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//===- Target/TargetJITInfo.h - Target Information for JIT ------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file exposes an abstract interface used by the Just-In-Time code
// generator to perform target-specific activities, such as emitting stubs. If
// a TargetMachine supports JIT code generation, it should provide one of these
// objects through the getJITInfo() method.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TARGET_TARGETJITINFO_H
#define LLVM_TARGET_TARGETJITINFO_H
#include <cassert>
#include "llvm/Support/ErrorHandling.h"
#include "llvm/System/DataTypes.h"
namespace llvm {
class Function;
class GlobalValue;
class JITCodeEmitter;
class MachineRelocation;
/// TargetJITInfo - Target specific information required by the Just-In-Time
/// code generator.
class TargetJITInfo {
public:
virtual ~TargetJITInfo() {}
/// replaceMachineCodeForFunction - Make it so that calling the function
/// whose machine code is at OLD turns into a call to NEW, perhaps by
/// overwriting OLD with a branch to NEW. This is used for self-modifying
/// code.
///
virtual void replaceMachineCodeForFunction(void *Old, void *New) = 0;
/// emitGlobalValueIndirectSym - Use the specified JITCodeEmitter object
/// to emit an indirect symbol which contains the address of the specified
/// ptr.
virtual void *emitGlobalValueIndirectSym(const GlobalValue* GV, void *ptr,
JITCodeEmitter &JCE) {
assert(0 && "This target doesn't implement emitGlobalValueIndirectSym!");
return 0;
}
/// Records the required size and alignment for a call stub in bytes.
struct StubLayout {
size_t Size;
size_t Alignment;
};
/// Returns the maximum size and alignment for a call stub on this target.
virtual StubLayout getStubLayout() {
llvm_unreachable("This target doesn't implement getStubLayout!");
StubLayout Result = {0, 0};
return Result;
}
/// emitFunctionStub - Use the specified JITCodeEmitter object to emit a
/// small native function that simply calls the function at the specified
/// address. The JITCodeEmitter must already have storage allocated for the
/// stub. Return the address of the resultant function, which may have been
/// aligned from the address the JCE was set up to emit at.
virtual void *emitFunctionStub(const Function* F, void *Target,
JITCodeEmitter &JCE) {
assert(0 && "This target doesn't implement emitFunctionStub!");
return 0;
}
/// getPICJumpTableEntry - Returns the value of the jumptable entry for the
/// specific basic block.
virtual uintptr_t getPICJumpTableEntry(uintptr_t BB, uintptr_t JTBase) {
assert(0 && "This target doesn't implement getPICJumpTableEntry!");
return 0;
}
/// LazyResolverFn - This typedef is used to represent the function that
/// unresolved call points should invoke. This is a target specific
/// function that knows how to walk the stack and find out which stub the
/// call is coming from.
typedef void (*LazyResolverFn)();
/// JITCompilerFn - This typedef is used to represent the JIT function that
/// lazily compiles the function corresponding to a stub. The JIT keeps
/// track of the mapping between stubs and LLVM Functions, the target
/// provides the ability to figure out the address of a stub that is called
/// by the LazyResolverFn.
typedef void* (*JITCompilerFn)(void *);
/// getLazyResolverFunction - This method is used to initialize the JIT,
/// giving the target the function that should be used to compile a
/// function, and giving the JIT the target function used to do the lazy
/// resolving.
virtual LazyResolverFn getLazyResolverFunction(JITCompilerFn) {
assert(0 && "Not implemented for this target!");
return 0;
}
/// relocate - Before the JIT can run a block of code that has been emitted,
/// it must rewrite the code to contain the actual addresses of any
/// referenced global symbols.
virtual void relocate(void *Function, MachineRelocation *MR,
unsigned NumRelocs, unsigned char* GOTBase) {
assert(NumRelocs == 0 && "This target does not have relocations!");
}
/// allocateThreadLocalMemory - Each target has its own way of
/// handling thread local variables. This method returns a value only
/// meaningful to the target.
virtual char* allocateThreadLocalMemory(size_t size) {
assert(0 && "This target does not implement thread local storage!");
return 0;
}
/// needsGOT - Allows a target to specify that it would like the
/// JIT to manage a GOT for it.
bool needsGOT() const { return useGOT; }
/// hasCustomConstantPool - Allows a target to specify that constant
/// pool address resolution is handled by the target.
virtual bool hasCustomConstantPool() const { return false; }
/// hasCustomJumpTables - Allows a target to specify that jumptables
/// are emitted by the target.
virtual bool hasCustomJumpTables() const { return false; }
/// allocateSeparateGVMemory - If true, globals should be placed in
/// separately allocated heap memory rather than in the same
/// code memory allocated by JITCodeEmitter.
virtual bool allocateSeparateGVMemory() const { return false; }
protected:
bool useGOT;
};
} // End llvm namespace
#endif
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