1 //===---- CGLoopInfo.cpp - LLVM CodeGen for loop metadata -*- C++ -*-------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 #include "CGLoopInfo.h"
11 #include "llvm/IR/BasicBlock.h"
12 #include "llvm/IR/Constants.h"
13 #include "llvm/IR/InstrTypes.h"
14 #include "llvm/IR/Instructions.h"
15 #include "llvm/IR/Metadata.h"
16 using namespace clang;
17 using namespace CodeGen;
18 using namespace llvm;
19
createMetadata(LLVMContext & Ctx,const LoopAttributes & Attrs)20 static MDNode *createMetadata(LLVMContext &Ctx, const LoopAttributes &Attrs) {
21
22 if (!Attrs.IsParallel && Attrs.VectorizerWidth == 0 &&
23 Attrs.VectorizerUnroll == 0 &&
24 Attrs.VectorizerEnable == LoopAttributes::VecUnspecified)
25 return nullptr;
26
27 SmallVector<Metadata *, 4> Args;
28 // Reserve operand 0 for loop id self reference.
29 MDNode *TempNode = MDNode::getTemporary(Ctx, None);
30 Args.push_back(TempNode);
31
32 // Setting vectorizer.width
33 if (Attrs.VectorizerWidth > 0) {
34 Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.vectorize.width"),
35 ConstantAsMetadata::get(ConstantInt::get(
36 Type::getInt32Ty(Ctx), Attrs.VectorizerWidth))};
37 Args.push_back(MDNode::get(Ctx, Vals));
38 }
39
40 // Setting vectorizer.unroll
41 if (Attrs.VectorizerUnroll > 0) {
42 Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.interleave.count"),
43 ConstantAsMetadata::get(ConstantInt::get(
44 Type::getInt32Ty(Ctx), Attrs.VectorizerUnroll))};
45 Args.push_back(MDNode::get(Ctx, Vals));
46 }
47
48 // Setting vectorizer.enable
49 if (Attrs.VectorizerEnable != LoopAttributes::VecUnspecified) {
50 Metadata *Vals[] = {
51 MDString::get(Ctx, "llvm.loop.vectorize.enable"),
52 ConstantAsMetadata::get(ConstantInt::get(
53 Type::getInt1Ty(Ctx),
54 (Attrs.VectorizerEnable == LoopAttributes::VecEnable)))};
55 Args.push_back(MDNode::get(Ctx, Vals));
56 }
57
58 // Set the first operand to itself.
59 MDNode *LoopID = MDNode::get(Ctx, Args);
60 LoopID->replaceOperandWith(0, LoopID);
61 MDNode::deleteTemporary(TempNode);
62 return LoopID;
63 }
64
LoopAttributes(bool IsParallel)65 LoopAttributes::LoopAttributes(bool IsParallel)
66 : IsParallel(IsParallel), VectorizerEnable(LoopAttributes::VecUnspecified),
67 VectorizerWidth(0), VectorizerUnroll(0) {}
68
clear()69 void LoopAttributes::clear() {
70 IsParallel = false;
71 VectorizerWidth = 0;
72 VectorizerUnroll = 0;
73 VectorizerEnable = LoopAttributes::VecUnspecified;
74 }
75
LoopInfo(BasicBlock * Header,const LoopAttributes & Attrs)76 LoopInfo::LoopInfo(BasicBlock *Header, const LoopAttributes &Attrs)
77 : LoopID(nullptr), Header(Header), Attrs(Attrs) {
78 LoopID = createMetadata(Header->getContext(), Attrs);
79 }
80
push(BasicBlock * Header)81 void LoopInfoStack::push(BasicBlock *Header) {
82 Active.push_back(LoopInfo(Header, StagedAttrs));
83 // Clear the attributes so nested loops do not inherit them.
84 StagedAttrs.clear();
85 }
86
pop()87 void LoopInfoStack::pop() {
88 assert(!Active.empty() && "No active loops to pop");
89 Active.pop_back();
90 }
91
InsertHelper(Instruction * I) const92 void LoopInfoStack::InsertHelper(Instruction *I) const {
93 if (!hasInfo())
94 return;
95
96 const LoopInfo &L = getInfo();
97 if (!L.getLoopID())
98 return;
99
100 if (TerminatorInst *TI = dyn_cast<TerminatorInst>(I)) {
101 for (unsigned i = 0, ie = TI->getNumSuccessors(); i < ie; ++i)
102 if (TI->getSuccessor(i) == L.getHeader()) {
103 TI->setMetadata("llvm.loop", L.getLoopID());
104 break;
105 }
106 return;
107 }
108
109 if (L.getAttributes().IsParallel && I->mayReadOrWriteMemory())
110 I->setMetadata("llvm.mem.parallel_loop_access", L.getLoopID());
111 }
112