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llvm-6502/lib/Transforms/Scalar/SimplifyLibCalls.cpp
Nick Lewycky 6cd0c048b8 Move the libcall annotating part from doFinalization to doInitialization. 
Finalization occurs after all the FunctionPasses in the group have run, which
is clearly not what we want.

This also means that we have to make sure that we apply the right param 
attributes when creating a new function.

Also, add a missed optimization: strdup and strndup. NoCapture and 
NoAlias return!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61658 91177308-0d34-0410-b5e6-96231b3b80d8
2009-01-05 00:07:50 +00:00

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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/Analysis/ValueTracking.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"
#include "llvm/Support/Debug.h"
#include "llvm/Config/config.h"
using namespace llvm;
STATISTIC(NumSimplified, "Number of library calls simplified");
STATISTIC(NumAnnotated, "Number of attributes added to library functions");
//===----------------------------------------------------------------------===//
// 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);
/// EmitMemCmp - Emit a call to the memcmp function.
Value *EmitMemCmp(Value *Ptr1, Value *Ptr2, 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();
AttributeWithIndex AWI[2];
AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(~0u, Attribute::ReadOnly |
Attribute::NoUnwind);
Constant *StrLen =M->getOrInsertFunction("strlen", AttrListPtr::get(AWI, 2),
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 = Intrinsic::memcpy;
const Type *Tys[1];
Tys[0] = Len->getType();
Value *MemCpy = Intrinsic::getDeclaration(M, IID, Tys, 1);
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();
AttributeWithIndex AWI;
AWI = AttributeWithIndex::get(~0u, Attribute::ReadOnly | Attribute::NoUnwind);
Value *MemChr = M->getOrInsertFunction("memchr", AttrListPtr::get(&AWI, 1),
PointerType::getUnqual(Type::Int8Ty),
PointerType::getUnqual(Type::Int8Ty),
Type::Int32Ty, TD->getIntPtrType(),
NULL);
return B.CreateCall3(MemChr, CastToCStr(Ptr, B), Val, Len, "memchr");
}
/// EmitMemCmp - Emit a call to the memcmp function.
Value *LibCallOptimization::EmitMemCmp(Value *Ptr1, Value *Ptr2,
Value *Len, IRBuilder<> &B) {
Module *M = Caller->getParent();
AttributeWithIndex AWI[3];
AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(2, Attribute::NoCapture);
AWI[2] = AttributeWithIndex::get(~0u, Attribute::ReadOnly |
Attribute::NoUnwind);
Value *MemCmp = M->getOrInsertFunction("memcmp", AttrListPtr::get(AWI, 3),
Type::Int32Ty,
PointerType::getUnqual(Type::Int8Ty),
PointerType::getUnqual(Type::Int8Ty),
TD->getIntPtrType(), NULL);
return B.CreateCall3(MemCmp, CastToCStr(Ptr1, B), CastToCStr(Ptr2, B),
Len, "memcmp");
}
/// 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();
AttributeWithIndex AWI[2];
AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
Value *F = M->getOrInsertFunction("puts", AttrListPtr::get(AWI, 2),
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();
AttributeWithIndex AWI[2];
AWI[0] = AttributeWithIndex::get(2, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
Constant *F;
if (isa<PointerType>(File->getType()))
F = M->getOrInsertFunction("fputc", AttrListPtr::get(AWI, 2), Type::Int32Ty,
Type::Int32Ty, File->getType(), NULL);
else
F = M->getOrInsertFunction("fputc", Type::Int32Ty, Type::Int32Ty,
File->getType(), NULL);
Char = B.CreateIntCast(Char, Type::Int32Ty, "chari");
B.CreateCall2(F, Char, File, "fputc");
}
/// EmitFPutS - Emit a call to the puts function. Str is required to be a
/// pointer and File is a pointer to FILE.
void LibCallOptimization::EmitFPutS(Value *Str, Value *File, IRBuilder<> &B) {
Module *M = Caller->getParent();
AttributeWithIndex AWI[2];
AWI[0] = AttributeWithIndex::get(2, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
Constant *F;
if (isa<PointerType>(File->getType()))
F = M->getOrInsertFunction("fputs", AttrListPtr::get(AWI, 2), Type::Int32Ty,
PointerType::getUnqual(Type::Int8Ty),
File->getType(), NULL);
else
F = M->getOrInsertFunction("fputs", Type::Int32Ty,
PointerType::getUnqual(Type::Int8Ty),
File->getType(), NULL);
B.CreateCall2(F, CastToCStr(Str, B), File, "fputs");
}
/// 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 LibCallOptimization::EmitFWrite(Value *Ptr, Value *Size, Value *File,
IRBuilder<> &B) {
Module *M = Caller->getParent();
AttributeWithIndex AWI[3];
AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(4, Attribute::NoCapture);
AWI[2] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
Constant *F;
if (isa<PointerType>(File->getType()))
F = M->getOrInsertFunction("fwrite", AttrListPtr::get(AWI, 3),
TD->getIntPtrType(),
PointerType::getUnqual(Type::Int8Ty),
TD->getIntPtrType(), TD->getIntPtrType(),
File->getType(), NULL);
else
F = M->getOrInsertFunction("fwrite", TD->getIntPtrType(),
PointerType::getUnqual(Type::Int8Ty),
TD->getIntPtrType(), TD->getIntPtrType(),
File->getType(), NULL);
B.CreateCall4(F, CastToCStr(Ptr, B), Size,
ConstantInt::get(TD->getIntPtrType(), 1), File);
}
//===----------------------------------------------------------------------===//
// Helper Functions
//===----------------------------------------------------------------------===//
/// GetStringLengthH - If we can compute the length of the string pointed to by
/// the specified pointer, return 'len+1'. If we can't, return 0.
static uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) {
// Look through noop bitcast instructions.
if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
return GetStringLengthH(BCI->getOperand(0), PHIs);
// If this is a PHI node, there are two cases: either we have already seen it
// or we haven't.
if (PHINode *PN = dyn_cast<PHINode>(V)) {
if (!PHIs.insert(PN))
return ~0ULL; // already in the set.
// If it was new, see if all the input strings are the same length.
uint64_t LenSoFar = ~0ULL;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs);
if (Len == 0) return 0; // Unknown length -> unknown.
if (Len == ~0ULL) continue;
if (Len != LenSoFar && LenSoFar != ~0ULL)
return 0; // Disagree -> unknown.
LenSoFar = Len;
}
// Success, all agree.
return LenSoFar;
}
// strlen(select(c,x,y)) -> strlen(x) ^ strlen(y)
if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs);
if (Len1 == 0) return 0;
uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs);
if (Len2 == 0) return 0;
if (Len1 == ~0ULL) return Len2;
if (Len2 == ~0ULL) return Len1;
if (Len1 != Len2) return 0;
return Len1;
}
// If the value is not a GEP instruction nor a constant expression with a
// GEP instruction, then return unknown.
User *GEP = 0;
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
GEP = GEPI;
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() != Instruction::GetElementPtr)
return 0;
GEP = CE;
} else {
return 0;
}
// Make sure the GEP has exactly three arguments.
if (GEP->getNumOperands() != 3)
return 0;
// Check to make sure that the first operand of the GEP is an integer and
// has value 0 so that we are sure we're indexing into the initializer.
if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
if (!Idx->isZero())
return 0;
} else
return 0;
// If the second index isn't a ConstantInt, then this is a variable index
// into the array. If this occurs, we can't say anything meaningful about
// the string.
uint64_t StartIdx = 0;
if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
StartIdx = CI->getZExtValue();
else
return 0;
// The GEP instruction, constant or instruction, must reference a global
// variable that is a constant and is initialized. The referenced constant
// initializer is the array that we'll use for optimization.
GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
if (!GV || !GV->isConstant() || !GV->hasInitializer())
return 0;
Constant *GlobalInit = GV->getInitializer();
// Handle the ConstantAggregateZero case, which is a degenerate case. The
// initializer is constant zero so the length of the string must be zero.
if (isa<ConstantAggregateZero>(GlobalInit))
return 1; // Len = 0 offset by 1.
// Must be a Constant Array
ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
if (!Array || Array->getType()->getElementType() != Type::Int8Ty)
return false;
// Get the number of elements in the array
uint64_t NumElts = Array->getType()->getNumElements();
// Traverse the constant array from StartIdx (derived above) which is
// the place the GEP refers to in the array.
for (unsigned i = StartIdx; i != NumElts; ++i) {
Constant *Elt = Array->getOperand(i);
ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
if (!CI) // This array isn't suitable, non-int initializer.
return 0;
if (CI->isZero())
return i-StartIdx+1; // We found end of string, success!
}
return 0; // The array isn't null terminated, conservatively return 'unknown'.
}
/// GetStringLength - If we can compute the length of the string pointed to by
/// the specified pointer, return 'len+1'. If we can't, return 0.
static uint64_t GetStringLength(Value *V) {
if (!isa<PointerType>(V->getType())) return 0;
SmallPtrSet<PHINode*, 32> PHIs;
uint64_t Len = GetStringLengthH(V, PHIs);
// If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return
// an empty string as a length.
return Len == ~0ULL ? 1 : Len;
}
/// IsOnlyUsedInZeroEqualityComparison - Return true if it only matters that the
/// value is equal or not-equal to zero.
static bool IsOnlyUsedInZeroEqualityComparison(Value *V) {
for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
UI != E; ++UI) {
if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
if (IC->isEquality())
if (Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
if (C->isNullValue())
continue;
// Unknown instruction.
return false;
}
return true;
}
//===----------------------------------------------------------------------===//
// Miscellaneous LibCall Optimizations
//===----------------------------------------------------------------------===//
namespace {
//===---------------------------------------===//
// 'exit' Optimizations
/// ExitOpt - int main() { exit(4); } --> int main() { return 4; }
struct VISIBILITY_HIDDEN ExitOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify we have a reasonable prototype for exit.
if (Callee->arg_size() == 0 || !CI->use_empty())
return 0;
// Verify the caller is main, and that the result type of main matches the
// argument type of exit.
if (!Caller->isName("main") || !Caller->hasExternalLinkage() ||
Caller->getReturnType() != CI->getOperand(1)->getType())
return 0;
TerminatorInst *OldTI = CI->getParent()->getTerminator();
// Create the return after the call.
ReturnInst *RI = B.CreateRet(CI->getOperand(1));
// Drop all successor phi node entries.
for (unsigned i = 0, e = OldTI->getNumSuccessors(); i != e; ++i)
OldTI->getSuccessor(i)->removePredecessor(CI->getParent());
// Erase all instructions from after our return instruction until the end of
// the block.
BasicBlock::iterator FirstDead = RI; ++FirstDead;
CI->getParent()->getInstList().erase(FirstDead, CI->getParent()->end());
return CI;
}
};
//===----------------------------------------------------------------------===//
// String and Memory LibCall Optimizations
//===----------------------------------------------------------------------===//
//===---------------------------------------===//
// 'strcat' Optimizations
struct VISIBILITY_HIDDEN StrCatOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify the "strcat" function prototype.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 ||
FT->getReturnType() != PointerType::getUnqual(Type::Int8Ty) ||
FT->getParamType(0) != FT->getReturnType() ||
FT->getParamType(1) != FT->getReturnType())
return 0;
// Extract some information from the instruction
Value *Dst = CI->getOperand(1);
Value *Src = CI->getOperand(2);
// See if we can get the length of the input string.
uint64_t Len = GetStringLength(Src);
if (Len == 0) return 0;
--Len; // Unbias length.
// Handle the simple, do-nothing case: strcat(x, "") -> x
if (Len == 0)
return Dst;
// We need to find the end of the destination string. That's where the
// memory is to be moved to. We just generate a call to strlen.
Value *DstLen = EmitStrLen(Dst, B);
// Now that we have the destination's length, we must index into the
// destination's pointer to get the actual memcpy destination (end of
// the string .. we're concatenating).
Dst = B.CreateGEP(Dst, DstLen, "endptr");
// We have enough information to now generate the memcpy call to do the
// concatenation for us. Make a memcpy to copy the nul byte with align = 1.
EmitMemCpy(Dst, Src, ConstantInt::get(TD->getIntPtrType(), Len+1), 1, B);
return Dst;
}
};
//===---------------------------------------===//
// 'strchr' Optimizations
struct VISIBILITY_HIDDEN StrChrOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify the "strchr" function prototype.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 ||
FT->getReturnType() != PointerType::getUnqual(Type::Int8Ty) ||
FT->getParamType(0) != FT->getReturnType())
return 0;
Value *SrcStr = CI->getOperand(1);
// If the second operand is non-constant, see if we can compute the length
// of the input string and turn this into memchr.
ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getOperand(2));
if (CharC == 0) {
uint64_t Len = GetStringLength(SrcStr);
if (Len == 0 || FT->getParamType(1) != Type::Int32Ty) // memchr needs i32.
return 0;
return EmitMemChr(SrcStr, CI->getOperand(2), // include nul.
ConstantInt::get(TD->getIntPtrType(), Len), B);
}
// Otherwise, the character is a constant, see if the first argument is
// a string literal. If so, we can constant fold.
std::string Str;
if (!GetConstantStringInfo(SrcStr, Str))
return 0;
// strchr can find the nul character.
Str += '\0';
char CharValue = CharC->getSExtValue();
// Compute the offset.
uint64_t i = 0;
while (1) {
if (i == Str.size()) // Didn't find the char. strchr returns null.
return Constant::getNullValue(CI->getType());
// Did we find our match?
if (Str[i] == CharValue)
break;
++i;
}
// strchr(s+n,c) -> gep(s+n+i,c)
Value *Idx = ConstantInt::get(Type::Int64Ty, i);
return B.CreateGEP(SrcStr, Idx, "strchr");
}
};
//===---------------------------------------===//
// 'strcmp' Optimizations
struct VISIBILITY_HIDDEN StrCmpOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify the "strcmp" function prototype.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 || FT->getReturnType() != Type::Int32Ty ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty))
return 0;
Value *Str1P = CI->getOperand(1), *Str2P = CI->getOperand(2);
if (Str1P == Str2P) // strcmp(x,x) -> 0
return ConstantInt::get(CI->getType(), 0);
std::string Str1, Str2;
bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
if (HasStr1 && Str1.empty()) // strcmp("", x) -> *x
return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
if (HasStr2 && Str2.empty()) // strcmp(x,"") -> *x
return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
// strcmp(x, y) -> cnst (if both x and y are constant strings)
if (HasStr1 && HasStr2)
return ConstantInt::get(CI->getType(), strcmp(Str1.c_str(),Str2.c_str()));
// strcmp(P, "x") -> memcmp(P, "x", 2)
uint64_t Len1 = GetStringLength(Str1P);
uint64_t Len2 = GetStringLength(Str2P);
if (Len1 || Len2) {
// Choose the smallest Len excluding 0 which means 'unknown'.
