v8/src/jump-target-light.cc

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// Copyright 2010 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"
namespace v8 {
namespace internal {
DeferredCode::DeferredCode()
: masm_(CodeGeneratorScope::Current()->masm()),
statement_position_(masm_->positions_recorder()->
current_statement_position()),
position_(masm_->positions_recorder()->current_position()),
frame_state_(*CodeGeneratorScope::Current()->frame()) {
ASSERT(statement_position_ != RelocInfo::kNoPosition);
ASSERT(position_ != RelocInfo::kNoPosition);
CodeGeneratorScope::Current()->AddDeferred(this);
#ifdef DEBUG
comment_ = "";
#endif
}
// -------------------------------------------------------------------------
// BreakTarget implementation.
void BreakTarget::SetExpectedHeight() {
expected_height_ = cgen()->frame()->height();
}
void BreakTarget::Jump() {
ASSERT(cgen()->has_valid_frame());
int count = cgen()->frame()->height() - expected_height_;
if (count > 0) {
cgen()->frame()->Drop(count);
}
DoJump();
}
void BreakTarget::Branch(Condition cc, Hint hint) {
if (cc == al) {
Jump();
return;
}
ASSERT(cgen()->has_valid_frame());
int count = cgen()->frame()->height() - expected_height_;
if (count > 0) {
// We negate and branch here rather than using DoBranch's negate
// and branch. This gives us a hook to remove statement state
// from the frame.
JumpTarget fall_through;
// Branch to fall through will not negate, because it is a
// forward-only target.
fall_through.Branch(NegateCondition(cc), NegateHint(hint));
// Emit merge code.
cgen()->frame()->Drop(count);
DoJump();
fall_through.Bind();
} else {
DoBranch(cc, hint);
}
}
void BreakTarget::Bind() {
if (cgen()->has_valid_frame()) {
int count = cgen()->frame()->height() - expected_height_;
if (count > 0) {
cgen()->frame()->Drop(count);
}
}
DoBind();
}
} } // namespace v8::internal