| /* |
| * Copyright 2016 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "src/sksl/SkSLCFGGenerator.h" |
| |
| #include "src/sksl/ir/SkSLBinaryExpression.h" |
| #include "src/sksl/ir/SkSLConstructor.h" |
| #include "src/sksl/ir/SkSLDoStatement.h" |
| #include "src/sksl/ir/SkSLExpressionStatement.h" |
| #include "src/sksl/ir/SkSLExternalFunctionCall.h" |
| #include "src/sksl/ir/SkSLFieldAccess.h" |
| #include "src/sksl/ir/SkSLForStatement.h" |
| #include "src/sksl/ir/SkSLFunctionCall.h" |
| #include "src/sksl/ir/SkSLIfStatement.h" |
| #include "src/sksl/ir/SkSLIndexExpression.h" |
| #include "src/sksl/ir/SkSLPostfixExpression.h" |
| #include "src/sksl/ir/SkSLPrefixExpression.h" |
| #include "src/sksl/ir/SkSLReturnStatement.h" |
| #include "src/sksl/ir/SkSLSwitchStatement.h" |
| #include "src/sksl/ir/SkSLSwizzle.h" |
| #include "src/sksl/ir/SkSLTernaryExpression.h" |
| #include "src/sksl/ir/SkSLVarDeclarationsStatement.h" |
| #include "src/sksl/ir/SkSLWhileStatement.h" |
| |
| #if defined(STARBOARD) |
| #include "starboard/common/log.h" |
| #define PRINTF_SKSL(format) SbLogRaw(format) |
| #define PRINTFF_SKSL(format, ...) SbLogFormatF(format, __VA_ARGS__) |
| #else |
| #define PRINTF_SKSL printf |
| #define PRINTFF_SKSL printf |
| #endif |
| |
| namespace SkSL { |
| |
| BlockId CFG::newBlock() { |
| BlockId result = fBlocks.size(); |
| fBlocks.emplace_back(); |
| if (fBlocks.size() > 1) { |
| this->addExit(fCurrent, result); |
| } |
| fCurrent = result; |
| return result; |
| } |
| |
| BlockId CFG::newIsolatedBlock() { |
| BlockId result = fBlocks.size(); |
| fBlocks.emplace_back(); |
| return result; |
| } |
| |
| void CFG::addExit(BlockId from, BlockId to) { |
| if (from == 0 || fBlocks[from].fEntrances.size()) { |
| fBlocks[from].fExits.insert(to); |
| fBlocks[to].fEntrances.insert(from); |
| } |
| } |
| |
| void CFG::dump() { |
| for (size_t i = 0; i < fBlocks.size(); i++) { |
| PRINTFF_SKSL("Block %d\n-------\nBefore: ", (int)i); |
| const char* separator = ""; |
| for (auto iter = fBlocks[i].fBefore.begin(); iter != fBlocks[i].fBefore.end(); iter++) { |
| PRINTFF_SKSL("%s%s = %s", separator, iter->first->description().c_str(), |
| iter->second ? (*iter->second)->description().c_str() : "<undefined>"); |
| separator = ", "; |
| } |
| PRINTF_SKSL("\nEntrances: "); |
| separator = ""; |
| for (BlockId b : fBlocks[i].fEntrances) { |
| PRINTFF_SKSL("%s%d", separator, (int)b); |
| separator = ", "; |
| } |
| PRINTF_SKSL("\n"); |
| for (size_t j = 0; j < fBlocks[i].fNodes.size(); j++) { |
| BasicBlock::Node& n = fBlocks[i].fNodes[j]; |
| PRINTFF_SKSL("Node %d (%p): %s\n", (int)j, &n, |
| n.fKind == BasicBlock::Node::kExpression_Kind |
| ? (*n.expression())->description().c_str() |
| : (*n.statement())->description().c_str()); |
| } |
| PRINTF_SKSL("Exits: "); |
| separator = ""; |
| for (BlockId b : fBlocks[i].fExits) { |
| PRINTFF_SKSL("%s%d", separator, (int)b); |
| separator = ", "; |
| } |
| PRINTF_SKSL("\n\n"); |
| } |
| } |
| |
| bool BasicBlock::tryRemoveExpressionBefore(std::vector<BasicBlock::Node>::iterator* iter, |
| Expression* e) { |
| if (e->fKind == Expression::kTernary_Kind) { |
| return false; |
| } |
| bool result; |
| if ((*iter)->fKind == BasicBlock::Node::kExpression_Kind) { |
| SkASSERT((*iter)->expression()->get() != e); |
| Expression* old = (*iter)->expression()->get(); |
