Adding support for printing operands symbolically to llvm's public 'C'

disassembler API.  Hooked this up to the ARM target so such tools as Darwin's
otool(1) can now print things like branch targets for example this:
  blx _puts
instead of this:
  blx #-36
And even print the expression encoded in the Mach-O relocation entried for
things like this:
  movt r0, :upper16:((_foo-_bar)+1234)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129284 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 139 insertions, 6 deletions

diff --git a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index 74f8b53..579e1a4 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -422,6 +422,10 @@ bool ARMDisassembler::getInstruction(MCInst &MI,
   if (!Builder)
     return false;
 
+  Builder->setupBuilderForSymbolicDisassembly(getLLVMOpInfoCallback(),
+                                              getDisInfoBlock(), getMCContext(),
+                                              Address);
+
   if (!Builder->Build(MI, insn))
     return false;
 
@@ -504,6 +508,10 @@ bool ThumbDisassembler::getInstruction(MCInst &MI,
 
   Builder->SetSession(const_cast<Session *>(&SO));
 
+  Builder->setupBuilderForSymbolicDisassembly(getLLVMOpInfoCallback(),
+                                              getDisInfoBlock(), getMCContext(),
+                                              Address);
+
   if (!Builder->Build(MI, insn))
     return false;
 
diff --git a/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp b/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp
index 06a7773..d5675d2 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp
@@ -17,6 +17,7 @@
 
 #include "ARMDisassemblerCore.h"
 #include "ARMAddressingModes.h"
+#include "ARMMCExpr.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -1066,7 +1067,8 @@ static bool DisassembleDPFrm(MCInst &MI, unsigned Opcode, uint32_t insn,
     // We have an imm16 = imm4:imm12 (imm4=Inst{19:16}, imm12 = Inst{11:0}).
     assert(getIBit(insn) == 1 && "I_Bit != '1' reg/imm form");
     unsigned Imm16 = slice(insn, 19, 16) << 12 | slice(insn, 11, 0);
-    MI.addOperand(MCOperand::CreateImm(Imm16));
+    if (!B->tryAddingSymbolicOperand(Imm16, 4, MI))
+      MI.addOperand(MCOperand::CreateImm(Imm16));
     ++OpIdx;
   } else {
     // We have a reg/imm form.
@@ -3628,3 +3630,80 @@ ARMBasicMCBuilder *llvm::CreateMCBuilder(unsigned Opcode, ARMFormat Format) {
   return new ARMBasicMCBuilder(Opcode, Format,
                                ARMInsts[Opcode].getNumOperands());
 }
+
+/// tryAddingSymbolicOperand - tryAddingSymbolicOperand trys to add a symbolic
+/// operand in place of the immediate Value in the MCInst.  The immediate
+/// Value has had any PC adjustment made by the caller.  If the getOpInfo()
+/// function was set as part of the setupBuilderForSymbolicDisassembly() call
+/// then that function is called to get any symbolic information at the
+/// builder's Address for this instrution.  If that returns non-zero then the
+/// symbolic information is returns is used to create an MCExpr and that is
+/// added as an operand to the MCInst.  This function returns true if it adds
+/// an operand to the MCInst and false otherwise.
+bool ARMBasicMCBuilder::tryAddingSymbolicOperand(uint64_t Value,
+                                                 uint64_t InstSize,
+                                                 MCInst &MI) {
+  if (!GetOpInfo)
+    return false;
+
+  struct LLVMOpInfo1 SymbolicOp;
+  SymbolicOp.Value = Value;
+  if (!GetOpInfo(DisInfo, Address, 0 /* Offset */, InstSize, 1, &SymbolicOp))
+    return false;
+
+  const MCExpr *Add = NULL;
+  if (SymbolicOp.AddSymbol.Present) {
+    if (SymbolicOp.AddSymbol.Name) {
+      StringRef Name(SymbolicOp.AddSymbol.Name);
+      MCSymbol *Sym = Ctx->GetOrCreateSymbol(Name);
+      Add = MCSymbolRefExpr::Create(Sym, *Ctx);
+    } else {
+      Add = MCConstantExpr::Create(SymbolicOp.AddSymbol.Value, *Ctx);
+    }
+  }
+
+  const MCExpr *Sub = NULL;
+  if (SymbolicOp.SubtractSymbol.Present) {
+    if (SymbolicOp.SubtractSymbol.Name) {
+      StringRef Name(SymbolicOp.SubtractSymbol.Name);
+      MCSymbol *Sym = Ctx->GetOrCreateSymbol(Name);
+      Sub = MCSymbolRefExpr::Create(Sym, *Ctx);
+    } else {
+      Sub = MCConstantExpr::Create(SymbolicOp.SubtractSymbol.Value, *Ctx);
+    }
+  }
+
+  const MCExpr *Off = NULL;
+  if (SymbolicOp.Value != 0)
+    Off = MCConstantExpr::Create(SymbolicOp.Value, *Ctx);
+
+  const MCExpr *Expr;
+  if (Sub) {
+    const MCExpr *LHS;
+    if (Add)
+      LHS = MCBinaryExpr::CreateSub(Add, Sub, *Ctx);
+    else
+      LHS = MCUnaryExpr::CreateMinus(Sub, *Ctx);
+    if (Off != 0)
+      Expr = MCBinaryExpr::CreateAdd(LHS, Off, *Ctx);
+    else
+      Expr = LHS;
+  } else if (Add) {
+    if (Off != 0)
+      Expr = MCBinaryExpr::CreateAdd(Add, Off, *Ctx);
+    else
+      Expr = Add;
+  } else
+    Expr = Off;
+
+  if (SymbolicOp.VariantKind == LLVMDisassembler_VariantKind_ARM_HI16)
+    MI.addOperand(MCOperand::CreateExpr(ARMMCExpr::CreateUpper16(Expr, *Ctx)));
+  else if (SymbolicOp.VariantKind == LLVMDisassembler_VariantKind_ARM_LO16)
+    MI.addOperand(MCOperand::CreateExpr(ARMMCExpr::CreateLower16(Expr, *Ctx)));
+  else if (SymbolicOp.VariantKind == LLVMDisassembler_VariantKind_None)
+    MI.addOperand(MCOperand::CreateExpr(Expr));
+  else 
+    assert("bad SymbolicOp.VariantKind");
+
+  return true;
+}
diff --git a/lib/Target/ARM/Disassembler/ARMDisassemblerCore.h b/lib/Target/ARM/Disassembler/ARMDisassemblerCore.h
index 56dd85a..f720e14 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassemblerCore.h
+++ b/lib/Target/ARM/Disassembler/ARMDisassemblerCore.h
@@ -22,12 +22,17 @@
 #define ARMDISASSEMBLERCORE_H
 
