        Bytes.slice(Index, Size),
-                        SectionAddr + Index, outs(), "", *STI);
-          outs() << CommentStream.str();
-          Comments.clear();
+                                                   CommentStream);
+        if (Size == 0)
+          Size = 1;
+        PIP.printInst(*IP, Disassembled ? &Inst : nullptr,
+                      Bytes.slice(Index, Size),
+                      SectionAddr + Index, outs(), "", *STI);
+        outs() << CommentStream.str();
+        Comments.clear();
 
-          // Try to resolve the target of a call, tail call, etc. to a specific
-          // symbol.
-          if (MIA && (MIA->isCall(Inst) || MIA->isUnconditionalBranch(Inst) ||
-                      MIA->isConditionalBranch(Inst))) {
-            uint64_t Target;
-            if (MIA->evaluateBranch(Inst, SectionAddr + Index, Size, Target)) {
-              // In a relocatable object, the target's section must reside in
-              // the same section as the call instruction or it is accessed
-              // through a relocation.
-              //
-              // In a non-relocatable object, the target may be in any section.
-              //
-              // N.B. We don't walk the relocations in the relocatable case yet.
-              auto *TargetSectionSymbols = &Symbols;
-              if (!Obj->isRelocatableObject()) {
-                auto SectionAddress = std::upper_bound(
-                    SectionAddresses.begin(), SectionAddresses.end(), Target,
-                    [](uint64_t LHS,
-                       const std::pair<uint64_t, SectionRef> &RHS) {
-                      return LHS < RHS.first;
-                    });
-                if (SectionAddress != SectionAddresses.begin()) {
-                  --SectionAddress;
-                  TargetSectionSymbols = &AllSymbols[SectionAddress->second];
-                } else {
-                  TargetSectionSymbols = nullptr;
-                }
               }
+            }
 
-              // Find the first symbol in the section whose offset is less than
-              // or equal to the target.
-              if (TargetSectionSymbols) {
-                auto TargetSym = std::upper_bound(
-                    TargetSectionSymbols->begin(), TargetSectionSymbols->end(),
-                    Target, [](uint64_t LHS,
-                               const std::pair<uint64_t, StringRef> &RHS) {
-                      return LHS < RHS.first;
-                    });
-                if (TargetSym != TargetSectionSymbols->begin()) {
-                  --TargetSym;
-                  uint64_t TargetAddress = std::get<0>(*TargetSym);
-                  StringRef TargetName = std::get<1>(*TargetSym);
-                  outs() << " <" << TargetName;
-                  uint64_t Disp = Target - TargetAddress;
-                  if (Disp)
-                    outs() << '+' << utohexstr(Disp);
-                  outs() << '>';
-                }
               }
             }
           }
-          outs() << "\n";
-        } else {
-          errs() << ToolName << ": warning: invalid instruction encoding\n";
-          if (Size == 0)
-            Size = 1; // skip illegible bytes
         }
+        outs() << "\n";
 
         // Print relocation for instruction.
         while (rel_cur != rel_end) {