if (!Len1 || (Len2 && Len2 < Len1))
Len1 = Len2;
return EmitMemCmp(Str1P, Str2P,
ConstantInt::get(TD->getIntPtrType(), Len1), B);
}
return 0;
}
};
//===---------------------------------------===//
// 'strncmp' Optimizations
struct VISIBILITY_HIDDEN StrNCmpOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify the "strncmp" function prototype.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != Type::Int32Ty ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty) ||
!isa<IntegerType>(FT->getParamType(2)))
return 0;
Value *Str1P = CI->getOperand(1), *Str2P = CI->getOperand(2);
if (Str1P == Str2P) // strncmp(x,x,n) -> 0
return ConstantInt::get(CI->getType(), 0);
// Get the length argument if it is constant.
uint64_t Length;
if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getOperand(3)))
Length = LengthArg->getZExtValue();
else
return 0;
if (Length == 0) // strncmp(x,y,0) -> 0
return ConstantInt::get(CI->getType(), 0);
std::string Str1, Str2;
bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
if (HasStr1 && Str1.empty()) // strncmp("", x, n) -> *x
return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
if (HasStr2 && Str2.empty()) // strncmp(x, "", n) -> *x
return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
// strncmp(x, y) -> cnst (if both x and y are constant strings)
if (HasStr1 && HasStr2)
return ConstantInt::get(CI->getType(),
strncmp(Str1.c_str(), Str2.c_str(), Length));
return 0;
}
};
//===---------------------------------------===//
// 'strcpy' Optimizations
struct VISIBILITY_HIDDEN StrCpyOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify the "strcpy" function prototype.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty))
return 0;
Value *Dst = CI->getOperand(1), *Src = CI->getOperand(2);
if (Dst == Src) // strcpy(x,x) -> x
return Src;
// See if we can get the length of the input string.
uint64_t Len = GetStringLength(Src);
if (Len == 0) return 0;
// We have enough information to now generate the memcpy call to do the
// concatenation for us. Make a memcpy to copy the nul byte with align = 1.
EmitMemCpy(Dst, Src, ConstantInt::get(TD->getIntPtrType(), Len), 1, B);
return Dst;
}
};
//===---------------------------------------===//
// 'strlen' Optimizations
struct VISIBILITY_HIDDEN StrLenOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 1 ||
FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty) ||
!isa<IntegerType>(FT->getReturnType()))
return 0;
Value *Src = CI->getOperand(1);
// Constant folding: strlen("xyz") -> 3
if (uint64_t Len = GetStringLength(Src))
return ConstantInt::get(CI->getType(), Len-1);
// Handle strlen(p) != 0.
if (!IsOnlyUsedInZeroEqualityComparison(CI)) return 0;
// strlen(x) != 0 --> *x != 0
// strlen(x) == 0 --> *x == 0
return B.CreateZExt(B.CreateLoad(Src, "strlenfirst"), CI->getType());
}
};
//===---------------------------------------===//
// 'memcmp' Optimizations
struct VISIBILITY_HIDDEN MemCmpOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || !isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
FT->getReturnType() != Type::Int32Ty)
return 0;
Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2);
if (LHS == RHS) // memcmp(s,s,x) -> 0
return Constant::getNullValue(CI->getType());
// Make sure we have a constant length.
ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
if (!LenC) return 0;
uint64_t Len = LenC->getZExtValue();
if (Len == 0) // memcmp(s1,s2,0) -> 0
return Constant::getNullValue(CI->getType());
if (Len == 1) { // memcmp(S1,S2,1) -> *LHS - *RHS
Value *LHSV = B.CreateLoad(CastToCStr(LHS, B), "lhsv");
Value *RHSV = B.CreateLoad(CastToCStr(RHS, B), "rhsv");
return B.CreateZExt(B.CreateSub(LHSV, RHSV, "chardiff"), CI->getType());
}
// memcmp(S1,S2,2) != 0 -> (*(short*)LHS ^ *(short*)RHS) != 0
// memcmp(S1,S2,4) != 0 -> (*(int*)LHS ^ *(int*)RHS) != 0
if ((Len == 2 || Len == 4) && IsOnlyUsedInZeroEqualityComparison(CI)) {
const Type *PTy = PointerType::getUnqual(Len == 2 ?
Type::Int16Ty : Type::Int32Ty);
LHS = B.CreateBitCast(LHS, PTy, "tmp");
RHS = B.CreateBitCast(RHS, PTy, "tmp");
LoadInst *LHSV = B.CreateLoad(LHS, "lhsv");
LoadInst *RHSV = B.CreateLoad(RHS, "rhsv");
LHSV->setAlignment(1); RHSV->setAlignment(1); // Unaligned loads.
return B.CreateZExt(B.CreateXor(LHSV, RHSV, "shortdiff"), CI->getType());
}
return 0;
}
};
//===---------------------------------------===//
// 'memcpy' Optimizations
struct VISIBILITY_HIDDEN MemCpyOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
!isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
FT->getParamType(2) != TD->getIntPtrType())
return 0;
// memcpy(x, y, n) -> llvm.memcpy(x, y, n, 1)
EmitMemCpy(CI->getOperand(1), CI->getOperand(2), CI->getOperand(3), 1, B);
return CI->getOperand(1);
}
};
//===---------------------------------------===//
// 'memmove' Optimizations
struct VISIBILITY_HIDDEN MemMoveOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
!isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
FT->getParamType(2) != TD->getIntPtrType())
return 0;
// memmove(x, y, n) -> llvm.memmove(x, y, n, 1)
Module *M = Caller->getParent();
Intrinsic::ID IID = Intrinsic::memmove;
const Type *Tys[1];
Tys[0] = TD->getIntPtrType();
Value *MemMove = Intrinsic::getDeclaration(M, IID, Tys, 1);
Value *Dst = CastToCStr(CI->getOperand(1), B);
Value *Src = CastToCStr(CI->getOperand(2), B);
Value *Size = CI->getOperand(3);
Value *Align = ConstantInt::get(Type::Int32Ty, 1);
B.CreateCall4(MemMove, Dst, Src, Size, Align);
return CI->getOperand(1);
}
};
//===---------------------------------------===//
// 'memset' Optimizations
struct VISIBILITY_HIDDEN MemSetOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
!isa<PointerType>(FT->getParamType(0)) ||
FT->getParamType(1) != TD->getIntPtrType() ||
FT->getParamType(2) != TD->getIntPtrType())
return 0;
// memset(p, v, n) -> llvm.memset(p, v, n, 1)
Module *M = Caller->getParent();
Intrinsic::ID IID = Intrinsic::memset;
const Type *Tys[1];
Tys[0] = TD->getIntPtrType();
Value *MemSet = Intrinsic::getDeclaration(M, IID, Tys, 1);
Value *Dst = CastToCStr(CI->getOperand(1), B);
Value *Val = B.CreateTrunc(CI->getOperand(2), Type::Int8Ty);
Value *Size = CI->getOperand(3);
Value *Align = ConstantInt::get(Type::Int32Ty, 1);
B.CreateCall4(MemSet, Dst, Val, Size, Align);
return CI->getOperand(1);
}
};
//===----------------------------------------------------------------------===//
// Math Library Optimizations
//===----------------------------------------------------------------------===//
//===---------------------------------------===//
// 'pow*' Optimizations
struct VISIBILITY_HIDDEN PowOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// Just make sure this has 2 arguments of the same FP type, which match the
// result type.
