--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/asm/assembler.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,319 @@
+/*
+ * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code 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 General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "asm/codeBuffer.hpp"
+#include "asm/macroAssembler.hpp"
+#include "asm/macroAssembler.inline.hpp"
+#include "runtime/atomic.hpp"
+#include "runtime/icache.hpp"
+#include "runtime/os.hpp"
+#include "runtime/thread.hpp"
+
+
+// Implementation of AbstractAssembler
+//
+// The AbstractAssembler is generating code into a CodeBuffer. To make code generation faster,
+// the assembler keeps a copy of the code buffers boundaries & modifies them when
+// emitting bytes rather than using the code buffers accessor functions all the time.
+// The code buffer is updated via set_code_end(...) after emitting a whole instruction.
+
+AbstractAssembler::AbstractAssembler(CodeBuffer* code) {
+  if (code == NULL)  return;
+  CodeSection* cs = code->insts();
+  cs->clear_mark();   // new assembler kills old mark
+  if (cs->start() == NULL)  {
+    vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "CodeCache: no room for %s", code->name());
+  }
+  _code_section = cs;
+  _oop_recorder= code->oop_recorder();
+  DEBUG_ONLY( _short_branch_delta = 0; )
+}
+
+void AbstractAssembler::set_code_section(CodeSection* cs) {
+  assert(cs->outer() == code_section()->outer(), "sanity");
+  assert(cs->is_allocated(), "need to pre-allocate this section");
+  cs->clear_mark();  // new assembly into this section kills old mark
+  _code_section = cs;
+}
+
+// Inform CodeBuffer that incoming code and relocation will be for stubs
+address AbstractAssembler::start_a_stub(int required_space) {
+  CodeBuffer*  cb = code();
+  CodeSection* cs = cb->stubs();
+  assert(_code_section == cb->insts(), "not in insts?");
+  if (cs->maybe_expand_to_ensure_remaining(required_space)
+      && cb->blob() == NULL) {
+    return NULL;
+  }
+  set_code_section(cs);
+  return pc();
+}
+
+// Inform CodeBuffer that incoming code and relocation will be code
+// Should not be called if start_a_stub() returned NULL
+void AbstractAssembler::end_a_stub() {
+  assert(_code_section == code()->stubs(), "not in stubs?");
+  set_code_section(code()->insts());
+}
+
+// Inform CodeBuffer that incoming code and relocation will be for stubs
+address AbstractAssembler::start_a_const(int required_space, int required_align) {
+  CodeBuffer*  cb = code();
+  CodeSection* cs = cb->consts();
+  assert(_code_section == cb->insts() || _code_section == cb->stubs(), "not in insts/stubs?");
+  address end = cs->end();
+  int pad = -(intptr_t)end & (required_align-1);
+  if (cs->maybe_expand_to_ensure_remaining(pad + required_space)) {
+    if (cb->blob() == NULL)  return NULL;
+    end = cs->end();  // refresh pointer
+  }
+  if (pad > 0) {
+    while (--pad >= 0) { *end++ = 0; }
+    cs->set_end(end);
+  }
+  set_code_section(cs);
+  return end;
+}
+
+// Inform CodeBuffer that incoming code and relocation will be code
+// in section cs (insts or stubs).
+void AbstractAssembler::end_a_const(CodeSection* cs) {
+  assert(_code_section == code()->consts(), "not in consts?");
+  set_code_section(cs);
+}
+
+void AbstractAssembler::flush() {
+  ICache::invalidate_range(addr_at(0), offset());
+}
+
+void AbstractAssembler::bind(Label& L) {
+  if (L.is_bound()) {
+    // Assembler can bind a label more than once to the same place.
+    guarantee(L.loc() == locator(), "attempt to redefine label");
+    return;
+  }
+  L.bind_loc(locator());
+  L.patch_instructions((MacroAssembler*)this);
+}
+
+void AbstractAssembler::generate_stack_overflow_check(int frame_size_in_bytes) {
+  if (UseStackBanging) {
+    // Each code entry causes one stack bang n pages down the stack where n
+    // is configurable by StackShadowPages.  The setting depends on the maximum
+    // depth of VM call stack or native before going back into java code,
+    // since only java code can raise a stack overflow exception using the
+    // stack banging mechanism.  The VM and native code does not detect stack
+    // overflow.
