llvm-project/llvm/lib/Target/NVPTX/NVPTXLowerAlloca.cpp

119 lines
4.2 KiB
C++

//===-- NVPTXLowerAlloca.cpp - Make alloca to use local memory =====--===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// For all alloca instructions, and add a pair of cast to local address for
// each of them. For example,
//
// %A = alloca i32
// store i32 0, i32* %A ; emits st.u32
//
// will be transformed to
//
// %A = alloca i32
// %Local = addrspacecast i32* %A to i32 addrspace(5)*
// %Generic = addrspacecast i32 addrspace(5)* %A to i32*
// store i32 0, i32 addrspace(5)* %Generic ; emits st.local.u32
//
// And we will rely on NVPTXFavorNonGenericAddrSpace to combine the last
// two instructions.
//
//===----------------------------------------------------------------------===//
#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 initializeNVPTXLowerAllocaPass(PassRegistry &);
}
namespace {
class NVPTXLowerAlloca : public BasicBlockPass {
bool runOnBasicBlock(BasicBlock &BB) override;
public:
static char ID; // Pass identification, replacement for typeid
NVPTXLowerAlloca() : BasicBlockPass(ID) {}
StringRef getPassName() const override {
return "convert address space of alloca'ed memory to local";
}
};
} // namespace
char NVPTXLowerAlloca::ID = 1;
INITIALIZE_PASS(NVPTXLowerAlloca, "nvptx-lower-alloca",
"Lower Alloca", false, false)
// =============================================================================
// Main function for this pass.
// =============================================================================
bool NVPTXLowerAlloca::runOnBasicBlock(BasicBlock &BB) {
if (skipBasicBlock(BB))
return false;
bool Changed = false;
for (auto &I : BB) {
if (auto allocaInst = dyn_cast<AllocaInst>(&I)) {
Changed = true;
auto PTy = dyn_cast<PointerType>(allocaInst->getType());
auto ETy = PTy->getElementType();
auto LocalAddrTy = PointerType::get(ETy, ADDRESS_SPACE_LOCAL);
auto NewASCToLocal = new AddrSpaceCastInst(allocaInst, LocalAddrTy, "");
auto GenericAddrTy = PointerType::get(ETy, ADDRESS_SPACE_GENERIC);
auto NewASCToGeneric = new AddrSpaceCastInst(NewASCToLocal,
GenericAddrTy, "");
NewASCToLocal->insertAfter(allocaInst);
NewASCToGeneric->insertAfter(NewASCToLocal);
for (Value::use_iterator UI = allocaInst->use_begin(),
UE = allocaInst->use_end();
UI != UE; ) {
// Check Load, Store, GEP, and BitCast Uses on alloca and make them
// use the converted generic address, in order to expose non-generic
// addrspacecast to NVPTXFavorNonGenericAddrSpace. For other types
// of instructions this is unnecessary and may introduce redundant
// address cast.
const auto &AllocaUse = *UI++;
auto LI = dyn_cast<LoadInst>(AllocaUse.getUser());
if (LI && LI->getPointerOperand() == allocaInst && !LI->isVolatile()) {
LI->setOperand(LI->getPointerOperandIndex(), NewASCToGeneric);
continue;
}
auto SI = dyn_cast<StoreInst>(AllocaUse.getUser());
if (SI && SI->getPointerOperand() == allocaInst && !SI->isVolatile()) {
SI->setOperand(SI->getPointerOperandIndex(), NewASCToGeneric);
continue;
}
auto GI = dyn_cast<GetElementPtrInst>(AllocaUse.getUser());
if (GI && GI->getPointerOperand() == allocaInst) {
GI->setOperand(GI->getPointerOperandIndex(), NewASCToGeneric);
continue;
}
auto BI = dyn_cast<BitCastInst>(AllocaUse.getUser());
if (BI && BI->getOperand(0) == allocaInst) {
BI->setOperand(0, NewASCToGeneric);
continue;
}
}
}
}
return Changed;
}
BasicBlockPass *llvm::createNVPTXLowerAllocaPass() {
return new NVPTXLowerAlloca();
}