blob: c279d18043c02e693c94fe3acbf4431e7fa675fa [file] [log] [blame]
//===------ SimplifyLibCalls.cpp - Library calls simplifier ---------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the library calls simplifier. It does not implement
// any pass, but can't be used by other passes to do simplifications.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/BlockFrequencyInfo.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Transforms/Utils/BuildLibCalls.h"
#include "llvm/Transforms/Utils/SizeOpts.h"
using namespace llvm;
using namespace PatternMatch;
static cl::opt<bool>
EnableUnsafeFPShrink("enable-double-float-shrink", cl::Hidden,
cl::init(false),
cl::desc("Enable unsafe double to float "
"shrinking for math lib calls"));
//===----------------------------------------------------------------------===//
// Helper Functions
//===----------------------------------------------------------------------===//
static bool ignoreCallingConv(LibFunc Func) {
return Func == LibFunc_abs || Func == LibFunc_labs ||
Func == LibFunc_llabs || Func == LibFunc_strlen;
}
static bool isCallingConvCCompatible(CallInst *CI) {
switch(CI->getCallingConv()) {
default:
return false;
case llvm::CallingConv::C:
return true;
case llvm::CallingConv::ARM_APCS:
case llvm::CallingConv::ARM_AAPCS:
case llvm::CallingConv::ARM_AAPCS_VFP: {
// The iOS ABI diverges from the standard in some cases, so for now don't
// try to simplify those calls.
if (Triple(CI->getModule()->getTargetTriple()).isiOS())
return false;
auto *FuncTy = CI->getFunctionType();
if (!FuncTy->getReturnType()->isPointerTy() &&
!FuncTy->getReturnType()->isIntegerTy() &&
!FuncTy->getReturnType()->isVoidTy())
return false;
for (auto Param : FuncTy->params()) {
if (!Param->isPointerTy() && !Param->isIntegerTy())
return false;
}
return true;
}
}
return false;
}
/// Return true if it is only used in equality comparisons with With.
static bool isOnlyUsedInEqualityComparison(Value *V, Value *With) {
for (User *U : V->users()) {
if (ICmpInst *IC = dyn_cast<ICmpInst>(U))
if (IC->isEquality() && IC->getOperand(1) == With)
continue;
// Unknown instruction.
return false;
}
return true;
}
static bool callHasFloatingPointArgument(const CallInst *CI) {
return any_of(CI->operands(), [](const Use &OI) {
return OI->getType()->isFloatingPointTy();
});
}
static bool callHasFP128Argument(const CallInst *CI) {
return any_of(CI->operands(), [](const Use &OI) {
return OI->getType()->isFP128Ty();
});
}
static Value *convertStrToNumber(CallInst *CI, StringRef &Str, int64_t Base) {
if (Base < 2 || Base > 36)
// handle special zero base
if (Base != 0)
return nullptr;
char *End;
std::string nptr = Str.str();
errno = 0;
long long int Result = strtoll(nptr.c_str(), &End, Base);
if (errno)
return nullptr;
// if we assume all possible target locales are ASCII supersets,
// then if strtoll successfully parses a number on the host,
// it will also successfully parse the same way on the target
if (*End != '\0')
return nullptr;
if (!isIntN(CI->getType()->getPrimitiveSizeInBits(), Result))
return nullptr;
return ConstantInt::get(CI->getType(), Result);
}
static bool isOnlyUsedInComparisonWithZero(Value *V) {
for (User *U : V->users()) {
if (ICmpInst *IC = dyn_cast<ICmpInst>(U))
if (Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
if (C->isNullValue())
continue;
// Unknown instruction.
return false;
}
return true;
}
static bool canTransformToMemCmp(CallInst *CI, Value *Str, uint64_t Len,
const DataLayout &DL) {
if (!isOnlyUsedInComparisonWithZero(CI))
return false;
if (!isDereferenceableAndAlignedPointer(Str, Align(1), APInt(64, Len), DL))
return false;
if (CI->getFunction()->hasFnAttribute(Attribute::SanitizeMemory))
return false;
return true;
}
static void annotateDereferenceableBytes(CallInst *CI,
ArrayRef<unsigned> ArgNos,
uint64_t DereferenceableBytes) {
const Function *F = CI->getCaller();
if (!F)
return;
for (unsigned ArgNo : ArgNos) {
uint64_t DerefBytes = DereferenceableBytes;
unsigned AS = CI->getArgOperand(ArgNo)->getType()->getPointerAddressSpace();
if (!llvm::NullPointerIsDefined(F, AS) ||
CI->paramHasAttr(ArgNo, Attribute::NonNull))
DerefBytes = std::max(CI->getDereferenceableOrNullBytes(
ArgNo + AttributeList::FirstArgIndex),
DereferenceableBytes);
if (CI->getDereferenceableBytes(ArgNo + AttributeList::FirstArgIndex) <
DerefBytes) {
CI->removeParamAttr(ArgNo, Attribute::Dereferenceable);
if (!llvm::NullPointerIsDefined(F, AS) ||
CI->paramHasAttr(ArgNo, Attribute::NonNull))
CI->removeParamAttr(ArgNo, Attribute::DereferenceableOrNull);
CI->addParamAttr(ArgNo, Attribute::getWithDereferenceableBytes(
CI->getContext(), DerefBytes));
}
}
}
static void annotateNonNullNoUndefBasedOnAccess(CallInst *CI,
ArrayRef<unsigned> ArgNos) {
Function *F = CI->getCaller();
if (!F)
return;
for (unsigned ArgNo : ArgNos) {
if (!CI->paramHasAttr(ArgNo, Attribute::NoUndef))
CI->addParamAttr(ArgNo, Attribute::NoUndef);
if (CI->paramHasAttr(ArgNo, Attribute::NonNull))
continue;
unsigned AS = CI->getArgOperand(ArgNo)->getType()->getPointerAddressSpace();
if (llvm::NullPointerIsDefined(F, AS))
continue;
CI->addParamAttr(ArgNo, Attribute::NonNull);
annotateDereferenceableBytes(CI, ArgNo, 1);
}
}
static void annotateNonNullAndDereferenceable(CallInst *CI, ArrayRef<unsigned> ArgNos,
Value *Size, const DataLayout &DL) {
if (ConstantInt *LenC = dyn_cast<ConstantInt>(Size)) {
annotateNonNullNoUndefBasedOnAccess(CI, ArgNos);
annotateDereferenceableBytes(CI, ArgNos, LenC->getZExtValue());
} else if (isKnownNonZero(Size, DL)) {
annotateNonNullNoUndefBasedOnAccess(CI, ArgNos);
const APInt *X, *Y;
uint64_t DerefMin = 1;
if (match(Size, m_Select(m_Value(), m_APInt(X), m_APInt(Y)))) {
DerefMin = std::min(X->getZExtValue(), Y->getZExtValue());
annotateDereferenceableBytes(CI, ArgNos, DerefMin);
}
}
}
//===----------------------------------------------------------------------===//
// String and Memory Library Call Optimizations
//===----------------------------------------------------------------------===//
Value *LibCallSimplifier::optimizeStrCat(CallInst *CI, IRBuilderBase &B) {
// Extract some information from the instruction
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
// See if we can get the length of the input string.
uint64_t Len = GetStringLength(Src);
if (Len)
annotateDereferenceableBytes(CI, 1, Len);
else
return nullptr;
--Len; // Unbias length.
// Handle the simple, do-nothing case: strcat(x, "") -> x
if (Len == 0)
return Dst;
return emitStrLenMemCpy(Src, Dst, Len, B);
}
Value *LibCallSimplifier::emitStrLenMemCpy(Value *Src, Value *Dst, uint64_t Len,
IRBuilderBase &B) {
// 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, DL, TLI);
if (!DstLen)
return nullptr;
// 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).
Value *CpyDst = B.CreateGEP(B.getInt8Ty(), 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.
B.CreateMemCpy(
CpyDst, Align(1), Src, Align(1),
ConstantInt::get(DL.getIntPtrType(Src->getContext()), Len + 1));
return Dst;
}
Value *LibCallSimplifier::optimizeStrNCat(CallInst *CI, IRBuilderBase &B) {
// Extract some information from the instruction.
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
uint64_t Len;
annotateNonNullNoUndefBasedOnAccess(CI, 0);
if (isKnownNonZero(Size, DL))
annotateNonNullNoUndefBasedOnAccess(CI, 1);
// We don't do anything if length is not constant.
ConstantInt *LengthArg = dyn_cast<ConstantInt>(Size);
if (LengthArg) {
Len = LengthArg->getZExtValue();
// strncat(x, c, 0) -> x
if (!Len)
return Dst;
} else {
return nullptr;
}
// See if we can get the length of the input string.
uint64_t SrcLen = GetStringLength(Src);
if (SrcLen) {
annotateDereferenceableBytes(CI, 1, SrcLen);
--SrcLen; // Unbias length.
