// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/signature.h"
#include "src/bit-vector.h"
#include "src/flags.h"
#include "src/handles.h"
#include "src/zone/zone-containers.h"
#include "src/wasm/ast-decoder.h"
#include "src/wasm/decoder.h"
#include "src/wasm/wasm-module.h"
#include "src/wasm/wasm-opcodes.h"
#include "src/ostreams.h"
#include "src/compiler/wasm-compiler.h"
namespace v8 {
namespace internal {
namespace wasm {
#if DEBUG
#define TRACE(...) \
do { \
if (FLAG_trace_wasm_decoder) PrintF(__VA_ARGS__); \
} while (false)
#else
#define TRACE(...)
#endif
#define CHECK_PROTOTYPE_OPCODE(flag) \
if (module_ && module_->origin == kAsmJsOrigin) { \
error("Opcode not supported for asmjs modules"); \
} \
if (!FLAG_##flag) { \
error("Invalid opcode (enable with --" #flag ")"); \
break; \
}
// TODO(titzer): this is only for intermediate migration.
#define IMPLICIT_FUNCTION_END 1
// An SsaEnv environment carries the current local variable renaming
// as well as the current effect and control dependency in the TF graph.
// It maintains a control state that tracks whether the environment
// is reachable, has reached a control end, or has been merged.
struct SsaEnv {
enum State { kControlEnd, kUnreachable, kReached, kMerged };
State state;
TFNode* control;
TFNode* effect;
TFNode** locals;
bool go() { return state >= kReached; }
void Kill(State new_state = kControlEnd) {
state = new_state;
locals = nullptr;
control = nullptr;
effect = nullptr;
}
void SetNotMerged() {
if (state == kMerged) state = kReached;
}
};
// An entry on the value stack.
struct Value {
const byte* pc;
TFNode* node;
LocalType type;
};
struct TryInfo : public ZoneObject {
SsaEnv* catch_env;
TFNode* exception;
explicit TryInfo(SsaEnv* c) : catch_env(c), exception(nullptr) {}
};
struct MergeValues {
uint32_t arity;
union {
Value* array;
Value first;
} vals; // Either multiple values or a single value.
Value& first() {
DCHECK_GT(arity, 0u);
return arity == 1 ? vals.first : vals.array[0];
}
};
static Value* NO_VALUE = nullptr;
enum ControlKind { kControlIf, kControlBlock, kControlLoop, kControlTry };
// An entry on the control stack (i.e. if, block, loop).
struct Control {
const byte* pc;
ControlKind kind;
int stack_depth; // stack height at the beginning of the construct.
SsaEnv* end_env; // end environment for the construct.
SsaEnv* false_env; // false environment (only for if).
TryInfo* try_info; // Information used for compiling try statements.
int32_t previous_catch; // The previous Control (on the stack) with a catch.
// Values merged into the end of this control construct.
MergeValues merge;
inline bool is_if() const { return kind == kControlIf; }
inline bool is_block() const { return kind == kControlBlock; }
inline bool is_loop() const { return kind == kControlLoop; }
inline bool is_try() const { return kind == kControlTry; }
// Named constructors.
static Control Block(const byte* pc, int stack_depth, SsaEnv* end_env,
int32_t previous_catch) {
return {pc, kControlBlock, stack_depth, end_env,
nullptr, nullptr, previous_catch, {0, {NO_VALUE}}};
}
static Control If(const byte* pc, int stack_depth, SsaEnv* end_env,
SsaEnv* false_env, int32_t previous_catch) {
return {pc, kControlIf, stack_depth, end_env,
false_env, nullptr, previous_catch, {0, {NO_VALUE}}};
}
static Control Loop(const byte* pc, int stack_depth, SsaEnv* end_env,
int32_t previous_catch) {
return {pc, kControlLoop, stack_depth, end_env,
nullptr, nullptr, previous_catch, {0, {NO_VALUE}}};
}
static Control Try(const byte* pc, int stack_depth, SsaEnv* end_env,
Zone* zone, SsaEnv* catch_env, int32_t previous_catch) {
DCHECK_NOT_NULL(catch_env);
TryInfo* try_info = new (zone) TryInfo(catch_env);
return {pc, kControlTry, stack_depth, end_env,
nullptr, try_info, previous_catch, {0, {NO_VALUE}}};
}
};
// Macros that build nodes only if there is a graph and the current SSA
// environment is reachable from start. This avoids problems with malformed
// TF graphs when decoding inputs that have unreachable code.
#define BUILD(func, ...) \
(build() ? CheckForException(builder_->func(__VA_ARGS__)) : nullptr)
#define BUILD0(func) (build() ? CheckForException(builder_->func()) : nullptr)
struct LaneOperand {
uint8_t lane;
unsigned length;
inline LaneOperand(Decoder* decoder, const byte* pc) {
lane = decoder->checked_read_u8(pc, 2, "lane");
length = 1;
}
};
// Generic Wasm bytecode decoder with utilities for decoding operands,
// lengths, etc.
class WasmDecoder : public Decoder {
public:
WasmDecoder(ModuleEnv* module, FunctionSig* sig, const byte* start,
const byte* end)
: Decoder(start, end),
module_(module),
sig_(sig),
total_locals_(0),
local_types_(nullptr) {}
ModuleEnv* module_;
FunctionSig* sig_;
size_t total_locals_;
ZoneVector<LocalType>* local_types_;
inline bool Validate(const byte* pc, LocalIndexOperand& operand) {
if (operand.index < total_locals_) {
if (local_types_) {
operand.type = local_types_->at(operand.index);
} else {
operand.type = kAstStmt;
}
return true;
}
error(pc, pc + 1, "invalid local index: %u", operand.index);
return false;
}
inline bool Validate(const byte* pc, GlobalIndexOperand& operand) {
ModuleEnv* m = module_;
if (m && m->module && operand.index < m->module->globals.size()) {
operand.global = &m->module->globals[operand.index];
operand.type = operand.global->type;
return true;
}
error(pc, pc + 1, "invalid global index: %u", operand.index);
return false;
}
inline bool Complete(const byte* pc, CallFunctionOperand& operand) {
ModuleEnv* m = module_;
if (m && m->module && operand.index < m->module->functions.size()) {
operand.sig = m->module->functions[operand.index].sig;
return true;
}
return false;
}
inline bool Validate(const byte* pc, CallFunctionOperand& operand) {
if (Complete(pc, operand)) {
return true;
}
error(pc, pc + 1, "invalid function index: %u", operand.index);
return false;
}
inline bool Complete(const byte* pc, CallIndirectOperand& operand) {
ModuleEnv* m = module_;
if (m && m->module && operand.index < m->module->signatures.size()) {
operand.sig = m->module->signatures[operand.index];
return true;
}
return false;
}
inline bool Validate(const byte* pc, CallIndirectOperand& operand) {
uint32_t table_index = 0;
if (!module_->IsValidTable(table_index)) {
error("function table has to exist to execute call_indirect");
return false;
}
if (Complete(pc, operand)) {
return true;
}
error(pc, pc + 1, "invalid signature index: #%u", operand.index);
return false;
}
inline bool Validate(const byte* pc, BreakDepthOperand& operand,
ZoneVector<Control>& control) {
if (operand.depth < control.size()) {
operand.target = &control[control.size() - operand.depth - 1];
return true;
}
error(pc, pc + 1, "invalid break depth: %u", operand.depth);
return false;
}
bool Validate(const byte* pc, BranchTableOperand& operand,
size_t block_depth) {
// TODO(titzer): add extra redundant validation for br_table here?
