249 lines
7.9 KiB
C++
249 lines
7.9 KiB
C++
//===---- CGLoopInfo.cpp - LLVM CodeGen for loop metadata -*- C++ -*-------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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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 "clang/Sema/LoopHint.h"
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#include "llvm/IR/BasicBlock.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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if (!Attrs.IsParallel && Attrs.VectorizeWidth == 0 &&
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Attrs.InterleaveCount == 0 && Attrs.UnrollCount == 0 &&
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Attrs.VectorizeEnable == LoopAttributes::Unspecified &&
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Attrs.UnrollEnable == LoopAttributes::Unspecified)
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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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// 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 interleave.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 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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// 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), VectorizeWidth(0),
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InterleaveCount(0), UnrollCount(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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VectorizeEnable = LoopAttributes::Unspecified;
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UnrollEnable = LoopAttributes::Unspecified;
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}
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LoopInfo::LoopInfo(BasicBlock *Header, const LoopAttributes &Attrs)
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: LoopID(nullptr), Header(Header), Attrs(Attrs) {
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LoopID = createMetadata(Header->getContext(), Attrs);
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}
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void LoopInfoStack::push(BasicBlock *Header) {
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Active.push_back(LoopInfo(Header, StagedAttrs));
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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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// 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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// Skip non loop hint attributes
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if (!LH)
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continue;
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auto *ValueExpr = LH->getValue();
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unsigned ValueInt = 1;
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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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LoopHintAttr::OptionType Option = LH->getOption();
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LoopHintAttr::LoopHintState State = LH->getState();
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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::UnrollCount:
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case LoopHintAttr::VectorizeWidth:
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case LoopHintAttr::InterleaveCount:
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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::UnrollCount:
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case LoopHintAttr::VectorizeWidth:
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case LoopHintAttr::InterleaveCount:
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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::UnrollCount:
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case LoopHintAttr::VectorizeWidth:
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case LoopHintAttr::InterleaveCount:
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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::Vectorize:
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case LoopHintAttr::Interleave:
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case LoopHintAttr::UnrollCount:
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case LoopHintAttr::VectorizeWidth:
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case LoopHintAttr::InterleaveCount:
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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::Unroll:
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case LoopHintAttr::Vectorize:
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case LoopHintAttr::Interleave:
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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);
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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 (!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 (TerminatorInst *TI = dyn_cast<TerminatorInst>(I)) {
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for (unsigned i = 0, ie = TI->getNumSuccessors(); i < ie; ++i)
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if (TI->getSuccessor(i) == L.getHeader()) {
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TI->setMetadata("llvm.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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if (L.getAttributes().IsParallel && I->mayReadOrWriteMemory())
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I->setMetadata("llvm.mem.parallel_loop_access", L.getLoopID());
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}
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