if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
!FT->getParamType(0)->isFloatingPoint())
return 0;
Value *Op1 = CI->getOperand(1), *Op2 = CI->getOperand(2);
if (ConstantFP *Op1C = dyn_cast<ConstantFP>(Op1)) {
if (Op1C->isExactlyValue(1.0)) // pow(1.0, x) -> 1.0
return Op1C;
if (Op1C->isExactlyValue(2.0)) // pow(2.0, x) -> exp2(x)
return EmitUnaryFloatFnCall(Op2, "exp2", B);
}
ConstantFP *Op2C = dyn_cast<ConstantFP>(Op2);
if (Op2C == 0) return 0;
if (Op2C->getValueAPF().isZero()) // pow(x, 0.0) -> 1.0
return ConstantFP::get(CI->getType(), 1.0);
if (Op2C->isExactlyValue(0.5)) {
// FIXME: This is not safe for -0.0 and -inf. This can only be done when
// 'unsafe' math optimizations are allowed.
// x pow(x, 0.5) sqrt(x)
// ---------------------------------------------
// -0.0 +0.0 -0.0
// -inf +inf NaN
#if 0
// pow(x, 0.5) -> sqrt(x)
return B.CreateCall(get_sqrt(), Op1, "sqrt");
#endif
}
if (Op2C->isExactlyValue(1.0)) // pow(x, 1.0) -> x
return Op1;
if (Op2C->isExactlyValue(2.0)) // pow(x, 2.0) -> x*x
return B.CreateMul(Op1, Op1, "pow2");
if (Op2C->isExactlyValue(-1.0)) // pow(x, -1.0) -> 1.0/x
return B.CreateFDiv(ConstantFP::get(CI->getType(), 1.0), Op1, "powrecip");
return 0;
}
};
//===---------------------------------------===//
// 'exp2' Optimizations
struct VISIBILITY_HIDDEN Exp2Opt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// Just make sure this has 1 argument of FP type, which matches the
// result type.
if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
!FT->getParamType(0)->isFloatingPoint())
return 0;
Value *Op = CI->getOperand(1);
// Turn exp2(sitofp(x)) -> ldexp(1.0, sext(x)) if sizeof(x) <= 32
// Turn exp2(uitofp(x)) -> ldexp(1.0, zext(x)) if sizeof(x) < 32
Value *LdExpArg = 0;
if (SIToFPInst *OpC = dyn_cast<SIToFPInst>(Op)) {
if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() <= 32)
LdExpArg = B.CreateSExt(OpC->getOperand(0), Type::Int32Ty, "tmp");
} else if (UIToFPInst *OpC = dyn_cast<UIToFPInst>(Op)) {
if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() < 32)
LdExpArg = B.CreateZExt(OpC->getOperand(0), Type::Int32Ty, "tmp");
}
if (LdExpArg) {
const char *Name;
if (Op->getType() == Type::FloatTy)
Name = "ldexpf";
else if (Op->getType() == Type::DoubleTy)
Name = "ldexp";
else
Name = "ldexpl";
Constant *One = ConstantFP::get(APFloat(1.0f));
if (Op->getType() != Type::FloatTy)
One = ConstantExpr::getFPExtend(One, Op->getType());
Module *M = Caller->getParent();
Value *Callee = M->getOrInsertFunction(Name, Op->getType(),
Op->getType(), Type::Int32Ty,NULL);
return B.CreateCall2(Callee, One, LdExpArg);
}
return 0;
}
};
//===---------------------------------------===//
// Double -> Float Shrinking Optimizations for Unary Functions like 'floor'
struct VISIBILITY_HIDDEN UnaryDoubleFPOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 1 || FT->getReturnType() != Type::DoubleTy ||
FT->getParamType(0) != Type::DoubleTy)
return 0;
// If this is something like 'floor((double)floatval)', convert to floorf.
FPExtInst *Cast = dyn_cast<FPExtInst>(CI->getOperand(1));
if (Cast == 0 || Cast->getOperand(0)->getType() != Type::FloatTy)
return 0;
// floor((double)floatval) -> (double)floorf(floatval)
Value *V = Cast->getOperand(0);
V = EmitUnaryFloatFnCall(V, Callee->getNameStart(), B);
return B.CreateFPExt(V, Type::DoubleTy);
}
};
//===----------------------------------------------------------------------===//
// Integer Optimizations
//===----------------------------------------------------------------------===//
//===---------------------------------------===//
// 'ffs*' Optimizations
struct VISIBILITY_HIDDEN FFSOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// Just make sure this has 2 arguments of the same FP type, which match the
// result type.
if (FT->getNumParams() != 1 || FT->getReturnType() != Type::Int32Ty ||
!isa<IntegerType>(FT->getParamType(0)))
return 0;
Value *Op = CI->getOperand(1);
// Constant fold.
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op)) {
if (CI->getValue() == 0) // ffs(0) -> 0.
return Constant::getNullValue(CI->getType());
return ConstantInt::get(Type::Int32Ty, // ffs(c) -> cttz(c)+1
CI->getValue().countTrailingZeros()+1);
}
// ffs(x) -> x != 0 ? (i32)llvm.cttz(x)+1 : 0
const Type *ArgType = Op->getType();
Value *F = Intrinsic::getDeclaration(Callee->getParent(),
Intrinsic::cttz, &ArgType, 1);
Value *V = B.CreateCall(F, Op, "cttz");
V = B.CreateAdd(V, ConstantInt::get(Type::Int32Ty, 1), "tmp");
V = B.CreateIntCast(V, Type::Int32Ty, false, "tmp");
Value *Cond = B.CreateICmpNE(Op, Constant::getNullValue(ArgType), "tmp");
return B.CreateSelect(Cond, V, ConstantInt::get(Type::Int32Ty, 0));
}
};
//===---------------------------------------===//
// 'isdigit' Optimizations
struct VISIBILITY_HIDDEN IsDigitOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// We require integer(i32)
if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) ||
FT->getParamType(0) != Type::Int32Ty)
return 0;
// isdigit(c) -> (c-'0') <u 10
Value *Op = CI->getOperand(1);
Op = B.CreateSub(Op, ConstantInt::get(Type::Int32Ty, '0'), "isdigittmp");
Op = B.CreateICmpULT(Op, ConstantInt::get(Type::Int32Ty, 10), "isdigit");
return B.CreateZExt(Op, CI->getType());
}
};
//===---------------------------------------===//
// 'isascii' Optimizations
struct VISIBILITY_HIDDEN IsAsciiOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// We require integer(i32)
if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) ||
FT->getParamType(0) != Type::Int32Ty)
return 0;
// isascii(c) -> c <u 128
Value *Op = CI->getOperand(1);
Op = B.CreateICmpULT(Op, ConstantInt::get(Type::Int32Ty, 128), "isascii");
return B.CreateZExt(Op, CI->getType());
}
};
//===---------------------------------------===//
// 'abs', 'labs', 'llabs' Optimizations
struct VISIBILITY_HIDDEN AbsOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// We require integer(integer) where the types agree.
