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//===- SimplifyLibCalls.cpp - Optimize specific well-known library calls --===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a simple pass that applies a variety of small
// optimizations for calls to specific well-known function calls (e.g. runtime
// library functions). For example, a call to the function "exit(3)" that
// occurs within the main() function can be transformed into a simple "return 3"
// instruction. Any optimization that takes this form (replace call to library
// function with simpler code that provides the same result) belongs in this
// file.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "simplify-libcalls"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Intrinsics.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/IRBuilder.h"
#include "llvm/Target/TargetData.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Compiler.h"
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#include "llvm/Config/config.h"
using namespace llvm;
STATISTIC(NumSimplified, "Number of library calls simplified");
//===----------------------------------------------------------------------===//
// Optimizer Base Class
//===----------------------------------------------------------------------===//
/// This class is the abstract base class for the set of optimizations that
/// corresponds to one library call.
namespace {
class VISIBILITY_HIDDEN LibCallOptimization {
protected:
Function *Caller;
const TargetData *TD;
public:
LibCallOptimization() { }
virtual ~LibCallOptimization() {}
/// CallOptimizer - This pure virtual method is implemented by base classes to
/// do various optimizations. If this returns null then no transformation was
/// performed. If it returns CI, then it transformed the call and CI is to be
/// deleted. If it returns something else, replace CI with the new value and
/// delete CI.
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) =0;
Value *OptimizeCall(CallInst *CI, const TargetData &TD, IRBuilder &B) {
Caller = CI->getParent()->getParent();
this->TD = &TD;
return CallOptimizer(CI->getCalledFunction(), CI, B);
}
/// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*.
Value *CastToCStr(Value *V, IRBuilder &B);
/// EmitStrLen - Emit a call to the strlen function to the builder, for the
/// specified pointer. Ptr is required to be some pointer type, and the
/// return value has 'intptr_t' type.
Value *EmitStrLen(Value *Ptr, IRBuilder &B);
/// EmitMemCpy - Emit a call to the memcpy function to the builder. This
/// always expects that the size has type 'intptr_t' and Dst/Src are pointers.
Value *EmitMemCpy(Value *Dst, Value *Src, Value *Len,
unsigned Align, IRBuilder &B);
/// EmitMemChr - Emit a call to the memchr function. This assumes that Ptr is
/// a pointer, Val is an i32 value, and Len is an 'intptr_t' value.
Value *EmitMemChr(Value *Ptr, Value *Val, Value *Len, IRBuilder &B);
/// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g.
/// 'floor'). This function is known to take a single of type matching 'Op'
/// and returns one value with the same type. If 'Op' is a long double, 'l'
/// is added as the suffix of name, if 'Op' is a float, we add a 'f' suffix.
Value *EmitUnaryFloatFnCall(Value *Op, const char *Name, IRBuilder &B);
/// EmitPutChar - Emit a call to the putchar function. This assumes that Char
/// is an integer.
void EmitPutChar(Value *Char, IRBuilder &B);
/// EmitPutS - Emit a call to the puts function. This assumes that Str is
/// some pointer.
void EmitPutS(Value *Str, IRBuilder &B);
/// EmitFPutC - Emit a call to the fputc function. This assumes that Char is
/// an i32, and File is a pointer to FILE.
void EmitFPutC(Value *Char, Value *File, IRBuilder &B);
/// EmitFPutS - Emit a call to the puts function. Str is required to be a
/// pointer and File is a pointer to FILE.
void EmitFPutS(Value *Str, Value *File, IRBuilder &B);
/// EmitFWrite - Emit a call to the fwrite function. This assumes that Ptr is
/// a pointer, Size is an 'intptr_t', and File is a pointer to FILE.
void EmitFWrite(Value *Ptr, Value *Size, Value *File, IRBuilder &B);
};
} // End anonymous namespace.
/// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*.
Value *LibCallOptimization::CastToCStr(Value *V, IRBuilder &B) {
return B.CreateBitCast(V, PointerType::getUnqual(Type::Int8Ty), "cstr");
}
/// EmitStrLen - Emit a call to the strlen function to the builder, for the
/// specified pointer. This always returns an integer value of size intptr_t.