return true;
}
inline bool Validate(const byte* pc, LaneOperand& operand) {
if (operand.lane < 0 || operand.lane > 3) {
error(pc_, pc_ + 2, "invalid extract lane value");
return false;
} else {
return true;
}
}
unsigned OpcodeLength(const byte* pc) {
switch (static_cast<byte>(*pc)) {
#define DECLARE_OPCODE_CASE(name, opcode, sig) case kExpr##name:
FOREACH_LOAD_MEM_OPCODE(DECLARE_OPCODE_CASE)
FOREACH_STORE_MEM_OPCODE(DECLARE_OPCODE_CASE)
#undef DECLARE_OPCODE_CASE
{
MemoryAccessOperand operand(this, pc, UINT32_MAX);
return 1 + operand.length;
}
case kExprBr:
case kExprBrIf: {
BreakDepthOperand operand(this, pc);
return 1 + operand.length;
}
case kExprSetGlobal:
case kExprGetGlobal: {
GlobalIndexOperand operand(this, pc);
return 1 + operand.length;
}
case kExprCallFunction: {
CallFunctionOperand operand(this, pc);
return 1 + operand.length;
}
case kExprCallIndirect: {
CallIndirectOperand operand(this, pc);
return 1 + operand.length;
}
case kExprTry:
case kExprIf: // fall thru
case kExprLoop:
case kExprBlock: {
BlockTypeOperand operand(this, pc);
return 1 + operand.length;
}
case kExprSetLocal:
case kExprTeeLocal:
case kExprGetLocal:
case kExprCatch: {
LocalIndexOperand operand(this, pc);
return 1 + operand.length;
}
case kExprBrTable: {
BranchTableOperand operand(this, pc);
BranchTableIterator iterator(this, operand);
return 1 + iterator.length();
}
case kExprI32Const: {
ImmI32Operand operand(this, pc);
return 1 + operand.length;
}
case kExprI64Const: {
ImmI64Operand operand(this, pc);
return 1 + operand.length;
}
case kExprGrowMemory:
case kExprMemorySize: {
MemoryIndexOperand operand(this, pc);
return 1 + operand.length;
}
case kExprI8Const:
return 2;
case kExprF32Const:
return 5;
case kExprF64Const:
return 9;
case kSimdPrefix: {
byte simd_index = checked_read_u8(pc, 1, "simd_index");
WasmOpcode opcode =
static_cast<WasmOpcode>(kSimdPrefix << 8 | simd_index);
switch (opcode) {
#define DECLARE_OPCODE_CASE(name, opcode, sig) case kExpr##name:
FOREACH_SIMD_0_OPERAND_OPCODE(DECLARE_OPCODE_CASE)
#undef DECLARE_OPCODE_CASE
{
return 2;
}
#define DECLARE_OPCODE_CASE(name, opcode, sig) case kExpr##name:
FOREACH_SIMD_1_OPERAND_OPCODE(DECLARE_OPCODE_CASE)
#undef DECLARE_OPCODE_CASE
{
return 3;
}
default:
error("invalid SIMD opcode");
return 2;
}
}
default:
return 1;
}
}
};
static const int32_t kNullCatch = -1;
// The full WASM decoder for bytecode. Both verifies bytecode and generates
// a TurboFan IR graph.
class WasmFullDecoder : public WasmDecoder {
public:
WasmFullDecoder(Zone* zone, TFBuilder* builder, const FunctionBody& body)
: WasmDecoder(body.module, body.sig, body.start, body.end),
zone_(zone),
builder_(builder),
base_(body.base),
local_type_vec_(zone),
stack_(zone),
control_(zone),
last_end_found_(false),
current_catch_(kNullCatch) {
local_types_ = &local_type_vec_;
}
bool Decode() {
base::ElapsedTimer decode_timer;
if (FLAG_trace_wasm_decode_time) {
decode_timer.Start();
}
stack_.clear();
control_.clear();
if (end_ < pc_) {
error("function body end < start");
return false;
}
DecodeLocalDecls();
InitSsaEnv();
DecodeFunctionBody();
if (failed()) return TraceFailed();
#if IMPLICIT_FUNCTION_END
// With implicit end support (old style), the function block
// remains on the stack. Other control blocks are an error.
if (control_.size() > 1) {
error(pc_, control_.back().pc, "unterminated control structure");
return TraceFailed();
}
// Assume an implicit end to the function body block.
if (control_.size() == 1) {
Control* c = &control_.back();
if (ssa_env_->go()) {
FallThruTo(c);
}
if (c->end_env->go()) {
// Push the end values onto the stack.
stack_.resize(c->stack_depth);
if (c->merge.arity == 1) {
stack_.push_back(c->merge.vals.first);
} else {
for (unsigned i = 0; i < c->merge.arity; i++) {
stack_.push_back(c->merge.vals.array[i]);
}
}
TRACE(" @%-8d #xx:%-20s|", startrel(pc_), "ImplicitReturn");
SetEnv("function:end", c->end_env);
DoReturn();
TRACE("\n");
}
}
#else
if (!control_.empty()) {
error(pc_, control_.back().pc, "unterminated control structure");
return TraceFailed();
}
if (!last_end_found_) {
error("function body must end with \"end\" opcode.");
return false;
}
#endif
if (FLAG_trace_wasm_decode_time) {
double ms = decode_timer.Elapsed().InMillisecondsF();
PrintF("wasm-decode %s (%0.3f ms)\n\n", ok() ? "ok" : "failed", ms);
} else {
TRACE("wasm-decode %s\n\n", ok() ? "ok" : "failed");
}
return true;
}
bool TraceFailed() {
TRACE("wasm-error module+%-6d func+%d: %s\n\n", baserel(error_pc_),
startrel(error_pc_), error_msg_.get());
return false;
}
bool DecodeLocalDecls(AstLocalDecls& decls) {
DecodeLocalDecls();
if (failed()) return false;
decls.decls_encoded_size = pc_offset();
decls.local_types.reserve(local_type_vec_.size());
for (size_t pos = 0; pos < local_type_vec_.size();) {
uint32_t count = 0;
LocalType type = local_type_vec_[pos];
while (pos < local_type_vec_.size() && local_type_vec_[pos] == type) {
pos++;
count++;
}
decls.local_types.push_back(std::pair<LocalType, uint32_t>(type, count));
}
decls.total_local_count = static_cast<uint32_t>(local_type_vec_.size());
return true;
}
BitVector* AnalyzeLoopAssignmentForTesting(const byte* pc,
size_t num_locals) {
total_locals_ = num_locals;
local_type_vec_.reserve(num_locals);
if (num_locals > local_type_vec_.size()) {
local_type_vec_.insert(local_type_vec_.end(),
num_locals - local_type_vec_.size(), kAstI32);
}
return AnalyzeLoopAssignment(pc);
}
private:
static const size_t kErrorMsgSize = 128;
Zone* zone_;
TFBuilder* builder_;
const byte* base_;
SsaEnv* ssa_env_;
ZoneVector<LocalType> local_type_vec_; // types of local variables.
ZoneVector<Value> stack_; // stack of values.
ZoneVector<Control> control_; // stack of blocks, loops, and ifs.
bool last_end_found_;
int32_t current_catch_;
TryInfo* current_try_info() { return control_[current_catch_].try_info; }
inline bool build() { return builder_ && ssa_env_->go(); }
void InitSsaEnv() {
TFNode* start = nullptr;
SsaEnv* ssa_env = reinterpret_cast<SsaEnv*>(zone_->New(sizeof(SsaEnv)));
size_t size = sizeof(TFNode*) * EnvironmentCount();
ssa_env->state = SsaEnv::kReached;
ssa_env->locals =
size > 0 ? reinterpret_cast<TFNode**>(zone_->New(size)) : nullptr;
if (builder_) {
start = builder_->Start(static_cast<int>(sig_->parameter_count() + 1));
// Initialize local variables.
uint32_t index = 0;
while (index < sig_->parameter_count()) {
ssa_env->locals[index] = builder_->Param(index, local_type_vec_[index]);
index++;
}
while (index < local_type_vec_.size()) {
LocalType type = local_type_vec_[index];
TFNode* node = DefaultValue(type);
while (index < local_type_vec_.size() &&
local_type_vec_[index] == type) {
// Do a whole run of like-typed locals at a time.
