mirror of
https://github.com/intel/llvm.git
synced 2026-02-03 02:26:27 +08:00
76b178d949
Summary:
[OpenCL] Generate 'unroll.enable' metadata for __attribute__((opencl_unroll_hint))
For both !{!"llvm.loop.unroll.enable"} and !{!"llvm.loop.unroll.full"} the unroller
will try to fully unroll a loop unless the trip count is not known at compile time.
In that case for '.full' metadata no unrolling will be processed, while for '.enable'
the loop will be partially unrolled with a heuristically chosen unroll factor.
See: docs/LanguageExtensions.rst
From https://www.khronos.org/registry/OpenCL/sdk/2.0/docs/man/xhtml/attributes-loopUnroll.html
__attribute__((opencl_unroll_hint))
for (int i=0; i<2; i++)
{
...
}
In the example above, the compiler will determine how much to unroll the loop.
Before the patch for __attribute__((opencl_unroll_hint)) was generated metadata
!{!"llvm.loop.unroll.full"}, which limits ability of loop unroller to decide, how
much to unroll the loop.
Reviewers: Anastasia, yaxunl
Reviewed By: Anastasia
Subscribers: zzheng, dmgreen, jdoerfert, cfe-commits, asavonic, AlexeySotkin
Tags: #clang
Differential Revision: https://reviews.llvm.org/D59493
llvm-svn: 356571
402 lines
14 KiB
C++
402 lines
14 KiB
C++
//===---- CGLoopInfo.cpp - LLVM CodeGen for loop metadata -*- 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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#include "CGLoopInfo.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/AST/Attr.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/CFG.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/InstrTypes.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/Metadata.h"
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using namespace clang::CodeGen;
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using namespace llvm;
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static MDNode *createMetadata(LLVMContext &Ctx, const LoopAttributes &Attrs,
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const llvm::DebugLoc &StartLoc,
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const llvm::DebugLoc &EndLoc, MDNode *&AccGroup) {
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if (!Attrs.IsParallel && Attrs.VectorizeWidth == 0 &&
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Attrs.InterleaveCount == 0 && Attrs.UnrollCount == 0 &&
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Attrs.UnrollAndJamCount == 0 && !Attrs.PipelineDisabled &&
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Attrs.PipelineInitiationInterval == 0 &&
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Attrs.VectorizeEnable == LoopAttributes::Unspecified &&
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Attrs.UnrollEnable == LoopAttributes::Unspecified &&
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Attrs.UnrollAndJamEnable == LoopAttributes::Unspecified &&
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Attrs.DistributeEnable == LoopAttributes::Unspecified && !StartLoc &&
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!EndLoc)
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return nullptr;
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SmallVector<Metadata *, 4> Args;
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// Reserve operand 0 for loop id self reference.
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auto TempNode = MDNode::getTemporary(Ctx, None);
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Args.push_back(TempNode.get());
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// If we have a valid start debug location for the loop, add it.
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if (StartLoc) {
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Args.push_back(StartLoc.getAsMDNode());
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// If we also have a valid end debug location for the loop, add it.
