clang 19.0.0git
CGGPUBuiltin.cpp
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1//===------ CGGPUBuiltin.cpp - Codegen for GPU builtins -------------------===//
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// Generates code for built-in GPU calls which are not runtime-specific.
10// (Runtime-specific codegen lives in programming model specific files.)
11//
12//===----------------------------------------------------------------------===//
13
14#include "CodeGenFunction.h"
16#include "llvm/IR/DataLayout.h"
17#include "llvm/IR/Instruction.h"
18#include "llvm/Support/MathExtras.h"
19#include "llvm/Transforms/Utils/AMDGPUEmitPrintf.h"
20
21using namespace clang;
22using namespace CodeGen;
23
24namespace {
25llvm::Function *GetVprintfDeclaration(llvm::Module &M) {
26 llvm::Type *ArgTypes[] = {llvm::PointerType::getUnqual(M.getContext()),
27 llvm::PointerType::getUnqual(M.getContext())};
28 llvm::FunctionType *VprintfFuncType = llvm::FunctionType::get(
29 llvm::Type::getInt32Ty(M.getContext()), ArgTypes, false);
30
31 if (auto *F = M.getFunction("vprintf")) {
32 // Our CUDA system header declares vprintf with the right signature, so
33 // nobody else should have been able to declare vprintf with a bogus
34 // signature.
35 assert(F->getFunctionType() == VprintfFuncType);
36 return F;
37 }
38
39 // vprintf doesn't already exist; create a declaration and insert it into the
40 // module.
41 return llvm::Function::Create(
42 VprintfFuncType, llvm::GlobalVariable::ExternalLinkage, "vprintf", &M);
43}
44
45llvm::Function *GetOpenMPVprintfDeclaration(CodeGenModule &CGM) {
46 const char *Name = "__llvm_omp_vprintf";
47 llvm::Module &M = CGM.getModule();
48 llvm::Type *ArgTypes[] = {llvm::PointerType::getUnqual(M.getContext()),
49 llvm::PointerType::getUnqual(M.getContext()),
50 llvm::Type::getInt32Ty(M.getContext())};
51 llvm::FunctionType *VprintfFuncType = llvm::FunctionType::get(
52 llvm::Type::getInt32Ty(M.getContext()), ArgTypes, false);
53
54 if (auto *F = M.getFunction(Name)) {
55 if (F->getFunctionType() != VprintfFuncType) {
57 "Invalid type declaration for __llvm_omp_vprintf");
58 return nullptr;
59 }
60 return F;
61 }
62
63 return llvm::Function::Create(
64 VprintfFuncType, llvm::GlobalVariable::ExternalLinkage, Name, &M);
65}
66
67// Transforms a call to printf into a call to the NVPTX vprintf syscall (which
68// isn't particularly special; it's invoked just like a regular function).
69// vprintf takes two args: A format string, and a pointer to a buffer containing
70// the varargs.
71//
72// For example, the call
73//
74// printf("format string", arg1, arg2, arg3);
75//
76// is converted into something resembling
77//
78// struct Tmp {
79// Arg1 a1;
80// Arg2 a2;
81// Arg3 a3;
82// };
83// char* buf = alloca(sizeof(Tmp));
84// *(Tmp*)buf = {a1, a2, a3};
85// vprintf("format string", buf);
86//
87// buf is aligned to the max of {alignof(Arg1), ...}. Furthermore, each of the
88// args is itself aligned to its preferred alignment.
89//
90// Note that by the time this function runs, E's args have already undergone the
91// standard C vararg promotion (short -> int, float -> double, etc.).
92
93std::pair<llvm::Value *, llvm::TypeSize>
94packArgsIntoNVPTXFormatBuffer(CodeGenFunction *CGF, const CallArgList &Args) {
95 const llvm::DataLayout &DL = CGF->CGM.getDataLayout();
96 llvm::LLVMContext &Ctx = CGF->CGM.getLLVMContext();
97 CGBuilderTy &Builder = CGF->Builder;
98
99 // Construct and fill the args buffer that we'll pass to vprintf.