} else {
return nullptr;
}
// strncat(x, "", c) -> x
if (SrcLen == 0)
return Dst;
// We don't optimize this case.
if (Len < SrcLen)
return nullptr;
// strncat(x, s, c) -> strcat(x, s)
// s is constant so the strcat can be optimized further.
return emitStrLenMemCpy(Src, Dst, SrcLen, B);
}
Value *LibCallSimplifier::optimizeStrChr(CallInst *CI, IRBuilderBase &B) {
Function *Callee = CI->getCalledFunction();
FunctionType *FT = Callee->getFunctionType();
Value *SrcStr = CI->getArgOperand(0);
annotateNonNullNoUndefBasedOnAccess(CI, 0);
// 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->getArgOperand(1));
if (!CharC) {
uint64_t Len = GetStringLength(SrcStr);
if (Len)
annotateDereferenceableBytes(CI, 0, Len);
else
return nullptr;
if (!FT->getParamType(1)->isIntegerTy(32)) // memchr needs i32.
return nullptr;
return emitMemChr(SrcStr, CI->getArgOperand(1), // include nul.
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len),
B, DL, TLI);
}
// Otherwise, the character is a constant, see if the first argument is
// a string literal. If so, we can constant fold.
StringRef Str;
if (!getConstantStringInfo(SrcStr, Str)) {
if (CharC->isZero()) // strchr(p, 0) -> p + strlen(p)
if (Value *StrLen = emitStrLen(SrcStr, B, DL, TLI))
return B.CreateGEP(B.getInt8Ty(), SrcStr, StrLen, "strchr");
return nullptr;
}
// Compute the offset, make sure to handle the case when we're searching for
// zero (a weird way to spell strlen).
size_t I = (0xFF & CharC->getSExtValue()) == 0
? Str.size()
: Str.find(CharC->getSExtValue());
if (I == StringRef::npos) // Didn't find the char. strchr returns null.
return Constant::getNullValue(CI->getType());
// strchr(s+n,c) -> gep(s+n+i,c)
return B.CreateGEP(B.getInt8Ty(), SrcStr, B.getInt64(I), "strchr");
}
Value *LibCallSimplifier::optimizeStrRChr(CallInst *CI, IRBuilderBase &B) {
Value *SrcStr = CI->getArgOperand(0);
ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getArgOperand(1));
annotateNonNullNoUndefBasedOnAccess(CI, 0);
// Cannot fold anything if we're not looking for a constant.
if (!CharC)
return nullptr;
StringRef Str;
if (!getConstantStringInfo(SrcStr, Str)) {
// strrchr(s, 0) -> strchr(s, 0)
if (CharC->isZero())
return emitStrChr(SrcStr, '\0', B, TLI);
return nullptr;
}
// Compute the offset.
size_t I = (0xFF & CharC->getSExtValue()) == 0
? Str.size()
: Str.rfind(CharC->getSExtValue());
if (I == StringRef::npos) // Didn't find the char. Return null.
return Constant::getNullValue(CI->getType());
// strrchr(s+n,c) -> gep(s+n+i,c)
return B.CreateGEP(B.getInt8Ty(), SrcStr, B.getInt64(I), "strrchr");
}
Value *LibCallSimplifier::optimizeStrCmp(CallInst *CI, IRBuilderBase &B) {
Value *Str1P = CI->getArgOperand(0), *Str2P = CI->getArgOperand(1);
if (Str1P == Str2P) // strcmp(x,x) -> 0
return ConstantInt::get(CI->getType(), 0);
StringRef Str1, Str2;
bool HasStr1 = getConstantStringInfo(Str1P, Str1);
bool HasStr2 = getConstantStringInfo(Str2P, Str2);
// strcmp(x, y) -> cnst (if both x and y are constant strings)
if (HasStr1 && HasStr2)
return ConstantInt::get(CI->getType(), Str1.compare(Str2));
if (HasStr1 && Str1.empty()) // strcmp("", x) -> -*x
return B.CreateNeg(B.CreateZExt(
B.CreateLoad(B.getInt8Ty(), Str2P, "strcmpload"), CI->getType()));
if (HasStr2 && Str2.empty()) // strcmp(x,"") -> *x
return B.CreateZExt(B.CreateLoad(B.getInt8Ty(), Str1P, "strcmpload"),
CI->getType());
// strcmp(P, "x") -> memcmp(P, "x", 2)
uint64_t Len1 = GetStringLength(Str1P);
if (Len1)
annotateDereferenceableBytes(CI, 0, Len1);
uint64_t Len2 = GetStringLength(Str2P);
if (Len2)
annotateDereferenceableBytes(CI, 1, Len2);
if (Len1 && Len2) {
return emitMemCmp(Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()),
std::min(Len1, Len2)),
B, DL, TLI);
}
// strcmp to memcmp
if (!HasStr1 && HasStr2) {
if (canTransformToMemCmp(CI, Str1P, Len2, DL))
return emitMemCmp(
Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len2), B, DL,
TLI);
} else if (HasStr1 && !HasStr2) {
if (canTransformToMemCmp(CI, Str2P, Len1, DL))
return emitMemCmp(
Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len1), B, DL,
TLI);
}
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
return nullptr;
}
Value *LibCallSimplifier::optimizeStrNCmp(CallInst *CI, IRBuilderBase &B) {
Value *Str1P = CI->getArgOperand(0);
Value *Str2P = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
if (Str1P == Str2P) // strncmp(x,x,n) -> 0
return ConstantInt::get(CI->getType(), 0);
if (isKnownNonZero(Size, DL))
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
// Get the length argument if it is constant.
uint64_t Length;
if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(Size))
Length = LengthArg->getZExtValue();
else
return nullptr;
if (Length == 0) // strncmp(x,y,0) -> 0
return ConstantInt::get(CI->getType(), 0);
if (Length == 1) // strncmp(x,y,1) -> memcmp(x,y,1)
return emitMemCmp(Str1P, Str2P, Size, B, DL, TLI);
StringRef Str1, Str2;
bool HasStr1 = getConstantStringInfo(Str1P, Str1);
bool HasStr2 = getConstantStringInfo(Str2P, Str2);
// strncmp(x, y) -> cnst (if both x and y are constant strings)
if (HasStr1 && HasStr2) {
StringRef SubStr1 = Str1.substr(0, Length);
StringRef SubStr2 = Str2.substr(0, Length);
return ConstantInt::get(CI->getType(), SubStr1.compare(SubStr2));
}
if (HasStr1 && Str1.empty()) // strncmp("", x, n) -> -*x
return B.CreateNeg(B.CreateZExt(
B.CreateLoad(B.getInt8Ty(), Str2P, "strcmpload"), CI->getType()));
if (HasStr2 && Str2.empty()) // strncmp(x, "", n) -> *x
return B.CreateZExt(B.CreateLoad(B.getInt8Ty(), Str1P, "strcmpload"),
CI->getType());
uint64_t Len1 = GetStringLength(Str1P);
if (Len1)
annotateDereferenceableBytes(CI, 0, Len1);
uint64_t Len2 = GetStringLength(Str2P);
if (Len2)
annotateDereferenceableBytes(CI, 1, Len2);
// strncmp to memcmp
if (!HasStr1 && HasStr2) {
Len2 = std::min(Len2, Length);
if (canTransformToMemCmp(CI, Str1P, Len2, DL))
return emitMemCmp(
Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len2), B, DL,
TLI);
} else if (HasStr1 && !HasStr2) {
Len1 = std::min(Len1, Length);
if (canTransformToMemCmp(CI, Str2P, Len1, DL))
return emitMemCmp(
Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len1), B, DL,
TLI);
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStrNDup(CallInst *CI, IRBuilderBase &B) {
Value *Src = CI->getArgOperand(0);
ConstantInt *Size = dyn_cast<ConstantInt>(CI->getArgOperand(1));
uint64_t SrcLen = GetStringLength(Src);
if (SrcLen && Size) {
annotateDereferenceableBytes(CI, 0, SrcLen);
if (SrcLen <= Size->getZExtValue() + 1)
return emitStrDup(Src, B, TLI);
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStrCpy(CallInst *CI, IRBuilderBase &B) {
Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1);
if (Dst == Src) // strcpy(x,x) -> x
return Src;
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
// See if we can get the length of the input string.
uint64_t Len = GetStringLength(Src);
if (Len)
annotateDereferenceableBytes(CI, 1, Len);
else
return nullptr;
// We have enough information to now generate the memcpy call to do the
// copy for us. Make a memcpy to copy the nul byte with align = 1.
CallInst *NewCI =
B.CreateMemCpy(Dst, Align(1), Src, Align(1),
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len));
NewCI->setAttributes(CI->getAttributes());
NewCI->removeAttributes(AttributeList::ReturnIndex,
AttributeFuncs::typeIncompatible(NewCI->getType()));
return Dst;
}
Value *LibCallSimplifier::optimizeStpCpy(CallInst *CI, IRBuilderBase &B) {
Function *Callee = CI->getCalledFunction();
Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1);
if (Dst == Src) { // stpcpy(x,x) -> x+strlen(x)
Value *StrLen = emitStrLen(Src, B, DL, TLI);
return StrLen ? B.CreateInBoundsGEP(B.getInt8Ty(), Dst, StrLen) : nullptr;
}
// See if we can get the length of the input string.
uint64_t Len = GetStringLength(Src);
if (Len)
annotateDereferenceableBytes(CI, 1, Len);
else
return nullptr;
Type *PT = Callee->getFunctionType()->getParamType(0);
Value *LenV = ConstantInt::get(DL.getIntPtrType(PT), Len);
Value *DstEnd = B.CreateGEP(B.getInt8Ty(), Dst,
ConstantInt::get(DL.getIntPtrType(PT), Len - 1));
// We have enough information to now generate the memcpy call to do the
// copy for us. Make a memcpy to copy the nul byte with align = 1.
