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/*
* Copyright 2016 WebAssembly Community Group participants
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef wasm_ir_properties_h
#define wasm_ir_properties_h
#include "wasm.h"
#include "ir/bits.h"
namespace wasm {
namespace Properties {
inline bool emitsBoolean(Expression* curr) {
if (auto* unary = curr->dynCast<Unary>()) {
return unary->isRelational();
} else if (auto* binary = curr->dynCast<Binary>()) {
return binary->isRelational();
}
return false;
}
inline bool isSymmetric(Binary* binary) {
switch (binary->op) {
case AddInt32:
case MulInt32:
case AndInt32:
case OrInt32:
case XorInt32:
case EqInt32:
case NeInt32:
case AddInt64:
case MulInt64:
case AndInt64:
case OrInt64:
case XorInt64:
case EqInt64:
case NeInt64: return true;
default: return false;
}
}
// Check if an expression is a control flow construct with a name,
// which implies it may have breaks to it.
inline bool isNamedControlFlow(Expression* curr) {
if (auto* block = curr->dynCast<Block>()) {
return block->name.is();
} else if (auto* loop = curr->dynCast<Loop>()) {
return loop->name.is();
}
return false;
}
// Check if an expression is a sign-extend, and if so, returns the value
// that is extended, otherwise nullptr
inline Expression* getSignExtValue(Expression* curr) {
if (auto* outer = curr->dynCast<Binary>()) {
if (outer->op == ShrSInt32) {
if (auto* outerConst = outer->right->dynCast<Const>()) {
if (outerConst->value.geti32() != 0) {
if (auto* inner = outer->left->dynCast<Binary>()) {
if (inner->op == ShlInt32) {
if (auto* innerConst = inner->right->dynCast<Const>()) {
if (outerConst->value == innerConst->value) {
return inner->left;
}
}
}
}
}
}
}
}
return nullptr;
}
// gets the size of the sign-extended value
inline Index getSignExtBits(Expression* curr) {
return 32 - Bits::getEffectiveShifts(curr->cast<Binary>()->right);
}
// Check if an expression is almost a sign-extend: perhaps the inner shift
// is too large. We can split the shifts in that case, which is sometimes
// useful (e.g. if we can remove the signext)
inline Expression* getAlmostSignExt(Expression* curr) {
if (auto* outer = curr->dynCast<Binary>()) {
if (outer->op == ShrSInt32) {
if (auto* outerConst = outer->right->dynCast<Const>()) {
if (outerConst->value.geti32() != 0) {
if (auto* inner = outer->left->dynCast<Binary>()) {
if (inner->op == ShlInt32) {
if (auto* innerConst = inner->right->dynCast<Const>()) {
if (Bits::getEffectiveShifts(outerConst) <= Bits::getEffectiveShifts(innerConst)) {
return inner->left;
}
}
}
}
}
}
}
}
return nullptr;
}
// gets the size of the almost sign-extended value, as well as the
// extra shifts, if any
inline Index getAlmostSignExtBits(Expression* curr, Index& extraShifts) {
extraShifts = Bits::getEffectiveShifts(curr->cast<Binary>()->left->cast<Binary>()->right) -
Bits::getEffectiveShifts(curr->cast<Binary>()->right);
return getSignExtBits(curr);
}
// Check if an expression is a zero-extend, and if so, returns the value
// that is extended, otherwise nullptr
inline Expression* getZeroExtValue(Expression* curr) {
if (auto* binary = curr->dynCast<Binary>()) {
if (binary->op == AndInt32) {
if (auto* c = binary->right->dynCast<Const>()) {
if (Bits::getMaskedBits(c->value.geti32())) {
return binary->right;
}
}
}
}
return nullptr;
}
// gets the size of the sign-extended value
inline Index getZeroExtBits(Expression* curr) {
return Bits::getMaskedBits(curr->cast<Binary>()->right->cast<Const>()->value.geti32());
}
// Returns a falling-through value, that is, it looks through a tee_local
// and other operations that receive a value and let it flow through them.
inline Expression* getFallthrough(Expression* curr) {
// If the current node is unreachable, there is no value
// falling through.
if (curr->type == unreachable) {
return curr;
}
if (auto* set = curr->dynCast<SetLocal>()) {
if (set->isTee()) {
return getFallthrough(set->value);
}
} else if (auto* block = curr->dynCast<Block>()) {
// if no name, we can't be broken to, and then can look at the fallthrough
if (!block->name.is() && block->list.size() > 0) {
return getFallthrough(block->list.back());
}
} else if (auto* loop = curr->dynCast<Loop>()) {
return getFallthrough(loop->body);
} else if (auto* iff = curr->dynCast<If>()) {
if (iff->ifFalse) {
// Perhaps just one of the two actually returns.
if (iff->ifTrue->type == unreachable) {
return getFallthrough(iff->ifFalse);
} else if (iff->ifFalse->type == unreachable) {
return getFallthrough(iff->ifTrue);
}
}
} else if (auto* br = curr->dynCast<Break>()) {
if (br->condition && br->value) {
return getFallthrough(br->value);
}
}
return curr;
}
} // Properties
} // wasm
#endif // wasm_ir_properties_h
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