| do { |
| if ((*iter) == fNodes.begin()) { |
| return false; |
| } |
| --(*iter); |
| } while ((*iter)->fKind != BasicBlock::Node::kExpression_Kind || |
| (*iter)->expression()->get() != e); |
| result = this->tryRemoveExpression(iter); |
| while ((*iter)->fKind != BasicBlock::Node::kExpression_Kind || |
| (*iter)->expression()->get() != old) { |
| SkASSERT(*iter != fNodes.end()); |
| ++(*iter); |
| } |
| } else { |
| Statement* old = (*iter)->statement()->get(); |
| do { |
| if ((*iter) == fNodes.begin()) { |
| return false; |
| } |
| --(*iter); |
| } while ((*iter)->fKind != BasicBlock::Node::kExpression_Kind || |
| (*iter)->expression()->get() != e); |
| result = this->tryRemoveExpression(iter); |
| while ((*iter)->fKind != BasicBlock::Node::kStatement_Kind || |
| (*iter)->statement()->get() != old) { |
| SkASSERT(*iter != fNodes.end()); |
| ++(*iter); |
| } |
| } |
| return result; |
| } |
| |
| bool BasicBlock::tryRemoveLValueBefore(std::vector<BasicBlock::Node>::iterator* iter, |
| Expression* lvalue) { |
| switch (lvalue->fKind) { |
| case Expression::kExternalValue_Kind: // fall through |
| case Expression::kVariableReference_Kind: |
| return true; |
| case Expression::kSwizzle_Kind: |
| return this->tryRemoveLValueBefore(iter, ((Swizzle*) lvalue)->fBase.get()); |
| case Expression::kFieldAccess_Kind: |
| return this->tryRemoveLValueBefore(iter, ((FieldAccess*) lvalue)->fBase.get()); |
| case Expression::kIndex_Kind: |
| if (!this->tryRemoveLValueBefore(iter, ((IndexExpression*) lvalue)->fBase.get())) { |
| return false; |
| } |
| return this->tryRemoveExpressionBefore(iter, ((IndexExpression*) lvalue)->fIndex.get()); |
| case Expression::kTernary_Kind: |
| if (!this->tryRemoveExpressionBefore(iter, |
| ((TernaryExpression*) lvalue)->fTest.get())) { |
| return false; |
| } |
| if (!this->tryRemoveLValueBefore(iter, ((TernaryExpression*) lvalue)->fIfTrue.get())) { |
| return false; |
| } |
| return this->tryRemoveLValueBefore(iter, ((TernaryExpression*) lvalue)->fIfFalse.get()); |
| default: |
| ABORT("invalid lvalue: %s\n", lvalue->description().c_str()); |
| } |
| } |
| |
| bool BasicBlock::tryRemoveExpression(std::vector<BasicBlock::Node>::iterator* iter) { |
| Expression* expr = (*iter)->expression()->get(); |
| switch (expr->fKind) { |
| case Expression::kBinary_Kind: { |
| BinaryExpression* b = (BinaryExpression*) expr; |
| if (b->fOperator == Token::EQ) { |
| if (!this->tryRemoveLValueBefore(iter, b->fLeft.get())) { |
| return false; |
| } |
| } else if (!this->tryRemoveExpressionBefore(iter, b->fLeft.get())) { |
| return false; |
| } |
| if (!this->tryRemoveExpressionBefore(iter, b->fRight.get())) { |
| return false; |
| } |
| SkASSERT((*iter)->expression()->get() == expr); |
| *iter = fNodes.erase(*iter); |
| return true; |
| } |
| case Expression::kTernary_Kind: { |
| // ternaries cross basic block boundaries, must regenerate the CFG to remove it |
| return false; |
| } |
| case Expression::kFieldAccess_Kind: { |
| FieldAccess* f = (FieldAccess*) expr; |
| if (!this->tryRemoveExpressionBefore(iter, f->fBase.get())) { |
| return false; |
| } |
| *iter = fNodes.erase(*iter); |
| return true; |
| } |
| case Expression::kSwizzle_Kind: { |
| Swizzle* s = (Swizzle*) expr; |
| if (s->fBase && !this->tryRemoveExpressionBefore(iter, s->fBase.get())) { |