CallInst *NewCI = B.CreateMemCpy(Dst, Align(1), Src, Align(1), LenV);
NewCI->setAttributes(CI->getAttributes());
NewCI->removeAttributes(AttributeList::ReturnIndex,
AttributeFuncs::typeIncompatible(NewCI->getType()));
return DstEnd;
}
Value *LibCallSimplifier::optimizeStrNCpy(CallInst *CI, IRBuilderBase &B) {
Function *Callee = CI->getCalledFunction();
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
annotateNonNullNoUndefBasedOnAccess(CI, 0);
if (isKnownNonZero(Size, DL))
annotateNonNullNoUndefBasedOnAccess(CI, 1);
uint64_t Len;
if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(Size))
Len = LengthArg->getZExtValue();
else
return nullptr;
// strncpy(x, y, 0) -> x
if (Len == 0)
return Dst;
// See if we can get the length of the input string.
uint64_t SrcLen = GetStringLength(Src);
if (SrcLen) {
annotateDereferenceableBytes(CI, 1, SrcLen);
--SrcLen; // Unbias length.
} else {
return nullptr;
}
if (SrcLen == 0) {
// strncpy(x, "", y) -> memset(align 1 x, '\0', y)
CallInst *NewCI = B.CreateMemSet(Dst, B.getInt8('\0'), Size, Align(1));
AttrBuilder ArgAttrs(CI->getAttributes().getParamAttributes(0));
NewCI->setAttributes(NewCI->getAttributes().addParamAttributes(
CI->getContext(), 0, ArgAttrs));
return Dst;
}
// strncpy(a, "a", 4) - > memcpy(a, "a\0\0\0", 4)
if (Len > SrcLen + 1) {
if (Len <= 128) {
StringRef Str;
if (!getConstantStringInfo(Src, Str))
return nullptr;
std::string SrcStr = Str.str();
SrcStr.resize(Len, '\0');
Src = B.CreateGlobalString(SrcStr, "str");
} else {
return nullptr;
}
}
Type *PT = Callee->getFunctionType()->getParamType(0);
// strncpy(x, s, c) -> memcpy(align 1 x, align 1 s, c) [s and c are constant]
CallInst *NewCI = B.CreateMemCpy(Dst, Align(1), Src, Align(1),
ConstantInt::get(DL.getIntPtrType(PT), Len));
NewCI->setAttributes(CI->getAttributes());
NewCI->removeAttributes(AttributeList::ReturnIndex,
AttributeFuncs::typeIncompatible(NewCI->getType()));
return Dst;
}
Value *LibCallSimplifier::optimizeStringLength(CallInst *CI, IRBuilderBase &B,
unsigned CharSize) {
Value *Src = CI->getArgOperand(0);
// Constant folding: strlen("xyz") -> 3
if (uint64_t Len = GetStringLength(Src, CharSize))
return ConstantInt::get(CI->getType(), Len - 1);
// If s is a constant pointer pointing to a string literal, we can fold
// strlen(s + x) to strlen(s) - x, when x is known to be in the range
// [0, strlen(s)] or the string has a single null terminator '\0' at the end.
// We only try to simplify strlen when the pointer s points to an array
// of i8. Otherwise, we would need to scale the offset x before doing the
// subtraction. This will make the optimization more complex, and it's not
// very useful because calling strlen for a pointer of other types is
// very uncommon.
if (GEPOperator *GEP = dyn_cast<GEPOperator>(Src)) {
if (!isGEPBasedOnPointerToString(GEP, CharSize))
return nullptr;
ConstantDataArraySlice Slice;
if (getConstantDataArrayInfo(GEP->getOperand(0), Slice, CharSize)) {
uint64_t NullTermIdx;
if (Slice.Array == nullptr) {
NullTermIdx = 0;
} else {
NullTermIdx = ~((uint64_t)0);
for (uint64_t I = 0, E = Slice.Length; I < E; ++I) {
if (Slice.Array->getElementAsInteger(I + Slice.Offset) == 0) {
NullTermIdx = I;
break;
}
}
// If the string does not have '\0', leave it to strlen to compute
// its length.
if (NullTermIdx == ~((uint64_t)0))
return nullptr;
}
Value *Offset = GEP->getOperand(2);
KnownBits Known = computeKnownBits(Offset, DL, 0, nullptr, CI, nullptr);
Known.Zero.flipAllBits();
uint64_t ArrSize =
cast<ArrayType>(GEP->getSourceElementType())->getNumElements();
// KnownZero's bits are flipped, so zeros in KnownZero now represent
// bits known to be zeros in Offset, and ones in KnowZero represent
// bits unknown in Offset. Therefore, Offset is known to be in range
// [0, NullTermIdx] when the flipped KnownZero is non-negative and
// unsigned-less-than NullTermIdx.
//
// If Offset is not provably in the range [0, NullTermIdx], we can still
// optimize if we can prove that the program has undefined behavior when
// Offset is outside that range. That is the case when GEP->getOperand(0)
// is a pointer to an object whose memory extent is NullTermIdx+1.
if ((Known.Zero.isNonNegative() && Known.Zero.ule(NullTermIdx)) ||
(GEP->isInBounds() && isa<GlobalVariable>(GEP->getOperand(0)) &&
NullTermIdx == ArrSize - 1)) {
Offset = B.CreateSExtOrTrunc(Offset, CI->getType());
return B.CreateSub(ConstantInt::get(CI->getType(), NullTermIdx),
Offset);
}
}
}
// strlen(x?"foo":"bars") --> x ? 3 : 4
if (SelectInst *SI = dyn_cast<SelectInst>(Src)) {
uint64_t LenTrue = GetStringLength(SI->getTrueValue(), CharSize);
uint64_t LenFalse = GetStringLength(SI->getFalseValue(), CharSize);
if (LenTrue && LenFalse) {
ORE.emit([&]() {
return OptimizationRemark("instcombine", "simplify-libcalls", CI)
<< "folded strlen(select) to select of constants";
});
return B.CreateSelect(SI->getCondition(),
ConstantInt::get(CI->getType(), LenTrue - 1),
ConstantInt::get(CI->getType(), LenFalse - 1));
}
}
// strlen(x) != 0 --> *x != 0
// strlen(x) == 0 --> *x == 0
if (isOnlyUsedInZeroEqualityComparison(CI))
return B.CreateZExt(B.CreateLoad(B.getIntNTy(CharSize), Src, "strlenfirst"),
CI->getType());
return nullptr;
}
Value *LibCallSimplifier::optimizeStrLen(CallInst *CI, IRBuilderBase &B) {
if (Value *V = optimizeStringLength(CI, B, 8))
return V;
annotateNonNullNoUndefBasedOnAccess(CI, 0);
return nullptr;
}
Value *LibCallSimplifier::optimizeWcslen(CallInst *CI, IRBuilderBase &B) {
Module &M = *CI->getModule();
unsigned WCharSize = TLI->getWCharSize(M) * 8;
// We cannot perform this optimization without wchar_size metadata.
if (WCharSize == 0)
return nullptr;
return optimizeStringLength(CI, B, WCharSize);
}
Value *LibCallSimplifier::optimizeStrPBrk(CallInst *CI, IRBuilderBase &B) {
StringRef S1, S2;
bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1);
bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2);
// strpbrk(s, "") -> nullptr
// strpbrk("", s) -> nullptr
if ((HasS1 && S1.empty()) || (HasS2 && S2.empty()))
return Constant::getNullValue(CI->getType());
// Constant folding.
if (HasS1 && HasS2) {
size_t I = S1.find_first_of(S2);
if (I == StringRef::npos) // No match.
return Constant::getNullValue(CI->getType());
return B.CreateGEP(B.getInt8Ty(), CI->getArgOperand(0), B.getInt64(I),
"strpbrk");
}
// strpbrk(s, "a") -> strchr(s, 'a')
if (HasS2 && S2.size() == 1)
return emitStrChr(CI->getArgOperand(0), S2[0], B, TLI);
return nullptr;
}
Value *LibCallSimplifier::optimizeStrTo(CallInst *CI, IRBuilderBase &B) {
Value *EndPtr = CI->getArgOperand(1);
if (isa<ConstantPointerNull>(EndPtr)) {
// With a null EndPtr, this function won't capture the main argument.
// It would be readonly too, except that it still may write to errno.