ssa_env->locals[index++] = node;
}
}
builder_->set_module(module_);
}
ssa_env->control = start;
ssa_env->effect = start;
SetEnv("initial", ssa_env);
if (builder_) {
builder_->StackCheck(position());
}
}
TFNode* DefaultValue(LocalType type) {
switch (type) {
case kAstI32:
return builder_->Int32Constant(0);
case kAstI64:
return builder_->Int64Constant(0);
case kAstF32:
return builder_->Float32Constant(0);
case kAstF64:
return builder_->Float64Constant(0);
case kAstS128:
return builder_->CreateS128Value(0);
default:
UNREACHABLE();
return nullptr;
}
}
char* indentation() {
static const int kMaxIndent = 64;
static char bytes[kMaxIndent + 1];
for (int i = 0; i < kMaxIndent; ++i) bytes[i] = ' ';
bytes[kMaxIndent] = 0;
if (stack_.size() < kMaxIndent / 2) {
bytes[stack_.size() * 2] = 0;
}
return bytes;
}
// Decodes the locals declarations, if any, populating {local_type_vec_}.
void DecodeLocalDecls() {
DCHECK_EQ(0u, local_type_vec_.size());
// Initialize {local_type_vec} from signature.
if (sig_) {
local_type_vec_.reserve(sig_->parameter_count());
for (size_t i = 0; i < sig_->parameter_count(); ++i) {
local_type_vec_.push_back(sig_->GetParam(i));
}
}
// Decode local declarations, if any.
uint32_t entries = consume_u32v("local decls count");
TRACE("local decls count: %u\n", entries);
while (entries-- > 0 && pc_ < limit_) {
uint32_t count = consume_u32v("local count");
if (count > kMaxNumWasmLocals) {
error(pc_ - 1, "local count too large");
return;
}
byte code = consume_u8("local type");
LocalType type;
switch (code) {
case kLocalI32:
type = kAstI32;
break;
case kLocalI64:
type = kAstI64;
break;
case kLocalF32:
type = kAstF32;
break;
case kLocalF64:
type = kAstF64;
break;
case kLocalS128:
type = kAstS128;
break;
default:
error(pc_ - 1, "invalid local type");
return;
}
local_type_vec_.insert(local_type_vec_.end(), count, type);
}
total_locals_ = local_type_vec_.size();
}
// Decodes the body of a function.
void DecodeFunctionBody() {
TRACE("wasm-decode %p...%p (module+%d, %d bytes) %s\n",
reinterpret_cast<const void*>(start_),
reinterpret_cast<const void*>(limit_), baserel(pc_),
static_cast<int>(limit_ - start_), builder_ ? "graph building" : "");
{
// Set up initial function block.
SsaEnv* break_env = ssa_env_;
SetEnv("initial env", Steal(break_env));
PushBlock(break_env);
Control* c = &control_.back();
c->merge.arity = static_cast<uint32_t>(sig_->return_count());
if (c->merge.arity == 1) {
c->merge.vals.first = {pc_, nullptr, sig_->GetReturn(0)};
} else if (c->merge.arity > 1) {
c->merge.vals.array = zone_->NewArray<Value>(c->merge.arity);
for (unsigned i = 0; i < c->merge.arity; i++) {
c->merge.vals.array[i] = {pc_, nullptr, sig_->GetReturn(i)};
}
}
}
if (pc_ >= limit_) return; // Nothing to do.
while (true) { // decoding loop.
unsigned len = 1;
WasmOpcode opcode = static_cast<WasmOpcode>(*pc_);
if (!WasmOpcodes::IsPrefixOpcode(opcode)) {
TRACE(" @%-8d #%02x:%-20s|", startrel(pc_), opcode,
WasmOpcodes::ShortOpcodeName(opcode));
}
FunctionSig* sig = WasmOpcodes::Signature(opcode);
if (sig) {
BuildSimpleOperator(opcode, sig);
} else {
// Complex bytecode.
switch (opcode) {
case kExprNop:
break;
case kExprBlock: {
// The break environment is the outer environment.
BlockTypeOperand operand(this, pc_);
SsaEnv* break_env = ssa_env_;
PushBlock(break_env);
SetEnv("block:start", Steal(break_env));
SetBlockType(&control_.back(), operand);
len = 1 + operand.length;
break;
}
case kExprThrow: {
CHECK_PROTOTYPE_OPCODE(wasm_eh_prototype);
Value value = Pop(0, kAstI32);
BUILD(Throw, value.node);
break;
}
case kExprTry: {
CHECK_PROTOTYPE_OPCODE(wasm_eh_prototype);
BlockTypeOperand operand(this, pc_);
SsaEnv* outer_env = ssa_env_;
SsaEnv* try_env = Steal(outer_env);
SsaEnv* catch_env = UnreachableEnv();
PushTry(outer_env, catch_env);
SetEnv("try_catch:start", try_env);
SetBlockType(&control_.back(), operand);
len = 1 + operand.length;
break;
}
case kExprCatch: {
CHECK_PROTOTYPE_OPCODE(wasm_eh_prototype);
LocalIndexOperand operand(this, pc_);
len = 1 + operand.length;
if (control_.empty()) {
error("catch does not match any try");
break;
}
Control* c = &control_.back();
if (!c->is_try()) {
error("catch does not match any try");
break;
}
if (c->try_info->catch_env == nullptr) {
error(pc_, "catch already present for try with catch");
break;
}
if (ssa_env_->go()) {
MergeValuesInto(c);
}
stack_.resize(c->stack_depth);
DCHECK_NOT_NULL(c->try_info);
SsaEnv* catch_env = c->try_info->catch_env;
c->try_info->catch_env = nullptr;
SetEnv("catch:begin", catch_env);
current_catch_ = c->previous_catch;
if (Validate(pc_, operand)) {
if (ssa_env_->locals) {
TFNode* exception_as_i32 =
BUILD(Catch, c->try_info->exception, position());
ssa_env_->locals[operand.index] = exception_as_i32;
}
}
break;
}
case kExprLoop: {
BlockTypeOperand operand(this, pc_);
SsaEnv* finish_try_env = Steal(ssa_env_);
// The continue environment is the inner environment.
SsaEnv* loop_body_env = PrepareForLoop(pc_, finish_try_env);
SetEnv("loop:start", loop_body_env);
ssa_env_->SetNotMerged();
PushLoop(finish_try_env);
SetBlockType(&control_.back(), operand);
len = 1 + operand.length;
break;
}
case kExprIf: {
// Condition on top of stack. Split environments for branches.
BlockTypeOperand operand(this, pc_);
Value cond = Pop(0, kAstI32);
TFNode* if_true = nullptr;
TFNode* if_false = nullptr;
BUILD(BranchNoHint, cond.node, &if_true, &if_false);
SsaEnv* end_env = ssa_env_;
SsaEnv* false_env = Split(ssa_env_);
false_env->control = if_false;
SsaEnv* true_env = Steal(ssa_env_);
true_env->control = if_true;
PushIf(end_env, false_env);
SetEnv("if:true", true_env);
SetBlockType(&control_.back(), operand);
len = 1 + operand.length;
break;
}
case kExprElse: {
if (control_.empty()) {
error("else does not match any if");
break;
}
Control* c = &control_.back();
if (!c->is_if()) {
error(pc_, c->pc, "else does not match an if");
break;
}
if (c->false_env == nullptr) {
error(pc_, c->pc, "else already present for if");
break;
}
FallThruTo(c);
// Switch to environment for false branch.
stack_.resize(c->stack_depth);
SetEnv("if_else:false", c->false_env);
c->false_env = nullptr; // record that an else is already seen
break;
}
case kExprEnd: {
if (control_.empty()) {
error("end does not match any if, try, or block");
return;
}
const char* name = "block:end";
Control* c = &control_.back();
if (c->is_loop()) {
// A loop just leaves the values on the stack.
