michael@0: // Copyright (c) 2010, Google Inc.
michael@0: // All rights reserved.
michael@0: //
michael@0: // Redistribution and use in source and binary forms, with or without
michael@0: // modification, are permitted provided that the following conditions are
michael@0: // met:
michael@0: //
michael@0: //     * Redistributions of source code must retain the above copyright
michael@0: // notice, this list of conditions and the following disclaimer.
michael@0: //     * Redistributions in binary form must reproduce the above
michael@0: // copyright notice, this list of conditions and the following disclaimer
michael@0: // in the documentation and/or other materials provided with the
michael@0: // distribution.
michael@0: //     * Neither the name of Google Inc. nor the names of its
michael@0: // contributors may be used to endorse or promote products derived from
michael@0: // this software without specific prior written permission.
michael@0: //
michael@0: // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0: // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
michael@0: // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
michael@0: // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
michael@0: // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
michael@0: // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
michael@0: // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
michael@0: // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0: // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
michael@0: // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0: 
michael@0: // Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
michael@0: 
michael@0: // test_assembler.cc: Implementation of google_breakpad::TestAssembler.
michael@0: // See test_assembler.h for details.
michael@0: 
michael@0: #include "common/test_assembler.h"
michael@0: 
michael@0: #include <assert.h>
michael@0: #include <stdio.h>
michael@0: 
michael@0: #include <iterator>
michael@0: 
michael@0: namespace google_breakpad {
michael@0: namespace test_assembler {
michael@0: 
michael@0: using std::back_insert_iterator;
michael@0: 
michael@0: Label::Label() : value_(new Binding()) { }
michael@0: Label::Label(uint64_t value) : value_(new Binding(value)) { }
michael@0: Label::Label(const Label &label) {
michael@0:   value_ = label.value_;
michael@0:   value_->Acquire();
michael@0: }
michael@0: Label::~Label() {
michael@0:   if (value_->Release()) delete value_;
michael@0: }
michael@0: 
michael@0: Label &Label::operator=(uint64_t value) {
michael@0:   value_->Set(NULL, value);
michael@0:   return *this;
michael@0: }
michael@0: 
michael@0: Label &Label::operator=(const Label &label) {
michael@0:   value_->Set(label.value_, 0);
michael@0:   return *this;
michael@0: }
michael@0: 
michael@0: Label Label::operator+(uint64_t addend) const {
michael@0:   Label l;
michael@0:   l.value_->Set(this->value_, addend);
michael@0:   return l;
michael@0: }
michael@0: 
michael@0: Label Label::operator-(uint64_t subtrahend) const {
michael@0:   Label l;
michael@0:   l.value_->Set(this->value_, -subtrahend);
michael@0:   return l;
michael@0: }
michael@0: 
michael@0: // When NDEBUG is #defined, assert doesn't evaluate its argument. This
michael@0: // means you can't simply use assert to check the return value of a
michael@0: // function with necessary side effects.
michael@0: //
michael@0: // ALWAYS_EVALUATE_AND_ASSERT(x) evaluates x regardless of whether
michael@0: // NDEBUG is #defined; when NDEBUG is not #defined, it further asserts
michael@0: // that x is true.
michael@0: #ifdef NDEBUG
michael@0: #define ALWAYS_EVALUATE_AND_ASSERT(x) x
michael@0: #else
michael@0: #define ALWAYS_EVALUATE_AND_ASSERT(x) assert(x)
michael@0: #endif
michael@0: 
michael@0: uint64_t Label::operator-(const Label &label) const {
michael@0:   uint64_t offset;
michael@0:   ALWAYS_EVALUATE_AND_ASSERT(IsKnownOffsetFrom(label, &offset));
michael@0:   return offset;
michael@0: }
michael@0: 
michael@0: uint64_t Label::Value() const {
michael@0:   uint64_t v = 0;
michael@0:   ALWAYS_EVALUATE_AND_ASSERT(IsKnownConstant(&v));
michael@0:   return v;
michael@0: };
michael@0: 
michael@0: bool Label::IsKnownConstant(uint64_t *value_p) const {
michael@0:   Binding *base;
michael@0:   uint64_t addend;
michael@0:   value_->Get(&base, &addend);
michael@0:   if (base != NULL) return false;
michael@0:   if (value_p) *value_p = addend;
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool Label::IsKnownOffsetFrom(const Label &label, uint64_t *offset_p) const
michael@0: {
michael@0:   Binding *label_base, *this_base;
michael@0:   uint64_t label_addend, this_addend;
michael@0:   label.value_->Get(&label_base, &label_addend);
michael@0:   value_->Get(&this_base, &this_addend);
michael@0:   // If this and label are related, Get will find their final
michael@0:   // common ancestor, regardless of how indirect the relation is. This
michael@0:   // comparison also handles the constant vs. constant case.