if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) ||
FT->getParamType(0) != FT->getReturnType())
return 0;
// abs(x) -> x >s -1 ? x : -x
Value *Op = CI->getOperand(1);
Value *Pos = B.CreateICmpSGT(Op,ConstantInt::getAllOnesValue(Op->getType()),
"ispos");
Value *Neg = B.CreateNeg(Op, "neg");
return B.CreateSelect(Pos, Op, Neg);
}
};
//===---------------------------------------===//
// 'toascii' Optimizations
struct VISIBILITY_HIDDEN ToAsciiOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// We require i32(i32)
if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != Type::Int32Ty)
return 0;
// isascii(c) -> c & 0x7f
return B.CreateAnd(CI->getOperand(1), ConstantInt::get(CI->getType(),0x7F));
}
};
//===----------------------------------------------------------------------===//
// Formatting and IO Optimizations
//===----------------------------------------------------------------------===//
//===---------------------------------------===//
// 'printf' Optimizations
struct VISIBILITY_HIDDEN PrintFOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Require one fixed pointer argument and an integer/void result.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() < 1 || !isa<PointerType>(FT->getParamType(0)) ||
!(isa<IntegerType>(FT->getReturnType()) ||
FT->getReturnType() == Type::VoidTy))
return 0;
// Check for a fixed format string.
std::string FormatStr;
if (!GetConstantStringInfo(CI->getOperand(1), FormatStr))
return 0;
// Empty format string -> noop.
if (FormatStr.empty()) // Tolerate printf's declared void.
return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 0);
// printf("x") -> putchar('x'), even for '%'.
if (FormatStr.size() == 1) {
EmitPutChar(ConstantInt::get(Type::Int32Ty, FormatStr[0]), B);
return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 1);
}
// printf("foo\n") --> puts("foo")
if (FormatStr[FormatStr.size()-1] == '\n' &&
FormatStr.find('%') == std::string::npos) { // no format characters.
// Create a string literal with no \n on it. We expect the constant merge
// pass to be run after this pass, to merge duplicate strings.
FormatStr.erase(FormatStr.end()-1);
Constant *C = ConstantArray::get(FormatStr, true);
C = new GlobalVariable(C->getType(), true,GlobalVariable::InternalLinkage,
C, "str", Callee->getParent());
EmitPutS(C, B);
return CI->use_empty() ? (Value*)CI :
ConstantInt::get(CI->getType(), FormatStr.size()+1);
}
// Optimize specific format strings.
// printf("%c", chr) --> putchar(*(i8*)dst)
if (FormatStr == "%c" && CI->getNumOperands() > 2 &&
isa<IntegerType>(CI->getOperand(2)->getType())) {
EmitPutChar(CI->getOperand(2), B);
return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 1);
}
// printf("%s\n", str) --> puts(str)
if (FormatStr == "%s\n" && CI->getNumOperands() > 2 &&
isa<PointerType>(CI->getOperand(2)->getType()) &&
CI->use_empty()) {
EmitPutS(CI->getOperand(2), B);
return CI;
}
return 0;
}
};
//===---------------------------------------===//
// 'sprintf' Optimizations
struct VISIBILITY_HIDDEN SPrintFOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Require two fixed pointer arguments and an integer result.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
!isa<IntegerType>(FT->getReturnType()))
return 0;
// Check for a fixed format string.
std::string FormatStr;
if (!GetConstantStringInfo(CI->getOperand(2), FormatStr))
return 0;
// If we just have a format string (nothing else crazy) transform it.
if (CI->getNumOperands() == 3) {
// Make sure there's no % in the constant array. We could try to handle
// %% -> % in the future if we cared.
for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
if (FormatStr[i] == '%')
return 0; // we found a format specifier, bail out.
// sprintf(str, fmt) -> llvm.memcpy(str, fmt, strlen(fmt)+1, 1)
EmitMemCpy(CI->getOperand(1), CI->getOperand(2), // Copy the nul byte.
ConstantInt::get(TD->getIntPtrType(), FormatStr.size()+1),1,B);
return ConstantInt::get(CI->getType(), FormatStr.size());
}
// The remaining optimizations require the format string to be "%s" or "%c"
// and have an extra operand.
if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->getNumOperands() <4)
return 0;
// Decode the second character of the format string.
if (FormatStr[1] == 'c') {
// sprintf(dst, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0
if (!isa<IntegerType>(CI->getOperand(3)->getType())) return 0;
Value *V = B.CreateTrunc(CI->getOperand(3), Type::Int8Ty, "char");
Value *Ptr = CastToCStr(CI->getOperand(1), B);
B.CreateStore(V, Ptr);
Ptr = B.CreateGEP(Ptr, ConstantInt::get(Type::Int32Ty, 1), "nul");
B.CreateStore(Constant::getNullValue(Type::Int8Ty), Ptr);
return ConstantInt::get(CI->getType(), 1);
}
if (FormatStr[1] == 's') {
// sprintf(dest, "%s", str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
if (!isa<PointerType>(CI->getOperand(3)->getType())) return 0;
Value *Len = EmitStrLen(CI->getOperand(3), B);
Value *IncLen = B.CreateAdd(Len, ConstantInt::get(Len->getType(), 1),
"leninc");
EmitMemCpy(CI->getOperand(1), CI->getOperand(3), IncLen, 1, B);
// The sprintf result is the unincremented number of bytes in the string.
return B.CreateIntCast(Len, CI->getType(), false);
}
return 0;
}
};
//===---------------------------------------===//
// 'fwrite' Optimizations
struct VISIBILITY_HIDDEN FWriteOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Require a pointer, an integer, an integer, a pointer, returning integer.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 4 || !isa<PointerType>(FT->getParamType(0)) ||
!isa<IntegerType>(FT->getParamType(1)) ||
!isa<IntegerType>(FT->getParamType(2)) ||
!isa<PointerType>(FT->getParamType(3)) ||
!isa<IntegerType>(FT->getReturnType()))
return 0;
// Get the element size and count.
ConstantInt *SizeC = dyn_cast<ConstantInt>(CI->getOperand(2));
ConstantInt *CountC = dyn_cast<ConstantInt>(CI->getOperand(3));
if (!SizeC || !CountC) return 0;
uint64_t Bytes = SizeC->getZExtValue()*CountC->getZExtValue();
// If this is writing zero records, remove the call (it's a noop).
if (Bytes == 0)
return ConstantInt::get(CI->getType(), 0);
// If this is writing one byte, turn it into fputc.
if (Bytes == 1) { // fwrite(S,1,1,F) -> fputc(S[0],F)
Value *Char = B.CreateLoad(CastToCStr(CI->getOperand(1), B), "char");
EmitFPutC(Char, CI->getOperand(4), B);
return ConstantInt::get(CI->getType(), 1);
}
return 0;
}
};
//===---------------------------------------===//
// 'fputs' Optimizations
struct VISIBILITY_HIDDEN FPutsOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Require two pointers. Also, we can't optimize if return value is used.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
!CI->use_empty())
return 0;
// fputs(s,F) --> fwrite(s,1,strlen(s),F)
uint64_t Len = GetStringLength(CI->getOperand(1));
if (!Len) return 0;
EmitFWrite(CI->getOperand(1), ConstantInt::get(TD->getIntPtrType(), Len-1),
CI->getOperand(2), B);
return CI; // Known to have no uses (see above).
