1 //===- PNaCl.cpp ----------------------------------------------------------===//
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 #include "ABIInfoImpl.h"
10 #include "TargetInfo.h"
11
12 using namespace clang;
13 using namespace clang::CodeGen;
14
15 //===----------------------------------------------------------------------===//
16 // le32/PNaCl bitcode ABI Implementation
17 //
18 // This is a simplified version of the x86_32 ABI. Arguments and return values
19 // are always passed on the stack.
20 //===----------------------------------------------------------------------===//
21
22 class PNaClABIInfo : public ABIInfo {
23 public:
PNaClABIInfo(CodeGen::CodeGenTypes & CGT)24 PNaClABIInfo(CodeGen::CodeGenTypes &CGT) : ABIInfo(CGT) {}
25
26 ABIArgInfo classifyReturnType(QualType RetTy) const;
27 ABIArgInfo classifyArgumentType(QualType RetTy) const;
28
29 void computeInfo(CGFunctionInfo &FI) const override;
30 RValue EmitVAArg(CodeGenFunction &CGF, Address VAListAddr, QualType Ty,
31 AggValueSlot Slot) const override;
32 };
33
34 class PNaClTargetCodeGenInfo : public TargetCodeGenInfo {
35 public:
PNaClTargetCodeGenInfo(CodeGen::CodeGenTypes & CGT)36 PNaClTargetCodeGenInfo(CodeGen::CodeGenTypes &CGT)
37 : TargetCodeGenInfo(std::make_unique<PNaClABIInfo>(CGT)) {}
38 };
39
computeInfo(CGFunctionInfo & FI) const40 void PNaClABIInfo::computeInfo(CGFunctionInfo &FI) const {
41 if (!getCXXABI().classifyReturnType(FI))
42 FI.getReturnInfo() = classifyReturnType(FI.getReturnType());
43
44 for (auto &I : FI.arguments())
45 I.info = classifyArgumentType(I.type);
46 }
47
EmitVAArg(CodeGenFunction & CGF,Address VAListAddr,QualType Ty,AggValueSlot Slot) const48 RValue PNaClABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
49 QualType Ty, AggValueSlot Slot) const {
50 // The PNaCL ABI is a bit odd, in that varargs don't use normal
51 // function classification. Structs get passed directly for varargs
52 // functions, through a rewriting transform in
53 // pnacl-llvm/lib/Transforms/NaCl/ExpandVarArgs.cpp, which allows
54 // this target to actually support a va_arg instructions with an
55 // aggregate type, unlike other targets.
56 return CGF.EmitLoadOfAnyValue(
57 CGF.MakeAddrLValue(
58 EmitVAArgInstr(CGF, VAListAddr, Ty, ABIArgInfo::getDirect()), Ty),
59 Slot);
60 }
61
62 /// Classify argument of given type \p Ty.
classifyArgumentType(QualType Ty) const63 ABIArgInfo PNaClABIInfo::classifyArgumentType(QualType Ty) const {
64 if (isAggregateTypeForABI(Ty)) {
65 if (CGCXXABI::RecordArgABI RAA = getRecordArgABI(Ty, getCXXABI()))
66 return getNaturalAlignIndirect(Ty, RAA == CGCXXABI::RAA_DirectInMemory);
67 return getNaturalAlignIndirect(Ty);
68 } else if (const EnumType *EnumTy = Ty->getAs<EnumType>()) {
69 // Treat an enum type as its underlying type.
70 Ty = EnumTy->getDecl()->getIntegerType();
71 } else if (Ty->isFloatingType()) {
72 // Floating-point types don't go inreg.
73 return ABIArgInfo::getDirect();
74 } else if (const auto *EIT = Ty->getAs<BitIntType>()) {
75 // Treat bit-precise integers as integers if <= 64, otherwise pass
76 // indirectly.
77 if (EIT->getNumBits() > 64)
78 return getNaturalAlignIndirect(Ty);
79 return ABIArgInfo::getDirect();
80 }
81
82 return (isPromotableIntegerTypeForABI(Ty) ? ABIArgInfo::getExtend(Ty)
83 : ABIArgInfo::getDirect());
84 }
85
classifyReturnType(QualType RetTy) const86 ABIArgInfo PNaClABIInfo::classifyReturnType(QualType RetTy) const {
87 if (RetTy->isVoidType())
88 return ABIArgInfo::getIgnore();
89
90 // In the PNaCl ABI we always return records/structures on the stack.
91 if (isAggregateTypeForABI(RetTy))
92 return getNaturalAlignIndirect(RetTy);
93
94 // Treat bit-precise integers as integers if <= 64, otherwise pass indirectly.
95 if (const auto *EIT = RetTy->getAs<BitIntType>()) {
96 if (EIT->getNumBits() > 64)
97 return getNaturalAlignIndirect(RetTy);
98 return ABIArgInfo::getDirect();
99 }
100
101 // Treat an enum type as its underlying type.
102 if (const EnumType *EnumTy = RetTy->getAs<EnumType>())
103 RetTy = EnumTy->getDecl()->getIntegerType();
104
105 return (isPromotableIntegerTypeForABI(RetTy) ? ABIArgInfo::getExtend(RetTy)
106 : ABIArgInfo::getDirect());
107 }
108
109 std::unique_ptr<TargetCodeGenInfo>
createPNaClTargetCodeGenInfo(CodeGenModule & CGM)110 CodeGen::createPNaClTargetCodeGenInfo(CodeGenModule &CGM) {
111 return std::make_unique<PNaClTargetCodeGenInfo>(CGM.getTypes());
112 }
113