TypeCheckLoopFallThru(c);
PopControl();
SetEnv("loop:end", ssa_env_);
break;
}
if (c->is_if()) {
if (c->false_env != nullptr) {
// End the true branch of a one-armed if.
Goto(c->false_env, c->end_env);
if (ssa_env_->go() &&
static_cast<int>(stack_.size()) != c->stack_depth) {
error("end of if expected empty stack");
stack_.resize(c->stack_depth);
}
if (c->merge.arity > 0) {
error("non-void one-armed if");
}
name = "if:merge";
} else {
// End the false branch of a two-armed if.
name = "if_else:merge";
}
} else if (c->is_try()) {
name = "try:end";
// validate that catch was seen.
if (c->try_info->catch_env != nullptr) {
error(pc_, "missing catch in try");
break;
}
}
FallThruTo(c);
SetEnv(name, c->end_env);
// Push the end values onto the stack.
stack_.resize(c->stack_depth);
if (c->merge.arity == 1) {
stack_.push_back(c->merge.vals.first);
} else {
for (unsigned i = 0; i < c->merge.arity; i++) {
stack_.push_back(c->merge.vals.array[i]);
}
}
PopControl();
if (control_.empty()) {
// If the last (implicit) control was popped, check we are at end.
if (pc_ + 1 != end_) {
error(pc_, pc_ + 1, "trailing code after function end");
}
last_end_found_ = true;
if (ssa_env_->go()) {
// The result of the block is the return value.
TRACE(" @%-8d #xx:%-20s|", startrel(pc_), "ImplicitReturn");
DoReturn();
TRACE("\n");
}
return;
}
break;
}
case kExprSelect: {
Value cond = Pop(2, kAstI32);
Value fval = Pop();
Value tval = Pop();
if (tval.type == kAstStmt || tval.type != fval.type) {
if (tval.type != kAstEnd && fval.type != kAstEnd) {
error("type mismatch in select");
break;
}
}
if (build()) {
DCHECK(tval.type != kAstEnd);
DCHECK(fval.type != kAstEnd);
DCHECK(cond.type != kAstEnd);
TFNode* controls[2];
builder_->BranchNoHint(cond.node, &controls[0], &controls[1]);
TFNode* merge = builder_->Merge(2, controls);
TFNode* vals[2] = {tval.node, fval.node};
TFNode* phi = builder_->Phi(tval.type, 2, vals, merge);
Push(tval.type, phi);
ssa_env_->control = merge;
} else {
Push(tval.type, nullptr);
}
break;
}
case kExprBr: {
BreakDepthOperand operand(this, pc_);
if (Validate(pc_, operand, control_)) {
BreakTo(operand.depth);
}
len = 1 + operand.length;
EndControl();
break;
}
case kExprBrIf: {
BreakDepthOperand operand(this, pc_);
Value cond = Pop(0, kAstI32);
if (ok() && Validate(pc_, operand, control_)) {
SsaEnv* fenv = ssa_env_;
SsaEnv* tenv = Split(fenv);
fenv->SetNotMerged();
BUILD(BranchNoHint, cond.node, &tenv->control, &fenv->control);
ssa_env_ = tenv;
BreakTo(operand.depth);
ssa_env_ = fenv;
}
len = 1 + operand.length;
break;
}
case kExprBrTable: {
BranchTableOperand operand(this, pc_);
BranchTableIterator iterator(this, operand);
if (Validate(pc_, operand, control_.size())) {
Value key = Pop(0, kAstI32);
if (failed()) break;
SsaEnv* break_env = ssa_env_;
if (operand.table_count > 0) {
// Build branches to the various blocks based on the table.
TFNode* sw = BUILD(Switch, operand.table_count + 1, key.node);
SsaEnv* copy = Steal(break_env);
ssa_env_ = copy;
while (ok() && iterator.has_next()) {
uint32_t i = iterator.cur_index();
const byte* pos = iterator.pc();
uint32_t target = iterator.next();
if (target >= control_.size()) {
error(pos, "improper branch in br_table");
break;
}
ssa_env_ = Split(copy);
ssa_env_->control = (i == operand.table_count)
? BUILD(IfDefault, sw)
: BUILD(IfValue, i, sw);
BreakTo(target);
}
if (failed()) break;
} else {
// Only a default target. Do the equivalent of br.
const byte* pos = iterator.pc();
uint32_t target = iterator.next();
if (target >= control_.size()) {
error(pos, "improper branch in br_table");
break;
}
BreakTo(target);
}
// br_table ends the control flow like br.
ssa_env_ = break_env;
}
len = 1 + iterator.length();
break;
}
case kExprReturn: {
DoReturn();
break;
}
case kExprUnreachable: {
BUILD(Unreachable, position());
EndControl();
break;
}
case kExprI8Const: {
ImmI8Operand operand(this, pc_);
Push(kAstI32, BUILD(Int32Constant, operand.value));
len = 1 + operand.length;
break;
}
case kExprI32Const: {
ImmI32Operand operand(this, pc_);
Push(kAstI32, BUILD(Int32Constant, operand.value));
len = 1 + operand.length;
break;
}
case kExprI64Const: {
ImmI64Operand operand(this, pc_);
Push(kAstI64, BUILD(Int64Constant, operand.value));
len = 1 + operand.length;
break;
}
case kExprF32Const: {
ImmF32Operand operand(this, pc_);
Push(kAstF32, BUILD(Float32Constant, operand.value));
len = 1 + operand.length;
break;
}
case kExprF64Const: {
ImmF64Operand operand(this, pc_);
Push(kAstF64, BUILD(Float64Constant, operand.value));
len = 1 + operand.length;
break;
}
case kExprGetLocal: {
LocalIndexOperand operand(this, pc_);
if (Validate(pc_, operand)) {
if (build()) {
Push(operand.type, ssa_env_->locals[operand.index]);
} else {
Push(operand.type, nullptr);
}
}
len = 1 + operand.length;
break;
}
case kExprSetLocal: {
LocalIndexOperand operand(this, pc_);
if (Validate(pc_, operand)) {
Value val = Pop(0, local_type_vec_[operand.index]);
if (ssa_env_->locals) ssa_env_->locals[operand.index] = val.node;
}
len = 1 + operand.length;
break;
}
case kExprTeeLocal: {
LocalIndexOperand operand(this, pc_);
if (Validate(pc_, operand)) {
Value val = Pop(0, local_type_vec_[operand.index]);
if (ssa_env_->locals) ssa_env_->locals[operand.index] = val.node;
Push(val.type, val.node);
}
len = 1 + operand.length;
break;
}
case kExprDrop: {
Pop();
break;
}
case kExprGetGlobal: {
GlobalIndexOperand operand(this, pc_);
if (Validate(pc_, operand)) {
Push(operand.type, BUILD(GetGlobal, operand.index));
}
len = 1 + operand.length;
break;
}
case kExprSetGlobal: {
GlobalIndexOperand operand(this, pc_);
if (Validate(pc_, operand)) {
if (operand.global->mutability) {
Value val = Pop(0, operand.type);
BUILD(SetGlobal, operand.index, val.node);
} else {
error(pc_, pc_ + 1, "immutable global #%u cannot be assigned",