CI->addParamAttr(0, Attribute::NoCapture);
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStrSpn(CallInst *CI, IRBuilderBase &B) {
StringRef S1, S2;
bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1);
bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2);
// strspn(s, "") -> 0
// strspn("", s) -> 0
if ((HasS1 && S1.empty()) || (HasS2 && S2.empty()))
return Constant::getNullValue(CI->getType());
// Constant folding.
if (HasS1 && HasS2) {
size_t Pos = S1.find_first_not_of(S2);
if (Pos == StringRef::npos)
Pos = S1.size();
return ConstantInt::get(CI->getType(), Pos);
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStrCSpn(CallInst *CI, IRBuilderBase &B) {
StringRef S1, S2;
bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1);
bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2);
// strcspn("", s) -> 0
if (HasS1 && S1.empty())
return Constant::getNullValue(CI->getType());
// Constant folding.
if (HasS1 && HasS2) {
size_t Pos = S1.find_first_of(S2);
if (Pos == StringRef::npos)
Pos = S1.size();
return ConstantInt::get(CI->getType(), Pos);
}
// strcspn(s, "") -> strlen(s)
if (HasS2 && S2.empty())
return emitStrLen(CI->getArgOperand(0), B, DL, TLI);
return nullptr;
}
Value *LibCallSimplifier::optimizeStrStr(CallInst *CI, IRBuilderBase &B) {
// fold strstr(x, x) -> x.
if (CI->getArgOperand(0) == CI->getArgOperand(1))
return B.CreateBitCast(CI->getArgOperand(0), CI->getType());
// fold strstr(a, b) == a -> strncmp(a, b, strlen(b)) == 0
if (isOnlyUsedInEqualityComparison(CI, CI->getArgOperand(0))) {
Value *StrLen = emitStrLen(CI->getArgOperand(1), B, DL, TLI);
if (!StrLen)
return nullptr;
Value *StrNCmp = emitStrNCmp(CI->getArgOperand(0), CI->getArgOperand(1),
StrLen, B, DL, TLI);
if (!StrNCmp)
return nullptr;
for (User *U : llvm::make_early_inc_range(CI->users())) {
ICmpInst *Old = cast<ICmpInst>(U);
Value *Cmp =
B.CreateICmp(Old->getPredicate(), StrNCmp,
ConstantInt::getNullValue(StrNCmp->getType()), "cmp");
replaceAllUsesWith(Old, Cmp);
}
return CI;
}
// See if either input string is a constant string.
StringRef SearchStr, ToFindStr;
bool HasStr1 = getConstantStringInfo(CI->getArgOperand(0), SearchStr);
bool HasStr2 = getConstantStringInfo(CI->getArgOperand(1), ToFindStr);
// fold strstr(x, "") -> x.
if (HasStr2 && ToFindStr.empty())
return B.CreateBitCast(CI->getArgOperand(0), CI->getType());
// If both strings are known, constant fold it.
if (HasStr1 && HasStr2) {
size_t Offset = SearchStr.find(ToFindStr);
if (Offset == StringRef::npos) // strstr("foo", "bar") -> null
return Constant::getNullValue(CI->getType());
// strstr("abcd", "bc") -> gep((char*)"abcd", 1)
Value *Result = castToCStr(CI->getArgOperand(0), B);
Result =
B.CreateConstInBoundsGEP1_64(B.getInt8Ty(), Result, Offset, "strstr");
return B.CreateBitCast(Result, CI->getType());
}
// fold strstr(x, "y") -> strchr(x, 'y').
if (HasStr2 && ToFindStr.size() == 1) {
Value *StrChr = emitStrChr(CI->getArgOperand(0), ToFindStr[0], B, TLI);
return StrChr ? B.CreateBitCast(StrChr, CI->getType()) : nullptr;
}
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
return nullptr;
}
Value *LibCallSimplifier::optimizeMemRChr(CallInst *CI, IRBuilderBase &B) {
if (isKnownNonZero(CI->getOperand(2), DL))
annotateNonNullNoUndefBasedOnAccess(CI, 0);
return nullptr;
}
Value *LibCallSimplifier::optimizeMemChr(CallInst *CI, IRBuilderBase &B) {
Value *SrcStr = CI->getArgOperand(0);
Value *Size = CI->getArgOperand(2);
annotateNonNullAndDereferenceable(CI, 0, Size, DL);
ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getArgOperand(1));
ConstantInt *LenC = dyn_cast<ConstantInt>(Size);
// memchr(x, y, 0) -> null
if (LenC) {
if (LenC->isZero())
return Constant::getNullValue(CI->getType());
} else {
// From now on we need at least constant length and string.
return nullptr;
}
StringRef Str;
if (!getConstantStringInfo(SrcStr, Str, 0, /*TrimAtNul=*/false))
return nullptr;
// Truncate the string to LenC. If Str is smaller than LenC we will still only
// scan the string, as reading past the end of it is undefined and we can just
// return null if we don't find the char.
Str = Str.substr(0, LenC->getZExtValue());
// If the char is variable but the input str and length are not we can turn
// this memchr call into a simple bit field test. Of course this only works
// when the return value is only checked against null.
//
// It would be really nice to reuse switch lowering here but we can't change
// the CFG at this point.
//
// memchr("\r\n", C, 2) != nullptr -> (1 << C & ((1 << '\r') | (1 << '\n')))
// != 0
// after bounds check.
if (!CharC && !Str.empty() && isOnlyUsedInZeroEqualityComparison(CI)) {
unsigned char Max =
*std::max_element(reinterpret_cast<const unsigned char *>(Str.begin()),
reinterpret_cast<const unsigned char *>(Str.end()));
// Make sure the bit field we're about to create fits in a register on the
// target.
// FIXME: On a 64 bit architecture this prevents us from using the
// interesting range of alpha ascii chars. We could do better by emitting
// two bitfields or shifting the range by 64 if no lower chars are used.
if (!DL.fitsInLegalInteger(Max + 1))
return nullptr;
// For the bit field use a power-of-2 type with at least 8 bits to avoid
// creating unnecessary illegal types.
unsigned char Width = NextPowerOf2(std::max((unsigned char)7, Max));
// Now build the bit field.
APInt Bitfield(Width, 0);
for (char C : Str)
Bitfield.setBit((unsigned char)C);
Value *BitfieldC = B.getInt(Bitfield);
// Adjust width of "C" to the bitfield width, then mask off the high bits.
Value *C = B.CreateZExtOrTrunc(CI->getArgOperand(1), BitfieldC->getType());
C = B.CreateAnd(C, B.getIntN(Width, 0xFF));
// First check that the bit field access is within bounds.
Value *Bounds = B.CreateICmp(ICmpInst::ICMP_ULT, C, B.getIntN(Width, Width),
"memchr.bounds");
// Create code that checks if the given bit is set in the field.
Value *Shl = B.CreateShl(B.getIntN(Width, 1ULL), C);
Value *Bits = B.CreateIsNotNull(B.CreateAnd(Shl, BitfieldC), "memchr.bits");
// Finally merge both checks and cast to pointer type. The inttoptr
// implicitly zexts the i1 to intptr type.
return B.CreateIntToPtr(B.CreateAnd(Bounds, Bits, "memchr"), CI->getType());
}
// Check if all arguments are constants. If so, we can constant fold.
if (!CharC)
return nullptr;
// Compute the offset.
size_t I = Str.find(CharC->getSExtValue() & 0xFF);
if (I == StringRef::npos) // Didn't find the char. memchr returns null.
return Constant::getNullValue(CI->getType());
// memchr(s+n,c,l) -> gep(s+n+i,c)
return B.CreateGEP(B.getInt8Ty(), SrcStr, B.getInt64(I), "memchr");
}
static Value *optimizeMemCmpConstantSize(CallInst *CI, Value *LHS, Value *RHS,
uint64_t Len, IRBuilderBase &B,
const DataLayout &DL) {
if (Len == 0) // memcmp(s1,s2,0) -> 0
return Constant::getNullValue(CI->getType());
// memcmp(S1,S2,1) -> *(unsigned char*)LHS - *(unsigned char*)RHS
if (Len == 1) {
Value *LHSV =
B.CreateZExt(B.CreateLoad(B.getInt8Ty(), castToCStr(LHS, B), "lhsc"),
CI->getType(), "lhsv");
Value *RHSV =
B.CreateZExt(B.CreateLoad(B.getInt8Ty(), castToCStr(RHS, B), "rhsc"),
CI->getType(), "rhsv");
return B.CreateSub(LHSV, RHSV, "chardiff");
}
// memcmp(S1,S2,N/8)==0 -> (*(intN_t*)S1 != *(intN_t*)S2)==0
// TODO: The case where both inputs are constants does not need to be limited
// to legal integers or equality comparison. See block below this.
if (DL.isLegalInteger(Len * 8) && isOnlyUsedInZeroEqualityComparison(CI)) {
IntegerType *IntType = IntegerType::get(CI->getContext(), Len * 8);
unsigned PrefAlignment = DL.getPrefTypeAlignment(IntType);
// First, see if we can fold either argument to a constant.
Value *LHSV = nullptr;
if (auto *LHSC = dyn_cast<Constant>(LHS)) {
LHSC = ConstantExpr::getBitCast(LHSC, IntType->getPointerTo());
LHSV = ConstantFoldLoadFromConstPtr(LHSC, IntType, DL);
}
Value *RHSV = nullptr;
if (auto *RHSC = dyn_cast<Constant>(RHS)) {
RHSC = ConstantExpr::getBitCast(RHSC, IntType->getPointerTo());
RHSV = ConstantFoldLoadFromConstPtr(RHSC, IntType, DL);
}
// Don't generate unaligned loads. If either source is constant data,
// alignment doesn't matter for that source because there is no load.
if ((LHSV || getKnownAlignment(LHS, DL, CI) >= PrefAlignment) &&
(RHSV || getKnownAlignment(RHS, DL, CI) >= PrefAlignment)) {
if (!LHSV) {
Type *LHSPtrTy =
IntType->getPointerTo(LHS->getType()->getPointerAddressSpace());
LHSV = B.CreateLoad(IntType, B.CreateBitCast(LHS, LHSPtrTy), "lhsv");
}
if (!RHSV) {
Type *RHSPtrTy =
IntType->getPointerTo(RHS->getType()->getPointerAddressSpace());
RHSV = B.CreateLoad(IntType, B.CreateBitCast(RHS, RHSPtrTy), "rhsv");
}
return B.CreateZExt(B.CreateICmpNE(LHSV, RHSV), CI->getType(), "memcmp");
}
}
// Constant folding: memcmp(x, y, Len) -> constant (all arguments are const).