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if (EndLoc)
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Args.push_back(EndLoc.getAsMDNode());
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}
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// Setting vectorize.width
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if (Attrs.VectorizeWidth > 0) {
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Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.vectorize.width"),
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ConstantAsMetadata::get(ConstantInt::get(
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Type::getInt32Ty(Ctx), Attrs.VectorizeWidth))};
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Args.push_back(MDNode::get(Ctx, Vals));
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}
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// Setting interleave.count
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if (Attrs.InterleaveCount > 0) {
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Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.interleave.count"),
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ConstantAsMetadata::get(ConstantInt::get(
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Type::getInt32Ty(Ctx), Attrs.InterleaveCount))};
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Args.push_back(MDNode::get(Ctx, Vals));
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}
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// Setting unroll.count
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if (Attrs.UnrollCount > 0) {
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Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.unroll.count"),
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ConstantAsMetadata::get(ConstantInt::get(
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Type::getInt32Ty(Ctx), Attrs.UnrollCount))};
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Args.push_back(MDNode::get(Ctx, Vals));
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}
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// Setting unroll_and_jam.count
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if (Attrs.UnrollAndJamCount > 0) {
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Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.unroll_and_jam.count"),
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ConstantAsMetadata::get(ConstantInt::get(
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Type::getInt32Ty(Ctx), Attrs.UnrollAndJamCount))};
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Args.push_back(MDNode::get(Ctx, Vals));
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}
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// Setting vectorize.enable
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if (Attrs.VectorizeEnable != LoopAttributes::Unspecified) {
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Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.vectorize.enable"),
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ConstantAsMetadata::get(ConstantInt::get(
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Type::getInt1Ty(Ctx), (Attrs.VectorizeEnable ==
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LoopAttributes::Enable)))};
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Args.push_back(MDNode::get(Ctx, Vals));
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}
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// Setting unroll.full or unroll.disable
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if (Attrs.UnrollEnable != LoopAttributes::Unspecified) {
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std::string Name;
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if (Attrs.UnrollEnable == LoopAttributes::Enable)
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Name = "llvm.loop.unroll.enable";
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else if (Attrs.UnrollEnable == LoopAttributes::Full)
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Name = "llvm.loop.unroll.full";
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else
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Name = "llvm.loop.unroll.disable";
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Metadata *Vals[] = {MDString::get(Ctx, Name)};
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Args.push_back(MDNode::get(Ctx, Vals));
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}
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// Setting unroll_and_jam.full or unroll_and_jam.disable
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if (Attrs.UnrollAndJamEnable != LoopAttributes::Unspecified) {
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std::string Name;
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if (Attrs.UnrollAndJamEnable == LoopAttributes::Enable)
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Name = "llvm.loop.unroll_and_jam.enable";
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else if (Attrs.UnrollAndJamEnable == LoopAttributes::Full)
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Name = "llvm.loop.unroll_and_jam.full";
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else
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Name = "llvm.loop.unroll_and_jam.disable";
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Metadata *Vals[] = {MDString::get(Ctx, Name)};
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Args.push_back(MDNode::get(Ctx, Vals));
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}
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if (Attrs.DistributeEnable != LoopAttributes::Unspecified) {
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Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.distribute.enable"),
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ConstantAsMetadata::get(ConstantInt::get(
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Type::getInt1Ty(Ctx), (Attrs.DistributeEnable ==
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LoopAttributes::Enable)))};
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Args.push_back(MDNode::get(Ctx, Vals));
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}
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if (Attrs.IsParallel) {
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AccGroup = MDNode::getDistinct(Ctx, {});
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Args.push_back(MDNode::get(
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Ctx, {MDString::get(Ctx, "llvm.loop.parallel_accesses"), AccGroup}));
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}
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if (Attrs.PipelineDisabled) {
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Metadata *Vals[] = {
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MDString::get(Ctx, "llvm.loop.pipeline.disable"),
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ConstantAsMetadata::get(ConstantInt::get(
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Type::getInt1Ty(Ctx), (Attrs.PipelineDisabled == true)))};
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Args.push_back(MDNode::get(Ctx, Vals));
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}
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if (Attrs.PipelineInitiationInterval > 0) {
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Metadata *Vals[] = {
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MDString::get(Ctx, "llvm.loop.pipeline.initiationinterval"),
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ConstantAsMetadata::get(ConstantInt::get(
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Type::getInt32Ty(Ctx), Attrs.PipelineInitiationInterval))};
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Args.push_back(MDNode::get(Ctx, Vals));
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}
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// Set the first operand to itself.
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MDNode *LoopID = MDNode::get(Ctx, Args);
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LoopID->replaceOperandWith(0, LoopID);
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return LoopID;
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}
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LoopAttributes::LoopAttributes(bool IsParallel)
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: IsParallel(IsParallel), VectorizeEnable(LoopAttributes::Unspecified),
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UnrollEnable(LoopAttributes::Unspecified),
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UnrollAndJamEnable(LoopAttributes::Unspecified), VectorizeWidth(0),
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InterleaveCount(0), UnrollCount(0), UnrollAndJamCount(0),
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DistributeEnable(LoopAttributes::Unspecified), PipelineDisabled(false),
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PipelineInitiationInterval(0) {}
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void LoopAttributes::clear() {
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IsParallel = false;
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VectorizeWidth = 0;
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InterleaveCount = 0;
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UnrollCount = 0;
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UnrollAndJamCount = 0;
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VectorizeEnable = LoopAttributes::Unspecified;
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UnrollEnable = LoopAttributes::Unspecified;
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UnrollAndJamEnable = LoopAttributes::Unspecified;
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DistributeEnable = LoopAttributes::Unspecified;
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PipelineDisabled = false;
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PipelineInitiationInterval = 0;
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}
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LoopInfo::LoopInfo(BasicBlock *Header, const LoopAttributes &Attrs,
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const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc)
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: LoopID(nullptr), Header(Header), Attrs(Attrs) {
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LoopID =
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createMetadata(Header->getContext(), Attrs, StartLoc, EndLoc, AccGroup);
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}
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void LoopInfoStack::push(BasicBlock *Header, const llvm::DebugLoc &StartLoc,
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const llvm::DebugLoc &EndLoc) {
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Active.push_back(LoopInfo(Header, StagedAttrs, StartLoc, EndLoc));
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// Clear the attributes so nested loops do not inherit them.
