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//===--------------------- NVPTXAliasAnalysis.cpp--------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
/// This is the NVPTX address space based alias analysis pass.
//===----------------------------------------------------------------------===//
#include "NVPTXAliasAnalysis.h"
#include "MCTargetDesc/NVPTXBaseInfo.h"
#include "NVPTX.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/Instructions.h"
using namespace llvm;
#define DEBUG_TYPE "NVPTX-aa"
AnalysisKey NVPTXAA::Key;
char NVPTXAAWrapperPass::ID = 0;
char NVPTXExternalAAWrapper::ID = 0;
INITIALIZE_PASS(NVPTXAAWrapperPass, "nvptx-aa",
"NVPTX Address space based Alias Analysis", false, true)
INITIALIZE_PASS(NVPTXExternalAAWrapper, "nvptx-aa-wrapper",
"NVPTX Address space based Alias Analysis Wrapper", false, true)
ImmutablePass *llvm::createNVPTXAAWrapperPass() {
return new NVPTXAAWrapperPass();
}
ImmutablePass *llvm::createNVPTXExternalAAWrapperPass() {
return new NVPTXExternalAAWrapper();
}
NVPTXAAWrapperPass::NVPTXAAWrapperPass() : ImmutablePass(ID) {
initializeNVPTXAAWrapperPassPass(*PassRegistry::getPassRegistry());
}
void NVPTXAAWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
}
static AliasResult::Kind getAliasResult(unsigned AS1, unsigned AS2) {
if ((AS1 == ADDRESS_SPACE_GENERIC) || (AS2 == ADDRESS_SPACE_GENERIC))
return AliasResult::MayAlias;
// PTX s6.4.1.1. Generic Addressing:
// A generic address maps to global memory unless it falls within
// the window for const, local, or shared memory. The Kernel
// Function Parameters (.param) window is contained within the
// .global window.
//
// Therefore a global pointer may alias with a param pointer on some
// GPUs via addrspacecast(param->generic->global) when cvta.param
// instruction is used (PTX 7.7+ and SM_70+).
//
// TODO: cvta.param is not yet supported. We need to change aliasing
// rules once it is added.
return (AS1 == AS2 ? AliasResult::MayAlias : AliasResult::NoAlias);
}
AliasResult NVPTXAAResult::alias(const MemoryLocation &Loc1,
const MemoryLocation &Loc2, AAQueryInfo &AAQI,
const Instruction *) {
unsigned AS1 = Loc1.Ptr->getType()->getPointerAddressSpace();
unsigned AS2 = Loc2.Ptr->getType()->getPointerAddressSpace();
return getAliasResult(AS1, AS2);
}
// TODO: .param address space may be writable in presence of cvta.param, but
// this instruction is currently not supported. NVPTXLowerArgs also does not
// allow any writes to .param pointers.
static bool isConstOrParam(unsigned AS) {
return AS == AddressSpace::ADDRESS_SPACE_CONST ||
AS == AddressSpace::ADDRESS_SPACE_PARAM;
}
ModRefInfo NVPTXAAResult::getModRefInfoMask(const MemoryLocation &Loc,
AAQueryInfo &AAQI,
bool IgnoreLocals) {
if (isConstOrParam(Loc.Ptr->getType()->getPointerAddressSpace()))
return ModRefInfo::NoModRef;
const Value *Base = getUnderlyingObject(Loc.Ptr);
if (isConstOrParam(Base->getType()->getPointerAddressSpace()))
return ModRefInfo::NoModRef;
return ModRefInfo::ModRef;
}
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