| return false; |
| } |
| *iter = fNodes.erase(*iter); |
| return true; |
| } |
| case Expression::kIndex_Kind: { |
| IndexExpression* idx = (IndexExpression*) expr; |
| if (!this->tryRemoveExpressionBefore(iter, idx->fBase.get())) { |
| return false; |
| } |
| if (!this->tryRemoveExpressionBefore(iter, idx->fIndex.get())) { |
| return false; |
| } |
| *iter = fNodes.erase(*iter); |
| return true; |
| } |
| case Expression::kConstructor_Kind: { |
| Constructor* c = (Constructor*) expr; |
| for (auto& arg : c->fArguments) { |
| if (!this->tryRemoveExpressionBefore(iter, arg.get())) { |
| return false; |
| } |
| SkASSERT((*iter)->expression()->get() == expr); |
| } |
| *iter = fNodes.erase(*iter); |
| return true; |
| } |
| case Expression::kFunctionCall_Kind: { |
| FunctionCall* f = (FunctionCall*) expr; |
| for (auto& arg : f->fArguments) { |
| if (!this->tryRemoveExpressionBefore(iter, arg.get())) { |
| return false; |
| } |
| SkASSERT((*iter)->expression()->get() == expr); |
| } |
| *iter = fNodes.erase(*iter); |
| return true; |
| } |
| case Expression::kPrefix_Kind: |
| if (!this->tryRemoveExpressionBefore(iter, |
| ((PrefixExpression*) expr)->fOperand.get())) { |
| return false; |
| } |
| *iter = fNodes.erase(*iter); |
| return true; |
| case Expression::kPostfix_Kind: |
| if (!this->tryRemoveExpressionBefore(iter, |
| ((PrefixExpression*) expr)->fOperand.get())) { |
| return false; |
| } |
| *iter = fNodes.erase(*iter); |
| return true; |
| case Expression::kBoolLiteral_Kind: // fall through |
| case Expression::kFloatLiteral_Kind: // fall through |
| case Expression::kIntLiteral_Kind: // fall through |
| case Expression::kSetting_Kind: // fall through |
| case Expression::kVariableReference_Kind: |
| *iter = fNodes.erase(*iter); |
| return true; |
| default: |
| ABORT("unhandled expression: %s\n", expr->description().c_str()); |
| } |
| } |
| |
| bool BasicBlock::tryInsertExpression(std::vector<BasicBlock::Node>::iterator* iter, |
| std::unique_ptr<Expression>* expr) { |
| switch ((*expr)->fKind) { |
| case Expression::kBinary_Kind: { |
| BinaryExpression* b = (BinaryExpression*) expr->get(); |
| if (!this->tryInsertExpression(iter, &b->fRight)) { |
| return false; |
| } |
| ++(*iter); |
| if (!this->tryInsertExpression(iter, &b->fLeft)) { |
| return false; |
| } |
| ++(*iter); |
| BasicBlock::Node node = { BasicBlock::Node::kExpression_Kind, true, expr, nullptr }; |
| *iter = fNodes.insert(*iter, node); |
| return true; |
| } |
| case Expression::kBoolLiteral_Kind: // fall through |
| case Expression::kFloatLiteral_Kind: // fall through |
| case Expression::kIntLiteral_Kind: // fall through |
| case Expression::kVariableReference_Kind: { |
| BasicBlock::Node node = { BasicBlock::Node::kExpression_Kind, true, expr, nullptr }; |
| *iter = fNodes.insert(*iter, node); |
| return true; |
| } |
| case Expression::kConstructor_Kind: { |
| Constructor* c = (Constructor*) expr->get(); |
| for (auto& arg : c->fArguments) { |
| if (!this->tryInsertExpression(iter, &arg)) { |
| return false; |
| } |
| ++(*iter); |
| } |
| BasicBlock::Node node = { BasicBlock::Node::kExpression_Kind, true, expr, nullptr }; |
| *iter = fNodes.insert(*iter, node); |
| return true; |
| } |
| case Expression::kSwizzle_Kind: { |
| Swizzle* s = (Swizzle*) expr->get(); |
| if (!this->tryInsertExpression(iter, &s->fBase)) { |