+    // The code in JavaCalls::call() checks that there is at least n pages
+    // available, so all entry code needs to do is bang once for the end of
+    // this shadow zone.
+    // The entry code may need to bang additional pages if the framesize
+    // is greater than a page.
+
+    const int page_size = os::vm_page_size();
+    int bang_end = (int)JavaThread::stack_shadow_zone_size();
+
+    // This is how far the previous frame's stack banging extended.
+    const int bang_end_safe = bang_end;
+
+    if (frame_size_in_bytes > page_size) {
+      bang_end += frame_size_in_bytes;
+    }
+
+    int bang_offset = bang_end_safe;
+    while (bang_offset <= bang_end) {
+      // Need at least one stack bang at end of shadow zone.
+      bang_stack_with_offset(bang_offset);
+      bang_offset += page_size;
+    }
+  } // end (UseStackBanging)
+}
+
+void Label::add_patch_at(CodeBuffer* cb, int branch_loc) {
+  assert(_loc == -1, "Label is unbound");
+  // Don't add patch locations during scratch emit.
+  if (cb->insts()->scratch_emit()) { return; }
+  if (_patch_index < PatchCacheSize) {
+    _patches[_patch_index] = branch_loc;
+  } else {
+    if (_patch_overflow == NULL) {
+      _patch_overflow = cb->create_patch_overflow();
+    }
+    _patch_overflow->push(branch_loc);
+  }
+  ++_patch_index;
+}
+
+void Label::patch_instructions(MacroAssembler* masm) {
+  assert(is_bound(), "Label is bound");
+  CodeBuffer* cb = masm->code();
+  int target_sect = CodeBuffer::locator_sect(loc());
+  address target = cb->locator_address(loc());
+  while (_patch_index > 0) {
+    --_patch_index;
+    int branch_loc;
+    if (_patch_index >= PatchCacheSize) {
+      branch_loc = _patch_overflow->pop();
+    } else {
+      branch_loc = _patches[_patch_index];
+    }
+    int branch_sect = CodeBuffer::locator_sect(branch_loc);
+    address branch = cb->locator_address(branch_loc);
+    if (branch_sect == CodeBuffer::SECT_CONSTS) {
+      // The thing to patch is a constant word.
+      *(address*)branch = target;
+      continue;
+    }
+
+#ifdef ASSERT
+    // Cross-section branches only work if the
+    // intermediate section boundaries are frozen.
+    if (target_sect != branch_sect) {
+      for (int n = MIN2(target_sect, branch_sect),
+               nlimit = (target_sect + branch_sect) - n;
+           n < nlimit; n++) {
+        CodeSection* cs = cb->code_section(n);
+        assert(cs->is_frozen(), "cross-section branch needs stable offsets");
+      }
+    }
+#endif //ASSERT
+
+    // Push the target offset into the branch instruction.
+    masm->pd_patch_instruction(branch, target);
+  }
+}
+
+struct DelayedConstant {
+  typedef void (*value_fn_t)();
+  BasicType type;
+  intptr_t value;
+  value_fn_t value_fn;
+  // This limit of 20 is generous for initial uses.
+  // The limit needs to be large enough to store the field offsets
+  // into classes which do not have statically fixed layouts.
+  // (Initial use is for method handle object offsets.)
+  // Look for uses of "delayed_value" in the source code
+  // and make sure this number is generous enough to handle all of them.
