[Complex Text Layouts] Add third-party TextServer dependencies (ICU, HarfBuzz, Graphite).

thirdparty/graphite/src/direct_machine.cpp

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+/*  GRAPHITE2 LICENSING
+
+    Copyright 2010, SIL International
+    All rights reserved.
+
+    This library is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published
+    by the Free Software Foundation; either version 2.1 of License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should also have received a copy of the GNU Lesser General Public
+    License along with this library in the file named "LICENSE".
+    If not, write to the Free Software Foundation, 51 Franklin Street,
+    Suite 500, Boston, MA 02110-1335, USA or visit their web page on the
+    internet at http://www.fsf.org/licenses/lgpl.html.
+
+Alternatively, the contents of this file may be used under the terms of the
+Mozilla Public License (http://mozilla.org/MPL) or the GNU General Public
+License, as published by the Free Software Foundation, either version 2
+of the License or (at your option) any later version.
+*/
+// This direct threaded interpreter implmentation for machine.h
+// Author: Tim Eves
+
+// Build either this interpreter or the call_machine implementation.
+// The direct threaded interpreter is relies upon a gcc feature called
+// labels-as-values so is only portable to compilers that support the
+// extension (gcc only as far as I know) however it should build on any
+// architecture gcc supports.
+// This is twice as fast as the call threaded model and is likely faster on
+// inorder processors with short pipelines and little branch prediction such
+// as the ARM and possibly Atom chips.
+
+
+#include <cassert>
+#include <cstring>
+#include "inc/Machine.h"
+#include "inc/Segment.h"
+#include "inc/Slot.h"
+#include "inc/Rule.h"
+
+#define STARTOP(name)           name: {
+#define ENDOP                   }; goto *((sp - sb)/Machine::STACK_MAX ? &&end : *++ip);
+#define EXIT(status)            { push(status); goto end; }
+
+#define do_(name)               &&name
+
+
+using namespace graphite2;
+using namespace vm;
+
+namespace {
+
+// The GCC manual has this to say about labels as values:
+//   The &&foo expressions for the same label might have different values
+//   if the containing function is inlined or cloned. If a program relies
+//   on them being always the same, __attribute__((__noinline__,__noclone__))
+//   should be used to prevent inlining and cloning.
+//
+// is_return in Code.cpp relies on being able to do comparisons, so it needs
+// them to be always the same.
+//
+// The GCC manual further adds:
+//   If &&foo is used in a static variable initializer, inlining and
+//   cloning is forbidden.
+//
+// In this file, &&foo *is* used in a static variable initializer, and it's not
+// entirely clear whether this should prevent inlining of the function or not.
+// In practice, though, clang 7 can end up inlining the function with ThinLTO,
+// which breaks at least is_return. https://bugs.llvm.org/show_bug.cgi?id=39241
+// So all in all, we need at least the __noinline__ attribute. __noclone__
+// is not supported by clang.
+__attribute__((__noinline__))
+const void * direct_run(const bool          get_table_mode,
+                        const instr       * program,
+                        const byte        * data,
+                        Machine::stack_t  * stack,
+                        slotref         * & __map,
+                        uint8                _dir,
+                        Machine::status_t & status,
+                        SlotMap           * __smap=0)
+{
+    // We need to define and return to opcode table from within this function
+    // other inorder to take the addresses of the instruction bodies.
+    #include "inc/opcode_table.h"
+    if (get_table_mode)
+        return opcode_table;
+
+    // Declare virtual machine registers
+    const instr           * ip = program;
+    const byte            * dp = data;
+    Machine::stack_t      * sp = stack + Machine::STACK_GUARD,
+                    * const sb = sp;
+    SlotMap             & smap = *__smap;
+    Segment              & seg = smap.segment;
+    slotref                 is = *__map,
+                         * map = __map,
+                  * const mapb = smap.begin()+smap.context();
+    uint8                  dir = _dir;
+    int8                 flags = 0;
+
+    // start the program
+    goto **ip;
+
+    // Pull in the opcode definitions
+    #include "inc/opcodes.h"
+
+    end:
+    __map  = map;
+    *__map = is;
+    return sp;
+}
+
+}
+
+const opcode_t * Machine::getOpcodeTable() throw()
+{
+    slotref * dummy;
+    Machine::status_t dumstat = Machine::finished;
+    return static_cast<const opcode_t *>(direct_run(true, 0, 0, 0, dummy, 0, dumstat));
+}
+
+
+Machine::stack_t  Machine::run(const instr   * program,
+                               const byte    * data,
+                               slotref     * & is)
+{
+    assert(program != 0);
+
+    const stack_t *sp = static_cast<const stack_t *>(
+                direct_run(false, program, data, _stack, is, _map.dir(), _status, &_map));
+    const stack_t ret = sp == _stack+STACK_GUARD+1 ? *sp-- : 0;
+    check_final_stack(sp);
+    return ret;
+}