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llvm-mirror/lib/Transforms/Utils/MatrixUtils.cpp
Florian Hahn 992d1824c2 [Matrix] Add TileInfo abstraction for tiled matrix code-gen.
This patch adds a TileInfo abstraction and utilities to
create a 3-level loop nest for tiling.

Reviewers: anemet

Reviewed By: anemet

Differential Revision: https://reviews.llvm.org/D77550
2020-07-20 18:49:08 +01:00

105 lines
4.1 KiB
C++

//===- MatrixUtils.cpp - Utilities to lower matrix intrinsics ---*- 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
//
//===----------------------------------------------------------------------===//
//
// Utilities for generating tiled loops for matrix operations.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/MatrixUtils.h"
#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Type.h"
using namespace llvm;
BasicBlock *TileInfo::CreateLoop(BasicBlock *Preheader, BasicBlock *Exit,
Value *Bound, Value *Step, StringRef Name,
IRBuilderBase &B, DomTreeUpdater &DTU, Loop *L,
LoopInfo &LI) {
LLVMContext &Ctx = Preheader->getContext();
BasicBlock *Header = BasicBlock::Create(
Preheader->getContext(), Name + ".header", Preheader->getParent(), Exit);
BasicBlock *Body = BasicBlock::Create(Header->getContext(), Name + ".body",
Header->getParent(), Exit);
BasicBlock *Latch = BasicBlock::Create(Header->getContext(), Name + ".latch",
Header->getParent(), Exit);
Type *I32Ty = Type::getInt64Ty(Ctx);
BranchInst::Create(Body, Header);
BranchInst::Create(Latch, Body);
PHINode *IV =
PHINode::Create(I32Ty, 2, Name + ".iv", Header->getTerminator());
IV->addIncoming(ConstantInt::get(I32Ty, 0), Preheader);
B.SetInsertPoint(Latch);
Value *Inc = B.CreateAdd(IV, Step, Name + ".step");
Value *Cond = B.CreateICmpNE(Inc, Bound, Name + ".cond");
BranchInst::Create(Header, Exit, Cond, Latch);
IV->addIncoming(Inc, Latch);
BranchInst *PreheaderBr = cast<BranchInst>(Preheader->getTerminator());
BasicBlock *Tmp = PreheaderBr->getSuccessor(0);
PreheaderBr->setSuccessor(0, Header);
DTU.applyUpdatesPermissive({
{DominatorTree::Delete, Preheader, Tmp},
{DominatorTree::Insert, Header, Body},
{DominatorTree::Insert, Body, Latch},
{DominatorTree::Insert, Latch, Header},
{DominatorTree::Insert, Latch, Exit},
{DominatorTree::Insert, Preheader, Header},
});
L->addBasicBlockToLoop(Header, LI);
L->addBasicBlockToLoop(Body, LI);
L->addBasicBlockToLoop(Latch, LI);
return Body;
}
// Creates the following loop nest skeleton:
// for C = 0; C < NumColumns; C += TileSize
// for R = 0; R < NumRows; R += TileSize
// for K = 0; K < Inner ; K += TileSize
BasicBlock *TileInfo::CreateTiledLoops(BasicBlock *Start, BasicBlock *End,
IRBuilderBase &B, DomTreeUpdater &DTU,
LoopInfo &LI) {
Loop *ColLoop = LI.AllocateLoop();
Loop *RowLoop = LI.AllocateLoop();
Loop *InnerLoop = LI.AllocateLoop();
RowLoop->addChildLoop(InnerLoop);
ColLoop->addChildLoop(RowLoop);
if (Loop *ParentL = LI.getLoopFor(Start))
ParentL->addChildLoop(ColLoop);
else
LI.addTopLevelLoop(ColLoop);
BasicBlock *ColBody =
CreateLoop(Start, End, B.getInt64(NumColumns), B.getInt64(TileSize),
"cols", B, DTU, ColLoop, LI);
BasicBlock *ColLatch = ColBody->getSingleSuccessor();
BasicBlock *RowBody =
CreateLoop(ColBody, ColLatch, B.getInt64(NumRows), B.getInt64(TileSize),
"rows", B, DTU, RowLoop, LI);
RowLoopLatch = RowBody->getSingleSuccessor();
BasicBlock *InnerBody =
CreateLoop(RowBody, RowLoopLatch, B.getInt64(NumInner),
B.getInt64(TileSize), "inner", B, DTU, InnerLoop, LI);
InnerLoopLatch = InnerBody->getSingleSuccessor();
ColumnLoopHeader = ColBody->getSinglePredecessor();
RowLoopHeader = RowBody->getSinglePredecessor();
InnerLoopHeader = InnerBody->getSinglePredecessor();
CurrentRow = &*RowLoopHeader->begin();
CurrentCol = &*ColumnLoopHeader->begin();
CurrentK = &*InnerLoopHeader->begin();
return InnerBody;
}