// TODO: This is limited to i8 arrays.
StringRef LHSStr, RHSStr;
if (getConstantStringInfo(LHS, LHSStr) &&
getConstantStringInfo(RHS, RHSStr)) {
// Make sure we're not reading out-of-bounds memory.
if (Len > LHSStr.size() || Len > RHSStr.size())
return nullptr;
// Fold the memcmp and normalize the result. This way we get consistent
// results across multiple platforms.
uint64_t Ret = 0;
int Cmp = memcmp(LHSStr.data(), RHSStr.data(), Len);
if (Cmp < 0)
Ret = -1;
else if (Cmp > 0)
Ret = 1;
return ConstantInt::get(CI->getType(), Ret);
}
return nullptr;
}
// Most simplifications for memcmp also apply to bcmp.
Value *LibCallSimplifier::optimizeMemCmpBCmpCommon(CallInst *CI,
IRBuilderBase &B) {
Value *LHS = CI->getArgOperand(0), *RHS = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
if (LHS == RHS) // memcmp(s,s,x) -> 0
return Constant::getNullValue(CI->getType());
annotateNonNullAndDereferenceable(CI, {0, 1}, Size, DL);
// Handle constant lengths.
ConstantInt *LenC = dyn_cast<ConstantInt>(Size);
if (!LenC)
return nullptr;
// memcmp(d,s,0) -> 0
if (LenC->getZExtValue() == 0)
return Constant::getNullValue(CI->getType());
if (Value *Res =
optimizeMemCmpConstantSize(CI, LHS, RHS, LenC->getZExtValue(), B, DL))
return Res;
return nullptr;
}
Value *LibCallSimplifier::optimizeMemCmp(CallInst *CI, IRBuilderBase &B) {
if (Value *V = optimizeMemCmpBCmpCommon(CI, B))
return V;
// memcmp(x, y, Len) == 0 -> bcmp(x, y, Len) == 0
// bcmp can be more efficient than memcmp because it only has to know that
// there is a difference, not how different one is to the other.
if (TLI->has(LibFunc_bcmp) && isOnlyUsedInZeroEqualityComparison(CI)) {
Value *LHS = CI->getArgOperand(0);
Value *RHS = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
return emitBCmp(LHS, RHS, Size, B, DL, TLI);
}
return nullptr;
}
Value *LibCallSimplifier::optimizeBCmp(CallInst *CI, IRBuilderBase &B) {
return optimizeMemCmpBCmpCommon(CI, B);
}
Value *LibCallSimplifier::optimizeMemCpy(CallInst *CI, IRBuilderBase &B) {
Value *Size = CI->getArgOperand(2);
annotateNonNullAndDereferenceable(CI, {0, 1}, Size, DL);
if (isa<IntrinsicInst>(CI))
return nullptr;
// memcpy(x, y, n) -> llvm.memcpy(align 1 x, align 1 y, n)
CallInst *NewCI = B.CreateMemCpy(CI->getArgOperand(0), Align(1),
CI->getArgOperand(1), Align(1), Size);
NewCI->setAttributes(CI->getAttributes());
NewCI->removeAttributes(AttributeList::ReturnIndex,
AttributeFuncs::typeIncompatible(NewCI->getType()));
return CI->getArgOperand(0);
}
Value *LibCallSimplifier::optimizeMemCCpy(CallInst *CI, IRBuilderBase &B) {
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
ConstantInt *StopChar = dyn_cast<ConstantInt>(CI->getArgOperand(2));
ConstantInt *N = dyn_cast<ConstantInt>(CI->getArgOperand(3));
StringRef SrcStr;
if (CI->use_empty() && Dst == Src)
return Dst;
// memccpy(d, s, c, 0) -> nullptr
if (N) {
if (N->isNullValue())
return Constant::getNullValue(CI->getType());
if (!getConstantStringInfo(Src, SrcStr, /*Offset=*/0,
/*TrimAtNul=*/false) ||
!StopChar)
return nullptr;
} else {
return nullptr;
}
// Wrap arg 'c' of type int to char
size_t Pos = SrcStr.find(StopChar->getSExtValue() & 0xFF);
if (Pos == StringRef::npos) {
if (N->getZExtValue() <= SrcStr.size()) {
B.CreateMemCpy(Dst, Align(1), Src, Align(1), CI->getArgOperand(3));
return Constant::getNullValue(CI->getType());
}
return nullptr;
}
Value *NewN =
ConstantInt::get(N->getType(), std::min(uint64_t(Pos + 1), N->getZExtValue()));
// memccpy -> llvm.memcpy
B.CreateMemCpy(Dst, Align(1), Src, Align(1), NewN);
return Pos + 1 <= N->getZExtValue()
? B.CreateInBoundsGEP(B.getInt8Ty(), Dst, NewN)
: Constant::getNullValue(CI->getType());
}
Value *LibCallSimplifier::optimizeMemPCpy(CallInst *CI, IRBuilderBase &B) {
Value *Dst = CI->getArgOperand(0);
Value *N = CI->getArgOperand(2);
// mempcpy(x, y, n) -> llvm.memcpy(align 1 x, align 1 y, n), x + n
CallInst *NewCI =
B.CreateMemCpy(Dst, Align(1), CI->getArgOperand(1), Align(1), N);
// Propagate attributes, but memcpy has no return value, so make sure that
// any return attributes are compliant.
// TODO: Attach return value attributes to the 1st operand to preserve them?
NewCI->setAttributes(CI->getAttributes());
NewCI->removeAttributes(AttributeList::ReturnIndex,
AttributeFuncs::typeIncompatible(NewCI->getType()));
return B.CreateInBoundsGEP(B.getInt8Ty(), Dst, N);
}
Value *LibCallSimplifier::optimizeMemMove(CallInst *CI, IRBuilderBase &B) {
Value *Size = CI->getArgOperand(2);
annotateNonNullAndDereferenceable(CI, {0, 1}, Size, DL);
if (isa<IntrinsicInst>(CI))
return nullptr;
// memmove(x, y, n) -> llvm.memmove(align 1 x, align 1 y, n)
CallInst *NewCI = B.CreateMemMove(CI->getArgOperand(0), Align(1),
CI->getArgOperand(1), Align(1), Size);
NewCI->setAttributes(CI->getAttributes());
NewCI->removeAttributes(AttributeList::ReturnIndex,
AttributeFuncs::typeIncompatible(NewCI->getType()));
return CI->getArgOperand(0);
}
/// Fold memset[_chk](malloc(n), 0, n) --> calloc(1, n).
Value *LibCallSimplifier::foldMallocMemset(CallInst *Memset, IRBuilderBase &B) {
// This has to be a memset of zeros (bzero).
auto *FillValue = dyn_cast<ConstantInt>(Memset->getArgOperand(1));
if (!FillValue || FillValue->getZExtValue() != 0)
return nullptr;
// TODO: We should handle the case where the malloc has more than one use.
// This is necessary to optimize common patterns such as when the result of
// the malloc is checked against null or when a memset intrinsic is used in
// place of a memset library call.
auto *Malloc = dyn_cast<CallInst>(Memset->getArgOperand(0));
if (!Malloc || !Malloc->hasOneUse())
return nullptr;
// Is the inner call really malloc()?
Function *InnerCallee = Malloc->getCalledFunction();
if (!InnerCallee)
return nullptr;
LibFunc Func;
if (!TLI->getLibFunc(*InnerCallee, Func) || !TLI->has(Func) ||
Func != LibFunc_malloc)
return nullptr;
// The memset must cover the same number of bytes that are malloc'd.
if (Memset->getArgOperand(2) != Malloc->getArgOperand(0))
return nullptr;
// Replace the malloc with a calloc. We need the data layout to know what the
// actual size of a 'size_t' parameter is.
