139 lines
4.5 KiB
C++
139 lines
4.5 KiB
C++
//==--AArch64StackOffset.h ---------------------------------------*- C++ -*-==//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the declaration of the StackOffset class, which is used to
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// describe scalable and non-scalable offsets during frame lowering.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_AARCH64_AARCH64STACKOFFSET_H
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#define LLVM_LIB_TARGET_AARCH64_AARCH64STACKOFFSET_H
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#include "llvm/Support/MachineValueType.h"
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#include "llvm/Support/TypeSize.h"
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namespace llvm {
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/// StackOffset is a wrapper around scalable and non-scalable offsets and is
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/// used in several functions such as 'isAArch64FrameOffsetLegal' and
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/// 'emitFrameOffset()'. StackOffsets are described by MVTs, e.g.
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//
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/// StackOffset(1, MVT::nxv16i8)
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//
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/// would describe an offset as being the size of a single SVE vector.
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///
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/// The class also implements simple arithmetic (addition/subtraction) on these
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/// offsets, e.g.
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//
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/// StackOffset(1, MVT::nxv16i8) + StackOffset(1, MVT::i64)
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//
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/// describes an offset that spans the combined storage required for an SVE
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/// vector and a 64bit GPR.
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class StackOffset {
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int64_t Bytes;
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int64_t ScalableBytes;
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explicit operator int() const;
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public:
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using Part = std::pair<int64_t, MVT>;
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StackOffset() : Bytes(0), ScalableBytes(0) {}
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StackOffset(int64_t Offset, MVT::SimpleValueType T) : StackOffset() {
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assert(MVT(T).isByteSized() && "Offset type is not a multiple of bytes");
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*this += Part(Offset, T);
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}
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StackOffset(const StackOffset &Other)
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: Bytes(Other.Bytes), ScalableBytes(Other.ScalableBytes) {}
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StackOffset &operator=(const StackOffset &) = default;
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StackOffset &operator+=(const StackOffset::Part &Other) {
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const TypeSize Size = Other.second.getSizeInBits();
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if (Size.isScalable())
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ScalableBytes += Other.first * ((int64_t)Size.getKnownMinSize() / 8);
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else
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Bytes += Other.first * ((int64_t)Size.getFixedSize() / 8);
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return *this;
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}
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StackOffset &operator+=(const StackOffset &Other) {
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Bytes += Other.Bytes;
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ScalableBytes += Other.ScalableBytes;
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return *this;
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}
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StackOffset operator+(const StackOffset &Other) const {
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StackOffset Res(*this);
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Res += Other;
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return Res;
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}
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StackOffset &operator-=(const StackOffset &Other) {
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Bytes -= Other.Bytes;
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ScalableBytes -= Other.ScalableBytes;
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return *this;
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}
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StackOffset operator-(const StackOffset &Other) const {
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StackOffset Res(*this);
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Res -= Other;
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return Res;
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}
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StackOffset operator-() const {
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StackOffset Res = {};
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const StackOffset Other(*this);
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Res -= Other;
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return Res;
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}
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/// Returns the scalable part of the offset in bytes.
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int64_t getScalableBytes() const { return ScalableBytes; }
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/// Returns the non-scalable part of the offset in bytes.
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int64_t getBytes() const { return Bytes; }
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/// Returns the offset in parts to which this frame offset can be
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/// decomposed for the purpose of describing a frame offset.
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/// For non-scalable offsets this is simply its byte size.
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void getForFrameOffset(int64_t &NumBytes, int64_t &NumPredicateVectors,
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int64_t &NumDataVectors) const {
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assert(isValid() && "Invalid frame offset");
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NumBytes = Bytes;
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NumDataVectors = 0;
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NumPredicateVectors = ScalableBytes / 2;
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// This method is used to get the offsets to adjust the frame offset.
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// If the function requires ADDPL to be used and needs more than two ADDPL
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// instructions, part of the offset is folded into NumDataVectors so that it
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// uses ADDVL for part of it, reducing the number of ADDPL instructions.
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if (NumPredicateVectors % 8 == 0 || NumPredicateVectors < -64 ||
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NumPredicateVectors > 62) {
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NumDataVectors = NumPredicateVectors / 8;
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NumPredicateVectors -= NumDataVectors * 8;
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}
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}
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/// Returns whether the offset is known zero.
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explicit operator bool() const { return Bytes || ScalableBytes; }
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bool isValid() const {
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// The smallest scalable element supported by scaled SVE addressing
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// modes are predicates, which are 2 scalable bytes in size. So the scalable
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// byte offset must always be a multiple of 2.
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return ScalableBytes % 2 == 0;
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}
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};
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} // end namespace llvm
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#endif
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