mirror of
https://github.com/corda/corda.git
synced 2025-02-03 01:31:24 +00:00
afabe8e07e
This rather large commit modifies the VM to use non-local returns to throw exceptions instead of simply setting Thread::exception and returning frame-by-frame as it used to. This has several benefits: * Functions no longer need to check Thread::exception after each call which might throw an exception (which would be especially tedious and error-prone now that any function which allocates objects directly or indirectly might throw an OutOfMemoryError) * There's no need to audit the code for calls to functions which previously did not throw exceptions but later do * Performance should be improved slightly due to both the reduced need for conditionals and because undwinding now occurs in a single jump instead of a series of returns The main disadvantages are: * Slightly higher overhead for entering and leaving the VM via the JNI and JDK methods * Non-local returns can make the code harder to read * We must be careful to register destructors for stack-allocated resources with the Thread so they can be called prior to a non-local return The non-local return implementation is similar to setjmp/longjmp, except it uses continuation-passing style to avoid the need for cooperation from the C/C++ compiler. Native C++ exceptions would have also been an option, but that would introduce a dependence on libstdc++, which we're trying to avoid for portability reasons. Finally, this commit ensures that the VM throws an OutOfMemoryError instead of aborting when it reaches its memory ceiling. Currently, we treat the ceiling as a soft limit and temporarily exceed it as necessary to allow garbage collection and certain internal allocations to succeed, but refuse to allocate any Java objects until the heap size drops back below the ceiling.
573 lines
18 KiB
C++
573 lines
18 KiB
C++
/* Copyright (c) 2008-2010, Avian Contributors
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Permission to use, copy, modify, and/or distribute this software
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for any purpose with or without fee is hereby granted, provided
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that the above copyright notice and this permission notice appear
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in all copies.
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There is NO WARRANTY for this software. See license.txt for
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details. */
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#include "bootimage.h"
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#include "heapwalk.h"
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#include "common.h"
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#include "machine.h"
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#include "util.h"
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#include "assembler.h"
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// since we aren't linking against libstdc++, we must implement this
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// ourselves:
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extern "C" void __cxa_pure_virtual(void) { abort(); }
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using namespace vm;
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namespace {
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const unsigned HeapCapacity = 768 * 1024 * 1024;
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// Notes on immutable references in the heap image:
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//
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// One of the advantages of a bootimage-based build is that reduces
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// the overhead of major GCs at runtime since we can avoid scanning
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// the pre-built heap image entirely. However, this only works if we
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// can ensure that no part of the heap image (with exceptions noted
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// below) ever points to runtime-allocated objects. Therefore (most)
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// references in the heap image are considered immutable, and any
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// attempt to update them at runtime will cause the process to abort.
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//
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// However, some references in the heap image really must be updated
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// at runtime: e.g. the static field table for each class. Therefore,
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// we allocate these as "fixed" objects, subject to mark-and-sweep
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// collection, instead of as "copyable" objects subject to copying
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// collection. This strategy avoids the necessity of maintaining
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// "dirty reference" bitsets at runtime for the entire heap image;
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// each fixed object has its own bitset specific to that object.
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//
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// In addition to the "fixed" object solution, there are other
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// strategies available to avoid attempts to update immutable
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// references at runtime:
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//
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// * Table-based: use a lazily-updated array or vector to associate
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// runtime data with heap image objects (see
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// e.g. getClassRuntimeData in machine.cpp).
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//
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// * Update references at build time: for example, we set the names
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// of primitive classes before generating the heap image so that we
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// need not populate them lazily at runtime.