B.SetInsertPoint(Malloc->getParent(), ++Malloc->getIterator());
const DataLayout &DL = Malloc->getModule()->getDataLayout();
IntegerType *SizeType = DL.getIntPtrType(B.GetInsertBlock()->getContext());
if (Value *Calloc = emitCalloc(ConstantInt::get(SizeType, 1),
Malloc->getArgOperand(0),
Malloc->getAttributes(), B, *TLI)) {
substituteInParent(Malloc, Calloc);
return Calloc;
}
return nullptr;
}
Value *LibCallSimplifier::optimizeMemSet(CallInst *CI, IRBuilderBase &B) {
Value *Size = CI->getArgOperand(2);
annotateNonNullAndDereferenceable(CI, 0, Size, DL);
if (isa<IntrinsicInst>(CI))
return nullptr;
if (auto *Calloc = foldMallocMemset(CI, B))
return Calloc;
// memset(p, v, n) -> llvm.memset(align 1 p, v, n)
Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(), false);
CallInst *NewCI = B.CreateMemSet(CI->getArgOperand(0), Val, Size, Align(1));
NewCI->setAttributes(CI->getAttributes());
NewCI->removeAttributes(AttributeList::ReturnIndex,
AttributeFuncs::typeIncompatible(NewCI->getType()));
return CI->getArgOperand(0);
}
Value *LibCallSimplifier::optimizeRealloc(CallInst *CI, IRBuilderBase &B) {
if (isa<ConstantPointerNull>(CI->getArgOperand(0)))
return emitMalloc(CI->getArgOperand(1), B, DL, TLI);
return nullptr;
}
//===----------------------------------------------------------------------===//
// Math Library Optimizations
//===----------------------------------------------------------------------===//
// Replace a libcall \p CI with a call to intrinsic \p IID
static Value *replaceUnaryCall(CallInst *CI, IRBuilderBase &B,
Intrinsic::ID IID) {
// Propagate fast-math flags from the existing call to the new call.
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(CI->getFastMathFlags());
Module *M = CI->getModule();
Value *V = CI->getArgOperand(0);
Function *F = Intrinsic::getDeclaration(M, IID, CI->getType());
CallInst *NewCall = B.CreateCall(F, V);
NewCall->takeName(CI);
return NewCall;
}
/// Return a variant of Val with float type.
/// Currently this works in two cases: If Val is an FPExtension of a float
/// value to something bigger, simply return the operand.
/// If Val is a ConstantFP but can be converted to a float ConstantFP without
/// loss of precision do so.
static Value *valueHasFloatPrecision(Value *Val) {
if (FPExtInst *Cast = dyn_cast<FPExtInst>(Val)) {
Value *Op = Cast->getOperand(0);
if (Op->getType()->isFloatTy())
return Op;
}
if (ConstantFP *Const = dyn_cast<ConstantFP>(Val)) {
APFloat F = Const->getValueAPF();
bool losesInfo;
(void)F.convert(APFloat::IEEEsingle(), APFloat::rmNearestTiesToEven,
&losesInfo);
if (!losesInfo)
return ConstantFP::get(Const->getContext(), F);
}
return nullptr;
}
/// Shrink double -> float functions.
static Value *optimizeDoubleFP(CallInst *CI, IRBuilderBase &B,
bool isBinary, bool isPrecise = false) {
Function *CalleeFn = CI->getCalledFunction();
if (!CI->getType()->isDoubleTy() || !CalleeFn)
return nullptr;
// If not all the uses of the function are converted to float, then bail out.
// This matters if the precision of the result is more important than the
// precision of the arguments.
if (isPrecise)
for (User *U : CI->users()) {
FPTruncInst *Cast = dyn_cast<FPTruncInst>(U);
if (!Cast || !Cast->getType()->isFloatTy())
return nullptr;
}
// If this is something like 'g((double) float)', convert to 'gf(float)'.
Value *V[2];
V[0] = valueHasFloatPrecision(CI->getArgOperand(0));
V[1] = isBinary ? valueHasFloatPrecision(CI->getArgOperand(1)) : nullptr;
if (!V[0] || (isBinary && !V[1]))
return nullptr;
// If call isn't an intrinsic, check that it isn't within a function with the
// same name as the float version of this call, otherwise the result is an
// infinite loop. For example, from MinGW-w64:
//
// float expf(float val) { return (float) exp((double) val); }
StringRef CalleeName = CalleeFn->getName();
bool IsIntrinsic = CalleeFn->isIntrinsic();
if (!IsIntrinsic) {
StringRef CallerName = CI->getFunction()->getName();
if (!CallerName.empty() && CallerName.back() == 'f' &&
CallerName.size() == (CalleeName.size() + 1) &&
CallerName.startswith(CalleeName))
return nullptr;
}
// Propagate the math semantics from the current function to the new function.
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(CI->getFastMathFlags());
// g((double) float) -> (double) gf(float)
Value *R;
if (IsIntrinsic) {
Module *M = CI->getModule();
Intrinsic::ID IID = CalleeFn->getIntrinsicID();
Function *Fn = Intrinsic::getDeclaration(M, IID, B.getFloatTy());
R = isBinary ? B.CreateCall(Fn, V) : B.CreateCall(Fn, V[0]);
} else {
AttributeList CalleeAttrs = CalleeFn->getAttributes();
R = isBinary ? emitBinaryFloatFnCall(V[0], V[1], CalleeName, B, CalleeAttrs)
: emitUnaryFloatFnCall(V[0], CalleeName, B, CalleeAttrs);
}
return B.CreateFPExt(R, B.getDoubleTy());
}
/// Shrink double -> float for unary functions.
static Value *optimizeUnaryDoubleFP(CallInst *CI, IRBuilderBase &B,
bool isPrecise = false) {
return optimizeDoubleFP(CI, B, false, isPrecise);
}
/// Shrink double -> float for binary functions.
static Value *optimizeBinaryDoubleFP(CallInst *CI, IRBuilderBase &B,
bool isPrecise = false) {
return optimizeDoubleFP(CI, B, true, isPrecise);
}
// cabs(z) -> sqrt((creal(z)*creal(z)) + (cimag(z)*cimag(z)))
Value *LibCallSimplifier::optimizeCAbs(CallInst *CI, IRBuilderBase &B) {
if (!CI->isFast())
return nullptr;
// Propagate fast-math flags from the existing call to new instructions.
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(CI->getFastMathFlags());
Value *Real, *Imag;
if (CI->getNumArgOperands() == 1) {
Value *Op = CI->getArgOperand(0);
assert(Op->getType()->isArrayTy() && "Unexpected signature for cabs!");
Real = B.CreateExtractValue(Op, 0, "real");
Imag = B.CreateExtractValue(Op, 1, "imag");
} else {
assert(CI->getNumArgOperands() == 2 && "Unexpected signature for cabs!");
Real = CI->getArgOperand(0);
Imag = CI->getArgOperand(1);
}
Value *RealReal = B.CreateFMul(Real, Real);
Value *ImagImag = B.CreateFMul(Imag, Imag);
Function *FSqrt = Intrinsic::getDeclaration(CI->getModule(), Intrinsic::sqrt,
CI->getType());
return B.CreateCall(FSqrt, B.CreateFAdd(RealReal, ImagImag), "cabs");
}
static Value *optimizeTrigReflections(CallInst *Call, LibFunc Func,
IRBuilderBase &B) {
if (!isa<FPMathOperator>(Call))
return nullptr;
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(Call->getFastMathFlags());
// TODO: Can this be shared to also handle LLVM intrinsics?
Value *X;
switch (Func) {
case LibFunc_sin:
case LibFunc_sinf:
case LibFunc_sinl:
case LibFunc_tan:
case LibFunc_tanf:
case LibFunc_tanl:
// sin(-X) --> -sin(X)
// tan(-X) --> -tan(X)
if (match(Call->getArgOperand(0), m_OneUse(m_FNeg(m_Value(X)))))
return B.CreateFNeg(B.CreateCall(Call->getCalledFunction(), X));
break;
case LibFunc_cos:
case LibFunc_cosf:
case LibFunc_cosl:
// cos(-X) --> cos(X)
if (match(Call->getArgOperand(0), m_FNeg(m_Value(X))))
return B.CreateCall(Call->getCalledFunction(), X, "cos");
break;
default:
break;
}
return nullptr;
}
static Value *getPow(Value *InnerChain[33], unsigned Exp, IRBuilderBase &B) {
// Multiplications calculated using Addition Chains.
// Refer: http://wwwhomes.uni-bielefeld.de/achim/addition_chain.html
assert(Exp != 0 && "Incorrect exponent 0 not handled");
if (InnerChain[Exp])
return InnerChain[Exp];
static const unsigned AddChain[33][2] = {
{0, 0}, // Unused.
{0, 0}, // Unused (base case = pow1).
{1, 1}, // Unused (pre-computed).
{1, 2}, {2, 2}, {2, 3}, {3, 3}, {2, 5}, {4, 4},
{1, 8}, {5, 5}, {1, 10}, {6, 6}, {4, 9}, {7, 7},
{3, 12}, {8, 8}, {8, 9}, {2, 16}, {1, 18}, {10, 10},
{6, 15}, {11, 11}, {3, 20}, {12, 12}, {8, 17}, {13, 13},
{3, 24}, {14, 14}, {4, 25}, {15, 15}, {3, 28}, {16, 16},
};
InnerChain[Exp] = B.CreateFMul(getPow(InnerChain, AddChain[Exp][0], B),
getPow(InnerChain, AddChain[Exp][1], B));
return InnerChain[Exp];
}
// Return a properly extended 32-bit integer if the operation is an itofp.
static Value *getIntToFPVal(Value *I2F, IRBuilderBase &B) {
if (isa<SIToFPInst>(I2F) || isa<UIToFPInst>(I2F)) {
Value *Op = cast<Instruction>(I2F)->getOperand(0);
// Make sure that the exponent fits inside an int32_t,
// thus avoiding any range issues that FP has not.
unsigned BitWidth = Op->getType()->getPrimitiveSizeInBits();
if (BitWidth < 32 ||
(BitWidth == 32 && isa<SIToFPInst>(I2F)))
return isa<SIToFPInst>(I2F) ? B.CreateSExt(Op, B.getInt32Ty())
: B.CreateZExt(Op, B.getInt32Ty());
}
return nullptr;
}
/// Use exp{,2}(x * y) for pow(exp{,2}(x), y);
/// ldexp(1.0, x) for pow(2.0, itofp(x)); exp2(n * x) for pow(2.0 ** n, x);
/// exp10(x) for pow(10.0, x); exp2(log2(n) * x) for pow(n, x).