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StagedAttrs.clear();
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}
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void LoopInfoStack::push(BasicBlock *Header, clang::ASTContext &Ctx,
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ArrayRef<const clang::Attr *> Attrs,
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const llvm::DebugLoc &StartLoc,
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const llvm::DebugLoc &EndLoc) {
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// Identify loop hint attributes from Attrs.
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for (const auto *Attr : Attrs) {
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const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(Attr);
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const OpenCLUnrollHintAttr *OpenCLHint =
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dyn_cast<OpenCLUnrollHintAttr>(Attr);
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// Skip non loop hint attributes
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if (!LH && !OpenCLHint) {
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continue;
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}
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LoopHintAttr::OptionType Option = LoopHintAttr::Unroll;
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LoopHintAttr::LoopHintState State = LoopHintAttr::Disable;
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unsigned ValueInt = 1;
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// Translate opencl_unroll_hint attribute argument to
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// equivalent LoopHintAttr enums.
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// OpenCL v2.0 s6.11.5:
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// 0 - enable unroll (no argument).
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// 1 - disable unroll.
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// other positive integer n - unroll by n.
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if (OpenCLHint) {
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ValueInt = OpenCLHint->getUnrollHint();
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if (ValueInt == 0) {
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State = LoopHintAttr::Enable;
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} else if (ValueInt != 1) {
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Option = LoopHintAttr::UnrollCount;
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State = LoopHintAttr::Numeric;
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}
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} else if (LH) {
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auto *ValueExpr = LH->getValue();
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if (ValueExpr) {
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llvm::APSInt ValueAPS = ValueExpr->EvaluateKnownConstInt(Ctx);
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ValueInt = ValueAPS.getSExtValue();
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}
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Option = LH->getOption();
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State = LH->getState();
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}
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switch (State) {
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case LoopHintAttr::Disable:
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switch (Option) {
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case LoopHintAttr::Vectorize:
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// Disable vectorization by specifying a width of 1.
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setVectorizeWidth(1);
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break;
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case LoopHintAttr::Interleave:
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// Disable interleaving by speciyfing a count of 1.
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setInterleaveCount(1);
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break;
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case LoopHintAttr::Unroll:
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setUnrollState(LoopAttributes::Disable);
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break;
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case LoopHintAttr::UnrollAndJam:
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setUnrollAndJamState(LoopAttributes::Disable);
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break;
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case LoopHintAttr::Distribute:
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setDistributeState(false);
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break;
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case LoopHintAttr::PipelineDisabled:
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setPipelineDisabled(true);
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break;
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case LoopHintAttr::UnrollCount:
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case LoopHintAttr::UnrollAndJamCount:
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case LoopHintAttr::VectorizeWidth:
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case LoopHintAttr::InterleaveCount:
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case LoopHintAttr::PipelineInitiationInterval:
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llvm_unreachable("Options cannot be disabled.");
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break;
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}
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break;
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case LoopHintAttr::Enable:
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switch (Option) {
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case LoopHintAttr::Vectorize:
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case LoopHintAttr::Interleave:
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setVectorizeEnable(true);
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break;
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case LoopHintAttr::Unroll:
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setUnrollState(LoopAttributes::Enable);
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break;
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case LoopHintAttr::UnrollAndJam:
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setUnrollAndJamState(LoopAttributes::Enable);
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break;
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case LoopHintAttr::Distribute:
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setDistributeState(true);
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break;
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case LoopHintAttr::UnrollCount:
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case LoopHintAttr::UnrollAndJamCount:
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case LoopHintAttr::VectorizeWidth:
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case LoopHintAttr::InterleaveCount:
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case LoopHintAttr::PipelineDisabled:
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case LoopHintAttr::PipelineInitiationInterval:
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llvm_unreachable("Options cannot enabled.");
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break;
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}
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break;
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case LoopHintAttr::AssumeSafety:
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switch (Option) {
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case LoopHintAttr::Vectorize:
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case LoopHintAttr::Interleave:
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// Apply "llvm.mem.parallel_loop_access" metadata to load/stores.