operand.index);
}
}
len = 1 + operand.length;
break;
}
case kExprI32LoadMem8S:
len = DecodeLoadMem(kAstI32, MachineType::Int8());
break;
case kExprI32LoadMem8U:
len = DecodeLoadMem(kAstI32, MachineType::Uint8());
break;
case kExprI32LoadMem16S:
len = DecodeLoadMem(kAstI32, MachineType::Int16());
break;
case kExprI32LoadMem16U:
len = DecodeLoadMem(kAstI32, MachineType::Uint16());
break;
case kExprI32LoadMem:
len = DecodeLoadMem(kAstI32, MachineType::Int32());
break;
case kExprI64LoadMem8S:
len = DecodeLoadMem(kAstI64, MachineType::Int8());
break;
case kExprI64LoadMem8U:
len = DecodeLoadMem(kAstI64, MachineType::Uint8());
break;
case kExprI64LoadMem16S:
len = DecodeLoadMem(kAstI64, MachineType::Int16());
break;
case kExprI64LoadMem16U:
len = DecodeLoadMem(kAstI64, MachineType::Uint16());
break;
case kExprI64LoadMem32S:
len = DecodeLoadMem(kAstI64, MachineType::Int32());
break;
case kExprI64LoadMem32U:
len = DecodeLoadMem(kAstI64, MachineType::Uint32());
break;
case kExprI64LoadMem:
len = DecodeLoadMem(kAstI64, MachineType::Int64());
break;
case kExprF32LoadMem:
len = DecodeLoadMem(kAstF32, MachineType::Float32());
break;
case kExprF64LoadMem:
len = DecodeLoadMem(kAstF64, MachineType::Float64());
break;
case kExprI32StoreMem8:
len = DecodeStoreMem(kAstI32, MachineType::Int8());
break;
case kExprI32StoreMem16:
len = DecodeStoreMem(kAstI32, MachineType::Int16());
break;
case kExprI32StoreMem:
len = DecodeStoreMem(kAstI32, MachineType::Int32());
break;
case kExprI64StoreMem8:
len = DecodeStoreMem(kAstI64, MachineType::Int8());
break;
case kExprI64StoreMem16:
len = DecodeStoreMem(kAstI64, MachineType::Int16());
break;
case kExprI64StoreMem32:
len = DecodeStoreMem(kAstI64, MachineType::Int32());
break;
case kExprI64StoreMem:
len = DecodeStoreMem(kAstI64, MachineType::Int64());
break;
case kExprF32StoreMem:
len = DecodeStoreMem(kAstF32, MachineType::Float32());
break;
case kExprF64StoreMem:
len = DecodeStoreMem(kAstF64, MachineType::Float64());
break;
case kExprGrowMemory: {
MemoryIndexOperand operand(this, pc_);
if (module_->origin != kAsmJsOrigin) {
Value val = Pop(0, kAstI32);
Push(kAstI32, BUILD(GrowMemory, val.node));
} else {
error("grow_memory is not supported for asmjs modules");
}
len = 1 + operand.length;
break;
}
case kExprMemorySize: {
MemoryIndexOperand operand(this, pc_);
Push(kAstI32, BUILD(CurrentMemoryPages));
len = 1 + operand.length;
break;
}
case kExprCallFunction: {
CallFunctionOperand operand(this, pc_);
if (Validate(pc_, operand)) {
TFNode** buffer = PopArgs(operand.sig);
TFNode** rets = nullptr;
BUILD(CallDirect, operand.index, buffer, &rets, position());
PushReturns(operand.sig, rets);
}
len = 1 + operand.length;
break;
}
case kExprCallIndirect: {
CallIndirectOperand operand(this, pc_);
if (Validate(pc_, operand)) {
Value index = Pop(0, kAstI32);
TFNode** buffer = PopArgs(operand.sig);
if (buffer) buffer[0] = index.node;
TFNode** rets = nullptr;
BUILD(CallIndirect, operand.index, buffer, &rets, position());
PushReturns(operand.sig, rets);
}
len = 1 + operand.length;
break;
}
case kSimdPrefix: {
CHECK_PROTOTYPE_OPCODE(wasm_simd_prototype);
len++;
byte simd_index = checked_read_u8(pc_, 1, "simd index");
opcode = static_cast<WasmOpcode>(opcode << 8 | simd_index);
TRACE(" @%-4d #%02x #%02x:%-20s|", startrel(pc_), kSimdPrefix,
simd_index, WasmOpcodes::ShortOpcodeName(opcode));
len += DecodeSimdOpcode(opcode);
break;
}
case kAtomicPrefix: {
if (!module_ || module_->origin != kAsmJsOrigin) {
error("Atomics are allowed only in AsmJs modules");
break;
}
if (!FLAG_wasm_atomics_prototype) {
error("Invalid opcode (enable with --wasm_atomics_prototype)");
break;
}
len = 2;
byte atomic_opcode = checked_read_u8(pc_, 1, "atomic index");
opcode = static_cast<WasmOpcode>(opcode << 8 | atomic_opcode);
sig = WasmOpcodes::AtomicSignature(opcode);
if (sig) {
BuildAtomicOperator(opcode);
}
break;
}
default: {
// Deal with special asmjs opcodes.
if (module_ && module_->origin == kAsmJsOrigin) {
sig = WasmOpcodes::AsmjsSignature(opcode);
if (sig) {
BuildSimpleOperator(opcode, sig);
}
} else {
error("Invalid opcode");
return;
}
}
}
}
#if DEBUG
if (FLAG_trace_wasm_decoder) {
for (size_t i = 0; i < stack_.size(); ++i) {
Value& val = stack_[i];
WasmOpcode opcode = static_cast<WasmOpcode>(*val.pc);
if (WasmOpcodes::IsPrefixOpcode(opcode)) {
opcode = static_cast<WasmOpcode>(opcode << 8 | *(val.pc + 1));
}
PrintF(" %c@%d:%s", WasmOpcodes::ShortNameOf(val.type),
static_cast<int>(val.pc - start_),
WasmOpcodes::ShortOpcodeName(opcode));
switch (opcode) {
case kExprI32Const: {
ImmI32Operand operand(this, val.pc);
PrintF("[%d]", operand.value);
break;
}
case kExprGetLocal: {
LocalIndexOperand operand(this, val.pc);
PrintF("[%u]", operand.index);
break;
}
case kExprSetLocal: // fallthru
case kExprTeeLocal: {
LocalIndexOperand operand(this, val.pc);
PrintF("[%u]", operand.index);
break;
}
default:
break;
}
}
PrintF("\n");
}
#endif
pc_ += len;
if (pc_ >= limit_) {
// End of code reached or exceeded.
if (pc_ > limit_ && ok()) error("Beyond end of code");
return;
}
} // end decode loop
}
void EndControl() { ssa_env_->Kill(SsaEnv::kControlEnd); }
void SetBlockType(Control* c, BlockTypeOperand& operand) {
c->merge.arity = operand.arity;
if (c->merge.arity == 1) {
c->merge.vals.first = {pc_, nullptr, operand.read_entry(0)};
} else if (c->merge.arity > 1) {
c->merge.vals.array = zone_->NewArray<Value>(c->merge.arity);
for (unsigned i = 0; i < c->merge.arity; i++) {
c->merge.vals.array[i] = {pc_, nullptr, operand.read_entry(i)};
}
}
}
TFNode** PopArgs(FunctionSig* sig) {
if (build()) {
int count = static_cast<int>(sig->parameter_count());
TFNode** buffer = builder_->Buffer(count + 1);
buffer[0] = nullptr; // reserved for code object or function index.
