1 // WebAssemblyMachineFunctionInfo.h-WebAssembly machine function info-*- C++ -*-
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 ///
9 /// \file
10 /// This file declares WebAssembly-specific per-machine-function
11 /// information.
12 ///
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYMACHINEFUNCTIONINFO_H
16 #define LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYMACHINEFUNCTIONINFO_H
17 
18 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
19 #include "llvm/BinaryFormat/Wasm.h"
20 #include "llvm/CodeGen/MachineRegisterInfo.h"
21 #include "llvm/MC/MCSymbolWasm.h"
22 
23 namespace llvm {
24 
25 /// This class is derived from MachineFunctionInfo and contains private
26 /// WebAssembly-specific information for each MachineFunction.
27 class WebAssemblyFunctionInfo final : public MachineFunctionInfo {
28   MachineFunction &MF;
29 
30   std::vector<MVT> Params;
31   std::vector<MVT> Results;
32   std::vector<MVT> Locals;
33 
34   /// A mapping from CodeGen vreg index to WebAssembly register number.
35   std::vector<unsigned> WARegs;
36 
37   /// A mapping from CodeGen vreg index to a boolean value indicating whether
38   /// the given register is considered to be "stackified", meaning it has been
39   /// determined or made to meet the stack requirements:
40   ///   - single use (per path)
41   ///   - single def (per path)
42   ///   - defined and used in LIFO order with other stack registers
43   BitVector VRegStackified;
44 
45   // A virtual register holding the pointer to the vararg buffer for vararg
46   // functions. It is created and set in TLI::LowerFormalArguments and read by
47   // TLI::LowerVASTART
48   unsigned VarargVreg = -1U;
49 
50   // A virtual register holding the base pointer for functions that have
51   // overaligned values on the user stack.
52   unsigned BasePtrVreg = -1U;
53 
54 public:
55   explicit WebAssemblyFunctionInfo(MachineFunction &MF) : MF(MF) {}
56   ~WebAssemblyFunctionInfo() override;
57 
58   void addParam(MVT VT) { Params.push_back(VT); }
59   const std::vector<MVT> &getParams() const { return Params; }
60 
61   void addResult(MVT VT) { Results.push_back(VT); }
62   const std::vector<MVT> &getResults() const { return Results; }
63 
64   void clearParamsAndResults() {
65     Params.clear();
66     Results.clear();
67   }
68 
69   void setNumLocals(size_t NumLocals) { Locals.resize(NumLocals, MVT::i32); }
70   void setLocal(size_t i, MVT VT) { Locals[i] = VT; }
71   void addLocal(MVT VT) { Locals.push_back(VT); }
72   const std::vector<MVT> &getLocals() const { return Locals; }
73 
74   unsigned getVarargBufferVreg() const {
75     assert(VarargVreg != -1U && "Vararg vreg hasn't been set");
76     return VarargVreg;
77   }
78   void setVarargBufferVreg(unsigned Reg) { VarargVreg = Reg; }
79 
80   unsigned getBasePointerVreg() const {
81     assert(BasePtrVreg != -1U && "Base ptr vreg hasn't been set");
82     return BasePtrVreg;
83   }
84   void setBasePointerVreg(unsigned Reg) { BasePtrVreg = Reg; }
85 
86   static const unsigned UnusedReg = -1u;
87 
88   void stackifyVReg(unsigned VReg) {
89     assert(MF.getRegInfo().getUniqueVRegDef(VReg));
90     auto I = TargetRegisterInfo::virtReg2Index(VReg);
91     if (I >= VRegStackified.size())
92       VRegStackified.resize(I + 1);
93     VRegStackified.set(I);
94   }
95   bool isVRegStackified(unsigned VReg) const {
96     auto I = TargetRegisterInfo::virtReg2Index(VReg);
97     if (I >= VRegStackified.size())
98       return false;
99     return VRegStackified.test(I);
100   }
101 
102   void initWARegs();
103   void setWAReg(unsigned VReg, unsigned WAReg) {
104     assert(WAReg != UnusedReg);
105     auto I = TargetRegisterInfo::virtReg2Index(VReg);
106     assert(I < WARegs.size());
107     WARegs[I] = WAReg;
108   }
109   unsigned getWAReg(unsigned VReg) const {
110     auto I = TargetRegisterInfo::virtReg2Index(VReg);
111     assert(I < WARegs.size());
112     return WARegs[I];
113   }
114 
115   // For a given stackified WAReg, return the id number to print with push/pop.
116   static unsigned getWARegStackId(unsigned Reg) {
117     assert(Reg & INT32_MIN);
118     return Reg & INT32_MAX;
119   }
120 };
121 
122 void computeLegalValueVTs(const Function &F, const TargetMachine &TM, Type *Ty,
123                           SmallVectorImpl<MVT> &ValueVTs);
124 
125 // Compute the signature for a given FunctionType (Ty). Note that it's not the
126 // signature for F (F is just used to get varous context)
127 void computeSignatureVTs(const FunctionType *Ty, const Function &F,
128                          const TargetMachine &TM, SmallVectorImpl<MVT> &Params,
129                          SmallVectorImpl<MVT> &Results);
130 
131 void valTypesFromMVTs(const ArrayRef<MVT> &In,
132                       SmallVectorImpl<wasm::ValType> &Out);
133 
134 std::unique_ptr<wasm::WasmSignature>
135 signatureFromMVTs(const SmallVectorImpl<MVT> &Results,
136                   const SmallVectorImpl<MVT> &Params);
137 
138 } // end namespace llvm
139 
140 #endif
141