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//==--AArch64StackOffset.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
//
//===----------------------------------------------------------------------===//
//
// This file contains the declaration of the StackOffset class, which is used to
// describe scalable and non-scalable offsets during frame lowering.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_AARCH64_AARCH64STACKOFFSET_H
#define LLVM_LIB_TARGET_AARCH64_AARCH64STACKOFFSET_H
#include "llvm/Support/MachineValueType.h"
namespace llvm {
/// StackOffset is a wrapper around scalable and non-scalable offsets and is
/// used in several functions such as 'isAArch64FrameOffsetLegal' and
/// 'emitFrameOffset()'. StackOffsets are described by MVTs, e.g.
//
/// StackOffset(1, MVT::nxv16i8)
//
/// would describe an offset as being the size of a single SVE vector.
///
/// The class also implements simple arithmetic (addition/subtraction) on these
/// offsets, e.g.
//
/// StackOffset(1, MVT::nxv16i8) + StackOffset(1, MVT::i64)
//
/// describes an offset that spans the combined storage required for an SVE
/// vector and a 64bit GPR.
class StackOffset {
int64_t Bytes;
int64_t ScalableBytes;
explicit operator int() const;
public:
using Part = std::pair<int64_t, MVT>;
StackOffset() : Bytes(0), ScalableBytes(0) {}
StackOffset(int64_t Offset, MVT::SimpleValueType T) : StackOffset() {
assert(MVT(T).getSizeInBits() % 8 == 0 &&
"Offset type is not a multiple of bytes");
*this += Part(Offset, T);
}
StackOffset(const StackOffset &Other)
: Bytes(Other.Bytes), ScalableBytes(Other.ScalableBytes) {}
StackOffset &operator=(const StackOffset &) = default;
StackOffset &operator+=(const StackOffset::Part &Other) {
int64_t OffsetInBytes = Other.first * (Other.second.getSizeInBits() / 8);
if (Other.second.isScalableVector())
ScalableBytes += OffsetInBytes;
else
Bytes += OffsetInBytes;
return *this;
}
StackOffset &operator+=(const StackOffset &Other) {
Bytes += Other.Bytes;
ScalableBytes += Other.ScalableBytes;
return *this;
}
StackOffset operator+(const StackOffset &Other) const {
StackOffset Res(*this);
Res += Other;
return Res;
}
StackOffset &operator-=(const StackOffset &Other) {
Bytes -= Other.Bytes;
ScalableBytes -= Other.ScalableBytes;
return *this;
}
StackOffset operator-(const StackOffset &Other) const {
StackOffset Res(*this);
Res -= Other;
return Res;
}
StackOffset operator-() const {
StackOffset Res = {};
const StackOffset Other(*this);
Res -= Other;
return Res;
}
/// Returns the scalable part of the offset in bytes.
int64_t getScalableBytes() const { return ScalableBytes; }
/// Returns the non-scalable part of the offset in bytes.
int64_t getBytes() const { return Bytes; }
/// Returns the offset in parts to which this frame offset can be
/// decomposed for the purpose of describing a frame offset.
/// For non-scalable offsets this is simply its byte size.
void getForFrameOffset(int64_t &NumBytes, int64_t &NumPredicateVectors,
int64_t &NumDataVectors) const {
assert(isValid() && "Invalid frame offset");
NumBytes = Bytes;
NumDataVectors = 0;
NumPredicateVectors = ScalableBytes / 2;
// This method is used to get the offsets to adjust the frame offset.
// If the function requires ADDPL to be used and needs more than two ADDPL
// instructions, part of the offset is folded into NumDataVectors so that it
// uses ADDVL for part of it, reducing the number of ADDPL instructions.
if (NumPredicateVectors % 8 == 0 || NumPredicateVectors < -64 ||
NumPredicateVectors > 62) {
NumDataVectors = NumPredicateVectors / 8;
NumPredicateVectors -= NumDataVectors * 8;
}
}
/// Returns whether the offset is known zero.
explicit operator bool() const { return Bytes || ScalableBytes; }
bool isValid() const {
// The smallest scalable element supported by scaled SVE addressing
// modes are predicates, which are 2 scalable bytes in size. So the scalable
// byte offset must always be a multiple of 2.
return ScalableBytes % 2 == 0;
}
};
} // end namespace llvm
#endif
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