| return false; |
| } |
| ++(*iter); |
| BasicBlock::Node node = { BasicBlock::Node::kExpression_Kind, true, expr, nullptr }; |
| *iter = fNodes.insert(*iter, node); |
| return true; |
| } |
| default: |
| return false; |
| } |
| } |
| |
| void CFGGenerator::addExpression(CFG& cfg, std::unique_ptr<Expression>* e, bool constantPropagate) { |
| SkASSERT(e); |
| switch ((*e)->fKind) { |
| case Expression::kBinary_Kind: { |
| BinaryExpression* b = (BinaryExpression*) e->get(); |
| switch (b->fOperator) { |
| case Token::LOGICALAND: // fall through |
| case Token::LOGICALOR: { |
| // this isn't as precise as it could be -- we don't bother to track that if we |
| // early exit from a logical and/or, we know which branch of an 'if' we're going |
| // to hit -- but it won't make much difference in practice. |
| this->addExpression(cfg, &b->fLeft, constantPropagate); |
| BlockId start = cfg.fCurrent; |
| cfg.newBlock(); |
| this->addExpression(cfg, &b->fRight, constantPropagate); |
| cfg.newBlock(); |
| cfg.addExit(start, cfg.fCurrent); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ |
| BasicBlock::Node::kExpression_Kind, |
| constantPropagate, |
| e, |
| nullptr |
| }); |
| break; |
| } |
| case Token::EQ: { |
| this->addExpression(cfg, &b->fRight, constantPropagate); |
| this->addLValue(cfg, &b->fLeft); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ |
| BasicBlock::Node::kExpression_Kind, |
| constantPropagate, |
| e, |
| nullptr |
| }); |
| break; |
| } |
| default: |
| this->addExpression(cfg, &b->fLeft, !Compiler::IsAssignment(b->fOperator)); |
| this->addExpression(cfg, &b->fRight, constantPropagate); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ |
| BasicBlock::Node::kExpression_Kind, |
| constantPropagate, |
| e, |
| nullptr |
| }); |
| } |
| break; |
| } |
| case Expression::kConstructor_Kind: { |
| Constructor* c = (Constructor*) e->get(); |
| for (auto& arg : c->fArguments) { |
| this->addExpression(cfg, &arg, constantPropagate); |
| } |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind, |
| constantPropagate, e, nullptr }); |
| break; |
| } |
| case Expression::kExternalFunctionCall_Kind: { |
| ExternalFunctionCall* c = (ExternalFunctionCall*) e->get(); |
| for (auto& arg : c->fArguments) { |
| this->addExpression(cfg, &arg, constantPropagate); |
| } |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind, |
| constantPropagate, e, nullptr }); |
| break; |
| } |
| case Expression::kFunctionCall_Kind: { |
| FunctionCall* c = (FunctionCall*) e->get(); |
| for (auto& arg : c->fArguments) { |
| this->addExpression(cfg, &arg, constantPropagate); |
| } |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind, |
| constantPropagate, e, nullptr }); |
| break; |
| } |
| case Expression::kFieldAccess_Kind: |
| this->addExpression(cfg, &((FieldAccess*) e->get())->fBase, constantPropagate); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind, |
| constantPropagate, e, nullptr }); |
| break; |
| case Expression::kIndex_Kind: |
| this->addExpression(cfg, &((IndexExpression*) e->get())->fBase, constantPropagate); |
| this->addExpression(cfg, &((IndexExpression*) e->get())->fIndex, constantPropagate); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind, |
| constantPropagate, e, nullptr }); |
| break; |
| case Expression::kPrefix_Kind: { |
