1/*
2 * Copyright (C) 2017 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "AirFixSpillsAfterTerminals.h"
28
29#if ENABLE(B3_JIT)
30
31#include "AirBlockInsertionSet.h"
32#include "AirCode.h"
33#include "AirInsertionSet.h"
34#include "AirInstInlines.h"
35#include "AirTmpInlines.h"
36
37namespace JSC { namespace B3 { namespace Air {
38
39void fixSpillsAfterTerminals(Code& code)
40{
41 // Because there may be terminals that produce values, IRC may
42 // want to spill those terminals. It'll happen to spill it after
43 // the terminal. If we left the graph in this state, it'd be invalid
44 // because a terminal must be the last instruction in a block.
45 // We fix that here.
46
47 BlockInsertionSet blockInsertionSet(code);
48 InsertionSet insertionSet(code);
49
50 for (BasicBlock* block : code) {
51 unsigned terminalIndex = block->size();
52 bool foundTerminal = false;
53 while (terminalIndex--) {
54 if (block->at(terminalIndex).isTerminal()) {
55 foundTerminal = true;
56 break;
57 }
58 }
59 ASSERT_UNUSED(foundTerminal, foundTerminal);
60
61 if (terminalIndex == block->size() - 1)
62 continue;
63
64 // There must be instructions after the terminal because it's not the last instruction.
65 ASSERT(terminalIndex < block->size() - 1);
66 Vector<Inst, 1> instsToMove;
67 for (unsigned i = terminalIndex + 1; i < block->size(); i++)
68 instsToMove.append(block->at(i));
69 RELEASE_ASSERT(instsToMove.size());
70
71 for (FrequentedBlock& frequentedSuccessor : block->successors()) {
72 BasicBlock* successor = frequentedSuccessor.block();
73 // If successor's only predecessor is block, we can plant the spill inside
74 // the successor. Otherwise, we must split the critical edge and create
75 // a new block for the spill.
76 if (successor->numPredecessors() == 1) {
77 insertionSet.insertInsts(0, instsToMove);
78 insertionSet.execute(successor);
79 } else {
80 BasicBlock* newBlock = blockInsertionSet.insertBefore(successor, successor->frequency());
81 for (const Inst& inst : instsToMove)
82 newBlock->appendInst(inst);
83 newBlock->appendInst(Inst(Jump, instsToMove.last().origin));
84 newBlock->successors().append(successor);
85 frequentedSuccessor.block() = newBlock;
86 }
87 }
88
89 block->resize(terminalIndex + 1);
90 }
91
92 if (blockInsertionSet.execute())
93 code.resetReachability();
94}
95
96} } } // namespace JSC::B3::Air
97
98#endif // ENABLE(B3_JIT)
99
100