Imported QtWebKit TP3 (git b57bc6801f1876c3220d5a4bfea33d620d477443)

Change-Id: I3b1d8a2808782c9f34d50240000e20cb38d3680f
Reviewed-by: Konstantin Tokarev <annulen@yandex.ru>

1 files changed, 238 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/bytecode/BytecodeBasicBlock.cpp b/Source/JavaScriptCore/bytecode/BytecodeBasicBlock.cpp
new file mode 100644
index 000000000..7f17c0ef1
--- /dev/null
+++ b/Source/JavaScriptCore/bytecode/BytecodeBasicBlock.cpp
@@ -0,0 +1,238 @@
+/*
+ * Copyright (C) 2013, 2015 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "BytecodeBasicBlock.h"
+
+#include "CodeBlock.h"
+#include "JSCInlines.h"
+#include "PreciseJumpTargets.h"
+
+namespace JSC {
+
+void BytecodeBasicBlock::shrinkToFit()
+{
+    m_bytecodeOffsets.shrinkToFit();
+    m_successors.shrinkToFit();
+}
+
+static bool isBranch(OpcodeID opcodeID)
+{
+    switch (opcodeID) {
+    case op_jmp:
+    case op_jtrue:
+    case op_jfalse:
+    case op_jeq_null:
+    case op_jneq_null:
+    case op_jneq_ptr:
+    case op_jless:
+    case op_jlesseq:
+    case op_jgreater:
+    case op_jgreatereq:
+    case op_jnless:
+    case op_jnlesseq:
+    case op_jngreater:
+    case op_jngreatereq:
+    case op_switch_imm:
+    case op_switch_char:
+    case op_switch_string:
+    case op_save:
+        return true;
+    default:
+        return false;
+    }
+}
+
+static bool isUnconditionalBranch(OpcodeID opcodeID)
+{
+    switch (opcodeID) {
+    case op_jmp:
+        return true;
+    default:
+        return false;
+    }
+}
+
+static bool isTerminal(OpcodeID opcodeID)
+{
+    switch (opcodeID) {
+    case op_ret:
+    case op_end:
+        return true;
+    default:
+        return false;
+    }
+}
+
+static bool isThrow(OpcodeID opcodeID)
+{
+    switch (opcodeID) {
+    case op_throw:
+    case op_throw_static_error:
+        return true;
+    default:
+        return false;
+    }
+}
+
+static bool isJumpTarget(OpcodeID opcodeID, const Vector<unsigned, 32>& jumpTargets, unsigned bytecodeOffset)
+{
+    if (opcodeID == op_catch)
+        return true;
+
+    return std::binary_search(jumpTargets.begin(), jumpTargets.end(), bytecodeOffset);
+}
+
+static void linkBlocks(BytecodeBasicBlock* predecessor, BytecodeBasicBlock* successor)
+{
+    predecessor->addSuccessor(successor);
+}
+
+void computeBytecodeBasicBlocks(CodeBlock* codeBlock, Vector<std::unique_ptr<BytecodeBasicBlock>>& basicBlocks)
+{
+    Vector<unsigned, 32> jumpTargets;
+    computePreciseJumpTargets(codeBlock, jumpTargets);
+
+    // Create the entry and exit basic blocks.
+    basicBlocks.reserveCapacity(jumpTargets.size() + 2);
+
+    auto entry = std::make_unique<BytecodeBasicBlock>(BytecodeBasicBlock::EntryBlock);
+    auto firstBlock = std::make_unique<BytecodeBasicBlock>(0, 0);
+    linkBlocks(entry.get(), firstBlock.get());
+
+    basicBlocks.append(WTFMove(entry));
+    BytecodeBasicBlock* current = firstBlock.get();
+    basicBlocks.append(WTFMove(firstBlock));
+
+    auto exit = std::make_unique<BytecodeBasicBlock>(BytecodeBasicBlock::ExitBlock);
+
+    bool nextInstructionIsLeader = false;
+
+    Interpreter* interpreter = codeBlock->vm()->interpreter;
+    Instruction* instructionsBegin = codeBlock->instructions().begin();
+    unsigned instructionCount = codeBlock->instructions().size();
+    for (unsigned bytecodeOffset = 0; bytecodeOffset < instructionCount;) {
+        OpcodeID opcodeID = interpreter->getOpcodeID(instructionsBegin[bytecodeOffset].u.opcode);
+        unsigned opcodeLength = opcodeLengths[opcodeID];
+
+        bool createdBlock = false;
+        // If the current bytecode is a jump target, then it's the leader of its own basic block.
