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//===-- llvm/CodeGen/GlobalISel/ConstantFoldingMIRBuilder.h --*- C++ -*-==//
//
// 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 file implements a version of MachineIRBuilder which does trivial
/// constant folding.
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
namespace llvm {
/// An MIRBuilder which does trivial constant folding of binary ops.
/// Calls to buildInstr will also try to constant fold binary ops.
class ConstantFoldingMIRBuilder : public MachineIRBuilder {
public:
// Pull in base class constructors.
using MachineIRBuilder::MachineIRBuilder;
virtual ~ConstantFoldingMIRBuilder() = default;
// Try to provide an overload for buildInstr for binary ops in order to
// constant fold.
MachineInstrBuilder buildInstr(unsigned Opc, ArrayRef<DstOp> DstOps,
ArrayRef<SrcOp> SrcOps,
Optional<unsigned> Flags = None) override {
switch (Opc) {
default:
break;
case TargetOpcode::G_ADD:
case TargetOpcode::G_AND:
case TargetOpcode::G_ASHR:
case TargetOpcode::G_LSHR:
case TargetOpcode::G_MUL:
case TargetOpcode::G_OR:
case TargetOpcode::G_SHL:
case TargetOpcode::G_SUB:
case TargetOpcode::G_XOR:
case TargetOpcode::G_UDIV:
case TargetOpcode::G_SDIV:
case TargetOpcode::G_UREM:
case TargetOpcode::G_SREM: {
assert(DstOps.size() == 1 && "Invalid dst ops");
assert(SrcOps.size() == 2 && "Invalid src ops");
const DstOp &Dst = DstOps[0];
const SrcOp &Src0 = SrcOps[0];
const SrcOp &Src1 = SrcOps[1];
if (auto MaybeCst =
ConstantFoldBinOp(Opc, Src0.getReg(), Src1.getReg(), *getMRI()))
return buildConstant(Dst, MaybeCst->getSExtValue());
break;
}
case TargetOpcode::G_SEXT_INREG: {
assert(DstOps.size() == 1 && "Invalid dst ops");
assert(SrcOps.size() == 2 && "Invalid src ops");
const DstOp &Dst = DstOps[0];
const SrcOp &Src0 = SrcOps[0];
const SrcOp &Src1 = SrcOps[1];
if (auto MaybeCst =
ConstantFoldExtOp(Opc, Src0.getReg(), Src1.getImm(), *getMRI()))
return buildConstant(Dst, MaybeCst->getSExtValue());
break;
}
}
return MachineIRBuilder::buildInstr(Opc, DstOps, SrcOps);
}
};
} // namespace llvm
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