--- /dev/null
+/*
+ * 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 "DFGBinarySwitch.h"
+
+#if ENABLE(DFG_JIT)
+
+#include "JSCInlines.h"
+
+namespace JSC { namespace DFG {
+
+BinarySwitch::BinarySwitch(GPRReg value, const Vector<int64_t>& cases, Type type)
+ : m_value(value)
+ , m_index(0)
+ , m_caseIndex(UINT_MAX)
+ , m_medianBias(0)
+ , m_type(type)
+{
+ if (cases.isEmpty())
+ return;
+
+ for (unsigned i = 0; i < cases.size(); ++i)
+ m_cases.append(Case(cases[i], i));
+ std::sort(m_cases.begin(), m_cases.end());
+ build(0, m_cases.size());
+}
+
+bool BinarySwitch::advance(MacroAssembler& jit)
+{
+ if (m_cases.isEmpty()) {
+ m_fallThrough.append(jit.jump());
+ return false;
+ }
+
+ if (m_index == m_branches.size()) {
+ RELEASE_ASSERT(m_jumpStack.isEmpty());
+ return false;
+ }
+
+ for (;;) {
+ const BranchCode& code = m_branches[m_index++];
+ switch (code.kind) {
+ case NotEqualToFallThrough:
+ switch (m_type) {
+ case Int32:
+ m_fallThrough.append(jit.branch32(
+ MacroAssembler::NotEqual, m_value,
+ MacroAssembler::Imm32(static_cast<int32_t>(m_cases[code.index].value))));
+ break;
+ case IntPtr:
+ m_fallThrough.append(jit.branchPtr(
+ MacroAssembler::NotEqual, m_value,
+ MacroAssembler::ImmPtr(bitwise_cast<const void*>(static_cast<intptr_t>(m_cases[code.index].value)))));
+ break;
+ }
+ break;
+ case NotEqualToPush:
+ switch (m_type) {
+ case Int32:
+ m_jumpStack.append(jit.branch32(
+ MacroAssembler::NotEqual, m_value,
+ MacroAssembler::Imm32(static_cast<int32_t>(m_cases[code.index].value))));
+ break;
+ case IntPtr:
+ m_jumpStack.append(jit.branchPtr(
+ MacroAssembler::NotEqual, m_value,
+ MacroAssembler::ImmPtr(bitwise_cast<const void*>(static_cast<intptr_t>(m_cases[code.index].value)))));
+ break;
+ }
+ break;
+ case LessThanToPush:
+ switch (m_type) {
+ case Int32:
+ m_jumpStack.append(jit.branch32(
+ MacroAssembler::LessThan, m_value,
+ MacroAssembler::Imm32(static_cast<int32_t>(m_cases[code.index].value))));
+ break;
+ case IntPtr:
+ m_jumpStack.append(jit.branchPtr(
+ MacroAssembler::LessThan, m_value,
+ MacroAssembler::ImmPtr(bitwise_cast<const void*>(static_cast<intptr_t>(m_cases[code.index].value)))));
+ break;
+ }
+ break;
+ case Pop:
+ m_jumpStack.takeLast().link(&jit);
+ break;
+ case ExecuteCase:
+ m_caseIndex = code.index;
+ return true;
+ }
+ }
+}
+
+void BinarySwitch::build(unsigned start, unsigned end)
+{
+ unsigned size = end - start;
+
+ switch (size) {
+ case 0: {
+ RELEASE_ASSERT_NOT_REACHED();
+ break;
+ }
+
+ case 1: {
+ if (start
+ && m_cases[start - 1].value == m_cases[start].value - 1
+ && start + 1 < m_cases.size()
+ && m_cases[start + 1].value == m_cases[start].value + 1) {
+ m_branches.append(BranchCode(ExecuteCase, start));
+ break;
+ }
+
+ m_branches.append(BranchCode(NotEqualToFallThrough, start));
+ m_branches.append(BranchCode(ExecuteCase, start));
+ break;
+ }
+
+ case 2: {
+ if (m_cases[start].value + 1 == m_cases[start + 1].value
+ && start
+ && m_cases[start - 1].value == m_cases[start].value - 1
+ && start + 2 < m_cases.size()
+ && m_cases[start + 2].value == m_cases[start + 1].value + 1) {
+ m_branches.append(BranchCode(NotEqualToPush, start));
+ m_branches.append(BranchCode(ExecuteCase, start));
+ m_branches.append(BranchCode(Pop));
+ m_branches.append(BranchCode(ExecuteCase, start + 1));
+ break;
+ }
+
+ unsigned firstCase = start;
+ unsigned secondCase = start + 1;
+ if (m_medianBias)
+ std::swap(firstCase, secondCase);
+ m_medianBias ^= 1;
+
+ m_branches.append(BranchCode(NotEqualToPush, firstCase));
+ m_branches.append(BranchCode(ExecuteCase, firstCase));
+ m_branches.append(BranchCode(Pop));
+ m_branches.append(BranchCode(NotEqualToFallThrough, secondCase));
+ m_branches.append(BranchCode(ExecuteCase, secondCase));
+ break;
+ }
+
+ default: {
+ unsigned medianIndex = (start + end) / 2;
+ if (!(size & 1)) {
+ // Because end is exclusive, in the even case, this rounds up by
+ // default. Hence median bias sometimes flips to subtracing one
+ // in order to get round-down behavior.
+ medianIndex -= m_medianBias;
+ m_medianBias ^= 1;
+ }
+
+ RELEASE_ASSERT(medianIndex > start);
+ RELEASE_ASSERT(medianIndex + 1 < end);
+
+ m_branches.append(BranchCode(LessThanToPush, medianIndex));
+ m_branches.append(BranchCode(NotEqualToPush, medianIndex));
+ m_branches.append(BranchCode(ExecuteCase, medianIndex));
+
+ m_branches.append(BranchCode(Pop));
+ build(medianIndex + 1, end);
+
+ m_branches.append(BranchCode(Pop));
+ build(start, medianIndex);
+ break;
+ } }
+}
+
+} } // namespace JSC::DFG
+
+#endif // ENABLE(DFG_JIT)
+
projects / apple / javascriptcore.git / blobdiff