blob: c541a899d132081ecae39278a74418c8c46f244c [file] [log] [blame]
/*
* Copyright 2021 Google LLC
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "src/sksl/SkSLAnalysis.h"
#include "src/sksl/SkSLConstantFolder.h"
#include "src/sksl/SkSLContext.h"
#include "src/sksl/SkSLProgramSettings.h"
#include "src/sksl/ir/SkSLExpressionStatement.h"
#include "src/sksl/ir/SkSLIfStatement.h"
#include "src/sksl/ir/SkSLLiteral.h"
#include "src/sksl/ir/SkSLNop.h"
#include "src/sksl/ir/SkSLType.h"
namespace SkSL {
std::unique_ptr<Statement> IfStatement::clone() const {
return std::make_unique<IfStatement>(fLine, this->isStatic(), this->test()->clone(),
this->ifTrue()->clone(),
this->ifFalse() ? this->ifFalse()->clone() : nullptr);
}
std::string IfStatement::description() const {
std::string result;
if (this->isStatic()) {
result += "@";
}
result += "if (" + this->test()->description() + ") " + this->ifTrue()->description();
if (this->ifFalse()) {
result += " else " + this->ifFalse()->description();
}
return result;
}
std::unique_ptr<Statement> IfStatement::Convert(const Context& context, int line, bool isStatic,
std::unique_ptr<Expression> test,
std::unique_ptr<Statement> ifTrue,
std::unique_ptr<Statement> ifFalse) {
test = context.fTypes.fBool->coerceExpression(std::move(test), context);
if (!test) {
return nullptr;
}
SkASSERT(ifTrue);
if (Analysis::DetectVarDeclarationWithoutScope(*ifTrue, context.fErrors)) {
return nullptr;
}
if (ifFalse && Analysis::DetectVarDeclarationWithoutScope(*ifFalse, context.fErrors)) {
return nullptr;
}
return IfStatement::Make(context, line, isStatic, std::move(test),
std::move(ifTrue), std::move(ifFalse));
}
static std::unique_ptr<Statement> replace_empty_with_nop(std::unique_ptr<Statement> stmt,
bool isEmpty) {
return (stmt && (!isEmpty || stmt->is<Nop>())) ? std::move(stmt)
: Nop::Make();
}
std::unique_ptr<Statement> IfStatement::Make(const Context& context, int line, bool isStatic,
std::unique_ptr<Expression> test,
std::unique_ptr<Statement> ifTrue,
std::unique_ptr<Statement> ifFalse) {
SkASSERT(test->type().matches(*context.fTypes.fBool));
SkASSERT(!Analysis::DetectVarDeclarationWithoutScope(*ifTrue));
SkASSERT(!ifFalse || !Analysis::DetectVarDeclarationWithoutScope(*ifFalse));
const bool optimize = context.fConfig->fSettings.fOptimize;
bool trueIsEmpty = false;
bool falseIsEmpty = false;
if (optimize) {
// If both sides are empty, the if statement can be reduced to its test expression.
trueIsEmpty = ifTrue->isEmpty();
falseIsEmpty = !ifFalse || ifFalse->isEmpty();
if (trueIsEmpty && falseIsEmpty) {
return ExpressionStatement::Make(context, std::move(test));
}
}
if (isStatic || optimize) {
// Static Boolean values can fold down to a single branch.
const Expression* testValue = ConstantFolder::GetConstantValueForVariable(*test);
if (testValue->isBoolLiteral()) {
if (testValue->as<Literal>().boolValue()) {
return replace_empty_with_nop(std::move(ifTrue), trueIsEmpty);
} else {
return replace_empty_with_nop(std::move(ifFalse), falseIsEmpty);
}
}
}
if (optimize) {
// Replace an empty if-true branches with Nop; eliminate empty if-false branches entirely.
ifTrue = replace_empty_with_nop(std::move(ifTrue), trueIsEmpty);
if (falseIsEmpty) {
ifFalse = nullptr;
}
}
return std::make_unique<IfStatement>(line, isStatic, std::move(test),
std::move(ifTrue), std::move(ifFalse));
}
} // namespace SkSL