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// Copyright 2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * 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.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "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 THE COPYRIGHT
// OWNER 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 "v8.h"
#include "codegen-inl.h"
#include "jump-target-inl.h"
#include "register-allocator-inl.h"
namespace v8 {
namespace internal {
// -------------------------------------------------------------------------
// JumpTarget implementation.
#define __ ACCESS_MASM(cgen()->masm())
void JumpTarget::DoJump() {
ASSERT(cgen()->has_valid_frame());
// Live non-frame registers are not allowed at unconditional jumps
// because we have no way of invalidating the corresponding results
// which are still live in the C++ code.
ASSERT(cgen()->HasValidEntryRegisters());
if (is_bound()) {
// Backward jump. There already a frame expectation at the target.
ASSERT(direction_ == BIDIRECTIONAL);
cgen()->frame()->MergeTo(entry_frame_);
cgen()->DeleteFrame();
} else {
// Use the current frame as the expected one at the target if necessary.
if (entry_frame_ == NULL) {
entry_frame_ = cgen()->frame();
RegisterFile empty;
cgen()->SetFrame(NULL, &empty);
} else {
cgen()->frame()->MergeTo(entry_frame_);
cgen()->DeleteFrame();
}
// The predicate is_linked() should be made true. Its implementation
// detects the presence of a frame pointer in the reaching_frames_ list.
if (!is_linked()) {
reaching_frames_.Add(NULL);
ASSERT(is_linked());
}
}
__ jmp(&entry_label_);
}
void JumpTarget::DoBranch(Condition cc, Hint ignored) {
ASSERT(cgen()->has_valid_frame());
if (is_bound()) {
ASSERT(direction_ == BIDIRECTIONAL);
// Backward branch. We have an expected frame to merge to on the
// backward edge.
cgen()->frame()->MergeTo(entry_frame_);
} else {
// Clone the current frame to use as the expected one at the target if
// necessary.
if (entry_frame_ == NULL) {
entry_frame_ = new VirtualFrame(cgen()->frame());
}
// The predicate is_linked() should be made true. Its implementation
// detects the presence of a frame pointer in the reaching_frames_ list.
if (!is_linked()) {
reaching_frames_.Add(NULL);
ASSERT(is_linked());
}
}
__ b(cc, &entry_label_);
}
void JumpTarget::Call() {
// Call is used to push the address of the catch block on the stack as
// a return address when compiling try/catch and try/finally. We
// fully spill the frame before making the call. The expected frame
// at the label (which should be the only one) is the spilled current
// frame plus an in-memory return address. The "fall-through" frame
// at the return site is the spilled current frame.
ASSERT(cgen()->has_valid_frame());
// There are no non-frame references across the call.
ASSERT(cgen()->HasValidEntryRegisters());
ASSERT(!is_linked());
// Calls are always 'forward' so we use a copy of the current frame (plus
// one for a return address) as the expected frame.
ASSERT(entry_frame_ == NULL);
VirtualFrame* target_frame = new VirtualFrame(cgen()->frame());
target_frame->Adjust(1);
entry_frame_ = target_frame;
// The predicate is_linked() should now be made true. Its implementation
// detects the presence of a frame pointer in the reaching_frames_ list.
reaching_frames_.Add(NULL);
ASSERT(is_linked());
__ bl(&entry_label_);
}
void JumpTarget::DoBind() {
ASSERT(!is_bound());
// Live non-frame registers are not allowed at the start of a basic
// block.
ASSERT(!cgen()->has_valid_frame() || cgen()->HasValidEntryRegisters());
if (cgen()->has_valid_frame()) {
// If there is a current frame we can use it on the fall through.
if (entry_frame_ == NULL) {
entry_frame_ = new VirtualFrame(cgen()->frame());
} else {
ASSERT(cgen()->frame()->Equals(entry_frame_));
}
} else {
// If there is no current frame we must have an entry frame which we can
// copy.
ASSERT(entry_frame_ != NULL);
RegisterFile empty;
cgen()->SetFrame(new VirtualFrame(entry_frame_), &empty);
}
// The predicate is_linked() should be made false. Its implementation
// detects the presence (or absence) of frame pointers in the
// reaching_frames_ list. If we inserted a bogus frame to make
// is_linked() true, remove it now.
if (is_linked()) {
reaching_frames_.Clear();
}
__ bind(&entry_label_);
}
void BreakTarget::Jump() {
// On ARM we do not currently emit merge code for jumps, so we need to do
// it explicitly here. The only merging necessary is to drop extra
// statement state from the stack.
ASSERT(cgen()->has_valid_frame());
int count = cgen()->frame()->height() - expected_height_;
cgen()->frame()->Drop(count);
DoJump();
}
void BreakTarget::Jump(Result* arg) {
// On ARM we do not currently emit merge code for jumps, so we need to do
// it explicitly here. The only merging necessary is to drop extra
// statement state from the stack.
ASSERT(cgen()->has_valid_frame());
int count = cgen()->frame()->height() - expected_height_;
cgen()->frame()->Drop(count);
cgen()->frame()->Push(arg);
DoJump();
}
void BreakTarget::Bind() {
#ifdef DEBUG
// All the forward-reaching frames should have been adjusted at the
// jumps to this target.
for (int i = 0; i < reaching_frames_.length(); i++) {
ASSERT(reaching_frames_[i] == NULL ||
reaching_frames_[i]->height() == expected_height_);
}
#endif
// Drop leftover statement state from the frame before merging, even
// on the fall through. This is so we can bind the return target
// with state on the frame.
if (cgen()->has_valid_frame()) {
int count = cgen()->frame()->height() - expected_height_;
// On ARM we do not currently emit merge code at binding sites, so we need
// to do it explicitly here. The only merging necessary is to drop extra
// statement state from the stack.
cgen()->frame()->Drop(count);
}
DoBind();
}
void BreakTarget::Bind(Result* arg) {
#ifdef DEBUG
// All the forward-reaching frames should have been adjusted at the
// jumps to this target.
for (int i = 0; i < reaching_frames_.length(); i++) {
ASSERT(reaching_frames_[i] == NULL ||
reaching_frames_[i]->height() == expected_height_ + 1);
}
#endif
// Drop leftover statement state from the frame before merging, even
// on the fall through. This is so we can bind the return target
// with state on the frame.
if (cgen()->has_valid_frame()) {
int count = cgen()->frame()->height() - expected_height_;
// On ARM we do not currently emit merge code at binding sites, so we need
// to do it explicitly here. The only merging necessary is to drop extra
// statement state from the stack.
cgen()->frame()->ForgetElements(count);
cgen()->frame()->Push(arg);
}
DoBind();
*arg = cgen()->frame()->Pop();
}
#undef __
} } // namespace v8::internal
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