100 if (Args.size() <= 1) {
101 // If there are no args, pass a null pointer and size 0
102 llvm::Value *BufferPtr =
103 llvm::ConstantPointerNull::get(llvm::PointerType::getUnqual(Ctx));
104 return {BufferPtr, llvm::TypeSize::getFixed(0)};
105 } else {
107 for (unsigned I = 1, NumArgs = Args.size(); I < NumArgs; ++I)
108 ArgTypes.push_back(Args[I].getRValue(*CGF).getScalarVal()->getType());
109
110 // Using llvm::StructType is correct only because printf doesn't accept
111 // aggregates. If we had to handle aggregates here, we'd have to manually
112 // compute the offsets within the alloca -- we wouldn't be able to assume
113 // that the alignment of the llvm type was the same as the alignment of the
114 // clang type.
115 llvm::Type *AllocaTy = llvm::StructType::create(ArgTypes, "printf_args");
116 llvm::Value *Alloca = CGF->CreateTempAlloca(AllocaTy);
117
118 for (unsigned I = 1, NumArgs = Args.size(); I < NumArgs; ++I) {
119 llvm::Value *P = Builder.CreateStructGEP(AllocaTy, Alloca, I - 1);
120 llvm::Value *Arg = Args[I].getRValue(*CGF).getScalarVal();
121 Builder.CreateAlignedStore(Arg, P, DL.getPrefTypeAlign(Arg->getType()));
122 }
123 llvm::Value *BufferPtr =
124 Builder.CreatePointerCast(Alloca, llvm::PointerType::getUnqual(Ctx));
125 return {BufferPtr, DL.getTypeAllocSize(AllocaTy)};
126 }
127}
128
129bool containsNonScalarVarargs(CodeGenFunction *CGF, const CallArgList &Args) {
130 return llvm::any_of(llvm::drop_begin(Args), [&](const CallArg &A) {
131 return !A.getRValue(*CGF).isScalar();
132 });
133}
134
135RValue EmitDevicePrintfCallExpr(const CallExpr *E, CodeGenFunction *CGF,
136 llvm::Function *Decl, bool WithSizeArg) {
137 CodeGenModule &CGM = CGF->CGM;
138 CGBuilderTy &Builder = CGF->Builder;
139 assert(E->getBuiltinCallee() == Builtin::BIprintf ||
140 E->getBuiltinCallee() == Builtin::BI__builtin_printf);
141 assert(E->getNumArgs() >= 1); // printf always has at least one arg.
142
143 // Uses the same format as nvptx for the argument packing, but also passes
144 // an i32 for the total size of the passed pointer
145 CallArgList Args;
146 CGF->EmitCallArgs(Args,
148 E->arguments(), E->getDirectCallee(),
149 /* ParamsToSkip = */ 0);
150
151 // We don't know how to emit non-scalar varargs.
152 if (containsNonScalarVarargs(CGF, Args)) {
153 CGM.ErrorUnsupported(E, "non-scalar arg to printf");
154 return RValue::get(llvm::ConstantInt::get(CGF->IntTy, 0));
155 }
156
157 auto r = packArgsIntoNVPTXFormatBuffer(CGF, Args);
158 llvm::Value *BufferPtr = r.first;
159
161 Args[0].getRValue(*CGF).getScalarVal(), BufferPtr};
162 if (WithSizeArg) {
163 // Passing > 32bit of data as a local alloca doesn't work for nvptx or
164 // amdgpu
165 llvm::Constant *Size =
166 llvm::ConstantInt::get(llvm::Type::getInt32Ty(CGM.getLLVMContext()),
167 static_cast<uint32_t>(r.second.getFixedValue()));
168
169 Vec.push_back(Size);
170 }
171 return RValue::get(Builder.CreateCall(Decl, Vec));
172}
173} // namespace
174
175RValue CodeGenFunction::EmitNVPTXDevicePrintfCallExpr(const CallExpr *E) {
176 assert(getTarget().getTriple().isNVPTX());
177 return EmitDevicePrintfCallExpr(
178 E, this, GetVprintfDeclaration(CGM.getModule()), false);
179}
180
182 assert(getTarget().getTriple().getArch() == llvm::Triple::amdgcn);
183 assert(E->getBuiltinCallee() == Builtin::BIprintf ||
184 E->getBuiltinCallee() == Builtin::BI__builtin_printf);
185 assert(E->getNumArgs() >= 1); // printf always has at least one arg.
186
187 CallArgList CallArgs;
188 EmitCallArgs(CallArgs,
190 E->arguments(), E->getDirectCallee(),
191 /* ParamsToSkip = */ 0);
192
194 for (const auto &A : CallArgs) {
195 // We don't know how to emit non-scalar varargs.