+        if (isJumpTarget(opcodeID, jumpTargets, bytecodeOffset) || nextInstructionIsLeader) {
+            auto newBlock = std::make_unique<BytecodeBasicBlock>(bytecodeOffset, opcodeLength);
+            current = newBlock.get();
+            basicBlocks.append(WTFMove(newBlock));
+            createdBlock = true;
+            nextInstructionIsLeader = false;
+            bytecodeOffset += opcodeLength;
+        }
+
+        // If the current bytecode is a branch or a return, then the next instruction is the leader of its own basic block.
+        if (isBranch(opcodeID) || isTerminal(opcodeID) || isThrow(opcodeID))
+            nextInstructionIsLeader = true;
+
+        if (createdBlock)
+            continue;
+
+        // Otherwise, just add to the length of the current block.
+        current->addBytecodeLength(opcodeLength);
+        bytecodeOffset += opcodeLength;
+    }
+
+    // Link basic blocks together.
+    for (unsigned i = 0; i < basicBlocks.size(); i++) {
+        BytecodeBasicBlock* block = basicBlocks[i].get();
+
+        if (block->isEntryBlock() || block->isExitBlock())
+            continue;
+
+        bool fallsThrough = true; 
+        for (unsigned bytecodeOffset = block->leaderBytecodeOffset(); bytecodeOffset < block->leaderBytecodeOffset() + block->totalBytecodeLength();) {
+            const Instruction& currentInstruction = instructionsBegin[bytecodeOffset];
+            OpcodeID opcodeID = interpreter->getOpcodeID(currentInstruction.u.opcode);
+            unsigned opcodeLength = opcodeLengths[opcodeID];
+            // If we found a terminal bytecode, link to the exit block.
+            if (isTerminal(opcodeID)) {
+                ASSERT(bytecodeOffset + opcodeLength == block->leaderBytecodeOffset() + block->totalBytecodeLength());
+                linkBlocks(block, exit.get());
+                fallsThrough = false;
+                break;
+            }
+
+            // If we found a throw, get the HandlerInfo for this instruction to see where we will jump. 
+            // If there isn't one, treat this throw as a terminal. This is true even if we have a finally
+            // block because the finally block will create its own catch, which will generate a HandlerInfo.
+            if (isThrow(opcodeID)) {
+                ASSERT(bytecodeOffset + opcodeLength == block->leaderBytecodeOffset() + block->totalBytecodeLength());
+                HandlerInfo* handler = codeBlock->handlerForBytecodeOffset(bytecodeOffset);
+                fallsThrough = false;
+                if (!handler) {
+                    linkBlocks(block, exit.get());
+                    break;
+                }
+                for (unsigned i = 0; i < basicBlocks.size(); i++) {
+                    BytecodeBasicBlock* otherBlock = basicBlocks[i].get();
+                    if (handler->target == otherBlock->leaderBytecodeOffset()) {
+                        linkBlocks(block, otherBlock);
+                        break;
+                    }
+                }
+                break;
+            }
+
+            // If we found a branch, link to the block(s) that we jump to.
+            if (isBranch(opcodeID)) {
+                ASSERT(bytecodeOffset + opcodeLength == block->leaderBytecodeOffset() + block->totalBytecodeLength());
+                Vector<unsigned, 1> bytecodeOffsetsJumpedTo;
+                findJumpTargetsForBytecodeOffset(codeBlock, bytecodeOffset, bytecodeOffsetsJumpedTo);
+
+                for (unsigned i = 0; i < basicBlocks.size(); i++) {
+                    BytecodeBasicBlock* otherBlock = basicBlocks[i].get();
+                    if (bytecodeOffsetsJumpedTo.contains(otherBlock->leaderBytecodeOffset()))
+                        linkBlocks(block, otherBlock);
+                }
+
+                if (isUnconditionalBranch(opcodeID))
+                    fallsThrough = false;
+
+                break;
+            }
+            bytecodeOffset += opcodeLength;
+        }
+
+        // If we fall through then link to the next block in program order.
+        if (fallsThrough) {
+            ASSERT(i + 1 < basicBlocks.size());
+            BytecodeBasicBlock* nextBlock = basicBlocks[i + 1].get();
+            linkBlocks(block, nextBlock);
+        }
+    }
+
+    basicBlocks.append(WTFMove(exit));
+    
+    for (auto& basicBlock : basicBlocks)
+        basicBlock->shrinkToFit();
+}
+
+} // namespace JSC