}
};
//===---------------------------------------===//
// 'fprintf' Optimizations
struct VISIBILITY_HIDDEN FPrintFOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Require two fixed paramters as pointers and integer result.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
!isa<IntegerType>(FT->getReturnType()))
return 0;
// All the optimizations depend on the format string.
std::string FormatStr;
if (!GetConstantStringInfo(CI->getOperand(2), FormatStr))
return 0;
// fprintf(F, "foo") --> fwrite("foo", 3, 1, F)
if (CI->getNumOperands() == 3) {
for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
if (FormatStr[i] == '%') // Could handle %% -> % if we cared.
return 0; // We found a format specifier.
EmitFWrite(CI->getOperand(2), ConstantInt::get(TD->getIntPtrType(),
FormatStr.size()),
CI->getOperand(1), B);
return ConstantInt::get(CI->getType(), FormatStr.size());
}
// The remaining optimizations require the format string to be "%s" or "%c"
// and have an extra operand.
if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->getNumOperands() <4)
return 0;
// Decode the second character of the format string.
if (FormatStr[1] == 'c') {
// fprintf(F, "%c", chr) --> *(i8*)dst = chr
if (!isa<IntegerType>(CI->getOperand(3)->getType())) return 0;
EmitFPutC(CI->getOperand(3), CI->getOperand(1), B);
return ConstantInt::get(CI->getType(), 1);
}
if (FormatStr[1] == 's') {
// fprintf(F, "%s", str) -> fputs(str, F)
if (!isa<PointerType>(CI->getOperand(3)->getType()) || !CI->use_empty())
return 0;
EmitFPutS(CI->getOperand(3), CI->getOperand(1), B);
return CI;
}
return 0;
}
};
} // end anonymous namespace.
//===----------------------------------------------------------------------===//
// SimplifyLibCalls Pass Implementation
//===----------------------------------------------------------------------===//
namespace {
/// This pass optimizes well known library functions from libc and libm.
///
class VISIBILITY_HIDDEN SimplifyLibCalls : public FunctionPass {
StringMap<LibCallOptimization*> Optimizations;
// Miscellaneous LibCall Optimizations
ExitOpt Exit;
// String and Memory LibCall Optimizations
StrCatOpt StrCat; StrChrOpt StrChr; StrCmpOpt StrCmp; StrNCmpOpt StrNCmp;
StrCpyOpt StrCpy; StrLenOpt StrLen; MemCmpOpt MemCmp; MemCpyOpt MemCpy;
MemMoveOpt MemMove; MemSetOpt MemSet;
// Math Library Optimizations
PowOpt Pow; Exp2Opt Exp2; UnaryDoubleFPOpt UnaryDoubleFP;
// Integer Optimizations
FFSOpt FFS; AbsOpt Abs; IsDigitOpt IsDigit; IsAsciiOpt IsAscii;
ToAsciiOpt ToAscii;
// Formatting and IO Optimizations
SPrintFOpt SPrintF; PrintFOpt PrintF;
FWriteOpt FWrite; FPutsOpt FPuts; FPrintFOpt FPrintF;
bool Modified; // This is only used by doInitialization.
public:
static char ID; // Pass identification
SimplifyLibCalls() : FunctionPass(&ID) {}
void InitOptimizations();
bool runOnFunction(Function &F);
void setDoesNotAccessMemory(Function &F);
void setOnlyReadsMemory(Function &F);
void setDoesNotThrow(Function &F);
void setDoesNotCapture(Function &F, unsigned n);
void setDoesNotAlias(Function &F, unsigned n);
bool doInitialization(Module &M);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<TargetData>();
}
};
char SimplifyLibCalls::ID = 0;
} // end anonymous namespace.
static RegisterPass<SimplifyLibCalls>
X("simplify-libcalls", "Simplify well-known library calls");
// Public interface to the Simplify LibCalls pass.
FunctionPass *llvm::createSimplifyLibCallsPass() {
return new SimplifyLibCalls();
}
/// Optimizations - Populate the Optimizations map with all the optimizations
/// we know.
void SimplifyLibCalls::InitOptimizations() {
// Miscellaneous LibCall Optimizations
Optimizations["exit"] = &Exit;
// String and Memory LibCall Optimizations
Optimizations["strcat"] = &StrCat;
Optimizations["strchr"] = &StrChr;
Optimizations["strcmp"] = &StrCmp;
Optimizations["strncmp"] = &StrNCmp;
Optimizations["strcpy"] = &StrCpy;
Optimizations["strlen"] = &StrLen;
Optimizations["memcmp"] = &MemCmp;
Optimizations["memcpy"] = &MemCpy;
Optimizations["memmove"] = &MemMove;
Optimizations["memset"] = &MemSet;
// Math Library Optimizations
Optimizations["powf"] = &Pow;
Optimizations["pow"] = &Pow;
Optimizations["powl"] = &Pow;
Optimizations["llvm.pow.f32"] = &Pow;
Optimizations["llvm.pow.f64"] = &Pow;
Optimizations["llvm.pow.f80"] = &Pow;
Optimizations["llvm.pow.f128"] = &Pow;
Optimizations["llvm.pow.ppcf128"] = &Pow;
Optimizations["exp2l"] = &Exp2;
Optimizations["exp2"] = &Exp2;
Optimizations["exp2f"] = &Exp2;
Optimizations["llvm.exp2.ppcf128"] = &Exp2;
Optimizations["llvm.exp2.f128"] = &Exp2;
Optimizations["llvm.exp2.f80"] = &Exp2;
Optimizations["llvm.exp2.f64"] = &Exp2;
Optimizations["llvm.exp2.f32"] = &Exp2;
#ifdef HAVE_FLOORF
Optimizations["floor"] = &UnaryDoubleFP;
#endif
#ifdef HAVE_CEILF
Optimizations["ceil"] = &UnaryDoubleFP;
#endif
#ifdef HAVE_ROUNDF
Optimizations["round"] = &UnaryDoubleFP;
#endif
#ifdef HAVE_RINTF
Optimizations["rint"] = &UnaryDoubleFP;
#endif
#ifdef HAVE_NEARBYINTF
Optimizations["nearbyint"] = &UnaryDoubleFP;
#endif
// Integer Optimizations
Optimizations["ffs"] = &FFS;
Optimizations["ffsl"] = &FFS;
Optimizations["ffsll"] = &FFS;
Optimizations["abs"] = &Abs;
Optimizations["labs"] = &Abs;
Optimizations["llabs"] = &Abs;
Optimizations["isdigit"] = &IsDigit;
Optimizations["isascii"] = &IsAscii;
Optimizations["toascii"] = &ToAscii;
// Formatting and IO Optimizations
Optimizations["sprintf"] = &SPrintF;
Optimizations["printf"] = &PrintF;
Optimizations["fwrite"] = &FWrite;
Optimizations["fputs"] = &FPuts;
Optimizations["fprintf"] = &FPrintF;
}
/// runOnFunction - Top level algorithm.
///
bool SimplifyLibCalls::runOnFunction(Function &F) {
if (Optimizations.empty())
InitOptimizations();
const TargetData &TD = getAnalysis<TargetData>();
IRBuilder<> Builder;
bool Changed = false;
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
// Ignore non-calls.
CallInst *CI = dyn_cast<CallInst>(I++);
if (!CI) continue;
// Ignore indirect calls and calls to non-external functions.
Function *Callee = CI->getCalledFunction();
if (Callee == 0 || !Callee->isDeclaration() ||
!(Callee->hasExternalLinkage() || Callee->hasDLLImportLinkage()))
continue;
// Ignore unknown calls.
const char *CalleeName = Callee->getNameStart();
StringMap<LibCallOptimization*>::iterator OMI =
Optimizations.find(CalleeName, CalleeName+Callee->getNameLen());
if (OMI == Optimizations.end()) continue;
// Set the builder to the instruction after the call.
