1 //===----- CGCall.h - Encapsulate calling convention details ----*- C++ -*-===//
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 // These classes wrap the information about a call or function
11 // definition used to handle ABI compliancy.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_CLANG_LIB_CODEGEN_CGCALL_H
16 #define LLVM_CLANG_LIB_CODEGEN_CGCALL_H
17 
18 #include "CGValue.h"
19 #include "EHScopeStack.h"
20 #include "clang/AST/CanonicalType.h"
21 #include "clang/AST/Type.h"
22 #include "llvm/ADT/FoldingSet.h"
23 #include "llvm/IR/Value.h"
24 
25 // FIXME: Restructure so we don't have to expose so much stuff.
26 #include "ABIInfo.h"
27 
28 namespace llvm {
29   class AttributeSet;
30   class Function;
31   class Type;
32   class Value;
33 }
34 
35 namespace clang {
36   class ASTContext;
37   class Decl;
38   class FunctionDecl;
39   class ObjCMethodDecl;
40   class VarDecl;
41 
42 namespace CodeGen {
43   typedef SmallVector<llvm::AttributeSet, 8> AttributeListType;
44 
45   struct CallArg {
46     RValue RV;
47     QualType Ty;
48     bool NeedsCopy;
CallArgCallArg49     CallArg(RValue rv, QualType ty, bool needscopy)
50     : RV(rv), Ty(ty), NeedsCopy(needscopy)
51     { }
52   };
53 
54   /// CallArgList - Type for representing both the value and type of
55   /// arguments in a call.
56   class CallArgList :
57     public SmallVector<CallArg, 16> {
58   public:
CallArgList()59     CallArgList() : StackBase(nullptr) {}
60 
61     struct Writeback {
62       /// The original argument.  Note that the argument l-value
63       /// is potentially null.
64       LValue Source;
65 
66       /// The temporary alloca.
67       Address Temporary;
68 
69       /// A value to "use" after the writeback, or null.
70       llvm::Value *ToUse;
71     };
72 
73     struct CallArgCleanup {
74       EHScopeStack::stable_iterator Cleanup;
75 
76       /// The "is active" insertion point.  This instruction is temporary and
77       /// will be removed after insertion.
78       llvm::Instruction *IsActiveIP;
79     };
80 
81     void add(RValue rvalue, QualType type, bool needscopy = false) {
82       push_back(CallArg(rvalue, type, needscopy));
83     }
84 
addFrom(const CallArgList & other)85     void addFrom(const CallArgList &other) {
86       insert(end(), other.begin(), other.end());
87       Writebacks.insert(Writebacks.end(),
88                         other.Writebacks.begin(), other.Writebacks.end());
89     }
90 
addWriteback(LValue srcLV,Address temporary,llvm::Value * toUse)91     void addWriteback(LValue srcLV, Address temporary,
92                       llvm::Value *toUse) {
93       Writeback writeback = { srcLV, temporary, toUse };
94       Writebacks.push_back(writeback);
95     }
96 
hasWritebacks()97     bool hasWritebacks() const { return !Writebacks.empty(); }
98 
99     typedef llvm::iterator_range<SmallVectorImpl<Writeback>::const_iterator>
100       writeback_const_range;
101 
writebacks()102     writeback_const_range writebacks() const {
103       return writeback_const_range(Writebacks.begin(), Writebacks.end());
104     }
105 
addArgCleanupDeactivation(EHScopeStack::stable_iterator Cleanup,llvm::Instruction * IsActiveIP)106     void addArgCleanupDeactivation(EHScopeStack::stable_iterator Cleanup,
107                                    llvm::Instruction *IsActiveIP) {
108       CallArgCleanup ArgCleanup;
109       ArgCleanup.Cleanup = Cleanup;
110       ArgCleanup.IsActiveIP = IsActiveIP;
111       CleanupsToDeactivate.push_back(ArgCleanup);
112     }
113 
getCleanupsToDeactivate()114     ArrayRef<CallArgCleanup> getCleanupsToDeactivate() const {
115       return CleanupsToDeactivate;
116     }
117 
118     void allocateArgumentMemory(CodeGenFunction &CGF);
getStackBase()119     llvm::Instruction *getStackBase() const { return StackBase; }
120     void freeArgumentMemory(CodeGenFunction &CGF) const;
121 
122     /// \brief Returns if we're using an inalloca struct to pass arguments in
123     /// memory.
isUsingInAlloca()124     bool isUsingInAlloca() const { return StackBase; }
125 
126   private:
127     SmallVector<Writeback, 1> Writebacks;
128 
129     /// Deactivate these cleanups immediately before making the call.  This
130     /// is used to cleanup objects that are owned by the callee once the call
131     /// occurs.
132     SmallVector<CallArgCleanup, 1> CleanupsToDeactivate;
133 
134     /// The stacksave call.  It dominates all of the argument evaluation.
135     llvm::CallInst *StackBase;
136 
137     /// The iterator pointing to the stack restore cleanup.  We manually run and
138     /// deactivate this cleanup after the call in the unexceptional case because
139     /// it doesn't run in the normal order.
140     EHScopeStack::stable_iterator StackCleanup;
141   };
142 
143   /// FunctionArgList - Type for representing both the decl and type
144   /// of parameters to a function. The decl must be either a
145   /// ParmVarDecl or ImplicitParamDecl.
146   class FunctionArgList : public SmallVector<const VarDecl*, 16> {
147   };
148 
149   /// ReturnValueSlot - Contains the address where the return value of a
150   /// function can be stored, and whether the address is volatile or not.
151   class ReturnValueSlot {
152     llvm::PointerIntPair<llvm::Value *, 2, unsigned int> Value;
153     CharUnits Alignment;
154 
155     // Return value slot flags
156     enum Flags {
157       IS_VOLATILE = 0x1,
158       IS_UNUSED = 0x2,
159     };
160 
161   public:
ReturnValueSlot()162     ReturnValueSlot() {}
163     ReturnValueSlot(Address Addr, bool IsVolatile, bool IsUnused = false)
164       : Value(Addr.isValid() ? Addr.getPointer() : nullptr,
165               (IsVolatile ? IS_VOLATILE : 0) | (IsUnused ? IS_UNUSED : 0)),
166         Alignment(Addr.isValid() ? Addr.getAlignment() : CharUnits::Zero()) {}
167 
isNull()168     bool isNull() const { return !getValue().isValid(); }
169 
isVolatile()170     bool isVolatile() const { return Value.getInt() & IS_VOLATILE; }
getValue()171     Address getValue() const { return Address(Value.getPointer(), Alignment); }
isUnused()172     bool isUnused() const { return Value.getInt() & IS_UNUSED; }
173   };
174 
175 }  // end namespace CodeGen
176 }  // end namespace clang
177 
178 #endif
179