for (int i = count - 1; i >= 0; i--) {
buffer[i + 1] = Pop(i, sig->GetParam(i)).node;
}
return buffer;
} else {
int count = static_cast<int>(sig->parameter_count());
for (int i = count - 1; i >= 0; i--) {
Pop(i, sig->GetParam(i));
}
return nullptr;
}
}
LocalType GetReturnType(FunctionSig* sig) {
return sig->return_count() == 0 ? kAstStmt : sig->GetReturn();
}
void PushBlock(SsaEnv* end_env) {
const int stack_depth = static_cast<int>(stack_.size());
control_.emplace_back(
Control::Block(pc_, stack_depth, end_env, current_catch_));
}
void PushLoop(SsaEnv* end_env) {
const int stack_depth = static_cast<int>(stack_.size());
control_.emplace_back(
Control::Loop(pc_, stack_depth, end_env, current_catch_));
}
void PushIf(SsaEnv* end_env, SsaEnv* false_env) {
const int stack_depth = static_cast<int>(stack_.size());
control_.emplace_back(
Control::If(pc_, stack_depth, end_env, false_env, current_catch_));
}
void PushTry(SsaEnv* end_env, SsaEnv* catch_env) {
const int stack_depth = static_cast<int>(stack_.size());
control_.emplace_back(Control::Try(pc_, stack_depth, end_env, zone_,
catch_env, current_catch_));
current_catch_ = static_cast<int32_t>(control_.size() - 1);
}
void PopControl() { control_.pop_back(); }
int DecodeLoadMem(LocalType type, MachineType mem_type) {
MemoryAccessOperand operand(this, pc_,
ElementSizeLog2Of(mem_type.representation()));
Value index = Pop(0, kAstI32);
TFNode* node = BUILD(LoadMem, type, mem_type, index.node, operand.offset,
operand.alignment, position());
Push(type, node);
return 1 + operand.length;
}
int DecodeStoreMem(LocalType type, MachineType mem_type) {
MemoryAccessOperand operand(this, pc_,
ElementSizeLog2Of(mem_type.representation()));
Value val = Pop(1, type);
Value index = Pop(0, kAstI32);
BUILD(StoreMem, mem_type, index.node, operand.offset, operand.alignment,
val.node, position());
return 1 + operand.length;
}
unsigned ExtractLane(WasmOpcode opcode, LocalType type) {
LaneOperand operand(this, pc_);
if (Validate(pc_, operand)) {
TFNode* input = Pop(0, LocalType::kSimd128).node;
TFNode* node = BUILD(SimdExtractLane, opcode, operand.lane, input);
Push(type, node);
}
return operand.length;
}
unsigned DecodeSimdOpcode(WasmOpcode opcode) {
unsigned len = 0;
switch (opcode) {
case kExprI32x4ExtractLane: {
len = ExtractLane(opcode, LocalType::kWord32);
break;
}
case kExprF32x4ExtractLane: {
len = ExtractLane(opcode, LocalType::kFloat32);
break;
}
default: {
FunctionSig* sig = WasmOpcodes::Signature(opcode);
if (sig != nullptr) {
compiler::NodeVector inputs(sig->parameter_count(), zone_);
for (size_t i = sig->parameter_count(); i > 0; i--) {
Value val = Pop(static_cast<int>(i - 1), sig->GetParam(i - 1));
inputs[i - 1] = val.node;
}
TFNode* node = BUILD(SimdOp, opcode, inputs);
Push(GetReturnType(sig), node);
} else {
error("invalid simd opcode");
}
}
}
return len;
}
void BuildAtomicOperator(WasmOpcode opcode) { UNIMPLEMENTED(); }
void DoReturn() {
int count = static_cast<int>(sig_->return_count());
TFNode** buffer = nullptr;
if (build()) buffer = builder_->Buffer(count);
// Pop return values off the stack in reverse order.
for (int i = count - 1; i >= 0; i--) {
Value val = Pop(i, sig_->GetReturn(i));
if (buffer) buffer[i] = val.node;
}
BUILD(Return, count, buffer);
EndControl();
}
void Push(LocalType type, TFNode* node) {
if (type != kAstStmt && type != kAstEnd) {
stack_.push_back({pc_, node, type});
}
}
void PushReturns(FunctionSig* sig, TFNode** rets) {
for (size_t i = 0; i < sig->return_count(); i++) {
// When verifying only, then {rets} will be null, so push null.
Push(sig->GetReturn(i), rets ? rets[i] : nullptr);
}
}
const char* SafeOpcodeNameAt(const byte* pc) {
if (pc >= end_) return "<end>";
return WasmOpcodes::ShortOpcodeName(static_cast<WasmOpcode>(*pc));
}
Value Pop(int index, LocalType expected) {
if (!ssa_env_->go()) {
// Unreachable code is essentially not typechecked.
return {pc_, nullptr, expected};
}
Value val = Pop();
if (val.type != expected) {
if (val.type != kAstEnd) {
error(pc_, val.pc, "%s[%d] expected type %s, found %s of type %s",
SafeOpcodeNameAt(pc_), index, WasmOpcodes::TypeName(expected),
SafeOpcodeNameAt(val.pc), WasmOpcodes::TypeName(val.type));
}
}
return val;
}
Value Pop() {
if (!ssa_env_->go()) {
// Unreachable code is essentially not typechecked.
return {pc_, nullptr, kAstEnd};
}
size_t limit = control_.empty() ? 0 : control_.back().stack_depth;
if (stack_.size() <= limit) {
Value val = {pc_, nullptr, kAstStmt};
error(pc_, pc_, "%s found empty stack", SafeOpcodeNameAt(pc_));
return val;
}
Value val = stack_.back();
stack_.pop_back();
return val;
}
Value PopUpTo(int stack_depth) {
if (!ssa_env_->go()) {
// Unreachable code is essentially not typechecked.
return {pc_, nullptr, kAstEnd};
}
if (stack_depth == static_cast<int>(stack_.size())) {
Value val = {pc_, nullptr, kAstStmt};
return val;
} else {
DCHECK_LE(stack_depth, static_cast<int>(stack_.size()));
Value val = Pop();
stack_.resize(stack_depth);
return val;
}
}
int baserel(const byte* ptr) {
return base_ ? static_cast<int>(ptr - base_) : 0;
}
int startrel(const byte* ptr) { return static_cast<int>(ptr - start_); }
void BreakTo(unsigned depth) {
if (!ssa_env_->go()) return;
Control* c = &control_[control_.size() - depth - 1];
if (c->is_loop()) {
// This is the inner loop block, which does not have a value.
Goto(ssa_env_, c->end_env);
} else {
// Merge the value(s) into the end of the block.
if (c->stack_depth + c->merge.arity > stack_.size()) {
error(
pc_, pc_,
"expected at least %d values on the stack for br to @%d, found %d",
c->merge.arity, startrel(c->pc),
static_cast<int>(stack_.size() - c->stack_depth));
return;
}
MergeValuesInto(c);
}
}
void FallThruTo(Control* c) {
if (!ssa_env_->go()) return;
// Merge the value(s) into the end of the block.
int arity = static_cast<int>(c->merge.arity);
if (c->stack_depth + arity != static_cast<int>(stack_.size())) {
error(pc_, pc_, "expected %d elements on the stack for fallthru to @%d",
arity, startrel(c->pc));
return;
}
MergeValuesInto(c);
}
inline Value& GetMergeValueFromStack(Control* c, int i) {
return stack_[stack_.size() - c->merge.arity + i];
}
void TypeCheckLoopFallThru(Control* c) {
if (!ssa_env_->go()) return;
// Fallthru must match arity exactly.
int arity = static_cast<int>(c->merge.arity);
if (c->stack_depth + arity != static_cast<int>(stack_.size())) {
error(pc_, pc_, "expected %d elements on the stack for fallthru to @%d",
arity, startrel(c->pc));
return;
}
// Typecheck the values left on the stack.
