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Since the ARM constant pool handling supercedes the standard LLVM constant pool entirely, the JIT emitter does not allocate space for the constants, nor initialize the memory. The constant pool is considered part of the instruction stream. Likewise, when resolving relocations into the constant pool, a hook into the target back end is used to resolve from the constant ID# to the address where the constant is stored. For now, the support in the ARM emitter is limited to 32-bit integer. Future patches will expand this to the full range of constants necessary. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58338 91177308-0d34-0410-b5e6-96231b3b80d8
125 lines
5.0 KiB
C++
125 lines
5.0 KiB
C++
//===- Target/TargetJITInfo.h - Target Information for JIT ------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file exposes an abstract interface used by the Just-In-Time code
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// generator to perform target-specific activities, such as emitting stubs. If
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// a TargetMachine supports JIT code generation, it should provide one of these
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// objects through the getJITInfo() method.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TARGET_TARGETJITINFO_H
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#define LLVM_TARGET_TARGETJITINFO_H
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#include <cassert>
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#include "llvm/Support/DataTypes.h"
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namespace llvm {
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class Function;
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class GlobalValue;
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class MachineBasicBlock;
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class MachineCodeEmitter;
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class MachineRelocation;
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/// TargetJITInfo - Target specific information required by the Just-In-Time
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/// code generator.
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class TargetJITInfo {
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public:
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virtual ~TargetJITInfo() {}
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/// replaceMachineCodeForFunction - Make it so that calling the function
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/// whose machine code is at OLD turns into a call to NEW, perhaps by
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/// overwriting OLD with a branch to NEW. This is used for self-modifying
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/// code.
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///
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virtual void replaceMachineCodeForFunction(void *Old, void *New) = 0;
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/// emitGlobalValueLazyPtr - Use the specified MachineCodeEmitter object to
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/// emit a lazy pointer which contains the address of the specified ptr.
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virtual void *emitGlobalValueLazyPtr(const GlobalValue* GV, void *ptr,
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MachineCodeEmitter &MCE) {
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assert(0 && "This target doesn't implement emitGlobalValueLazyPtr!");
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return 0;
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}
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/// emitFunctionStub - Use the specified MachineCodeEmitter object to emit a
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/// small native function that simply calls the function at the specified
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/// address. Return the address of the resultant function.
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virtual void *emitFunctionStub(const Function* F, void *Fn,
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MachineCodeEmitter &MCE) {
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assert(0 && "This target doesn't implement emitFunctionStub!");
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return 0;
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}
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/// getPICJumpTableEntry - Returns the value of the jumptable entry for the
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/// specific basic block.
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virtual intptr_t getPICJumpTableEntry(intptr_t BB, intptr_t JTBase) {
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assert(0 && "This target doesn't implement getPICJumpTableEntry!");
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return 0;
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}
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/// LazyResolverFn - This typedef is used to represent the function that
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/// unresolved call points should invoke. This is a target specific
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/// function that knows how to walk the stack and find out which stub the
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/// call is coming from.
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typedef void (*LazyResolverFn)();
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/// JITCompilerFn - This typedef is used to represent the JIT function that
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/// lazily compiles the function corresponding to a stub. The JIT keeps
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/// track of the mapping between stubs and LLVM Functions, the target
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/// provides the ability to figure out the address of a stub that is called
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/// by the LazyResolverFn.
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typedef void* (*JITCompilerFn)(void *);
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/// getLazyResolverFunction - This method is used to initialize the JIT,
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/// giving the target the function that should be used to compile a
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/// function, and giving the JIT the target function used to do the lazy
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/// resolving.
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virtual LazyResolverFn getLazyResolverFunction(JITCompilerFn) {
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assert(0 && "Not implemented for this target!");
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return 0;
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}
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/// relocate - Before the JIT can run a block of code that has been emitted,
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/// it must rewrite the code to contain the actual addresses of any
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/// referenced global symbols.
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virtual void relocate(void *Function, MachineRelocation *MR,
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unsigned NumRelocs, unsigned char* GOTBase) {
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assert(NumRelocs == 0 && "This target does not have relocations!");
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}
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/// allocateThreadLocalMemory - Each target has its own way of
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/// handling thread local variables. This method returns a value only
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/// meaningful to the target.
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virtual char* allocateThreadLocalMemory(size_t size) {
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assert(0 && "This target does not implement thread local storage!");
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return 0;
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}
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/// needsGOT - Allows a target to specify that it would like the
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// JIT to manage a GOT for it.
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bool needsGOT() const { return useGOT; }
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/// hasCustomConstantPool - Allows a target to specify that constant
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/// pool address resolution is handled by the target.
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virtual bool hasCustomConstantPool() const { return false; }
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/// getCustomConstantPoolEntryAddress - When using a custom constant
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/// pool, resolve a constant pool index to the address of where the
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/// entry is stored.
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virtual intptr_t getCustomConstantPoolEntryAddress(unsigned CPI) const
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{return 0;}
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protected:
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bool useGOT;
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};
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} // End llvm namespace
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#endif
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