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bool
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endsWith(const char* suffix, const char* s, unsigned length)
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{
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unsigned suffixLength = strlen(suffix);
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return length >= suffixLength
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and memcmp(suffix, s + (length - suffixLength), suffixLength) == 0;
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}
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object
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makeCodeImage(Thread* t, Zone* zone, BootImage* image, uint8_t* code,
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uintptr_t* codeMap, const char* className,
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const char* methodName, const char* methodSpec)
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{
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object constants = 0;
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PROTECT(t, constants);
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object calls = 0;
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PROTECT(t, calls);
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DelayedPromise* addresses = 0;
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for (Finder::Iterator it
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(static_cast<Finder*>
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(systemClassLoaderFinder(t, root(t, Machine::BootLoader))));
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it.hasMore();)
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{
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unsigned nameSize = 0;
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const char* name = it.next(&nameSize);
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if (endsWith(".class", name, nameSize)
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and (className == 0 or strncmp(name, className, nameSize - 6) == 0))
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{
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// fprintf(stderr, "%.*s\n", nameSize - 6, name);
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object c = resolveSystemClass
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(t, root(t, Machine::BootLoader),
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makeByteArray(t, "%.*s", nameSize - 6, name), true);
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PROTECT(t, c);
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if (classMethodTable(t, c)) {
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for (unsigned i = 0; i < arrayLength(t, classMethodTable(t, c)); ++i) {
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object method = arrayBody(t, classMethodTable(t, c), i);
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if (((methodName == 0
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or ::strcmp
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(reinterpret_cast<char*>
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(&byteArrayBody
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(t, vm::methodName(t, method), 0)), methodName) == 0)
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and (methodSpec == 0
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or ::strcmp
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(reinterpret_cast<char*>
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(&byteArrayBody
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(t, vm::methodSpec(t, method), 0)), methodSpec)
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== 0)))
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{
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if (methodCode(t, method)
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or (methodFlags(t, method) & ACC_NATIVE))
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{
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PROTECT(t, method);
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t->m->processor->compileMethod
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(t, zone, &constants, &calls, &addresses, method);
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}
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object addendum = methodAddendum(t, method);
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if (addendum and methodAddendumExceptionTable(t, addendum)) {
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PROTECT(t, addendum);
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// resolve exception types now to avoid trying to update
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// immutable references at runtime
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for (unsigned i = 0; i < shortArrayLength
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(t, methodAddendumExceptionTable(t, addendum)); ++i)
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{
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uint16_t index = shortArrayBody
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(t, methodAddendumExceptionTable(t, addendum), i) - 1;
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object o = singletonObject
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(t, addendumPool(t, addendum), index);
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if (objectClass(t, o) == type(t, Machine::ReferenceType)) {
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o = resolveClass
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(t, root(t, Machine::BootLoader), referenceName(t, o));
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set(t, addendumPool(t, addendum),
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SingletonBody + (index * BytesPerWord), o);
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}
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}
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}
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}
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}
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}
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}
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}
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for (; calls; calls = tripleThird(t, calls)) {
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object method = tripleFirst(t, calls);
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uintptr_t address;
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if (methodFlags(t, method) & ACC_NATIVE) {
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address = reinterpret_cast<uintptr_t>(code + image->thunks.native.start);
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} else {
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address = codeCompiled(t, methodCode(t, method));
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}
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static_cast<ListenPromise*>(pointerValue(t, tripleSecond(t, calls)))
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->listener->resolve(address, 0);
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}
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for (; addresses; addresses = addresses->next) {
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uint8_t* value = reinterpret_cast<uint8_t*>(addresses->basis->value());
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assert(t, value >= code);
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void* location;
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bool flat = addresses->listener->resolve
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(reinterpret_cast<int64_t>(code), &location);
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uintptr_t offset = value - code;