 #include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCContext.h"
 #include "llvm/Target/TargetInstrInfo.h"
+#include "llvm-c/Disassembler.h"
 #include "ARMBaseInstrInfo.h"
 #include "ARMRegisterInfo.h"
 #include "ARMDisassembler.h"
 
 namespace llvm {
+class MCContext;
 
 class ARMUtils {
 public:
@@ -202,7 +207,7 @@ private:
 public:
   ARMBasicMCBuilder(ARMBasicMCBuilder &B)
     : Opcode(B.Opcode), Format(B.Format), NumOps(B.NumOps), Disasm(B.Disasm),
-      SP(B.SP) {
+      SP(B.SP), GetOpInfo(0), DisInfo(0), Ctx(0) {
     Err = 0;
   }
 
@@ -261,6 +266,44 @@ private:
     assert(SP);
     return slice(SP->ITState, 7, 4);
   }
+
+private:
+  //
+  // Hooks for symbolic disassembly via the public 'C' interface.
+  //
+  // The function to get the symbolic information for operands.
+  LLVMOpInfoCallback GetOpInfo;
+  // The pointer to the block of symbolic information for above call back.
+  void *DisInfo;
+  // The assembly context for creating symbols and MCExprs in place of
+  // immediate operands when there is symbolic information.
+  MCContext *Ctx;
+  // The address of the instruction being disassembled.
+  uint64_t Address;
+
+public:
+  void setupBuilderForSymbolicDisassembly(LLVMOpInfoCallback getOpInfo,
+                                          void *disInfo, MCContext *ctx,
+                                          uint64_t address) {
+    GetOpInfo = getOpInfo;
+    DisInfo = disInfo;
+    Ctx = ctx;
+    Address = address;
+  }
+
+  uint64_t getBuilderAddress() const { return Address; }
+
+  /// tryAddingSymbolicOperand - tryAddingSymbolicOperand trys to add a symbolic
+  /// operand in place of the immediate Value in the MCInst.  The immediate
+  /// Value has had any PC adjustment made by the caller.  If the getOpInfo()
+  /// function was set as part of the setupBuilderForSymbolicDisassembly() call
+  /// then that function is called to get any symbolic information at the
+  /// builder's Address for this instrution.  If that returns non-zero then the
+  /// symbolic information is returns is used to create an MCExpr and that is
+  /// added as an operand to the MCInst.  This function returns true if it adds
+  /// an operand to the MCInst and false otherwise.
+  bool tryAddingSymbolicOperand(uint64_t Value, uint64_t InstSize, MCInst &MI);
+
 };
 
 } // namespace llvm
diff --git a/lib/Target/ARM/Disassembler/ThumbDisassemblerCore.h b/lib/Target/ARM/Disassembler/ThumbDisassemblerCore.h
index 6185268..61c4a13 100644
--- a/lib/Target/ARM/Disassembler/ThumbDisassemblerCore.h
+++ b/lib/Target/ARM/Disassembler/ThumbDisassemblerCore.h
@@ -1570,9 +1570,10 @@ static bool DisassembleThumb2DPBinImm(MCInst &MI, unsigned Opcode,
   if (Opcode == ARM::t2ADDri12 || Opcode == ARM::t2SUBri12
       || Opcode == ARM::t2LEApcrel)
     MI.addOperand(MCOperand::CreateImm(getIImm3Imm8(insn)));
-  else if (Opcode == ARM::t2MOVi16 || Opcode == ARM::t2MOVTi16)
-    MI.addOperand(MCOperand::CreateImm(getImm16(insn)));
-  else if (Opcode == ARM::t2BFC || Opcode == ARM::t2BFI) {
+  else if (Opcode == ARM::t2MOVi16 || Opcode == ARM::t2MOVTi16) {
+    if (!B->tryAddingSymbolicOperand(getImm16(insn), 4, MI))
+      MI.addOperand(MCOperand::CreateImm(getImm16(insn)));
+  } else if (Opcode == ARM::t2BFC || Opcode == ARM::t2BFI) {
     uint32_t mask = 0;
     if (getBitfieldInvMask(insn, mask))
       MI.addOperand(MCOperand::CreateImm(mask));
@@ -1756,7 +1757,9 @@ static bool DisassembleThumb2BrMiscCtrl(MCInst &MI, unsigned Opcode,
     Offset = decodeImm32_BLX(insn);
     break;
   }
-  MI.addOperand(MCOperand::CreateImm(Offset));
+
+  if (!B->tryAddingSymbolicOperand(Offset + B->getBuilderAddress() + 4, 4, MI))
+    MI.addOperand(MCOperand::CreateImm(Offset));
 
   // This is an increment as some predicate operands may have been added first.
   NumOpsAdded += 1;