+  enum { DC_LIMIT = 20 };
+  static DelayedConstant delayed_constants[DC_LIMIT];
+  static DelayedConstant* add(BasicType type, value_fn_t value_fn);
+  bool match(BasicType t, value_fn_t cfn) {
+    return type == t && value_fn == cfn;
+  }
+  static void update_all();
+};
+
+DelayedConstant DelayedConstant::delayed_constants[DC_LIMIT];
+// Default C structure initialization rules have the following effect here:
+// = { { (BasicType)0, (intptr_t)NULL }, ... };
+
+DelayedConstant* DelayedConstant::add(BasicType type,
+                                      DelayedConstant::value_fn_t cfn) {
+  for (int i = 0; i < DC_LIMIT; i++) {
+    DelayedConstant* dcon = &delayed_constants[i];
+    if (dcon->match(type, cfn))
+      return dcon;
+    if (dcon->value_fn == NULL) {
+      // (cmpxchg not because this is multi-threaded but because I'm paranoid)
+      if (Atomic::cmpxchg_ptr(CAST_FROM_FN_PTR(void*, cfn), &dcon->value_fn, NULL) == NULL) {
+        dcon->type = type;
+        return dcon;
+      }
+    }
+  }
+  // If this assert is hit (in pre-integration testing!) then re-evaluate
+  // the comment on the definition of DC_LIMIT.
+  guarantee(false, "too many delayed constants");
+  return NULL;
+}
+
+void DelayedConstant::update_all() {
+  for (int i = 0; i < DC_LIMIT; i++) {
+    DelayedConstant* dcon = &delayed_constants[i];
+    if (dcon->value_fn != NULL && dcon->value == 0) {
+      typedef int     (*int_fn_t)();
+      typedef address (*address_fn_t)();
+      switch (dcon->type) {
+      case T_INT:     dcon->value = (intptr_t) ((int_fn_t)    dcon->value_fn)(); break;
+      case T_ADDRESS: dcon->value = (intptr_t) ((address_fn_t)dcon->value_fn)(); break;
+      default:        break;
+      }
+    }
+  }
+}
+
+RegisterOrConstant AbstractAssembler::delayed_value(int(*value_fn)(), Register tmp, int offset) {
+  intptr_t val = (intptr_t) (*value_fn)();
+  if (val != 0)  return val + offset;
+  return delayed_value_impl(delayed_value_addr(value_fn), tmp, offset);
+}
+RegisterOrConstant AbstractAssembler::delayed_value(address(*value_fn)(), Register tmp, int offset) {
+  intptr_t val = (intptr_t) (*value_fn)();
+  if (val != 0)  return val + offset;
+  return delayed_value_impl(delayed_value_addr(value_fn), tmp, offset);
+}
+intptr_t* AbstractAssembler::delayed_value_addr(int(*value_fn)()) {
+  DelayedConstant* dcon = DelayedConstant::add(T_INT, (DelayedConstant::value_fn_t) value_fn);
+  return &dcon->value;
+}
+intptr_t* AbstractAssembler::delayed_value_addr(address(*value_fn)()) {
+  DelayedConstant* dcon = DelayedConstant::add(T_ADDRESS, (DelayedConstant::value_fn_t) value_fn);
+  return &dcon->value;
+}
+void AbstractAssembler::update_delayed_values() {
+  DelayedConstant::update_all();
+}
+
+void AbstractAssembler::block_comment(const char* comment) {
+  if (sect() == CodeBuffer::SECT_INSTS) {
+    code_section()->outer()->block_comment(offset(), comment);
+  }
+}
+
+const char* AbstractAssembler::code_string(const char* str) {
+  if (sect() == CodeBuffer::SECT_INSTS || sect() == CodeBuffer::SECT_STUBS) {
+    return code_section()->outer()->code_string(str);
+  }
+  return NULL;
+}
+
+bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
+  // Exception handler checks the nmethod's implicit null checks table
+  // only when this method returns false.
+#ifdef _LP64
+  if (UseCompressedOops && Universe::narrow_oop_base() != NULL) {
+    assert (Universe::heap() != NULL, "java heap should be initialized");
+    // The first page after heap_base is unmapped and
+    // the 'offset' is equal to [heap_base + offset] for
+    // narrow oop implicit null checks.
+    uintptr_t base = (uintptr_t)Universe::narrow_oop_base();
+    if ((uintptr_t)offset >= base) {
+      // Normalize offset for the next check.
+      offset = (intptr_t)(pointer_delta((void*)offset, (void*)base, 1));
+    }
+  }
+#endif
+  return offset < 0 || os::vm_page_size() <= offset;
+}