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if (flat) {
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offset |= BootFlatConstant;
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}
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memcpy(location, &offset, BytesPerWord);
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assert(t, reinterpret_cast<intptr_t>(location)
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>= reinterpret_cast<intptr_t>(code));
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markBit(codeMap, reinterpret_cast<intptr_t>(location)
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- reinterpret_cast<intptr_t>(code));
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}
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return constants;
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}
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unsigned
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objectSize(Thread* t, object o)
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{
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assert(t, not objectExtended(t, o));
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return baseSize(t, o, objectClass(t, o));
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}
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void
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visitRoots(Thread* t, BootImage* image, HeapWalker* w, object constants)
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{
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Machine* m = t->m;
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for (HashMapIterator it(t, classLoaderMap(t, root(t, Machine::BootLoader)));
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it.hasMore();)
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{
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w->visitRoot(tripleSecond(t, it.next()));
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}
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image->bootLoader = w->visitRoot(root(t, Machine::BootLoader));
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image->appLoader = w->visitRoot(root(t, Machine::AppLoader));
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image->types = w->visitRoot(m->types);
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m->processor->visitRoots(t, w);
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for (; constants; constants = tripleThird(t, constants)) {
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w->visitRoot(tripleFirst(t, constants));
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}
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}
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HeapWalker*
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makeHeapImage(Thread* t, BootImage* image, uintptr_t* heap, uintptr_t* map,
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unsigned capacity, object constants)
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{
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class Visitor: public HeapVisitor {
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public:
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Visitor(Thread* t, uintptr_t* heap, uintptr_t* map, unsigned capacity):
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t(t), currentObject(0), currentNumber(0), currentOffset(0), heap(heap),
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map(map), position(0), capacity(capacity)
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{ }
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void visit(unsigned number) {
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if (currentObject) {
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unsigned offset = currentNumber - 1 + currentOffset;
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unsigned mark = heap[offset] & (~PointerMask);
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unsigned value = number | (mark << BootShift);
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if (value) markBit(map, offset);
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heap[offset] = value;
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}
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}
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virtual void root() {
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currentObject = 0;
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}
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virtual unsigned visitNew(object p) {
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if (p) {
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unsigned size = objectSize(t, p);
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unsigned number;
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if ((currentObject
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and (currentOffset * BytesPerWord) == ClassStaticTable)
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or instanceOf(t, type(t, Machine::SystemClassLoaderType), p))
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{
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// Static tables and system classloaders must be allocated
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// as fixed objects in the heap image so that they can be
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// marked as dirty and visited during GC. Otherwise,
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// attempts to update references in these objects to point
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// to runtime-allocated memory would fail because we don't
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// scan non-fixed objects in the heap image during GC.
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FixedAllocator allocator
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(t->m->system, reinterpret_cast<uint8_t*>(heap + position),
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(capacity - position) * BytesPerWord);
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unsigned totalInBytes;
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uintptr_t* dst = static_cast<uintptr_t*>
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(t->m->heap->allocateImmortalFixed
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(&allocator, size, true, &totalInBytes));
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memcpy(dst, p, size * BytesPerWord);
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dst[0] |= FixedMark;
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number = (dst - heap) + 1;
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position += ceiling(totalInBytes, BytesPerWord);
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} else {
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assert(t, position + size < capacity);
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memcpy(heap + position, p, size * BytesPerWord);
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number = position + 1;
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position += size;
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}
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visit(number);
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return number;
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} else {
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return 0;
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}
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}
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virtual void visitOld(object, unsigned number) {
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visit(number);
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}
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virtual void push(object object, unsigned number, unsigned offset) {
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currentObject = object;