for (unsigned i = 0; i < c->merge.arity; i++) {
Value& val = GetMergeValueFromStack(c, i);
Value& old =
c->merge.arity == 1 ? c->merge.vals.first : c->merge.vals.array[i];
if (val.type != old.type) {
error(pc_, pc_, "type error in merge[%d] (expected %s, got %s)", i,
WasmOpcodes::TypeName(old.type), WasmOpcodes::TypeName(val.type));
return;
}
}
}
void MergeValuesInto(Control* c) {
SsaEnv* target = c->end_env;
bool first = target->state == SsaEnv::kUnreachable;
Goto(ssa_env_, target);
for (unsigned i = 0; i < c->merge.arity; i++) {
Value& val = GetMergeValueFromStack(c, i);
Value& old =
c->merge.arity == 1 ? c->merge.vals.first : c->merge.vals.array[i];
if (val.type != old.type) {
error(pc_, pc_, "type error in merge[%d] (expected %s, got %s)", i,
WasmOpcodes::TypeName(old.type), WasmOpcodes::TypeName(val.type));
return;
}
if (builder_) {
old.node =
first ? val.node : CreateOrMergeIntoPhi(old.type, target->control,
old.node, val.node);
} else {
old.node = nullptr;
}
}
}
void SetEnv(const char* reason, SsaEnv* env) {
#if DEBUG
if (FLAG_trace_wasm_decoder) {
char state = 'X';
if (env) {
switch (env->state) {
case SsaEnv::kReached:
state = 'R';
break;
case SsaEnv::kUnreachable:
state = 'U';
break;
case SsaEnv::kMerged:
state = 'M';
break;
case SsaEnv::kControlEnd:
state = 'E';
break;
}
}
PrintF(" env = %p, state = %c, reason = %s", static_cast<void*>(env),
state, reason);
if (env && env->control) {
PrintF(", control = ");
compiler::WasmGraphBuilder::PrintDebugName(env->control);
}
PrintF("\n");
}
#endif
ssa_env_ = env;
if (builder_) {
builder_->set_control_ptr(&env->control);
builder_->set_effect_ptr(&env->effect);
}
}
TFNode* CheckForException(TFNode* node) {
if (node == nullptr) {
return nullptr;
}
const bool inside_try_scope = current_catch_ != kNullCatch;
if (!inside_try_scope) {
return node;
}
TFNode* if_success = nullptr;
TFNode* if_exception = nullptr;
if (!builder_->ThrowsException(node, &if_success, &if_exception)) {
return node;
}
SsaEnv* success_env = Steal(ssa_env_);
success_env->control = if_success;
SsaEnv* exception_env = Split(success_env);
exception_env->control = if_exception;
TryInfo* try_info = current_try_info();
Goto(exception_env, try_info->catch_env);
TFNode* exception = try_info->exception;
if (exception == nullptr) {
DCHECK_EQ(SsaEnv::kReached, try_info->catch_env->state);
try_info->exception = if_exception;
} else {
DCHECK_EQ(SsaEnv::kMerged, try_info->catch_env->state);
try_info->exception =
CreateOrMergeIntoPhi(kAstI32, try_info->catch_env->control,
try_info->exception, if_exception);
}
SetEnv("if_success", success_env);
return node;
}
void Goto(SsaEnv* from, SsaEnv* to) {
DCHECK_NOT_NULL(to);
if (!from->go()) return;
switch (to->state) {
case SsaEnv::kUnreachable: { // Overwrite destination.
to->state = SsaEnv::kReached;
to->locals = from->locals;
to->control = from->control;
to->effect = from->effect;
break;
}
case SsaEnv::kReached: { // Create a new merge.
to->state = SsaEnv::kMerged;
if (!builder_) break;
// Merge control.
TFNode* controls[] = {to->control, from->control};
TFNode* merge = builder_->Merge(2, controls);
to->control = merge;
// Merge effects.
if (from->effect != to->effect) {
TFNode* effects[] = {to->effect, from->effect, merge};
to->effect = builder_->EffectPhi(2, effects, merge);
}
// Merge SSA values.
for (int i = EnvironmentCount() - 1; i >= 0; i--) {
TFNode* a = to->locals[i];
TFNode* b = from->locals[i];
if (a != b) {
TFNode* vals[] = {a, b};
to->locals[i] = builder_->Phi(local_type_vec_[i], 2, vals, merge);
}
}
break;
}
case SsaEnv::kMerged: {
if (!builder_) break;
TFNode* merge = to->control;
// Extend the existing merge.
builder_->AppendToMerge(merge, from->control);
// Merge effects.
if (builder_->IsPhiWithMerge(to->effect, merge)) {
builder_->AppendToPhi(to->effect, from->effect);
} else if (to->effect != from->effect) {
uint32_t count = builder_->InputCount(merge);
TFNode** effects = builder_->Buffer(count);
for (uint32_t j = 0; j < count - 1; j++) {
effects[j] = to->effect;
}
effects[count - 1] = from->effect;
to->effect = builder_->EffectPhi(count, effects, merge);
}
// Merge locals.
for (int i = EnvironmentCount() - 1; i >= 0; i--) {
TFNode* tnode = to->locals[i];
TFNode* fnode = from->locals[i];
if (builder_->IsPhiWithMerge(tnode, merge)) {
builder_->AppendToPhi(tnode, fnode);
} else if (tnode != fnode) {
uint32_t count = builder_->InputCount(merge);
TFNode** vals = builder_->Buffer(count);
for (uint32_t j = 0; j < count - 1; j++) {
vals[j] = tnode;
}
vals[count - 1] = fnode;
to->locals[i] =
builder_->Phi(local_type_vec_[i], count, vals, merge);
}
}
break;
}
default:
UNREACHABLE();
}
return from->Kill();
}
TFNode* CreateOrMergeIntoPhi(LocalType type, TFNode* merge, TFNode* tnode,
TFNode* fnode) {
DCHECK_NOT_NULL(builder_);
if (builder_->IsPhiWithMerge(tnode, merge)) {
builder_->AppendToPhi(tnode, fnode);
} else if (tnode != fnode) {
uint32_t count = builder_->InputCount(merge);
TFNode** vals = builder_->Buffer(count);
for (uint32_t j = 0; j < count - 1; j++) vals[j] = tnode;
vals[count - 1] = fnode;
return builder_->Phi(type, count, vals, merge);
}
return tnode;
}
SsaEnv* PrepareForLoop(const byte* pc, SsaEnv* env) {
if (!builder_) return Split(env);
if (!env->go()) return Split(env);
env->state = SsaEnv::kMerged;
env->control = builder_->Loop(env->control);
env->effect = builder_->EffectPhi(1, &env->effect, env->control);
builder_->Terminate(env->effect, env->control);
if (FLAG_wasm_loop_assignment_analysis) {
BitVector* assigned = AnalyzeLoopAssignment(pc);
if (failed()) return env;
if (assigned != nullptr) {
// Only introduce phis for variables assigned in this loop.
for (int i = EnvironmentCount() - 1; i >= 0; i--) {
if (!assigned->Contains(i)) continue;
env->locals[i] = builder_->Phi(local_type_vec_[i], 1, &env->locals[i],
env->control);
}
SsaEnv* loop_body_env = Split(env);
builder_->StackCheck(position(), &(loop_body_env->effect),
&(loop_body_env->control));
return loop_body_env;
}
}
// Conservatively introduce phis for all local variables.
for (int i = EnvironmentCount() - 1; i >= 0; i--) {
env->locals[i] =
builder_->Phi(local_type_vec_[i], 1, &env->locals[i], env->control);
}
SsaEnv* loop_body_env = Split(env);
builder_->StackCheck(position(), &(loop_body_env->effect),
&(loop_body_env->control));
return loop_body_env;
}
// Create a complete copy of the {from}.
SsaEnv* Split(SsaEnv* from) {
DCHECK_NOT_NULL(from);
SsaEnv* result = reinterpret_cast<SsaEnv*>(zone_->New(sizeof(SsaEnv)));
size_t size = sizeof(TFNode*) * EnvironmentCount();
result->control = from->control;
result->effect = from->effect;
if (from->go()) {
result->state = SsaEnv::kReached;
result->locals =
size > 0 ? reinterpret_cast<TFNode**>(zone_->New(size)) : nullptr;
memcpy(result->locals, from->locals, size);
} else {
result->state = SsaEnv::kUnreachable;
result->locals = nullptr;
}
return result;
}
// Create a copy of {from} that steals its state and leaves {from}
// unreachable.
SsaEnv* Steal(SsaEnv* from) {
DCHECK_NOT_NULL(from);
if (!from->go()) return UnreachableEnv();
SsaEnv* result = reinterpret_cast<SsaEnv*>(zone_->New(sizeof(SsaEnv)));
result->state = SsaEnv::kReached;
result->locals = from->locals;
result->control = from->control;
result->effect = from->effect;
from->Kill(SsaEnv::kUnreachable);
return result;
}
// Create an unreachable environment.