| PrefixExpression* p = (PrefixExpression*) e->get(); |
| this->addExpression(cfg, &p->fOperand, constantPropagate && |
| p->fOperator != Token::PLUSPLUS && |
| p->fOperator != Token::MINUSMINUS); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind, |
| constantPropagate, e, nullptr }); |
| break; |
| } |
| case Expression::kPostfix_Kind: |
| this->addExpression(cfg, &((PostfixExpression*) e->get())->fOperand, false); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind, |
| constantPropagate, e, nullptr }); |
| break; |
| case Expression::kSwizzle_Kind: |
| this->addExpression(cfg, &((Swizzle*) e->get())->fBase, constantPropagate); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind, |
| constantPropagate, e, nullptr }); |
| break; |
| case Expression::kBoolLiteral_Kind: // fall through |
| case Expression::kExternalValue_Kind: // fall through |
| case Expression::kFloatLiteral_Kind: // fall through |
| case Expression::kIntLiteral_Kind: // fall through |
| case Expression::kNullLiteral_Kind: // fall through |
| case Expression::kSetting_Kind: // fall through |
| case Expression::kVariableReference_Kind: |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind, |
| constantPropagate, e, nullptr }); |
| break; |
| case Expression::kTernary_Kind: { |
| TernaryExpression* t = (TernaryExpression*) e->get(); |
| this->addExpression(cfg, &t->fTest, constantPropagate); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind, |
| constantPropagate, e, nullptr }); |
| BlockId start = cfg.fCurrent; |
| cfg.newBlock(); |
| this->addExpression(cfg, &t->fIfTrue, constantPropagate); |
| BlockId next = cfg.newBlock(); |
| cfg.fCurrent = start; |
| cfg.newBlock(); |
| this->addExpression(cfg, &t->fIfFalse, constantPropagate); |
| cfg.addExit(cfg.fCurrent, next); |
| cfg.fCurrent = next; |
| break; |
| } |
| case Expression::kFunctionReference_Kind: // fall through |
| case Expression::kTypeReference_Kind: // fall through |
| case Expression::kDefined_Kind: |
| SkASSERT(false); |
| break; |
| } |
| } |
| |
| // adds expressions that are evaluated as part of resolving an lvalue |
| void CFGGenerator::addLValue(CFG& cfg, std::unique_ptr<Expression>* e) { |
| switch ((*e)->fKind) { |
| case Expression::kFieldAccess_Kind: |
| this->addLValue(cfg, &((FieldAccess&) **e).fBase); |
| break; |
| case Expression::kIndex_Kind: |
| this->addLValue(cfg, &((IndexExpression&) **e).fBase); |
| this->addExpression(cfg, &((IndexExpression&) **e).fIndex, true); |
| break; |
| case Expression::kSwizzle_Kind: |
| this->addLValue(cfg, &((Swizzle&) **e).fBase); |
| break; |
| case Expression::kExternalValue_Kind: // fall through |
| case Expression::kVariableReference_Kind: |
| break; |
| case Expression::kTernary_Kind: |
| this->addExpression(cfg, &((TernaryExpression&) **e).fTest, true); |
| // Technically we will of course only evaluate one or the other, but if the test turns |
| // out to be constant, the ternary will get collapsed down to just one branch anyway. So |
| // it should be ok to pretend that we always evaluate both branches here. |
| this->addLValue(cfg, &((TernaryExpression&) **e).fIfTrue); |
| this->addLValue(cfg, &((TernaryExpression&) **e).fIfFalse); |
| break; |
| default: |
| // not an lvalue, can't happen |
| SkASSERT(false); |
| break; |
| } |
| } |
| |
| static bool is_true(Expression& expr) { |
