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Diffstat (limited to 'thirdparty/graphite/src/direct_machine.cpp')
| -rw-r--r-- | thirdparty/graphite/src/direct_machine.cpp | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/thirdparty/graphite/src/direct_machine.cpp b/thirdparty/graphite/src/direct_machine.cpp new file mode 100644 index 0000000000..86206cfe37 --- /dev/null +++ b/thirdparty/graphite/src/direct_machine.cpp @@ -0,0 +1,140 @@ +/* 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; +} |