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//===-- NVPTXLowerStructArgs.cpp - Copy struct args to local memory =====--===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Copy struct args to local memory. This is needed for kernel functions only.
// This is a preparation for handling cases like
//
// kernel void foo(struct A arg, ...)
// {
// struct A *p = &arg;
// ...
// ... = p->filed1 ... (this is no generic address for .param)
// p->filed2 = ... (this is no write access to .param)
// }
//
//===----------------------------------------------------------------------===//
#include "NVPTX.h"
#include "NVPTXUtilities.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/Pass.h"
using namespace llvm;
namespace llvm {
void initializeNVPTXLowerStructArgsPass(PassRegistry &);
}
namespace {
class NVPTXLowerStructArgs : public FunctionPass {
bool runOnFunction(Function &F) override;
void handleStructPtrArgs(Function &);
void handleParam(Argument *);
public:
static char ID; // Pass identification, replacement for typeid
NVPTXLowerStructArgs() : FunctionPass(ID) {}
const char *getPassName() const override {
return "Copy structure (byval *) arguments to stack";
}
};
} // namespace
char NVPTXLowerStructArgs::ID = 1;
INITIALIZE_PASS(NVPTXLowerStructArgs, "nvptx-lower-struct-args",
"Lower structure arguments (NVPTX)", false, false)
void NVPTXLowerStructArgs::handleParam(Argument *Arg) {
Function *Func = Arg->getParent();
Instruction *FirstInst = &(Func->getEntryBlock().front());
PointerType *PType = dyn_cast<PointerType>(Arg->getType());
assert(PType && "Expecting pointer type in handleParam");
Type *StructType = PType->getElementType();
AllocaInst *AllocA = new AllocaInst(StructType, Arg->getName(), FirstInst);
/* Set the alignment to alignment of the byval parameter. This is because,
* later load/stores assume that alignment, and we are going to replace
* the use of the byval parameter with this alloca instruction.
*/
AllocA->setAlignment(Func->getParamAlignment(Arg->getArgNo() + 1));
Arg->replaceAllUsesWith(AllocA);
// Get the cvt.gen.to.param intrinsic
Type *CvtTypes[] = {
Type::getInt8PtrTy(Func->getParent()->getContext(), ADDRESS_SPACE_PARAM),
Type::getInt8PtrTy(Func->getParent()->getContext(),
ADDRESS_SPACE_GENERIC)};
Function *CvtFunc = Intrinsic::getDeclaration(
Func->getParent(), Intrinsic::nvvm_ptr_gen_to_param, CvtTypes);
Value *BitcastArgs[] = {
new BitCastInst(Arg, Type::getInt8PtrTy(Func->getParent()->getContext(),
ADDRESS_SPACE_GENERIC),
Arg->getName(), FirstInst)};
CallInst *CallCVT =
CallInst::Create(CvtFunc, BitcastArgs, "cvt_to_param", FirstInst);
BitCastInst *BitCast = new BitCastInst(
CallCVT, PointerType::get(StructType, ADDRESS_SPACE_PARAM),
Arg->getName(), FirstInst);
LoadInst *LI = new LoadInst(BitCast, Arg->getName(), FirstInst);
new StoreInst(LI, AllocA, FirstInst);
}
// =============================================================================
// If the function had a struct ptr arg, say foo(%struct.x *byval %d), then
// add the following instructions to the first basic block :
//
// %temp = alloca %struct.x, align 8
// %tt1 = bitcast %struct.x * %d to i8 *
// %tt2 = llvm.nvvm.cvt.gen.to.param %tt2
// %tempd = bitcast i8 addrspace(101) * to %struct.x addrspace(101) *
// %tv = load %struct.x addrspace(101) * %tempd
// store %struct.x %tv, %struct.x * %temp, align 8
//
// The above code allocates some space in the stack and copies the incoming
// struct from param space to local space.
// Then replace all occurences of %d by %temp.
// =============================================================================
void NVPTXLowerStructArgs::handleStructPtrArgs(Function &F) {
for (Argument &Arg : F.args()) {
if (Arg.getType()->isPointerTy() && Arg.hasByValAttr()) {
handleParam(&Arg);
}
}
}
// =============================================================================
// Main function for this pass.
// =============================================================================
bool NVPTXLowerStructArgs::runOnFunction(Function &F) {
// Skip non-kernels. See the comments at the top of this file.
if (!isKernelFunction(F))
return false;
handleStructPtrArgs(F);
return true;
}
FunctionPass *llvm::createNVPTXLowerStructArgsPass() {
return new NVPTXLowerStructArgs();
}
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