196 if (!A.getRValue(*this).isScalar()) {
197 CGM.ErrorUnsupported(E, "non-scalar arg to printf");
198 return RValue::get(llvm::ConstantInt::get(IntTy, -1));
199 }
200
201 llvm::Value *Arg = A.getRValue(*this).getScalarVal();
202 Args.push_back(Arg);
203 }
204
205 llvm::IRBuilder<> IRB(Builder.GetInsertBlock(), Builder.GetInsertPoint());
206 IRB.SetCurrentDebugLocation(Builder.getCurrentDebugLocation());
207
208 bool isBuffered = (CGM.getTarget().getTargetOpts().AMDGPUPrintfKindVal ==
210 auto Printf = llvm::emitAMDGPUPrintfCall(IRB, Args, isBuffered);
211 Builder.SetInsertPoint(IRB.GetInsertBlock(), IRB.GetInsertPoint());
212 return RValue::get(Printf);
213}
214
216 assert(getTarget().getTriple().isNVPTX() ||
217 getTarget().getTriple().isAMDGCN());
218 return EmitDevicePrintfCallExpr(E, this, GetOpenMPVprintfDeclaration(CGM),
219 true);
220}
StringRef P
Defines enum values for all the target-independent builtin functions.
CallExpr - Represents a function call (C99 6.5.2.2, C++ [expr.call]).
Definition: Expr.h:2795
unsigned getBuiltinCallee() const
getBuiltinCallee - If this is a call to a builtin, return the builtin ID of the callee.
Definition: Expr.cpp:1548
FunctionDecl * getDirectCallee()
If the callee is a FunctionDecl, return it. Otherwise return null.
Definition: Expr.h:2965
unsigned getNumArgs() const
getNumArgs - Return the number of actual arguments to this call.
Definition: Expr.h:2973
arg_range arguments()
Definition: Expr.h:3034
CallArgList - Type for representing both the value and type of arguments in a call.
Definition: CGCall.h:258
CodeGenFunction - This class organizes the per-function state that is used while generating LLVM code...
void EmitCallArgs(CallArgList &Args, PrototypeWrapper Prototype, llvm::iterator_range< CallExpr::const_arg_iterator > ArgRange, AbstractCallee AC=AbstractCallee(), unsigned ParamsToSkip=0, EvaluationOrder Order=EvaluationOrder::Default)
llvm::AllocaInst * CreateTempAlloca(llvm::Type *Ty, const Twine &Name="tmp", llvm::Value *ArraySize=nullptr)
CreateTempAlloca - This creates an alloca and inserts it into the entry block if ArraySize is nullptr...
const TargetInfo & getTarget() const
RValue EmitAMDGPUDevicePrintfCallExpr(const CallExpr *E)
RValue EmitOpenMPDevicePrintfCallExpr(const CallExpr *E)
This class organizes the cross-function state that is used while generating LLVM code.
llvm::Module & getModule() const
void ErrorUnsupported(const Stmt *S, const char *Type)
Print out an error that codegen doesn't support the specified stmt yet.
const TargetInfo & getTarget() const
const llvm::DataLayout & getDataLayout() const
void Error(SourceLocation loc, StringRef error)
Emit a general error that something can't be done.
llvm::LLVMContext & getLLVMContext()
RValue - This trivial value class is used to represent the result of an expression that is evaluated.
Definition: CGValue.h:39
bool isScalar() const
Definition: CGValue.h:54
static RValue get(llvm::Value *V)
Definition: CGValue.h:89
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:85
Represents a prototype with parameter type info, e.g.
Definition: Type.h:4198
Encodes a location in the source.
TargetOptions & getTargetOpts() const
Retrieve the target options.
Definition: TargetInfo.h:303
@ Buffered
printf lowering scheme involving implicit printf buffers,
AMDGPUPrintfKind AMDGPUPrintfKindVal
AMDGPU Printf lowering scheme.
Definition: TargetOptions.h:96
const T * getAs() const
Member-template getAs<specific type>'.
Definition: Type.h:7652
QualType getType() const
Definition: Decl.h:717
The JSON file list parser is used to communicate input to InstallAPI.
RValue getRValue(CodeGenFunction &CGF) const
Definition: CGCall.cpp:4623
llvm::IntegerType * IntTy
int