michael@0:   if (this_base != label_base) return false;
michael@0:   if (offset_p) *offset_p = this_addend - label_addend;
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: Label::Binding::Binding() : base_(this), addend_(), reference_count_(1) { }
michael@0: 
michael@0: Label::Binding::Binding(uint64_t addend)
michael@0:     : base_(NULL), addend_(addend), reference_count_(1) { }
michael@0: 
michael@0: Label::Binding::~Binding() {
michael@0:   assert(reference_count_ == 0);
michael@0:   if (base_ && base_ != this && base_->Release())
michael@0:     delete base_;
michael@0: }
michael@0: 
michael@0: void Label::Binding::Set(Binding *binding, uint64_t addend) {
michael@0:   if (!base_ && !binding) {
michael@0:     // We're equating two constants. This could be okay.
michael@0:     assert(addend_ == addend);
michael@0:   } else if (!base_) {
michael@0:     // We are a known constant, but BINDING may not be, so turn the
michael@0:     // tables and try to set BINDING's value instead.
michael@0:     binding->Set(NULL, addend_ - addend);
michael@0:   } else {
michael@0:     if (binding) {
michael@0:       // Find binding's final value. Since the final value is always either
michael@0:       // completely unconstrained or a constant, never a reference to
michael@0:       // another variable (otherwise, it wouldn't be final), this
michael@0:       // guarantees we won't create cycles here, even for code like this:
michael@0:       //   l = m, m = n, n = l;
michael@0:       uint64_t binding_addend;
michael@0:       binding->Get(&binding, &binding_addend);
michael@0:       addend += binding_addend;
michael@0:     }
michael@0: 
michael@0:     // It seems likely that setting a binding to itself is a bug
michael@0:     // (although I can imagine this might turn out to be helpful to
michael@0:     // permit).
michael@0:     assert(binding != this);
michael@0: 
michael@0:     if (base_ != this) {
michael@0:       // Set the other bindings on our chain as well. Note that this
michael@0:       // is sufficient even though binding relationships form trees:
michael@0:       // All binding operations traverse their chains to the end, and
michael@0:       // all bindings related to us share some tail of our chain, so
michael@0:       // they will see the changes we make here.
michael@0:       base_->Set(binding, addend - addend_);
michael@0:       // We're not going to use base_ any more.
michael@0:       if (base_->Release()) delete base_;
michael@0:     }
michael@0:     
michael@0:     // Adopt BINDING as our base. Note that it should be correct to
michael@0:     // acquire here, after the release above, even though the usual
michael@0:     // reference-counting rules call for acquiring first, and then
michael@0:     // releasing: the self-reference assertion above should have
michael@0:     // complained if BINDING were 'this' or anywhere along our chain,
michael@0:     // so we didn't release BINDING.
michael@0:     if (binding) binding->Acquire();
michael@0:     base_ = binding;
michael@0:     addend_ = addend;
michael@0:   }
michael@0: }
michael@0: 
michael@0: void Label::Binding::Get(Binding **base, uint64_t *addend) {
michael@0:   if (base_ && base_ != this) {
michael@0:     // Recurse to find the end of our reference chain (the root of our
michael@0:     // tree), and then rewrite every binding along the chain to refer
michael@0:     // to it directly, adjusting addends appropriately. (This is why
michael@0:     // this member function isn't this-const.)