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setParallel(true);
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setVectorizeEnable(true);
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break;
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case LoopHintAttr::Unroll:
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case LoopHintAttr::UnrollAndJam:
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case LoopHintAttr::UnrollCount:
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case LoopHintAttr::UnrollAndJamCount:
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case LoopHintAttr::VectorizeWidth:
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case LoopHintAttr::InterleaveCount:
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case LoopHintAttr::Distribute:
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case LoopHintAttr::PipelineDisabled:
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case LoopHintAttr::PipelineInitiationInterval:
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llvm_unreachable("Options cannot be used to assume mem safety.");
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break;
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}
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break;
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case LoopHintAttr::Full:
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switch (Option) {
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case LoopHintAttr::Unroll:
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setUnrollState(LoopAttributes::Full);
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break;
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case LoopHintAttr::UnrollAndJam:
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setUnrollAndJamState(LoopAttributes::Full);
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break;
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case LoopHintAttr::Vectorize:
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case LoopHintAttr::Interleave:
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case LoopHintAttr::UnrollCount:
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case LoopHintAttr::UnrollAndJamCount:
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case LoopHintAttr::VectorizeWidth:
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case LoopHintAttr::InterleaveCount:
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case LoopHintAttr::Distribute:
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case LoopHintAttr::PipelineDisabled:
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case LoopHintAttr::PipelineInitiationInterval:
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llvm_unreachable("Options cannot be used with 'full' hint.");
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break;
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}
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break;
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case LoopHintAttr::Numeric:
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switch (Option) {
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case LoopHintAttr::VectorizeWidth:
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setVectorizeWidth(ValueInt);
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break;
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case LoopHintAttr::InterleaveCount:
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setInterleaveCount(ValueInt);
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break;
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case LoopHintAttr::UnrollCount:
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setUnrollCount(ValueInt);
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break;
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case LoopHintAttr::UnrollAndJamCount:
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setUnrollAndJamCount(ValueInt);
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break;
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case LoopHintAttr::PipelineInitiationInterval:
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setPipelineInitiationInterval(ValueInt);
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break;
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case LoopHintAttr::Unroll:
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case LoopHintAttr::UnrollAndJam:
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case LoopHintAttr::Vectorize:
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case LoopHintAttr::Interleave:
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case LoopHintAttr::Distribute:
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case LoopHintAttr::PipelineDisabled:
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llvm_unreachable("Options cannot be assigned a value.");
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break;
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}
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break;
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}
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}
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/// Stage the attributes.
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push(Header, StartLoc, EndLoc);
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}
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void LoopInfoStack::pop() {
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assert(!Active.empty() && "No active loops to pop");
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Active.pop_back();
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}
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void LoopInfoStack::InsertHelper(Instruction *I) const {
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if (I->mayReadOrWriteMemory()) {
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SmallVector<Metadata *, 4> AccessGroups;
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for (const LoopInfo &AL : Active) {
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// Here we assume that every loop that has an access group is parallel.
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if (MDNode *Group = AL.getAccessGroup())
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AccessGroups.push_back(Group);
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}
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MDNode *UnionMD = nullptr;
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if (AccessGroups.size() == 1)
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UnionMD = cast<MDNode>(AccessGroups[0]);
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else if (AccessGroups.size() >= 2)
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UnionMD = MDNode::get(I->getContext(), AccessGroups);
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I->setMetadata("llvm.access.group", UnionMD);
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}
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if (!hasInfo())
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return;
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const LoopInfo &L = getInfo();
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if (!L.getLoopID())
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return;
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if (I->isTerminator()) {
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for (BasicBlock *Succ : successors(I))
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if (Succ == L.getHeader()) {
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I->setMetadata(llvm::LLVMContext::MD_loop, L.getLoopID());
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break;
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}
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return;
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}
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}
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