| return expr.fKind == Expression::kBoolLiteral_Kind && ((BoolLiteral&) expr).fValue; |
| } |
| |
| void CFGGenerator::addStatement(CFG& cfg, std::unique_ptr<Statement>* s) { |
| switch ((*s)->fKind) { |
| case Statement::kBlock_Kind: |
| for (auto& child : ((Block&) **s).fStatements) { |
| addStatement(cfg, &child); |
| } |
| break; |
| case Statement::kIf_Kind: { |
| IfStatement& ifs = (IfStatement&) **s; |
| this->addExpression(cfg, &ifs.fTest, true); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false, |
| nullptr, s }); |
| BlockId start = cfg.fCurrent; |
| cfg.newBlock(); |
| this->addStatement(cfg, &ifs.fIfTrue); |
| BlockId next = cfg.newBlock(); |
| if (ifs.fIfFalse) { |
| cfg.fCurrent = start; |
| cfg.newBlock(); |
| this->addStatement(cfg, &ifs.fIfFalse); |
| cfg.addExit(cfg.fCurrent, next); |
| cfg.fCurrent = next; |
| } else { |
| cfg.addExit(start, next); |
| } |
| break; |
| } |
| case Statement::kExpression_Kind: { |
| this->addExpression(cfg, &((ExpressionStatement&) **s).fExpression, true); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false, |
| nullptr, s }); |
| break; |
| } |
| case Statement::kVarDeclarations_Kind: { |
| VarDeclarationsStatement& decls = ((VarDeclarationsStatement&) **s); |
| for (auto& stmt : decls.fDeclaration->fVars) { |
| if (stmt->fKind == Statement::kNop_Kind) { |
| continue; |
| } |
| VarDeclaration& vd = (VarDeclaration&) *stmt; |
| if (vd.fValue) { |
| this->addExpression(cfg, &vd.fValue, true); |
| } |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, |
| false, nullptr, &stmt }); |
| } |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false, |
| nullptr, s }); |
| break; |
| } |
| case Statement::kDiscard_Kind: |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false, |
| nullptr, s }); |
| cfg.fCurrent = cfg.newIsolatedBlock(); |
| break; |
| case Statement::kReturn_Kind: { |
| ReturnStatement& r = ((ReturnStatement&) **s); |
| if (r.fExpression) { |
| this->addExpression(cfg, &r.fExpression, true); |
| } |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false, |
| nullptr, s }); |
| cfg.fCurrent = cfg.newIsolatedBlock(); |
| break; |
| } |
| case Statement::kBreak_Kind: |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false, |
| nullptr, s }); |
| cfg.addExit(cfg.fCurrent, fLoopExits.top()); |
| cfg.fCurrent = cfg.newIsolatedBlock(); |
| break; |
| case Statement::kContinue_Kind: |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false, |
| nullptr, s }); |
| cfg.addExit(cfg.fCurrent, fLoopContinues.top()); |
| cfg.fCurrent = cfg.newIsolatedBlock(); |
| break; |
| case Statement::kWhile_Kind: { |
| WhileStatement& w = (WhileStatement&) **s; |
| BlockId loopStart = cfg.newBlock(); |
| fLoopContinues.push(loopStart); |
| BlockId loopExit = cfg.newIsolatedBlock(); |
| fLoopExits.push(loopExit); |
| this->addExpression(cfg, &w.fTest, true); |
| BlockId test = cfg.fCurrent; |
| if (!is_true(*w.fTest)) { |
| cfg.addExit(test, loopExit); |
| } |
| cfg.newBlock(); |
| this->addStatement(cfg, &w.fStatement); |
| cfg.addExit(cfg.fCurrent, loopStart); |
| fLoopContinues.pop(); |
| fLoopExits.pop(); |
| cfg.fCurrent = loopExit; |
| break; |
| } |
| case Statement::kDo_Kind: { |
| DoStatement& d = (DoStatement&) **s; |
| BlockId loopStart = cfg.newBlock(); |
| fLoopContinues.push(loopStart); |
