1 //===-- InstrinsicInst.cpp - Intrinsic Instruction Wrappers ---------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements methods that make it really easy to deal with intrinsic
11 // functions.
12 //
13 // All intrinsic function calls are instances of the call instruction, so these
14 // are all subclasses of the CallInst class.  Note that none of these classes
15 // has state or virtual methods, which is an important part of this gross/neat
16 // hack working.
17 //
18 // In some cases, arguments to intrinsics need to be generic and are defined as
19 // type pointer to empty struct { }*.  To access the real item of interest the
20 // cast instruction needs to be stripped away.
21 //
22 //===----------------------------------------------------------------------===//
23 
24 #include "llvm/IR/IntrinsicInst.h"
25 #include "llvm/IR/Constants.h"
26 #include "llvm/IR/GlobalVariable.h"
27 #include "llvm/IR/Metadata.h"
28 using namespace llvm;
29 
30 //===----------------------------------------------------------------------===//
31 /// DbgInfoIntrinsic - This is the common base class for debug info intrinsics
32 ///
33 
CastOperand(Value * C)34 static Value *CastOperand(Value *C) {
35   if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
36     if (CE->isCast())
37       return CE->getOperand(0);
38   return nullptr;
39 }
40 
StripCast(Value * C)41 Value *DbgInfoIntrinsic::StripCast(Value *C) {
42   if (Value *CO = CastOperand(C)) {
43     C = StripCast(CO);
44   } else if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
45     if (GV->hasInitializer())
46       if (Value *CO = CastOperand(GV->getInitializer()))
47         C = StripCast(CO);
48   }
49   return dyn_cast<GlobalVariable>(C);
50 }
51 
getValueImpl(Value * Op)52 static Value *getValueImpl(Value *Op) {
53   auto *MD = cast<MetadataAsValue>(Op)->getMetadata();
54   if (auto *V = dyn_cast<ValueAsMetadata>(MD))
55     return V->getValue();
56 
57   // When the value goes to null, it gets replaced by an empty MDNode.
58   assert(!cast<MDNode>(MD)->getNumOperands() && "Expected an empty MDNode");
59   return nullptr;
60 }
61 
62 //===----------------------------------------------------------------------===//
63 /// DbgDeclareInst - This represents the llvm.dbg.declare instruction.
64 ///
65 
getAddress() const66 Value *DbgDeclareInst::getAddress() const {
67   if (!getArgOperand(0))
68     return nullptr;
69 
70   return getValueImpl(getArgOperand(0));
71 }
72 
73 //===----------------------------------------------------------------------===//
74 /// DbgValueInst - This represents the llvm.dbg.value instruction.
75 ///
76 
getValue() const77 const Value *DbgValueInst::getValue() const {
78   return const_cast<DbgValueInst *>(this)->getValue();
79 }
80 
getValue()81 Value *DbgValueInst::getValue() { return getValueImpl(getArgOperand(0)); }
82