llvm-6502/lib/MC/MCExternalSymbolizer.cpp
Kevin Enderby 6f45b1f0d6 Add to the disassembler C API output reference types for
Objective-C data structures.

This is allows tools such as darwin's otool(1) that uses the
LLVM disassembler take a pointer value being loaded by
an instruction and add a comment to what it is being referenced
to make following disassembly of Objective-C programs
more readable.

For example disassembling the Mac OS X TextEdit app one
will see comments like the following:

movq    0x20684(%rip), %rsi ## Objc selector ref: standardUserDefaults
movq    0x21985(%rip), %rdi ## Objc class ref: _OBJC_CLASS_$_NSUserDefaults
movq    0x1d156(%rip), %r14 ## Objc message: +[NSUserDefaults standardUserDefaults]
leaq    0x23615(%rip), %rdx ## Objc cfstring ref: @"SelectLinePanel"
callq   0x10001386c ## Objc message: -[[%rdi super] initWithWindowNibName:]

These diffs also include putting quotes around C strings
in literal pools and uses "symbol address" in the comment
when adding a symbol name to the comment to tell these
types of references apart:

leaq	0x4f(%rip), %rax ## literal pool for: "Hello world"
movq    0x1c3ea(%rip), %rax ## literal pool symbol address: ___stack_chk_guard

Of course the easy changes are in the LLVM disassembler and
the hard work is up to the implementer of the SymbolLookUp()
call back.

rdar://10602439


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193833 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-01 00:00:07 +00:00

182 lines
7.4 KiB
C++

//===-- lib/MC/MCExternalSymbolizer.cpp - External symbolizer ---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCExternalSymbolizer.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/Support/raw_ostream.h"
#include <cstring>
using namespace llvm;
// This function tries 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 instruction is a branch instruction then IsBranch is true,
// else false. If the getOpInfo() function was set as part of the
// setupForSymbolicDisassembly() call then that function is called to get any
// symbolic information at the Address for this instruction. If that returns
// non-zero then the symbolic information it returns is used to create an MCExpr
// and that is added as an operand to the MCInst. If getOpInfo() returns zero
// and IsBranch is true then a symbol look up for Value is done and if a symbol
// is found an MCExpr is created with that, else an MCExpr with Value is
// created. This function returns true if it adds an operand to the MCInst and
// false otherwise.
bool MCExternalSymbolizer::tryAddingSymbolicOperand(MCInst &MI,
raw_ostream &cStream,
int64_t Value,
uint64_t Address,
bool IsBranch,
uint64_t Offset,
uint64_t InstSize) {
struct LLVMOpInfo1 SymbolicOp;
std::memset(&SymbolicOp, '\0', sizeof(struct LLVMOpInfo1));
SymbolicOp.Value = Value;
if (!GetOpInfo ||
!GetOpInfo(DisInfo, Address, Offset, InstSize, 1, &SymbolicOp)) {
// Clear SymbolicOp.Value from above and also all other fields.
std::memset(&SymbolicOp, '\0', sizeof(struct LLVMOpInfo1));
if (!SymbolLookUp)
return false;
uint64_t ReferenceType;
if (IsBranch)
ReferenceType = LLVMDisassembler_ReferenceType_In_Branch;
else
ReferenceType = LLVMDisassembler_ReferenceType_InOut_None;
const char *ReferenceName;
const char *Name = SymbolLookUp(DisInfo, Value, &ReferenceType, Address,
&ReferenceName);
if (Name) {
SymbolicOp.AddSymbol.Name = Name;
SymbolicOp.AddSymbol.Present = true;
}
// For branches always create an MCExpr so it gets printed as hex address.
else if (IsBranch) {
SymbolicOp.Value = Value;
}
if(ReferenceType == LLVMDisassembler_ReferenceType_Out_SymbolStub)
cStream << "symbol stub for: " << ReferenceName;
else if(ReferenceType == LLVMDisassembler_ReferenceType_Out_Objc_Message)
cStream << "Objc message: " << ReferenceName;
if (!Name && !IsBranch)
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((int)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((int)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 {
if (Off != 0)
Expr = Off;
else
Expr = MCConstantExpr::Create(0, Ctx);
}
Expr = RelInfo->createExprForCAPIVariantKind(Expr, SymbolicOp.VariantKind);
if (!Expr)
return false;
MI.addOperand(MCOperand::CreateExpr(Expr));
return true;
}
// This function tries to add a comment as to what is being referenced by a load
// instruction with the base register that is the Pc. These can often be values
// in a literal pool near the Address of the instruction. The Address of the
// instruction and its immediate Value are used as a possible literal pool entry.
// The SymbolLookUp call back will return the name of a symbol referenced by the
// literal pool's entry if the referenced address is that of a symbol. Or it
// will return a pointer to a literal 'C' string if the referenced address of
// the literal pool's entry is an address into a section with C string literals.
// Or if the reference is to an Objective-C data structure it will return a
// specific reference type for it and a string.
void MCExternalSymbolizer::tryAddingPcLoadReferenceComment(raw_ostream &cStream,
int64_t Value,
uint64_t Address) {
if (SymbolLookUp) {
uint64_t ReferenceType = LLVMDisassembler_ReferenceType_In_PCrel_Load;
const char *ReferenceName;
(void)SymbolLookUp(DisInfo, Value, &ReferenceType, Address, &ReferenceName);
if(ReferenceType == LLVMDisassembler_ReferenceType_Out_LitPool_SymAddr)
cStream << "literal pool symbol address: " << ReferenceName;
else if(ReferenceType ==
LLVMDisassembler_ReferenceType_Out_LitPool_CstrAddr)
cStream << "literal pool for: \"" << ReferenceName << "\"";
else if(ReferenceType ==
LLVMDisassembler_ReferenceType_Out_Objc_CFString_Ref)
cStream << "Objc cfstring ref: @\"" << ReferenceName << "\"";
else if(ReferenceType ==
LLVMDisassembler_ReferenceType_Out_Objc_Message)
cStream << "Objc message: " << ReferenceName;
else if(ReferenceType ==
LLVMDisassembler_ReferenceType_Out_Objc_Message_Ref)
cStream << "Objc message ref: " << ReferenceName;
else if(ReferenceType ==
LLVMDisassembler_ReferenceType_Out_Objc_Selector_Ref)
cStream << "Objc selector ref: " << ReferenceName;
else if(ReferenceType ==
LLVMDisassembler_ReferenceType_Out_Objc_Class_Ref)
cStream << "Objc class ref: " << ReferenceName;
}
}
namespace llvm {
MCSymbolizer *createMCSymbolizer(StringRef TT, LLVMOpInfoCallback GetOpInfo,
LLVMSymbolLookupCallback SymbolLookUp,
void *DisInfo,
MCContext *Ctx,
MCRelocationInfo *RelInfo) {
assert(Ctx != 0 && "No MCContext given for symbolic disassembly");
OwningPtr<MCRelocationInfo> RelInfoOwingPtr(RelInfo);
return new MCExternalSymbolizer(*Ctx, RelInfoOwingPtr, GetOpInfo,
SymbolLookUp, DisInfo);
}
}