| BlockId loopExit = cfg.newIsolatedBlock(); |
| fLoopExits.push(loopExit); |
| this->addStatement(cfg, &d.fStatement); |
| this->addExpression(cfg, &d.fTest, true); |
| cfg.addExit(cfg.fCurrent, loopExit); |
| cfg.addExit(cfg.fCurrent, loopStart); |
| fLoopContinues.pop(); |
| fLoopExits.pop(); |
| cfg.fCurrent = loopExit; |
| break; |
| } |
| case Statement::kFor_Kind: { |
| ForStatement& f = (ForStatement&) **s; |
| if (f.fInitializer) { |
| this->addStatement(cfg, &f.fInitializer); |
| } |
| BlockId loopStart = cfg.newBlock(); |
| BlockId next = cfg.newIsolatedBlock(); |
| fLoopContinues.push(next); |
| BlockId loopExit = cfg.newIsolatedBlock(); |
| fLoopExits.push(loopExit); |
| if (f.fTest) { |
| this->addExpression(cfg, &f.fTest, true); |
| // this isn't quite right; we should have an exit from here to the loop exit, and |
| // remove the exit from the loop body to the loop exit. Structuring it like this |
| // forces the optimizer to believe that the loop body is always executed at least |
| // once. While not strictly correct, this avoids incorrect "variable not assigned" |
| // errors on variables which are assigned within the loop. The correct solution to |
| // this is to analyze the loop to see whether or not at least one iteration is |
| // guaranteed to happen, but for the time being we take the easy way out. |
| } |
| cfg.newBlock(); |
| this->addStatement(cfg, &f.fStatement); |
| cfg.addExit(cfg.fCurrent, next); |
| cfg.fCurrent = next; |
| if (f.fNext) { |
| this->addExpression(cfg, &f.fNext, true); |
| } |
| cfg.addExit(cfg.fCurrent, loopStart); |
| cfg.addExit(cfg.fCurrent, loopExit); |
| fLoopContinues.pop(); |
| fLoopExits.pop(); |
| cfg.fCurrent = loopExit; |
| break; |
| } |
| case Statement::kSwitch_Kind: { |
| SwitchStatement& ss = (SwitchStatement&) **s; |
| this->addExpression(cfg, &ss.fValue, true); |
| cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false, |
| nullptr, s }); |
| BlockId start = cfg.fCurrent; |
| BlockId switchExit = cfg.newIsolatedBlock(); |
| fLoopExits.push(switchExit); |
| for (const auto& c : ss.fCases) { |
| cfg.newBlock(); |
| cfg.addExit(start, cfg.fCurrent); |
| if (c->fValue) { |
| // technically this should go in the start block, but it doesn't actually matter |
| // because it must be constant. Not worth running two loops for. |
| this->addExpression(cfg, &c->fValue, true); |
| } |
| for (auto& caseStatement : c->fStatements) { |
| this->addStatement(cfg, &caseStatement); |
| } |
| } |
| cfg.addExit(cfg.fCurrent, switchExit); |
| // note that unlike GLSL, our grammar requires the default case to be last |
| if (0 == ss.fCases.size() || ss.fCases[ss.fCases.size() - 1]->fValue) { |
| // switch does not have a default clause, mark that it can skip straight to the end |
| cfg.addExit(start, switchExit); |
| } |
| fLoopExits.pop(); |
| cfg.fCurrent = switchExit; |
| break; |
| } |
| case Statement::kNop_Kind: |
| break; |
| default: |
| PRINTFF_SKSL("statement: %s\n", (*s)->description().c_str()); |
| ABORT("unsupported statement kind"); |
| } |
| } |
| |
| CFG CFGGenerator::getCFG(FunctionDefinition& f) { |
| CFG result; |
| result.fStart = result.newBlock(); |
| result.fCurrent = result.fStart; |
| this->addStatement(result, &f.fBody); |
| result.newBlock(); |
| result.fExit = result.fCurrent; |
| return result; |
| } |
| |
| } // namespace |
