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Diffstat (limited to 'lib/Transforms/Scalar/SimplifyLibCalls.cpp')
| -rw-r--r-- | lib/Transforms/Scalar/SimplifyLibCalls.cpp | 1437 |
1 files changed, 1437 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp new file mode 100644 index 0000000000..a03bc7e9cf --- /dev/null +++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp @@ -0,0 +1,1437 @@ +//===- 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" +#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); + 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(); + Constant *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(); + Constant *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 +//===----------------------------------------------------------------------===// + +/// GetConstantStringInfo - This function computes the length of a +/// null-terminated C string pointed to by V. If successful, it returns true +/// and returns the string in Str. If unsuccessful, it returns false. +static bool GetConstantStringInfo(Value *V, std::string &Str) { + // Look bitcast instructions. + if (BitCastInst *BCI = dyn_cast<BitCastInst>(V)) + return GetConstantStringInfo(BCI->getOperand(0), Str); + + // If the value is not a GEP instruction nor a constant expression with a + // GEP instruction, then return false because ConstantArray can't occur + // any other way + 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 false; + GEP = CE; + } else { + return false; + } + + // Make sure the GEP has exactly three arguments. + if (GEP->getNumOperands() != 3) + return false; + + // 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 false; + } else + return false; + + // 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 false; + + // 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 false; + Constant *GlobalInit = GV->getInitializer(); + + // Handle the ConstantAggregateZero case + if (isa<ConstantAggregateZero>(GlobalInit)) { + // This is a degenerate case. The initializer is constant zero so the + // length of the string must be zero. + Str.clear(); + return true; + } + + // Must be a Constant Array + ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit); + if (Array == 0 || 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 false; + if (CI->isZero()) + return true; // we found end of string, success! + Str += (char)CI->getZExtValue(); + } + + return false; // The array isn't null terminated. +} + +/// 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 +//===----------------------------------------------------------------------===// + +//===---------------------------------------===// +// '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 false; + --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 false; + + // 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())); + 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 false; + + // 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 false; + 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)) { + LHS = B.CreateBitCast(LHS, PointerType::getUnqual(Type::Int16Ty), "tmp"); + RHS = B.CreateBitCast(RHS, LHS->getType(), "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); + } +}; + +//===----------------------------------------------------------------------===// +// 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; + } +}; + +//===---------------------------------------===// +// 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.Creat |