Value *LibCallSimplifier::replacePowWithExp(CallInst *Pow, IRBuilderBase &B) {
Value *Base = Pow->getArgOperand(0), *Expo = Pow->getArgOperand(1);
AttributeList Attrs; // Attributes are only meaningful on the original call
Module *Mod = Pow->getModule();
Type *Ty = Pow->getType();
bool Ignored;
// Evaluate special cases related to a nested function as the base.
// pow(exp(x), y) -> exp(x * y)
// pow(exp2(x), y) -> exp2(x * y)
// If exp{,2}() is used only once, it is better to fold two transcendental
// math functions into one. If used again, exp{,2}() would still have to be
// called with the original argument, then keep both original transcendental
// functions. However, this transformation is only safe with fully relaxed
// math semantics, since, besides rounding differences, it changes overflow
// and underflow behavior quite dramatically. For example:
// pow(exp(1000), 0.001) = pow(inf, 0.001) = inf
// Whereas:
// exp(1000 * 0.001) = exp(1)
// TODO: Loosen the requirement for fully relaxed math semantics.
// TODO: Handle exp10() when more targets have it available.
CallInst *BaseFn = dyn_cast<CallInst>(Base);
if (BaseFn && BaseFn->hasOneUse() && BaseFn->isFast() && Pow->isFast()) {
LibFunc LibFn;
Function *CalleeFn = BaseFn->getCalledFunction();
if (CalleeFn &&
TLI->getLibFunc(CalleeFn->getName(), LibFn) && TLI->has(LibFn)) {
StringRef ExpName;
Intrinsic::ID ID;
Value *ExpFn;
LibFunc LibFnFloat, LibFnDouble, LibFnLongDouble;
switch (LibFn) {
default:
return nullptr;
case LibFunc_expf: case LibFunc_exp: case LibFunc_expl:
ExpName = TLI->getName(LibFunc_exp);
ID = Intrinsic::exp;
LibFnFloat = LibFunc_expf;
LibFnDouble = LibFunc_exp;
LibFnLongDouble = LibFunc_expl;
break;
case LibFunc_exp2f: case LibFunc_exp2: case LibFunc_exp2l:
ExpName = TLI->getName(LibFunc_exp2);
ID = Intrinsic::exp2;
LibFnFloat = LibFunc_exp2f;
LibFnDouble = LibFunc_exp2;
LibFnLongDouble = LibFunc_exp2l;
break;
}
// Create new exp{,2}() with the product as its argument.
Value *FMul = B.CreateFMul(BaseFn->getArgOperand(0), Expo, "mul");
ExpFn = BaseFn->doesNotAccessMemory()
? B.CreateCall(Intrinsic::getDeclaration(Mod, ID, Ty),
FMul, ExpName)
: emitUnaryFloatFnCall(FMul, TLI, LibFnDouble, LibFnFloat,
LibFnLongDouble, B,
BaseFn->getAttributes());
// Since the new exp{,2}() is different from the original one, dead code
// elimination cannot be trusted to remove it, since it may have side
// effects (e.g., errno). When the only consumer for the original
// exp{,2}() is pow(), then it has to be explicitly erased.
substituteInParent(BaseFn, ExpFn);
return ExpFn;
}
}
// Evaluate special cases related to a constant base.
const APFloat *BaseF;
if (!match(Pow->getArgOperand(0), m_APFloat(BaseF)))
return nullptr;
// pow(2.0, itofp(x)) -> ldexp(1.0, x)
if (match(Base, m_SpecificFP(2.0)) &&
(isa<SIToFPInst>(Expo) || isa<UIToFPInst>(Expo)) &&
hasFloatFn(TLI, Ty, LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl)) {
if (Value *ExpoI = getIntToFPVal(Expo, B))
return emitBinaryFloatFnCall(ConstantFP::get(Ty, 1.0), ExpoI, TLI,
LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl,
B, Attrs);
}
// pow(2.0 ** n, x) -> exp2(n * x)
if (hasFloatFn(TLI, Ty, LibFunc_exp2, LibFunc_exp2f, LibFunc_exp2l)) {
APFloat BaseR = APFloat(1.0);
BaseR.convert(BaseF->getSemantics(), APFloat::rmTowardZero, &Ignored);
BaseR = BaseR / *BaseF;
bool IsInteger = BaseF->isInteger(), IsReciprocal = BaseR.isInteger();
const APFloat *NF = IsReciprocal ? &BaseR : BaseF;
APSInt NI(64, false);
if ((IsInteger || IsReciprocal) &&
NF->convertToInteger(NI, APFloat::rmTowardZero, &Ignored) ==
APFloat::opOK &&
NI > 1 && NI.isPowerOf2()) {
double N = NI.logBase2() * (IsReciprocal ? -1.0 : 1.0);
Value *FMul = B.CreateFMul(Expo, ConstantFP::get(Ty, N), "mul");
if (Pow->doesNotAccessMemory())
return B.CreateCall(Intrinsic::getDeclaration(Mod, Intrinsic::exp2, Ty),
FMul, "exp2");
else
return emitUnaryFloatFnCall(FMul, TLI, LibFunc_exp2, LibFunc_exp2f,
LibFunc_exp2l, B, Attrs);
}
}
// pow(10.0, x) -> exp10(x)
// TODO: There is no exp10() intrinsic yet, but some day there shall be one.
if (match(Base, m_SpecificFP(10.0)) &&
hasFloatFn(TLI, Ty, LibFunc_exp10, LibFunc_exp10f, LibFunc_exp10l))
return emitUnaryFloatFnCall(Expo, TLI, LibFunc_exp10, LibFunc_exp10f,
LibFunc_exp10l, B, Attrs);
// pow(x, y) -> exp2(log2(x) * y)
if (Pow->hasApproxFunc() && Pow->hasNoNaNs() && BaseF->isFiniteNonZero() &&
!BaseF->isNegative()) {
// pow(1, inf) is defined to be 1 but exp2(log2(1) * inf) evaluates to NaN.
// Luckily optimizePow has already handled the x == 1 case.
assert(!match(Base, m_FPOne()) &&
"pow(1.0, y) should have been simplified earlier!");
Value *Log = nullptr;
if (Ty->isFloatTy())
Log = ConstantFP::get(Ty, std::log2(BaseF->convertToFloat()));
else if (Ty->isDoubleTy())
Log = ConstantFP::get(Ty, std::log2(BaseF->convertToDouble()));
if (Log) {
Value *FMul = B.CreateFMul(Log, Expo, "mul");
if (Pow->doesNotAccessMemory())
return B.CreateCall(Intrinsic::getDeclaration(Mod, Intrinsic::exp2, Ty),
FMul, "exp2");
else if (hasFloatFn(TLI, Ty, LibFunc_exp2, LibFunc_exp2f, LibFunc_exp2l))
return emitUnaryFloatFnCall(FMul, TLI, LibFunc_exp2, LibFunc_exp2f,
LibFunc_exp2l, B, Attrs);
}
}
return nullptr;
}
static Value *getSqrtCall(Value *V, AttributeList Attrs, bool NoErrno,
Module *M, IRBuilderBase &B,
const TargetLibraryInfo *TLI) {
// If errno is never set, then use the intrinsic for sqrt().
if (NoErrno) {
Function *SqrtFn =
Intrinsic::getDeclaration(M, Intrinsic::sqrt, V->getType());
return B.CreateCall(SqrtFn, V, "sqrt");
}
// Otherwise, use the libcall for sqrt().
if (hasFloatFn(TLI, V->getType(), LibFunc_sqrt, LibFunc_sqrtf, LibFunc_sqrtl))
// TODO: We also should check that the target can in fact lower the sqrt()
// libcall. We currently have no way to ask this question, so we ask if
// the target has a sqrt() libcall, which is not exactly the same.
return emitUnaryFloatFnCall(V, TLI, LibFunc_sqrt, LibFunc_sqrtf,
LibFunc_sqrtl, B, Attrs);
return nullptr;
}
/// Use square root in place of pow(x, +/-0.5).