michael@0:     Binding *final_base;
michael@0:     uint64_t final_addend;
michael@0:     base_->Get(&final_base, &final_addend);
michael@0:     if (final_base) final_base->Acquire();
michael@0:     if (base_->Release()) delete base_;
michael@0:     base_ = final_base;
michael@0:     addend_ += final_addend;
michael@0:   }
michael@0:   *base = base_;
michael@0:   *addend = addend_;
michael@0: }
michael@0: 
michael@0: template<typename Inserter>
michael@0: static inline void InsertEndian(test_assembler::Endianness endianness,
michael@0:                                 size_t size, uint64_t number, Inserter dest) {
michael@0:   assert(size > 0);
michael@0:   if (endianness == kLittleEndian) {
michael@0:     for (size_t i = 0; i < size; i++) {
michael@0:       *dest++ = (char) (number & 0xff);
michael@0:       number >>= 8;
michael@0:     }
michael@0:   } else {
michael@0:     assert(endianness == kBigEndian);
michael@0:     // The loop condition is odd, but it's correct for size_t.
michael@0:     for (size_t i = size - 1; i < size; i--)
michael@0:       *dest++ = (char) ((number >> (i * 8)) & 0xff);
michael@0:   }
michael@0: }
michael@0: 
michael@0: Section &Section::Append(Endianness endianness, size_t size, uint64_t number) {
michael@0:   InsertEndian(endianness, size, number,
michael@0:                back_insert_iterator<string>(contents_));
michael@0:   return *this;
michael@0: }
michael@0: 
michael@0: Section &Section::Append(Endianness endianness, size_t size,
michael@0:                          const Label &label) {
michael@0:   // If this label's value is known, there's no reason to waste an
michael@0:   // entry in references_ on it.
michael@0:   uint64_t value;
michael@0:   if (label.IsKnownConstant(&value))
michael@0:     return Append(endianness, size, value);
michael@0: 
michael@0:   // This will get caught when the references are resolved, but it's
michael@0:   // nicer to find out earlier.
michael@0:   assert(endianness != kUnsetEndian);
michael@0: 
michael@0:   references_.push_back(Reference(contents_.size(), endianness, size, label));
michael@0:   contents_.append(size, 0);
michael@0:   return *this;
michael@0: }
michael@0: 
michael@0: #define ENDIANNESS_L kLittleEndian
michael@0: #define ENDIANNESS_B kBigEndian
michael@0: #define ENDIANNESS(e) ENDIANNESS_ ## e
michael@0: 
michael@0: #define DEFINE_SHORT_APPEND_NUMBER_ENDIAN(e, bits)                      \
michael@0:   Section &Section::e ## bits(uint ## bits ## _t v) {                  \
michael@0:     InsertEndian(ENDIANNESS(e), bits / 8, v,                            \
michael@0:                  back_insert_iterator<string>(contents_));              \
michael@0:     return *this;                                                       \
michael@0:   }
michael@0: 
michael@0: #define DEFINE_SHORT_APPEND_LABEL_ENDIAN(e, bits)                       \
michael@0:   Section &Section::e ## bits(const Label &v) {                         \
michael@0:     return Append(ENDIANNESS(e), bits / 8, v);                          \
michael@0:   }
michael@0: 
michael@0: // Define L16, B32, and friends.