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currentNumber = number;
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currentOffset = offset;
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}
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virtual void pop() {
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currentObject = 0;
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}
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Thread* t;
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object currentObject;
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unsigned currentNumber;
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unsigned currentOffset;
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uintptr_t* heap;
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uintptr_t* map;
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unsigned position;
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unsigned capacity;
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} visitor(t, heap, map, capacity / BytesPerWord);
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HeapWalker* w = makeHeapWalker(t, &visitor);
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visitRoots(t, image, w, constants);
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image->heapSize = visitor.position * BytesPerWord;
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return w;
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}
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void
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updateConstants(Thread* t, object constants, uint8_t* code, uintptr_t* codeMap,
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HeapMap* heapTable)
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{
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for (; constants; constants = tripleThird(t, constants)) {
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unsigned target = heapTable->find(tripleFirst(t, constants));
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assert(t, target > 0);
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for (Promise::Listener* pl = static_cast<ListenPromise*>
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(pointerValue(t, tripleSecond(t, constants)))->listener;
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pl; pl = pl->next)
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{
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void* location;
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bool flat = pl->resolve(0, &location);
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uintptr_t offset = target | BootHeapOffset;
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if (flat) {
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offset |= BootFlatConstant;
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}
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memcpy(location, &offset, BytesPerWord);
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assert(t, reinterpret_cast<intptr_t>(location)
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>= reinterpret_cast<intptr_t>(code));
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markBit(codeMap, reinterpret_cast<intptr_t>(location)
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- reinterpret_cast<intptr_t>(code));
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}
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}
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}
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unsigned
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offset(object a, uintptr_t* b)
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{
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return reinterpret_cast<uintptr_t>(b) - reinterpret_cast<uintptr_t>(a);
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}
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void
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writeBootImage2(Thread* t, FILE* out, BootImage* image, uint8_t* code,
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unsigned codeCapacity, const char* className,
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const char* methodName, const char* methodSpec)
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{
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Zone zone(t->m->system, t->m->heap, 64 * 1024);
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uintptr_t* codeMap = static_cast<uintptr_t*>
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(t->m->heap->allocate(codeMapSize(codeCapacity)));
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memset(codeMap, 0, codeMapSize(codeCapacity));
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object constants = makeCodeImage
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(t, &zone, image, code, codeMap, className, methodName, methodSpec);
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PROTECT(t, constants);
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// this map will not be used when the bootimage is loaded, so
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// there's no need to preserve it:
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setRoot(t, Machine::ByteArrayMap, makeWeakHashMap(t, 0, 0));
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// name all primitive classes so we don't try to update immutable
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// references at runtime:
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{ object name = makeByteArray(t, "void");
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set(t, type(t, Machine::JvoidType), ClassName, name);
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name = makeByteArray(t, "boolean");
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set(t, type(t, Machine::JbooleanType), ClassName, name);
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name = makeByteArray(t, "byte");
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set(t, type(t, Machine::JbyteType), ClassName, name);
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name = makeByteArray(t, "short");
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set(t, type(t, Machine::JshortType), ClassName, name);
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name = makeByteArray(t, "char");
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set(t, type(t, Machine::JcharType), ClassName, name);
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name = makeByteArray(t, "int");
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set(t, type(t, Machine::JintType), ClassName, name);
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name = makeByteArray(t, "float");
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set(t, type(t, Machine::JfloatType), ClassName, name);
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name = makeByteArray(t, "long");
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set(t, type(t, Machine::JlongType), ClassName, name);
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name = makeByteArray(t, "double");
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set(t, type(t, Machine::JdoubleType), ClassName, name);
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}
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collect(t, Heap::MajorCollection);
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uintptr_t* heap = static_cast<uintptr_t*>
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(t->m->heap->allocate(HeapCapacity));
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uintptr_t* heapMap = static_cast<uintptr_t*>
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(t->m->heap->allocate(heapMapSize(HeapCapacity)));
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memset(heapMap, 0, heapMapSize(HeapCapacity));
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HeapWalker* heapWalker = makeHeapImage
