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71 lines
2.3 KiB
71 lines
2.3 KiB
4 months ago
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//===--- VarBypassDetector.cpp - Bypass jumps detector ------------*- C++ -*-=//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains VarBypassDetector class, which is used to detect
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// local variable declarations which can be bypassed by jumps.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H
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#define LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H
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#include "clang/AST/Decl.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/DenseSet.h"
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#include "llvm/ADT/SmallVector.h"
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namespace clang {
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class Decl;
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class Stmt;
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class VarDecl;
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namespace CodeGen {
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/// The class detects jumps which bypass local variables declaration:
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/// goto L;
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/// int a;
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/// L:
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///
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/// This is simplified version of JumpScopeChecker. Primary differences:
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/// * Detects only jumps into the scope local variables.
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/// * Does not detect jumps out of the scope of local variables.
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/// * Not limited to variables with initializers, JumpScopeChecker is limited.
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class VarBypassDetector {
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// Scope information. Contains a parent scope and related variable
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// declaration.
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llvm::SmallVector<std::pair<unsigned, const VarDecl *>, 48> Scopes;
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// List of jumps with scopes.
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llvm::SmallVector<std::pair<const Stmt *, unsigned>, 16> FromScopes;
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// Lookup map to find scope for destinations.
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llvm::DenseMap<const Stmt *, unsigned> ToScopes;
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// Set of variables which were bypassed by some jump.
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llvm::DenseSet<const VarDecl *> Bypasses;
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// If true assume that all variables are being bypassed.
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bool AlwaysBypassed = false;
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public:
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void Init(const Stmt *Body);
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/// Returns true if the variable declaration was by bypassed by any goto or
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/// switch statement.
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bool IsBypassed(const VarDecl *D) const {
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return AlwaysBypassed || Bypasses.find(D) != Bypasses.end();
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}
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private:
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bool BuildScopeInformation(const Decl *D, unsigned &ParentScope);
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bool BuildScopeInformation(const Stmt *S, unsigned &origParentScope);
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void Detect();
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void Detect(unsigned From, unsigned To);
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};
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}
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}
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#endif
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