1 //===- UseListOrder.cpp - Implement Use List Order functions --------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Implement use list order functions to modify use-list order and verify it
11 // doesn't change after serialization.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/IR/UseListOrder.h"
17 #include "llvm/ADT/DenseSet.h"
18 #include "llvm/IR/Module.h"
19 #include "llvm/Support/CommandLine.h"
20 #include "llvm/Support/Debug.h"
25 #define DEBUG_TYPE "use-list-order"
29 static cl::opt<bool> PreserveBitcodeUseListOrder(
30 "preserve-bc-use-list-order",
31 cl::desc("Experimental support to preserve bitcode use-list order."),
32 cl::init(false), cl::Hidden);
34 static cl::opt<bool> PreserveAssemblyUseListOrder(
35 "preserve-ll-use-list-order",
36 cl::desc("Experimental support to preserve assembly use-list order."),
37 cl::init(false), cl::Hidden);
39 bool llvm::shouldPreserveBitcodeUseListOrder() {
40 return PreserveBitcodeUseListOrder;
43 bool llvm::shouldPreserveAssemblyUseListOrder() {
44 return PreserveAssemblyUseListOrder;
47 static void shuffleValueUseLists(Value *V, std::minstd_rand0 &Gen,
48 DenseSet<Value *> &Seen) {
49 if (!Seen.insert(V).second)
52 if (auto *C = dyn_cast<Constant>(V))
53 if (!isa<GlobalValue>(C))
54 for (Value *Op : C->operands())
55 shuffleValueUseLists(Op, Gen, Seen);
57 if (V->use_empty() || std::next(V->use_begin()) == V->use_end())
58 // Nothing to shuffle for 0 or 1 users.
61 // Generate random numbers between 10 and 99, which will line up nicely in
62 // debug output. We're not worried about collisons here.
63 DEBUG(dbgs() << "V = "; V->dump());
64 std::uniform_int_distribution<short> Dist(10, 99);
65 SmallDenseMap<const Use *, short, 16> Order;
66 for (const Use &U : V->uses()) {
69 DEBUG(dbgs() << " - order: " << I << ", op = " << U.getOperandNo()
74 DEBUG(dbgs() << " => shuffle\n");
76 [&Order](const Use &L, const Use &R) { return Order[&L] < Order[&R]; });
79 for (const Use &U : V->uses()) {
80 dbgs() << " - order: " << Order.lookup(&U)
81 << ", op = " << U.getOperandNo() << ", U = ";
87 void llvm::shuffleUseLists(Module &M, unsigned SeedOffset) {
88 DEBUG(dbgs() << "*** shuffle-use-lists ***\n");
89 std::minstd_rand0 Gen(std::minstd_rand0::default_seed + SeedOffset);
90 DenseSet<Value *> Seen;
92 // Shuffle the use-list of each value that would be serialized to an IR file
93 // (bitcode or assembly).
94 auto shuffle = [&](Value *V) { shuffleValueUseLists(V, Gen, Seen); };
97 for (GlobalVariable &G : M.globals())
99 for (GlobalAlias &A : M.aliases())
101 for (Function &F : M)
104 // Constants used by globals.
105 for (GlobalVariable &G : M.globals())
106 if (G.hasInitializer())
107 shuffle(G.getInitializer());
108 for (GlobalAlias &A : M.aliases())
109 shuffle(A.getAliasee());
110 for (Function &F : M)
111 if (F.hasPrefixData())
112 shuffle(F.getPrefixData());
115 for (Function &F : M) {
116 for (Argument &A : F.args())
118 for (BasicBlock &BB : F)
120 for (BasicBlock &BB : F)
121 for (Instruction &I : BB)
124 // Constants used by instructions.
125 for (BasicBlock &BB : F)
126 for (Instruction &I : BB)
127 for (Value *Op : I.operands())
128 if ((isa<Constant>(Op) && !isa<GlobalValue>(*Op)) ||
133 DEBUG(dbgs() << "\n");