Value *LibCallOptimization::EmitStrLen(Value *Ptr, IRBuilder &B) {
Module *M = Caller->getParent();
Constant *StrLen =M->getOrInsertFunction("strlen", TD->getIntPtrType(),
PointerType::getUnqual(Type::Int8Ty),
NULL);
return B.CreateCall(StrLen, CastToCStr(Ptr, B), "strlen");
}
/// EmitMemCpy - Emit a call to the memcpy function to the builder. This always
/// expects that the size has type 'intptr_t' and Dst/Src are pointers.
Value *LibCallOptimization::EmitMemCpy(Value *Dst, Value *Src, Value *Len,
unsigned Align, IRBuilder &B) {
Module *M = Caller->getParent();
Intrinsic::ID IID = TD->getIntPtrType() == Type::Int32Ty ?
Intrinsic::memcpy_i32 : Intrinsic::memcpy_i64;
Value *MemCpy = Intrinsic::getDeclaration(M, IID);
return B.CreateCall4(MemCpy, CastToCStr(Dst, B), CastToCStr(Src, B), Len,
ConstantInt::get(Type::Int32Ty, Align));
}
/// EmitMemChr - Emit a call to the memchr function. This assumes that Ptr is
/// a pointer, Val is an i32 value, and Len is an 'intptr_t' value.
Value *LibCallOptimization::EmitMemChr(Value *Ptr, Value *Val,
Value *Len, IRBuilder &B) {
Module *M = Caller->getParent();
Value *MemChr = M->getOrInsertFunction("memchr",
PointerType::getUnqual(Type::Int8Ty),
PointerType::getUnqual(Type::Int8Ty),
Type::Int32Ty, TD->getIntPtrType(),
NULL);
return B.CreateCall3(MemChr, CastToCStr(Ptr, B), Val, Len, "memchr");
}
/// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g.
/// 'floor'). This function is known to take a single of type matching 'Op' and
/// returns one value with the same type. If 'Op' is a long double, 'l' is
/// added as the suffix of name, if 'Op' is a float, we add a 'f' suffix.
Value *LibCallOptimization::EmitUnaryFloatFnCall(Value *Op, const char *Name,
IRBuilder &B) {
char NameBuffer[20];
if (Op->getType() != Type::DoubleTy) {
// If we need to add a suffix, copy into NameBuffer.
unsigned NameLen = strlen(Name);
assert(NameLen < sizeof(NameBuffer)-2);
memcpy(NameBuffer, Name, NameLen);
if (Op->getType() == Type::FloatTy)
NameBuffer[NameLen] = 'f'; // floorf
else
NameBuffer[NameLen] = 'l'; // floorl
NameBuffer[NameLen+1] = 0;
Name = NameBuffer;
}
Module *M = Caller->getParent();
Value *Callee = M->getOrInsertFunction(Name, Op->getType(),
Op->getType(), NULL);
return B.CreateCall(Callee, Op, Name);
}
/// EmitPutChar - Emit a call to the putchar function. This assumes that Char
/// is an integer.
void LibCallOptimization::EmitPutChar(Value *Char, IRBuilder &B) {
Module *M = Caller->getParent();
Value *F = M->getOrInsertFunction("putchar", Type::Int32Ty,
Type::Int32Ty, NULL);
B.CreateCall(F, B.CreateIntCast(Char, Type::Int32Ty, "chari"), "putchar");
}
/// EmitPutS - Emit a call to the puts function. This assumes that Str is
/// some pointer.
void LibCallOptimization::EmitPutS(Value *Str, IRBuilder &B) {
Module *M = Caller->getParent();
Value *F = M->getOrInsertFunction("puts", Type::Int32Ty,
PointerType::getUnqual(Type::Int8Ty), NULL);
B.CreateCall(F, CastToCStr(Str, B), "puts");
}
/// EmitFPutC - Emit a call to the fputc function. This assumes that Char is
/// an integer and File is a pointer to FILE.
void LibCallOptimization::EmitFPutC(Value *Char, Value *File, IRBuilder &B) {
Module *M = Caller->getParent();
Constant *F = M->getOrInsertFunction("fputc", Type::Int32Ty, Type::Int32Ty,
File->getType(), NULL);
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