michael@0: #define DEFINE_SHORT_APPEND_ENDIAN(e, bits)                             \
michael@0:   DEFINE_SHORT_APPEND_NUMBER_ENDIAN(e, bits)                            \
michael@0:   DEFINE_SHORT_APPEND_LABEL_ENDIAN(e, bits)
michael@0: 
michael@0: DEFINE_SHORT_APPEND_LABEL_ENDIAN(L, 8);
michael@0: DEFINE_SHORT_APPEND_LABEL_ENDIAN(B, 8);
michael@0: DEFINE_SHORT_APPEND_ENDIAN(L, 16);
michael@0: DEFINE_SHORT_APPEND_ENDIAN(L, 32);
michael@0: DEFINE_SHORT_APPEND_ENDIAN(L, 64);
michael@0: DEFINE_SHORT_APPEND_ENDIAN(B, 16);
michael@0: DEFINE_SHORT_APPEND_ENDIAN(B, 32);
michael@0: DEFINE_SHORT_APPEND_ENDIAN(B, 64);
michael@0: 
michael@0: #define DEFINE_SHORT_APPEND_NUMBER_DEFAULT(bits)                        \
michael@0:   Section &Section::D ## bits(uint ## bits ## _t v) {                  \
michael@0:     InsertEndian(endianness_, bits / 8, v,                              \
michael@0:                  back_insert_iterator<string>(contents_));              \
michael@0:     return *this;                                                       \
michael@0:   }
michael@0: #define DEFINE_SHORT_APPEND_LABEL_DEFAULT(bits)                         \
michael@0:   Section &Section::D ## bits(const Label &v) {                         \
michael@0:     return Append(endianness_, bits / 8, v);                            \
michael@0:   }
michael@0: #define DEFINE_SHORT_APPEND_DEFAULT(bits)                               \
michael@0:   DEFINE_SHORT_APPEND_NUMBER_DEFAULT(bits)                              \
michael@0:   DEFINE_SHORT_APPEND_LABEL_DEFAULT(bits)
michael@0: 
michael@0: DEFINE_SHORT_APPEND_LABEL_DEFAULT(8)
michael@0: DEFINE_SHORT_APPEND_DEFAULT(16);
michael@0: DEFINE_SHORT_APPEND_DEFAULT(32);
michael@0: DEFINE_SHORT_APPEND_DEFAULT(64);
michael@0: 
michael@0: Section &Section::Append(const Section &section) {
michael@0:   size_t base = contents_.size();
michael@0:   contents_.append(section.contents_);
michael@0:   for (vector<Reference>::const_iterator it = section.references_.begin();
michael@0:        it != section.references_.end(); it++)
michael@0:     references_.push_back(Reference(base + it->offset, it->endianness,
michael@0:                                     it->size, it->label));
michael@0:   return *this;
michael@0: }
michael@0: 
michael@0: Section &Section::LEB128(long long value) {
michael@0:   while (value < -0x40 || 0x3f < value) {
michael@0:     contents_ += (value & 0x7f) | 0x80;
michael@0:     if (value < 0)
michael@0:       value = (value >> 7) | ~(((unsigned long long) -1) >> 7);
michael@0:     else
michael@0:       value = (value >> 7);
michael@0:   }
michael@0:   contents_ += value & 0x7f;
michael@0:   return *this;
michael@0: }
michael@0: 
michael@0: Section &Section::ULEB128(uint64_t value) {
michael@0:   while (value > 0x7f) {
michael@0:     contents_ += (value & 0x7f) | 0x80;
michael@0:     value = (value >> 7);
michael@0:   }
michael@0:   contents_ += value;
michael@0:   return *this;
michael@0: }
michael@0: 
michael@0: Section &Section::Align(size_t alignment, uint8_t pad_byte) {
michael@0:   // ALIGNMENT must be a power of two.
michael@0:   assert(((alignment - 1) & alignment) == 0);
michael@0:   size_t new_size = (contents_.size() + alignment - 1) & ~(alignment - 1);
michael@0:   contents_.append(new_size - contents_.size(), pad_byte);
michael@0:   assert((contents_.size() & (alignment - 1)) == 0);
michael@0:   return *this;
michael@0: }
michael@0: 
michael@0: void Section::Clear() {
michael@0:   contents_.clear();
michael@0:   references_.clear();
michael@0: }
michael@0: 
michael@0: bool Section::GetContents(string *contents) {
michael@0:   // For each label reference, find the label's value, and patch it into
michael@0:   // the section's contents.
michael@0:   for (size_t i = 0; i < references_.size(); i++) {
michael@0:     Reference &r = references_[i];
michael@0:     uint64_t value;
michael@0:     if (!r.label.IsKnownConstant(&value)) {
michael@0:       fprintf(stderr, "Undefined label #%zu at offset 0x%zx\n", i, r.offset);
michael@0:       return false;
michael@0:     }
michael@0:     assert(r.offset < contents_.size());
michael@0:     assert(contents_.size() - r.offset >= r.size);
michael@0:     InsertEndian(r.endianness, r.size, value, contents_.begin() + r.offset);
michael@0:   }
michael@0:   contents->clear();
michael@0:   std::swap(contents_, *contents);
michael@0:   references_.clear();
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: }  // namespace test_assembler
michael@0: }  // namespace google_breakpad