JavaScriptCore-1218.tar.gz

[apple/javascriptcore.git] / bytecode / PreciseJumpTargets.cpp

diff --git a/bytecode/PreciseJumpTargets.cpp b/bytecode/PreciseJumpTargets.cpp
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+/*
+ * Copyright (C) 2013 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. ``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
+ * 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 "PreciseJumpTargets.h"
+
+namespace JSC {
+
+static void addSimpleSwitchTargets(SimpleJumpTable& jumpTable, unsigned bytecodeOffset, Vector<unsigned, 32>& out)
+{
+    for (unsigned i = jumpTable.branchOffsets.size(); i--;)
+        out.append(bytecodeOffset + jumpTable.branchOffsets[i]);
+}
+
+void computePreciseJumpTargets(CodeBlock* codeBlock, Vector<unsigned, 32>& out)
+{
+    ASSERT(out.isEmpty());
+    
+    // We will derive a superset of the jump targets that the code block thinks it has.
+    // So, if the code block claims there are none, then we are done.
+    if (!codeBlock->numberOfJumpTargets())
+        return;
+    
+    for (unsigned i = codeBlock->numberOfExceptionHandlers(); i--;)
+        out.append(codeBlock->exceptionHandler(i).target);
+    
+    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);
+        Instruction* current = instructionsBegin + bytecodeOffset;
+        switch (opcodeID) {
+        case op_jmp:
+            out.append(bytecodeOffset + current[1].u.operand);
+            break;
+        case op_jtrue:
+        case op_jfalse:
+        case op_jeq_null:
+        case op_jneq_null:
+            out.append(bytecodeOffset + current[2].u.operand);
+            break;
+        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:
+            out.append(bytecodeOffset + current[3].u.operand);
+            break;
+        case op_switch_imm:
+            addSimpleSwitchTargets(codeBlock->immediateSwitchJumpTable(current[1].u.operand), bytecodeOffset, out);
+            out.append(bytecodeOffset + current[2].u.operand);
+            break;
+        case op_switch_char:
+            addSimpleSwitchTargets(codeBlock->characterSwitchJumpTable(current[1].u.operand), bytecodeOffset, out);
+            out.append(bytecodeOffset + current[2].u.operand);
+            break;
+        case op_switch_string: {
+            StringJumpTable& table = codeBlock->stringSwitchJumpTable(current[1].u.operand);
+            StringJumpTable::StringOffsetTable::iterator iter = table.offsetTable.begin();
+            StringJumpTable::StringOffsetTable::iterator end = table.offsetTable.end();
+            for (; iter != end; ++iter)
+                out.append(bytecodeOffset + iter->value.branchOffset);
+            out.append(bytecodeOffset + current[2].u.operand);
+            break;
+        }
+        case op_get_pnames:
+            out.append(bytecodeOffset + current[5].u.operand);
+            break;
+        case op_next_pname:
+            out.append(bytecodeOffset + current[6].u.operand);
+            break;
+        case op_check_has_instance:
+            out.append(bytecodeOffset + current[4].u.operand);
+            break;
+        case op_loop_hint:
+            out.append(bytecodeOffset);
+            break;
+        default:
+            break;
+        }
+        bytecodeOffset += opcodeLengths[opcodeID];
+    }
+    
+    std::sort(out.begin(), out.end());
+    
+    // We will have duplicates, and we must remove them.
+    unsigned toIndex = 0;
+    unsigned fromIndex = 0;
+    unsigned lastValue = UINT_MAX;
+    while (fromIndex < out.size()) {
+        unsigned value = out[fromIndex++];
+        if (value == lastValue)
+            continue;
+        out[toIndex++] = value;
+        lastValue = value;
+    }
+    out.resize(toIndex);
+}
+
+} // namespace JSC
+