[llvm-objdump] Demangle C++ Symbols in branch and call targets

[zero9178]

Summary

Currently C++ symbols are demangled in the symbol table as well as in the disassembly and relocations. This patch adds demangling of C++ symbols in targets of calls and branches making it easier to decipher control flow in disassembly. This also matches up with objdump's behavior

[MaskRay]

Thanks!

[zero9178]

Thank you! Would need someone to commit this for me

[zero9178]

Friendly bump :)

[MaskRay]

In D77957#1990463, @zero9178 wrote:

Friendly bump :)

In general the name and the email address should be provided so that the committer can run git commit --amend --author <...>

For this case I was giving other reviewers a change to review.

llvm/test/tools/llvm-objdump/X86/demangle.s

 # RUN: llvm-mc %s -filetype=obj -triple=x86_64-pc-linux -o %t
 # RUN: llvm-objdump -t -r --demangle %t | FileCheck %s
 
 ## Check we demangle symbols when printing symbol table.
 # CHECK:      SYMBOL TABLE:
 # CHECK-NEXT: 0000000000000000 g     F .text           0000000000000000 foo()
 
 ## Check we demangle symbols when printing relocations.
 # CHECK:      000000000000001 R_X86_64_PLT32 foo()-0x4
 
 ## Check the case when relocations are inlined into disassembly.
 # RUN: llvm-objdump -d -r --demangle %t | FileCheck %s --check-prefix=INLINE
 # INLINE:      <foo()>:
-# INLINE-NEXT:  0: {{.*}}  callq   0x5 <_Z3foov+0x5>
+# INLINE-NEXT:  0: {{.*}}  callq   0x5 <foo()+0x5>
 # INLINE-NEXT:  0000000000000001:  R_X86_64_PLT32 foo()-0x4
 
 .text
 .globl _Z3foov
 .type _Z3foov,@function
 _Z3foov:
  callq _Z3foov@PLT

llvm/tools/llvm-objdump/llvm-objdump.cpp

for (unsigned SI = 0, SE = Symbols.size(); SI != SE; ++SI) {
                   AbsoluteSymbols,
                   [=](const SymbolInfoTy &O) {
                     return O.Addr <= Target;
                   });
             }
             if (TargetSym != TargetSectionSymbols->begin()) {
               --TargetSym;
               uint64_t TargetAddress = TargetSym->Addr;
-              StringRef TargetName = TargetSym->Name;
+              std::string TargetName = TargetSym->Name.str();
+              if (Demangle)
+                TargetName = demangle(TargetName);
+
               outs() << " <" << TargetName;
               uint64_t Disp = Target - TargetAddress;
               if (Disp)
                 outs() << "+0x" << Twine::utohexstr(Disp);
               outs() << '>';
             }
           }
         }