SsaEnv* UnreachableEnv() {
SsaEnv* result = reinterpret_cast<SsaEnv*>(zone_->New(sizeof(SsaEnv)));
result->state = SsaEnv::kUnreachable;
result->control = nullptr;
result->effect = nullptr;
result->locals = nullptr;
return result;
}
int EnvironmentCount() {
if (builder_) return static_cast<int>(local_type_vec_.size());
return 0; // if we aren't building a graph, don't bother with SSA renaming.
}
virtual void onFirstError() {
limit_ = start_; // Terminate decoding loop.
builder_ = nullptr; // Don't build any more nodes.
TRACE(" !%s\n", error_msg_.get());
}
BitVector* AnalyzeLoopAssignment(const byte* pc) {
if (pc >= limit_) return nullptr;
if (*pc != kExprLoop) return nullptr;
BitVector* assigned =
new (zone_) BitVector(static_cast<int>(local_type_vec_.size()), zone_);
int depth = 0;
// Iteratively process all AST nodes nested inside the loop.
while (pc < limit_ && ok()) {
WasmOpcode opcode = static_cast<WasmOpcode>(*pc);
unsigned length = 1;
switch (opcode) {
case kExprLoop:
case kExprIf:
case kExprBlock:
case kExprTry:
length = OpcodeLength(pc);
depth++;
break;
case kExprSetLocal: // fallthru
case kExprTeeLocal: {
LocalIndexOperand operand(this, pc);
if (assigned->length() > 0 &&
operand.index < static_cast<uint32_t>(assigned->length())) {
// Unverified code might have an out-of-bounds index.
assigned->Add(operand.index);
}
length = 1 + operand.length;
break;
}
case kExprEnd:
depth--;
break;
default:
length = OpcodeLength(pc);
break;
}
if (depth <= 0) break;
pc += length;
}
return ok() ? assigned : nullptr;
}
inline wasm::WasmCodePosition position() {
int offset = static_cast<int>(pc_ - start_);
DCHECK_EQ(pc_ - start_, offset); // overflows cannot happen
return offset;
}
inline void BuildSimpleOperator(WasmOpcode opcode, FunctionSig* sig) {
TFNode* node;
switch (sig->parameter_count()) {
case 1: {
Value val = Pop(0, sig->GetParam(0));
node = BUILD(Unop, opcode, val.node, position());
break;
}
case 2: {
Value rval = Pop(1, sig->GetParam(1));
Value lval = Pop(0, sig->GetParam(0));
node = BUILD(Binop, opcode, lval.node, rval.node, position());
break;
}
default:
UNREACHABLE();
node = nullptr;
break;
}
Push(GetReturnType(sig), node);
}
};
bool DecodeLocalDecls(AstLocalDecls& decls, const byte* start,
const byte* end) {
AccountingAllocator allocator;
Zone tmp(&allocator, ZONE_NAME);
FunctionBody body = {nullptr, nullptr, nullptr, start, end};
WasmFullDecoder decoder(&tmp, nullptr, body);
return decoder.DecodeLocalDecls(decls);
}
BytecodeIterator::BytecodeIterator(const byte* start, const byte* end,
AstLocalDecls* decls)
: Decoder(start, end) {
if (decls != nullptr) {
if (DecodeLocalDecls(*decls, start, end)) {
pc_ += decls->decls_encoded_size;
if (pc_ > end_) pc_ = end_;
}
}
}
DecodeResult VerifyWasmCode(AccountingAllocator* allocator,
FunctionBody& body) {
Zone zone(allocator, ZONE_NAME);
WasmFullDecoder decoder(&zone, nullptr, body);
decoder.Decode();
return decoder.toResult<DecodeStruct*>(nullptr);
}
DecodeResult BuildTFGraph(AccountingAllocator* allocator, TFBuilder* builder,
FunctionBody& body) {
Zone zone(allocator, ZONE_NAME);
WasmFullDecoder decoder(&zone, builder, body);
decoder.Decode();
return decoder.toResult<DecodeStruct*>(nullptr);
}
unsigned OpcodeLength(const byte* pc, const byte* end) {
WasmDecoder decoder(nullptr, nullptr, pc, end);
return decoder.OpcodeLength(pc);
}
void PrintAstForDebugging(const byte* start, const byte* end) {
AccountingAllocator allocator;
OFStream os(stdout);
PrintAst(&allocator, FunctionBodyForTesting(start, end), os, nullptr);
}
bool PrintAst(AccountingAllocator* allocator, const FunctionBody& body,
std::ostream& os,
std::vector<std::tuple<uint32_t, int, int>>* offset_table) {
Zone zone(allocator, ZONE_NAME);
WasmFullDecoder decoder(&zone, nullptr, body);
int line_nr = 0;
// Print the function signature.
if (body.sig) {
os << "// signature: " << *body.sig << std::endl;
++line_nr;
}
// Print the local declarations.
AstLocalDecls decls(&zone);
BytecodeIterator i(body.start, body.end, &decls);
if (body.start != i.pc()) {
os << "// locals: ";
for (auto p : decls.local_types) {
LocalType type = p.first;
uint32_t count = p.second;
os << " " << count << " " << WasmOpcodes::TypeName(type);
}
os << std::endl;
++line_nr;
for (const byte* locals = body.start; locals < i.pc(); locals++) {
os << (locals == body.start ? "0x" : " 0x") << AsHex(*locals, 2) << ",";
}
os << std::endl;
++line_nr;
}
os << "// body: " << std::endl;
++line_nr;
unsigned control_depth = 0;
for (; i.has_next(); i.next()) {
unsigned length = decoder.OpcodeLength(i.pc());
WasmOpcode opcode = i.current();
if (opcode == kExprElse) control_depth--;
int num_whitespaces = control_depth < 32 ? 2 * control_depth : 64;
if (offset_table) {
offset_table->push_back(
std::make_tuple(i.pc_offset(), line_nr, num_whitespaces));
}
// 64 whitespaces
const char* padding =
" ";
os.write(padding, num_whitespaces);
os << "k" << WasmOpcodes::OpcodeName(opcode) << ",";
for (size_t j = 1; j < length; ++j) {
os << " " << AsHex(i.pc()[j], 2) << ",";
}
switch (opcode) {
case kExprElse:
os << " // @" << i.pc_offset();
control_depth++;
break;
case kExprLoop:
case kExprIf:
case kExprBlock:
case kExprTry: {
BlockTypeOperand operand(&i, i.pc());
os << " // @" << i.pc_offset();
for (unsigned i = 0; i < operand.arity; i++) {
os << " " << WasmOpcodes::TypeName(operand.read_entry(i));
}
control_depth++;
break;
}
case kExprEnd:
os << " // @" << i.pc_offset();
control_depth--;
break;
case kExprBr: {
BreakDepthOperand operand(&i, i.pc());
os << " // depth=" << operand.depth;
break;
}
case kExprBrIf: {
BreakDepthOperand operand(&i, i.pc());
os << " // depth=" << operand.depth;
break;
}
case kExprBrTable: {
BranchTableOperand operand(&i, i.pc());
os << " // entries=" << operand.table_count;
break;
}
case kExprCallIndirect: {
CallIndirectOperand operand(&i, i.pc());
os << " // sig #" << operand.index;
if (decoder.Complete(i.pc(), operand)) {
os << ": " << *operand.sig;
}
break;
}
case kExprCallFunction: {
CallFunctionOperand operand(&i, i.pc());
os << " // function #" << operand.index;
if (decoder.Complete(i.pc(), operand)) {
os << ": " << *operand.sig;
}
break;
}
default:
break;
}
os << std::endl;
++line_nr;
}
return decoder.ok();
}
BitVector* AnalyzeLoopAssignmentForTesting(Zone* zone, size_t num_locals,
const byte* start, const byte* end) {
FunctionBody body = {nullptr, nullptr, nullptr, start, end};
WasmFullDecoder decoder(zone, nullptr, body);
return decoder.AnalyzeLoopAssignmentForTesting(start, num_locals);
}
} // namespace wasm
} // namespace internal
} // namespace v8