Builder.SetInsertPoint(BB, I);
// Try to optimize this call.
Value *Result = OMI->second->OptimizeCall(CI, TD, Builder);
if (Result == 0) continue;
DEBUG(DOUT << "SimplifyLibCalls simplified: " << *CI;
DOUT << " into: " << *Result << "\n");
// Something changed!
Changed = true;
++NumSimplified;
// Inspect the instruction after the call (which was potentially just
// added) next.
I = CI; ++I;
if (CI != Result && !CI->use_empty()) {
CI->replaceAllUsesWith(Result);
if (!Result->hasName())
Result->takeName(CI);
}
CI->eraseFromParent();
}
}
return Changed;
}
// Utility methods for doInitialization.
void SimplifyLibCalls::setDoesNotAccessMemory(Function &F) {
if (!F.doesNotAccessMemory()) {
F.setDoesNotAccessMemory();
++NumAnnotated;
Modified = true;
}
}
void SimplifyLibCalls::setOnlyReadsMemory(Function &F) {
if (!F.onlyReadsMemory()) {
F.setOnlyReadsMemory();
++NumAnnotated;
Modified = true;
}
}
void SimplifyLibCalls::setDoesNotThrow(Function &F) {
if (!F.doesNotThrow()) {
F.setDoesNotThrow();
++NumAnnotated;
Modified = true;
}
}
void SimplifyLibCalls::setDoesNotCapture(Function &F, unsigned n) {
if (!F.doesNotCapture(n)) {
F.setDoesNotCapture(n);
++NumAnnotated;
Modified = true;
}
}
void SimplifyLibCalls::setDoesNotAlias(Function &F, unsigned n) {
if (!F.doesNotAlias(n)) {
F.setDoesNotAlias(n);
++NumAnnotated;
Modified = true;
}
}
/// doInitialization - Add attributes to well-known functions.
///
bool SimplifyLibCalls::doInitialization(Module &M) {
Modified = false;
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
Function &F = *I;
if (!F.isDeclaration())
continue;
unsigned NameLen = F.getNameLen();
if (!NameLen)
continue;
const FunctionType *FTy = F.getFunctionType();
const char *NameStr = F.getNameStart();
switch (NameStr[0]) {
case 's':
if (NameLen == 6 && !strcmp(NameStr, "strlen")) {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setOnlyReadsMemory(F);
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if ((NameLen == 6 && !strcmp(NameStr, "strcpy")) ||
(NameLen == 6 && !strcmp(NameStr, "stpcpy")) ||
(NameLen == 6 && !strcmp(NameStr, "strcat")) ||
(NameLen == 7 && !strcmp(NameStr, "strncat")) ||
(NameLen == 7 && !strcmp(NameStr, "strncpy"))) {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (NameLen == 7 && !strcmp(NameStr, "strxfrm")) {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if ((NameLen == 6 && !strcmp(NameStr, "strcmp")) ||
(NameLen == 6 && !strcmp(NameStr, "strspn")) ||
(NameLen == 6 && !strcmp(NameStr, "strtol")) ||
(NameLen == 6 && !strcmp(NameStr, "strtod")) ||
(NameLen == 6 && !strcmp(NameStr, "strtof")) ||
(NameLen == 7 && !strcmp(NameStr, "strtoul")) ||
(NameLen == 7 && !strcmp(NameStr, "strtoll")) ||
(NameLen == 7 && !strcmp(NameStr, "strtold")) ||
(NameLen == 7 && !strcmp(NameStr, "strncmp")) ||
(NameLen == 7 && !strcmp(NameStr, "strcspn")) ||
(NameLen == 7 && !strcmp(NameStr, "strcoll")) ||
(NameLen == 8 && !strcmp(NameStr, "strtoull")) ||
(NameLen == 10 && !strcmp(NameStr, "strcasecmp")) ||
(NameLen == 11 && !strcmp(NameStr, "strncasecmp"))) {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setOnlyReadsMemory(F);
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if ((NameLen == 6 && !strcmp(NameStr, "strstr")) ||
(NameLen == 7 && !strcmp(NameStr, "strpbrk"))) {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setOnlyReadsMemory(F);
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if ((NameLen == 6 && !strcmp(NameStr, "strtok")) ||
(NameLen == 7 && !strcmp(NameStr, "strtok_r"))) {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if ((NameLen == 5 && !strcmp(NameStr, "scanf")) ||
(NameLen == 6 && !strcmp(NameStr, "setbuf")) ||
(NameLen == 7 && !strcmp(NameStr, "setvbuf"))) {
if (FTy->getNumParams() < 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (NameLen == 6 && !strcmp(NameStr, "sscanf")) {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if ((NameLen == 6 && !strcmp(NameStr, "strdup")) ||
(NameLen == 7 && !strcmp(NameStr, "strndup"))) {
if (FTy->getNumParams() < 1 ||
!isa<PointerType>(FTy->getReturnType()) ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
setDoesNotCapture(F, 1);
}
break;
case 'm':
if (NameLen == 6 && !strcmp(NameStr, "memcmp")) {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setOnlyReadsMemory(F);
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if ((NameLen == 6 && !strcmp(NameStr, "memchr")) ||
(NameLen == 7 && !strcmp(NameStr, "memrchr"))) {
if (FTy->getNumParams() != 3)
continue;
setOnlyReadsMemory(F);
setDoesNotThrow(F);
} else if ((NameLen == 6 && !strcmp(NameStr, "memcpy")) ||
(NameLen == 7 && !strcmp(NameStr, "memccpy")) ||
(NameLen == 7 && !strcmp(NameStr, "memmove"))) {
if (FTy->getNumParams() < 3 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
}
break;
case 'r':
if (NameLen == 7 && !strcmp(NameStr, "realloc")) {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getReturnType()))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
setDoesNotCapture(F, 1);
} else if (NameLen == 4 && !strcmp(NameStr, "read")) {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if ((NameLen == 5 && !strcmp(NameStr, "rmdir")) ||
(NameLen == 6 && !strcmp(NameStr, "rewind")) ||
(NameLen == 6 && !strcmp(NameStr, "remove"))) {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (NameLen == 6 && !strcmp(NameStr, "rename")) {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
}
break;
case 'w':
if (NameLen == 5 && !strcmp(NameStr, "write")) {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
}
break;
case 'b':
if (NameLen == 5 && !strcmp(NameStr, "bcopy")) {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (NameLen == 4 && !strcmp(NameStr, "bcmp")) {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setOnlyReadsMemory(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (NameLen == 5 && !strcmp(NameStr, "bzero")) {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'c':
if (NameLen == 6 && !strcmp(NameStr, "calloc")) {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getReturnType()))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
} else if ((NameLen == 5 && !strcmp(NameStr, "chown")) ||
(NameLen == 8 && !strcmp(NameStr, "clearerr")) ||
(NameLen == 8 && !strcmp(NameStr, "closedir"))) {
if (FTy->getNumParams() == 0 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'a':
if ((NameLen == 4 && !strcmp(NameStr, "atoi")) ||
