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/*========================== begin_copyright_notice ============================
Copyright (C) 2021 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
// The purpose of this pass is to add metadata to skip tagging generic pointers that are used
// for pointer arithmetic. We identify dependency of addrspacecast->inttoptr to recover the
// corresponding tag after the arithmetic is done.
#include "InsertGenericPtrArithmeticMetadata.hpp"
#include "Compiler/CodeGenPublicEnums.h"
#include "Compiler/IGCPassSupport.h"
#include "Probe/Assertion.h"
using namespace llvm;
using namespace IGC;
#define PASS_FLAG "insert-generic-ptr-arithmetic-metadata"
#define PASS_DESCRIPTION "Add metadata to skip tagging generic pointers that are used for pointer arithmetic"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false
IGC_INITIALIZE_PASS_BEGIN(InsertGenericPtrArithmeticMetadata, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_END(InsertGenericPtrArithmeticMetadata, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
char InsertGenericPtrArithmeticMetadata::ID = 0;
InsertGenericPtrArithmeticMetadata::InsertGenericPtrArithmeticMetadata() : FunctionPass(ID)
{
initializeInsertGenericPtrArithmeticMetadataPass(*PassRegistry::getPassRegistry());
}
bool InsertGenericPtrArithmeticMetadata::runOnFunction(Function& F)
{
m_context = &F.getContext();
visit(F);
return m_changed;
}
bool InsertGenericPtrArithmeticMetadata::hasOnlyArithmeticUses(Instruction* I) {
if (I->use_empty())
return true;
bool onlyArithmetic = true;
for (auto* user : I->users())
{
// early return if we already detected non-arithmetic operations
if (!onlyArithmetic) return false;
if (isa<GetElementPtrInst>(user))
{
onlyArithmetic = hasOnlyArithmeticUses(cast<Instruction>(user));
}
else if (auto* phi = dyn_cast<PHINode>(user))
{
if (m_visitedPHIs.find(phi) != m_visitedPHIs.end())
{
continue;
}
m_visitedPHIs.insert(phi);
onlyArithmetic = hasOnlyArithmeticUses(cast<Instruction>(user));
}
else if (auto* pti = dyn_cast<PtrToIntInst>(user))
{
IGC_ASSERT(pti->getPointerAddressSpace() == ADDRESS_SPACE_GENERIC);
if (pti->use_empty()) continue;
for (auto* ptiUser : pti->users())
{
if (auto* inst = dyn_cast<Instruction>(ptiUser))
{
onlyArithmetic = (inst->isBinaryOp() || inst->isShift() || inst->isBitwiseLogicOp());
}
}
}
else
{
// Since we don't recognize the user, lets safely assume that it's not an arithmetic operation
onlyArithmetic = false;
}
}
return onlyArithmetic;
}
void InsertGenericPtrArithmeticMetadata::visitAddrSpaceCast(AddrSpaceCastInst& I) {
if (I.getDestAddressSpace() == ADDRESS_SPACE_GENERIC)
{
if (hasOnlyArithmeticUses(&I))
{
// Add metadata to avoid tagging when emitting addrspacecast
MDNode* N = MDNode::get(*m_context, MDString::get(*m_context, "generic.arith"));
I.setMetadata("generic.arith", N);
m_changed = true;
}
m_visitedPHIs.clear();
}
}
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