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-rw-r--r--include/llvm/CodeGen/JumpInstrTables.h105
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diff --git a/include/llvm/CodeGen/JumpInstrTables.h b/include/llvm/CodeGen/JumpInstrTables.h
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-//===-- JumpInstrTables.h: Jump-Instruction Tables --------------*- C++ -*-===//
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-///
-/// \file
-/// \brief An implementation of tables consisting of jump instructions
-///
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_CODEGEN_JUMPINSTRTABLES_H
-#define LLVM_CODEGEN_JUMPINSTRTABLES_H
-
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/Pass.h"
-#include "llvm/Target/TargetOptions.h"
-
-namespace llvm {
-class Constant;
-class Function;
-class FunctionType;
-class JumpInstrTableInfo;
-class Module;
-
-/// A class to manage a set of jump tables indexed on function type. It looks at
-/// each function in the module to find all the functions that have the
-/// jumptable attribute set. For each such function, it creates a new
-/// jump-instruction-table function and stores the mapping in the ImmutablePass
-/// JumpInstrTableInfo.
-///
-/// These special functions get lowered in AsmPrinter to assembly of the form:
-/// \verbatim
-/// .globl f
-/// .type f,@function
-/// .align 8,0x90
-/// f:
-/// jmp f_orig@PLT
-/// \endverbatim
-///
-/// Support for an architecture depends on three functions in TargetInstrInfo:
-/// getUnconditionalBranch, getTrap, and getJumpInstrTableEntryBound. AsmPrinter
-/// uses these to generate the appropriate instructions for the jump statement
-/// (an unconditional branch) and for padding to make the table have a size that
-/// is a power of two. This padding uses a trap instruction to ensure that calls
-/// to this area halt the program. The default implementations of these
-/// functions call llvm_unreachable, except for getJumpInstrTableEntryBound,
-/// which returns 0 by default.
-class JumpInstrTables : public ModulePass {
-public:
- static char ID;
-
- JumpInstrTables();
- JumpInstrTables(JumpTable::JumpTableType JTT);
- virtual ~JumpInstrTables();
- bool runOnModule(Module &M) override;
- const char *getPassName() const override { return "Jump-Instruction Tables"; }
- void getAnalysisUsage(AnalysisUsage &AU) const override;
-
- /// Creates a jump-instruction table function for the Target and adds it to
- /// the tables.
- Function *insertEntry(Module &M, Function *Target);
-
- /// Checks to see if there is already a table for the given FunctionType.
- bool hasTable(FunctionType *FunTy);
-
- /// Maps the function into a subset of function types, depending on the
- /// jump-instruction table style selected from JumpTableTypes in
- /// JumpInstrTables.cpp. The choice of mapping determines the number of
- /// jump-instruction tables generated by this pass. E.g., the simplest mapping
- /// converts every function type into void f(); so, all functions end up in a
- /// single table.
- static FunctionType *transformType(JumpTable::JumpTableType JTT,
- FunctionType *FunTy);
-private:
- /// The metadata used while a jump table is being built
- struct TableMeta {
- /// The number of this table
- unsigned TableNum;
-
- /// The current number of jump entries in the table.
- unsigned Count;
- };
-
- typedef DenseMap<FunctionType *, struct TableMeta> JumpMap;
-
- /// The current state of functions and jump entries in the table(s).
- JumpMap Metadata;
-
- /// The ImmutablePass that stores information about the generated tables.
- JumpInstrTableInfo *JITI;
-
- /// The total number of tables.
- unsigned TableCount;
-
- /// The type of tables to build.
- JumpTable::JumpTableType JTType;
-};
-
-/// Creates a JumpInstrTables pass for the given type of jump table.
-ModulePass *createJumpInstrTablesPass(JumpTable::JumpTableType JTT);
-}
-
-#endif /* LLVM_CODEGEN_JUMPINSTRTABLES_H */