From dfe9ecd287579a8bc076ca4d5cbe2bc1b7895d8b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Rafael=20S=C3=A1=20Menezes?= Date: Tue, 25 Jun 2024 17:06:37 +0100 Subject: [PATCH] added loop bounds identification --- .../bounded-loop-unroller/frontend_visitor.h | 20 +- .../frontend_visitor.cpp | 190 ++++++++++++++---- 2 files changed, 157 insertions(+), 53 deletions(-) diff --git a/include/bounded-loop-unroller/frontend_visitor.h b/include/bounded-loop-unroller/frontend_visitor.h index 3828ce6..ec38167 100644 --- a/include/bounded-loop-unroller/frontend_visitor.h +++ b/include/bounded-loop-unroller/frontend_visitor.h @@ -29,31 +29,15 @@ namespace BoundedLoopUnroller { public: explicit frontend_visitor(clang::Rewriter &rewriter) : rewriter(rewriter) {} - bool VisitWhileStmt(clang::WhileStmt *expr); - - bool VisitIfStmt(clang::IfStmt *expr); - bool VisitForStmt(clang::ForStmt *expr); - bool VisitFunctionDecl(clang::FunctionDecl *F); - - /* - * SwitchCase - * dowhile - */ + // TODO: other loops, e.g.: while, do-while, backwards goto protected: - void InjectOnStmt(clang::Stmt *stmt); - - void InjectOnCompoundStmt(clang::CompoundStmt *stmt); - - void InjectOnNonCompoundStmt(clang::Stmt *stmt); + void RewriteForLoop(clang::ForStmt *expr, int64_t unfold_number); private: int counter = 0; clang::Rewriter &rewriter; - std::string goal_str(); - std::string goal_block_str(); - }; } diff --git a/src/bounded-loop-unroller/frontend_visitor.cpp b/src/bounded-loop-unroller/frontend_visitor.cpp index 04ce063..5ce9bef 100644 --- a/src/bounded-loop-unroller/frontend_visitor.cpp +++ b/src/bounded-loop-unroller/frontend_visitor.cpp @@ -1,55 +1,175 @@ #include #include +#include +#include namespace BoundedLoopUnroller { - bool frontend_visitor::VisitWhileStmt(clang::WhileStmt *expr) { - InjectOnStmt(expr->getBody()); - return true; - } - bool frontend_visitor::VisitIfStmt(clang::IfStmt *expr) { - InjectOnStmt(expr->getThen()); - InjectOnStmt(expr->getElse()); - return true; - } + bool check_assignment_over_var(const clang::Stmt *const E, + const clang::ValueDecl *const V) { + if (const clang::UnaryOperator *const op = + llvm::dyn_cast(E)) { + const clang::DeclRefExpr *const reference = + llvm::dyn_cast(op->getSubExpr()->IgnoreCasts()); - bool frontend_visitor::VisitForStmt(clang::ForStmt *expr) { - InjectOnStmt(expr->getBody()); + // TODO: This is too aggresive! :) + if (reference && reference->getDecl() == V) return true; + } else if (const clang::BinaryOperator *const op = + llvm::dyn_cast(E)) { + if (op->isAssignmentOp()) { + const clang::DeclRefExpr *const reference = + llvm::dyn_cast(op->getLHS()->IgnoreCasts()); + + if (reference && reference->getDecl() == V) + return true; + } } - bool frontend_visitor::VisitFunctionDecl(clang::FunctionDecl *F) { - InjectOnStmt(F->getBody()); + for (const auto &e : E->children()) + if (check_assignment_over_var(e, V)) return true; - } + + return false; + } + + bool frontend_visitor::VisitForStmt(clang::ForStmt *expr) { + std::cout << "Parsing loop\n"; + + /////////////////////////////////////////////////////////////// + // 1. Identify all elements: `for(INIT, COND, INC) { BODY }` // + /////////////////////////////////////////////////////////////// + const clang::DeclStmt *const init = llvm::dyn_cast(expr->getInit()); + const clang::Expr *const inc = expr->getInc(); + const clang::Expr *const cond = expr->getCond(); + const clang::Stmt *const body = expr->getBody(); + + if (!init || !inc || !cond || !body) + return false; + + int64_t cond_init_value; + int64_t cond_end_value; - void frontend_visitor::InjectOnStmt(clang::Stmt *stmt) { - if (!stmt) - return; + //////////////////////////////// + // 2. Check for preconditions // + //////////////////////////////// - if (stmt->getStmtClass() == clang::Stmt::CompoundStmtClass) { - InjectOnCompoundStmt(static_cast(stmt)); - } else { - InjectOnNonCompoundStmt(stmt); + // a. loop must be monothonic + // b. the condition must be over one variable + + // TODO: Right now we only support `var` op `number`, where op is <, <=, >, + // >=. + if (!llvm::isa(cond)) + return false; + + const clang::BinaryOperator *const bin_op = + llvm::dyn_cast(cond); + assert(bin_op); + + const clang::DeclRefExpr *const condition_var = + llvm::dyn_cast(bin_op->getLHS()->IgnoreCasts()); + const clang::IntegerLiteral *const condition_limit = + llvm::dyn_cast(bin_op->getRHS()->IgnoreCasts()); + + const std::array SUPPORTED_OP{clang::BinaryOperator::Opcode::BO_GE, clang::BinaryOperator::Opcode::BO_GT, clang::BinaryOperator::Opcode::BO_LE, clang::BinaryOperator::Opcode::BO_LT, }; + + if (!condition_var || !condition_limit || (std::find(SUPPORTED_OP.begin(), SUPPORTED_OP.end(), bin_op->getOpcode()) == SUPPORTED_OP.end())) + return false; + + + // Check if COND var is the same as initialized + bool init_var_check = false; + for (auto op : init->decls()) { + const clang::VarDecl *const op_cast = llvm::dyn_cast(op); + if (op_cast && condition_var->getDecl() == op_cast && op_cast->hasInit()) { + init_var_check = true; + if (const clang::IntegerLiteral *const value_cast = + llvm::dyn_cast(op_cast->getInit())) { + cond_init_value = value_cast->getValue().getSExtValue(); + cond_end_value = condition_limit->getValue().getSExtValue(); } - } + } + } - std::string frontend_visitor::goal_str() { - return fmt::format("__ESBMC_assert(0, \"{}\");", counter++); - } - - std::string frontend_visitor::goal_block_str() { - return fmt::format("{}__ESBMC_assert(0, \"{}\");", "{", counter++); + if (!init_var_check) + return false; + + + // Check if INC is the same as intialized + bool inc_var_check = false; + bool inc_is_increasing = false; + if (const clang::UnaryOperator *const op = + llvm::dyn_cast(inc)) { + switch (op->getOpcode()) { + case clang::UnaryOperator::Opcode::UO_PostInc: + case clang::UnaryOperator::Opcode::UO_PreInc: + inc_is_increasing = true; + break; + case clang::UnaryOperator::Opcode::UO_PostDec: + case clang::UnaryOperator::Opcode::UO_PreDec: + inc_is_increasing = false; + break; + default: + return false; + } + + const clang::DeclRefExpr *const reference = + llvm::dyn_cast(op->getSubExpr()->IgnoreCasts()); + + if (reference && reference->getDecl() == condition_var->getDecl()) + inc_var_check = true; + + //if (condition_cast == op_cast) + // inc_var_check = true; } - void frontend_visitor::InjectOnCompoundStmt(clang::CompoundStmt *stmt) { - // TODO: Not sure whether begin or end location is the best - rewriter.InsertTextAfter(stmt->getBeginLoc().getLocWithOffset(1), goal_str()); + + if (!inc_var_check) + return false; + + + // Check whether the BODY contains an assignment over the condition_variable + if (check_assignment_over_var(body, condition_var->getDecl())) + return false; + + + ///////////////////////////////////// + // 3. Compute number of iterations // + ///////////////////////////////////// + + + int64_t number_of_unfolds; + + if (!inc_is_increasing && + (bin_op->getOpcode() == clang::BinaryOperator::Opcode::BO_GE || + bin_op->getOpcode() == clang::BinaryOperator::Opcode::BO_GT)) { + if (bin_op->getOpcode() == clang::BinaryOperator::Opcode::BO_GE) + cond_end_value--; + + number_of_unfolds = cond_init_value - cond_end_value; } + else if (inc_is_increasing && (bin_op->getOpcode() == clang::BinaryOperator::Opcode::BO_LE || bin_op->getOpcode() == clang::BinaryOperator::Opcode::BO_LT )) { + if (bin_op->getOpcode() == clang::BinaryOperator::Opcode::BO_LE) + cond_end_value++; - void frontend_visitor::InjectOnNonCompoundStmt(clang::Stmt *stmt) { - // TODO: Not sure whether begin or end location is the best - rewriter.InsertTextAfter(stmt->getBeginLoc(), goal_block_str()); - rewriter.InsertTextAfter(stmt->getEndLoc().getLocWithOffset(1), "}"); + number_of_unfolds = cond_end_value - cond_init_value; } + else + return false; + + RewriteForLoop(expr, number_of_unfolds); + return true; + } + + + void frontend_visitor::RewriteForLoop(clang::ForStmt *expr, + int64_t unfold_number) { + unfold_number = unfold_number < 0 ? 0 : unfold_number; + std::cout << "Unrolling loop " << unfold_number << " times\n"; + + expr->getBody()->dumpColor(); + + } + + }