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(t, image, heap, heapMap, HeapCapacity, constants);
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updateConstants(t, constants, code, codeMap, heapWalker->map());
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image->bootClassCount = hashMapSize
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(t, classLoaderMap(t, root(t, Machine::BootLoader)));
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unsigned* bootClassTable = static_cast<unsigned*>
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(t->m->heap->allocate(image->bootClassCount * sizeof(unsigned)));
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{ unsigned i = 0;
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for (HashMapIterator it
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(t, classLoaderMap(t, root(t, Machine::BootLoader)));
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it.hasMore();)
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{
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bootClassTable[i++] = heapWalker->map()->find
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(tripleSecond(t, it.next()));
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}
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}
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image->appClassCount = hashMapSize
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(t, classLoaderMap(t, root(t, Machine::AppLoader)));
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unsigned* appClassTable = static_cast<unsigned*>
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(t->m->heap->allocate(image->appClassCount * sizeof(unsigned)));
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{ unsigned i = 0;
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for (HashMapIterator it
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(t, classLoaderMap(t, root(t, Machine::AppLoader)));
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it.hasMore();)
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{
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appClassTable[i++] = heapWalker->map()->find(tripleSecond(t, it.next()));
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}
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}
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image->stringCount = hashMapSize(t, root(t, Machine::StringMap));
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unsigned* stringTable = static_cast<unsigned*>
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(t->m->heap->allocate(image->stringCount * sizeof(unsigned)));
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{ unsigned i = 0;
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for (HashMapIterator it(t, root(t, Machine::StringMap)); it.hasMore();) {
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stringTable[i++] = heapWalker->map()->find
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(jreferenceTarget(t, tripleFirst(t, it.next())));
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}
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}
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unsigned* callTable = t->m->processor->makeCallTable(t, heapWalker);
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heapWalker->dispose();
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image->magic = BootImage::Magic;
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image->codeBase = reinterpret_cast<uintptr_t>(code);
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fprintf(stderr, "class count %d string count %d call count %d\n"
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"heap size %d code size %d\n",
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image->bootClassCount, image->stringCount, image->callCount,
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image->heapSize, image->codeSize);
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if (true) {
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fwrite(image, sizeof(BootImage), 1, out);
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fwrite(bootClassTable, image->bootClassCount * sizeof(unsigned), 1, out);
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fwrite(appClassTable, image->appClassCount * sizeof(unsigned), 1, out);
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fwrite(stringTable, image->stringCount * sizeof(unsigned), 1, out);
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fwrite(callTable, image->callCount * sizeof(unsigned) * 2, 1, out);
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unsigned offset = (image->bootClassCount * sizeof(unsigned))
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+ (image->appClassCount * sizeof(unsigned))
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+ (image->stringCount * sizeof(unsigned))
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+ (image->callCount * sizeof(unsigned) * 2);
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while (offset % BytesPerWord) {
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uint8_t c = 0;
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fwrite(&c, 1, 1, out);
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++ offset;
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}
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fwrite(heapMap, pad(heapMapSize(image->heapSize)), 1, out);
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fwrite(heap, pad(image->heapSize), 1, out);
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fwrite(codeMap, pad(codeMapSize(image->codeSize)), 1, out);
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fwrite(code, pad(image->codeSize), 1, out);
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|
}
|
|
}
|
|
|
|
uint64_t
|
|
writeBootImage(Thread* t, uintptr_t* arguments)
|
|
{
|
|
FILE* out = reinterpret_cast<FILE*>(arguments[0]);
|
|
BootImage* image = reinterpret_cast<BootImage*>(arguments[1]);
|
|
uint8_t* code = reinterpret_cast<uint8_t*>(arguments[2]);
|
|
unsigned codeCapacity = arguments[3];
|
|
const char* className = reinterpret_cast<const char*>(arguments[4]);
|
|
const char* methodName = reinterpret_cast<const char*>(arguments[5]);
|
|
const char* methodSpec = reinterpret_cast<const char*>(arguments[6]);
|
|
|
|
writeBootImage2
|
|
(t, out, image, code, codeCapacity, className, methodName, methodSpec);
|
|
|
|
return 1;
|
|
}
|
|
|
|
} // namespace
|
|
|
|
int
|
|
main(int ac, const char** av)
|
|
{
|
|
if (ac < 3 or ac > 6) {
|
|
fprintf(stderr, "usage: %s <classpath> <output file> "
|
|
"[<class name> [<method name> [<method spec>]]]\n", av[0]);
|
|
return -1;
|
|
}
|
|
|
|
System* s = makeSystem(0);
|
|
Heap* h = makeHeap(s, HeapCapacity * 2);
|
|
Classpath* c = makeClasspath(s, h, AVIAN_JAVA_HOME, AVIAN_EMBED_PREFIX);
|
|
Finder* f = makeFinder(s, h, av[1], 0);
|
|
Processor* p = makeProcessor(s, h, false);
|
|
|
|
BootImage image;
|
|
const unsigned CodeCapacity = 128 * 1024 * 1024;
|
|
uint8_t* code = static_cast<uint8_t*>(h->allocate(CodeCapacity));
|
|
p->initialize(&image, code, CodeCapacity);
|
|
|
|
Machine* m = new (h->allocate(sizeof(Machine))) Machine
|
|
(s, h, f, 0, p, c, 0, 0);
|
|
Thread* t = p->makeThread(m, 0, 0);
|
|
|
|
enter(t, Thread::ActiveState);
|
|
enter(t, Thread::IdleState);
|
|
|
|
FILE* output = vm::fopen(av[2], "wb");
|
|
if (output == 0) {
|
|
fprintf(stderr, "unable to open %s\n", av[2]);
|
|
return -1;
|
|
}
|
|
|
|
uintptr_t arguments[] = { reinterpret_cast<uintptr_t>(output),
|
|
reinterpret_cast<uintptr_t>(&image),
|
|
reinterpret_cast<uintptr_t>(code),
|
|
CodeCapacity,
|
|
reinterpret_cast<uintptr_t>(ac > 3 ? av[3] : 0),
|
|
reinterpret_cast<uintptr_t>(ac > 4 ? av[4] : 0),
|
|
reinterpret_cast<uintptr_t>(ac > 5 ? av[5] : 0) };
|
|
|
|
run(t, writeBootImage, arguments);
|
|
|
|
fclose(output);
|
|
|
|
if (t->exception) {
|
|
printTrace(t, t->exception);
|
|
return -1;
|
|
} else {
|
|
return 0;
|
|
}
|
|
}
|