1 //===-- NVPTXLowerStructArgs.cpp - Copy struct args to local memory =====--===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Copy struct args to local memory. This is needed for kernel functions only.
11 // This is a preparation for handling cases like
13 // kernel void foo(struct A arg, ...)
15 // struct A *p = &arg;
17 // ... = p->filed1 ... (this is no generic address for .param)
18 // p->filed2 = ... (this is no write access to .param)
21 //===----------------------------------------------------------------------===//
24 #include "NVPTXUtilities.h"
25 #include "llvm/IR/Function.h"
26 #include "llvm/IR/Instructions.h"
27 #include "llvm/IR/IntrinsicInst.h"
28 #include "llvm/IR/Module.h"
29 #include "llvm/IR/Type.h"
30 #include "llvm/Pass.h"
35 void initializeNVPTXLowerStructArgsPass(PassRegistry &);
38 class LLVM_LIBRARY_VISIBILITY NVPTXLowerStructArgs : public FunctionPass {
39 bool runOnFunction(Function &F) override;
41 void handleStructPtrArgs(Function &);
42 void handleParam(Argument *);
45 static char ID; // Pass identification, replacement for typeid
46 NVPTXLowerStructArgs() : FunctionPass(ID) {}
47 const char *getPassName() const override {
48 return "Copy structure (byval *) arguments to stack";
52 char NVPTXLowerStructArgs::ID = 1;
54 INITIALIZE_PASS(NVPTXLowerStructArgs, "nvptx-lower-struct-args",
55 "Lower structure arguments (NVPTX)", false, false)
57 void NVPTXLowerStructArgs::handleParam(Argument *Arg) {
58 Function *Func = Arg->getParent();
59 Instruction *FirstInst = &(Func->getEntryBlock().front());
60 PointerType *PType = dyn_cast<PointerType>(Arg->getType());
62 assert(PType && "Expecting pointer type in handleParam");
64 Type *StructType = PType->getElementType();
65 AllocaInst *AllocA = new AllocaInst(StructType, Arg->getName(), FirstInst);
67 /* Set the alignment to alignment of the byval parameter. This is because,
68 * later load/stores assume that alignment, and we are going to replace
69 * the use of the byval parameter with this alloca instruction.
71 AllocA->setAlignment(Func->getParamAlignment(Arg->getArgNo() + 1));
73 Arg->replaceAllUsesWith(AllocA);
75 // Get the cvt.gen.to.param intrinsic
77 Type::getInt8PtrTy(Func->getParent()->getContext(), ADDRESS_SPACE_PARAM),
78 Type::getInt8PtrTy(Func->getParent()->getContext(),
79 ADDRESS_SPACE_GENERIC)};
80 Function *CvtFunc = Intrinsic::getDeclaration(
81 Func->getParent(), Intrinsic::nvvm_ptr_gen_to_param, CvtTypes);
83 Value *BitcastArgs[] = {
84 new BitCastInst(Arg, Type::getInt8PtrTy(Func->getParent()->getContext(),
85 ADDRESS_SPACE_GENERIC),
86 Arg->getName(), FirstInst)};
88 CallInst::Create(CvtFunc, BitcastArgs, "cvt_to_param", FirstInst);
90 BitCastInst *BitCast = new BitCastInst(
91 CallCVT, PointerType::get(StructType, ADDRESS_SPACE_PARAM),
92 Arg->getName(), FirstInst);
93 LoadInst *LI = new LoadInst(BitCast, Arg->getName(), FirstInst);
94 new StoreInst(LI, AllocA, FirstInst);
97 // =============================================================================
98 // If the function had a struct ptr arg, say foo(%struct.x *byval %d), then
99 // add the following instructions to the first basic block :
101 // %temp = alloca %struct.x, align 8
102 // %tt1 = bitcast %struct.x * %d to i8 *
103 // %tt2 = llvm.nvvm.cvt.gen.to.param %tt2
104 // %tempd = bitcast i8 addrspace(101) * to %struct.x addrspace(101) *
105 // %tv = load %struct.x addrspace(101) * %tempd
106 // store %struct.x %tv, %struct.x * %temp, align 8
108 // The above code allocates some space in the stack and copies the incoming
109 // struct from param space to local space.
110 // Then replace all occurences of %d by %temp.
111 // =============================================================================
112 void NVPTXLowerStructArgs::handleStructPtrArgs(Function &F) {
113 for (Argument &Arg : F.args()) {
114 if (Arg.getType()->isPointerTy() && Arg.hasByValAttr()) {
120 // =============================================================================
121 // Main function for this pass.
122 // =============================================================================
123 bool NVPTXLowerStructArgs::runOnFunction(Function &F) {
124 // Skip non-kernels. See the comments at the top of this file.
125 if (!isKernelFunction(F))
128 handleStructPtrArgs(F);
132 FunctionPass *llvm::createNVPTXLowerStructArgsPass() {
133 return new NVPTXLowerStructArgs();