(NameLen == 4 && !strcmp(NameStr, "atol")) ||
(NameLen == 4 && !strcmp(NameStr, "atof")) ||
(NameLen == 5 && !strcmp(NameStr, "atoll"))) {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setOnlyReadsMemory(F);
setDoesNotCapture(F, 1);
} else if (NameLen == 6 && !strcmp(NameStr, "access")) {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'f':
if ((NameLen == 5 && !strcmp(NameStr, "fopen")) ||
(NameLen == 6 && !strcmp(NameStr, "fdopen"))) {
if (!isa<PointerType>(FTy->getReturnType()))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
} else if ((NameLen == 4 && !strcmp(NameStr, "feof")) ||
(NameLen == 4 && !strcmp(NameStr, "free")) ||
(NameLen == 5 && !strcmp(NameStr, "fseek")) ||
(NameLen == 5 && !strcmp(NameStr, "ftell")) ||
(NameLen == 5 && !strcmp(NameStr, "fgetc")) ||
(NameLen == 6 && !strcmp(NameStr, "fseeko")) ||
(NameLen == 6 && !strcmp(NameStr, "ftello")) ||
(NameLen == 6 && !strcmp(NameStr, "ferror")) ||
(NameLen == 6 && !strcmp(NameStr, "fileno")) ||
(NameLen == 6 && !strcmp(NameStr, "fflush")) ||
(NameLen == 6 && !strcmp(NameStr, "fclose"))) {
if (FTy->getNumParams() == 0 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if ((NameLen == 5 && !strcmp(NameStr, "fputc")) ||
(NameLen == 5 && !strcmp(NameStr, "fputs"))) {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (NameLen == 5 && !strcmp(NameStr, "fgets")) {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(2)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 3);
} else if ((NameLen == 5 && !strcmp(NameStr, "fread")) ||
(NameLen == 6 && !strcmp(NameStr, "fwrite"))) {
if (FTy->getNumParams() != 4 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(3)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 4);
} else if ((NameLen == 7 && !strcmp(NameStr, "fgetpos")) ||
(NameLen == 7 && !strcmp(NameStr, "fsetpos"))) {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (NameLen == 6 && !strcmp(NameStr, "fscanf")) {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
}
break;
case 'g':
if ((NameLen == 4 && !strcmp(NameStr, "getc")) ||
(NameLen == 10 && !strcmp(NameStr, "getlogin_r"))) {
if (FTy->getNumParams() == 0 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (NameLen == 6 && !strcmp(NameStr, "getenv")) {
if (!FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setOnlyReadsMemory(F);
setDoesNotCapture(F, 0);
}
break;
case 'u':
if (NameLen == 4 && !strcmp(NameStr, "ungetc")) {
if (!FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (NameLen == 6 && !strcmp(NameStr, "unlink")) {
if (!FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'p':
if (NameLen == 4 && !strcmp(NameStr, "putc")) {
if (!FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if ((NameLen == 4 && !strcmp(NameStr, "puts")) ||
(NameLen == 6 && !strcmp(NameStr, "perror"))) {
if (!FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'v':
if (NameLen == 6 && !strcmp(NameStr, "vscanf")) {
if (!FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if ((NameLen == 7 && !strcmp(NameStr, "vsscanf")) ||
(NameLen == 7 && !strcmp(NameStr, "vfscanf"))) {
if (!FTy->getNumParams() != 4 ||
!isa<PointerType>(FTy->getParamType(1)) ||
!isa<PointerType>(FTy->getParamType(2)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
}
break;
case 'o':
if (NameLen == 7 && !strcmp(NameStr, "opendir")) {
// The description of fdopendir sounds like opening the same fd
// twice might result in the same DIR* !
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
}
break;
case 't':
if (NameLen == 7 && !strcmp(NameStr, "tmpfile")) {
if (!isa<PointerType>(FTy->getReturnType()))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
}
case 'h':
if ((NameLen == 5 && !strcmp(NameStr, "htonl")) ||
(NameLen == 5 && !strcmp(NameStr, "htons"))) {
setDoesNotThrow(F);
setDoesNotAccessMemory(F);
}
break;
case 'n':
if ((NameLen == 5 && !strcmp(NameStr, "ntohl")) ||
(NameLen == 5 && !strcmp(NameStr, "ntohs"))) {
setDoesNotThrow(F);
setDoesNotAccessMemory(F);
}
break;
}
}
return Modified;
}
// TODO:
// Additional cases that we need to add to this file:
//
// cbrt:
// * cbrt(expN(X)) -> expN(x/3)
// * cbrt(sqrt(x)) -> pow(x,1/6)
// * cbrt(sqrt(x)) -> pow(x,1/9)
//
// cos, cosf, cosl:
// * cos(-x) -> cos(x)
//
// exp, expf, expl:
// * exp(log(x)) -> x
//
// log, logf, logl:
// * log(exp(x)) -> x
// * log(x**y) -> y*log(x)
// * log(exp(y)) -> y*log(e)
// * log(exp2(y)) -> y*log(2)
// * log(exp10(y)) -> y*log(10)
// * log(sqrt(x)) -> 0.5*log(x)
// * log(pow(x,y)) -> y*log(x)
//
// lround, lroundf, lroundl:
// * lround(cnst) -> cnst'
//
// memcmp:
// * memcmp(x,y,l) -> cnst
// (if all arguments are constant and strlen(x) <= l and strlen(y) <= l)
//
// pow, powf, powl:
// * pow(exp(x),y) -> exp(x*y)
// * pow(sqrt(x),y) -> pow(x,y*0.5)
// * pow(pow(x,y),z)-> pow(x,y*z)
//
// puts:
// * puts("") -> putchar("\n")
//
// round, roundf, roundl:
// * round(cnst) -> cnst'
//
// signbit:
// * signbit(cnst) -> cnst'
// * signbit(nncst) -> 0 (if pstv is a non-negative constant)
//
// sqrt, sqrtf, sqrtl:
// * sqrt(expN(x)) -> expN(x*0.5)
// * sqrt(Nroot(x)) -> pow(x,1/(2*N))
// * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
//
// stpcpy:
// * stpcpy(str, "literal") ->
// llvm.memcpy(str,"literal",strlen("literal")+1,1)
// strrchr:
// * strrchr(s,c) -> reverse_offset_of_in(c,s)
// (if c is a constant integer and s is a constant string)
// * strrchr(s1,0) -> strchr(s1,0)
//
// strncat:
// * strncat(x,y,0) -> x
// * strncat(x,y,0) -> x (if strlen(y) = 0)
// * strncat(x,y,l) -> strcat(x,y) (if y and l are constants an l > strlen(y))
//
// strncpy:
// * strncpy(d,s,0) -> d
// * strncpy(d,s,l) -> memcpy(d,s,l,1)
// (if s and l are constants)
//
// strpbrk:
// * strpbrk(s,a) -> offset_in_for(s,a)
// (if s and a are both constant strings)
// * strpbrk(s,"") -> 0
// * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
//
// strspn, strcspn:
// * strspn(s,a) -> const_int (if both args are constant)
// * strspn("",a) -> 0
// * strspn(s,"") -> 0
// * strcspn(s,a) -> const_int (if both args are constant)
// * strcspn("",a) -> 0
// * strcspn(s,"") -> strlen(a)
//
// strstr:
// * strstr(x,x) -> x
// * strstr(s1,s2) -> offset_of_s2_in(s1)
// (if s1 and s2 are constant strings)
//
// tan, tanf, tanl:
// * tan(atan(x)) -> x
//
// trunc, truncf, truncl:
// * trunc(cnst) -> cnst'
//
//
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