LLVM API Documentation
00001 //===-- IntrinsicLowering.h - Intrinsic Function Lowering -------*- C++ -*-===// 00002 // 00003 // The LLVM Compiler Infrastructure 00004 // 00005 // This file was developed by the LLVM research group and is distributed under 00006 // the University of Illinois Open Source License. See LICENSE.TXT for details. 00007 // 00008 //===----------------------------------------------------------------------===// 00009 // 00010 // This file defines the IntrinsicLowering interface. This interface allows 00011 // addition of domain-specific or front-end specific intrinsics to LLVM without 00012 // having to modify all of the code generators to support the new intrinsic. 00013 // Later, as desired, targets can incrementally add support for particular 00014 // intrinsic functions, as desired, to generate better code. 00015 // 00016 // If a code generator cannot handle or does not know about an intrinsic 00017 // function, it will use the intrinsic lowering interface to change an intrinsic 00018 // function name into a concrete function name which can be used to implement 00019 // the functionality of the intrinsic. For example, llvm.memcpy can be 00020 // implemented as a call to the math library 'memcpy' function if the target 00021 // doesn't have hardware support for the intrinsic, or if it has not yet been 00022 // implemented yet. 00023 // 00024 // Another use for this interface is the addition of domain-specific intrinsics. 00025 // The default implementation of this interface would then lower the intrinsics 00026 // to noop calls, allowing the direct execution of programs with instrumentation 00027 // or other hooks placed in them. When a specific tool or flag is used, a 00028 // different implementation of these interfaces may be used, which activates the 00029 // intrinsics in some way. 00030 // 00031 //===----------------------------------------------------------------------===// 00032 00033 #ifndef LLVM_CODEGEN_INTRINSICLOWERING_H 00034 #define LLVM_CODEGEN_INTRINSICLOWERING_H 00035 00036 #include "llvm/Intrinsics.h" 00037 00038 namespace llvm { 00039 class CallInst; 00040 class Module; 00041 00042 class IntrinsicLowering { 00043 public: 00044 virtual ~IntrinsicLowering() {} 00045 00046 /// AddPrototypes - This method, if called, causes all of the prototypes 00047 /// that might be needed by an intrinsic lowering implementation to be 00048 /// inserted into the module specified. 00049 virtual void AddPrototypes(Module &M) = 0; 00050 00051 /// LowerIntrinsicCall - This method returns the LLVM function which should 00052 /// be used to implement the specified intrinsic function call. If an 00053 /// intrinsic function must be implemented by the code generator (such as 00054 /// va_start), this function should print a message and abort. 00055 /// 00056 /// Otherwise, if an intrinsic function call can be lowered, the code to 00057 /// implement it (often a call to a non-intrinsic function) is inserted 00058 /// _after_ the call instruction and the call is deleted. The caller must 00059 /// be capable of handling this kind of change. 00060 /// 00061 virtual void LowerIntrinsicCall(CallInst *CI) = 0; 00062 }; 00063 00064 /// DefaultIntrinsicLower - This is the default intrinsic lowering pass which 00065 /// is used if no other one is specified. Custom intrinsic lowering 00066 /// implementations should pass any unhandled intrinsics to this 00067 /// implementation to allow for future extensibility. 00068 struct DefaultIntrinsicLowering : public IntrinsicLowering { 00069 virtual void AddPrototypes(Module &M); 00070 virtual void LowerIntrinsicCall(CallInst *CI); 00071 }; 00072 } 00073 00074 #endif