Value *LibCallSimplifier::replacePowWithSqrt(CallInst *Pow, IRBuilderBase &B) {
Value *Sqrt, *Base = Pow->getArgOperand(0), *Expo = Pow->getArgOperand(1);
AttributeList Attrs; // Attributes are only meaningful on the original call
Module *Mod = Pow->getModule();
Type *Ty = Pow->getType();
const APFloat *ExpoF;
if (!match(Expo, m_APFloat(ExpoF)) ||
(!ExpoF->isExactlyValue(0.5) && !ExpoF->isExactlyValue(-0.5)))
return nullptr;
// Converting pow(X, -0.5) to 1/sqrt(X) may introduce an extra rounding step,
// so that requires fast-math-flags (afn or reassoc).
if (ExpoF->isNegative() && (!Pow->hasApproxFunc() && !Pow->hasAllowReassoc()))
return nullptr;
// If we have a pow() library call (accesses memory) and we can't guarantee
// that the base is not an infinity, give up:
// pow(-Inf, 0.5) is optionally required to have a result of +Inf (not setting
// errno), but sqrt(-Inf) is required by various standards to set errno.
if (!Pow->doesNotAccessMemory() && !Pow->hasNoInfs() &&
!isKnownNeverInfinity(Base, TLI))
return nullptr;
Sqrt = getSqrtCall(Base, Attrs, Pow->doesNotAccessMemory(), Mod, B, TLI);
if (!Sqrt)
return nullptr;
// Handle signed zero base by expanding to fabs(sqrt(x)).
if (!Pow->hasNoSignedZeros()) {
Function *FAbsFn = Intrinsic::getDeclaration(Mod, Intrinsic::fabs, Ty);
Sqrt = B.CreateCall(FAbsFn, Sqrt, "abs");
}
// Handle non finite base by expanding to
// (x == -infinity ? +infinity : sqrt(x)).
if (!Pow->hasNoInfs()) {
Value *PosInf = ConstantFP::getInfinity(Ty),
*NegInf = ConstantFP::getInfinity(Ty, true);
Value *FCmp = B.CreateFCmpOEQ(Base, NegInf, "isinf");
Sqrt = B.CreateSelect(FCmp, PosInf, Sqrt);
}
// If the exponent is negative, then get the reciprocal.
if (ExpoF->isNegative())
Sqrt = B.CreateFDiv(ConstantFP::get(Ty, 1.0), Sqrt, "reciprocal");
return Sqrt;
}
static Value *createPowWithIntegerExponent(Value *Base, Value *Expo, Module *M,
IRBuilderBase &B) {
Value *Args[] = {Base, Expo};
Function *F = Intrinsic::getDeclaration(M, Intrinsic::powi, Base->getType());
return B.CreateCall(F, Args);
}
Value *LibCallSimplifier::optimizePow(CallInst *Pow, IRBuilderBase &B) {
Value *Base = Pow->getArgOperand(0);
Value *Expo = Pow->getArgOperand(1);
Function *Callee = Pow->getCalledFunction();
StringRef Name = Callee->getName();
Type *Ty = Pow->getType();
Module *M = Pow->getModule();
bool AllowApprox = Pow->hasApproxFunc();
bool Ignored;
// Propagate the math semantics from the call to any created instructions.
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(Pow->getFastMathFlags());
// Evaluate special cases related to the base.
// pow(1.0, x) -> 1.0
if (match(Base, m_FPOne()))
return Base;
if (Value *Exp = replacePowWithExp(Pow, B))
return Exp;
// Evaluate special cases related to the exponent.
// pow(x, -1.0) -> 1.0 / x
if (match(Expo, m_SpecificFP(-1.0)))
return B.CreateFDiv(ConstantFP::get(Ty, 1.0), Base, "reciprocal");
// pow(x, +/-0.0) -> 1.0
if (match(Expo, m_AnyZeroFP()))
return ConstantFP::get(Ty, 1.0);
// pow(x, 1.0) -> x
if (match(Expo, m_FPOne()))
return Base;
// pow(x, 2.0) -> x * x
if (match(Expo, m_SpecificFP(2.0)))
return B.CreateFMul(Base, Base, "square");
if (Value *Sqrt = replacePowWithSqrt(Pow, B))
return Sqrt;
// pow(x, n) -> x * x * x * ...
const APFloat *ExpoF;
if (AllowApprox && match(Expo, m_APFloat(ExpoF)) &&
!ExpoF->isExactlyValue(0.5) && !ExpoF->isExactlyValue(-0.5)) {
// We limit to a max of 7 multiplications, thus the maximum exponent is 32.
// If the exponent is an integer+0.5 we generate a call to sqrt and an
// additional fmul.
// TODO: This whole transformation should be backend specific (e.g. some
// backends might prefer libcalls or the limit for the exponent might
// be different) and it should also consider optimizing for size.
APFloat LimF(ExpoF->getSemantics(), 33),
ExpoA(abs(*ExpoF));
if (ExpoA < LimF) {
// This transformation applies to integer or integer+0.5 exponents only.
// For integer+0.5, we create a sqrt(Base) call.
Value *Sqrt = nullptr;
if (!ExpoA.isInteger()) {
APFloat Expo2 = ExpoA;
// To check if ExpoA is an integer + 0.5, we add it to itself. If there
// is no floating point exception and the result is an integer, then
// ExpoA == integer + 0.5
if (Expo2.add(ExpoA, APFloat::rmNearestTiesToEven) != APFloat::opOK)
return nullptr;
if (!Expo2.isInteger())
return nullptr;
Sqrt = getSqrtCall(Base, Pow->getCalledFunction()->getAttributes(),
Pow->doesNotAccessMemory(), M, B, TLI);
if (!Sqrt)
return nullptr;
}
// We will memoize intermediate products of the Addition Chain.
Value *InnerChain[33] = {nullptr};
InnerChain[1] = Base;
InnerChain[2] = B.CreateFMul(Base, Base, "square");
// We cannot readily convert a non-double type (like float) to a double.
// So we first convert it to something which could be converted to double.
ExpoA.convert(APFloat::IEEEdouble(), APFloat::rmTowardZero, &Ignored);
Value *FMul = getPow(InnerChain, ExpoA.convertToDouble(), B);
// Expand pow(x, y+0.5) to pow(x, y) * sqrt(x).
if (Sqrt)
FMul = B.CreateFMul(FMul, Sqrt);
// If the exponent is negative, then get the reciprocal.
if (ExpoF->isNegative())
FMul = B.CreateFDiv(ConstantFP::get(Ty, 1.0), FMul, "reciprocal");
return FMul;
}
APSInt IntExpo(32, /*isUnsigned=*/false);
// powf(x, n) -> powi(x, n) if n is a constant signed integer value
if (ExpoF->isInteger() &&
ExpoF->convertToInteger(IntExpo, APFloat::rmTowardZero, &Ignored) ==
APFloat::opOK) {
return createPowWithIntegerExponent(
Base, ConstantInt::get(B.getInt32Ty(), IntExpo), M, B);
}
}
// powf(x, itofp(y)) -> powi(x, y)
if (AllowApprox && (isa<SIToFPInst>(Expo) || isa<UIToFPInst>(Expo))) {
if (Value *ExpoI = getIntToFPVal(Expo, B))
return createPowWithIntegerExponent(Base, ExpoI, M, B);
}
// Shrink pow() to powf() if the arguments are single precision,
// unless the result is expected to be double precision.
if (UnsafeFPShrink && Name == TLI->getName(LibFunc_pow) &&
hasFloatVersion(Name)) {
if (Value *Shrunk = optimizeBinaryDoubleFP(Pow, B, true))
return Shrunk;
}
return nullptr;
}
Value *LibCallSimplifier::optimizeExp2(CallInst *CI, IRBuilderBase &B) {
Function *Callee = CI->getCalledFunction();
AttributeList Attrs; // Attributes are only meaningful on the original call
StringRef Name = Callee->getName();
Value *Ret = nullptr;
if (UnsafeFPShrink && Name == TLI->getName(LibFunc_exp2) &&
hasFloatVersion(Name))
Ret = optimizeUnaryDoubleFP(CI, B, true);
Type *Ty = CI->getType();
Value *Op = CI->getArgOperand(0);
// 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
if ((isa<SIToFPInst>(Op) || isa<UIToFPInst>(Op)) &&
hasFloatFn(TLI, Ty, LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl)) {
if (Value *Exp = getIntToFPVal(Op, B))
return emitBinaryFloatFnCall(ConstantFP::get(Ty, 1.0), Exp, TLI,
LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl,
B, Attrs);
}
return Ret;
}
Value *LibCallSimplifier::optimizeFMinFMax(CallInst *CI, IRBuilderBase &B) {
// If we can shrink the call to a float function rather than a double
// function, do that first.
Function *Callee = CI->getCalledFunction();
StringRef Name = Callee->getName();
if ((Name == "fmin" || Name == "fmax") && hasFloatVersion(Name))
if (Value *Ret = optimizeBinaryDoubleFP(CI, B))
return Ret;
// The LLVM intrinsics minnum/maxnum correspond to fmin/fmax. Canonicalize to
// the intrinsics for improved optimization (for example, vectorization).
// No-signed-zeros is implied by the definitions of fmax/fmin themselves.
// From the C standard draft WG14/N1256:
// "Ideally, fmax would be sensitive to the sign of zero, for example
// fmax(-0.0, +0.0) would return +0; however, implementation in software
// might be impractical."
IRBuilderBase::FastMathFlagGuard Guard(B);
FastMathFlags FMF = CI->getFastMathFlags();
FMF.setNoSignedZeros();
B.setFastMathFlags(FMF);
Intrinsic::ID IID = Callee->getName().startswith("fmin") ? Intrinsic::minnum
: Intrinsic::maxnum;
Function *F = Intrinsic::getDeclaration(CI->getModule(), IID, CI->getType());
return B.CreateCall(F, { CI->getArgOperand(0), CI->getArgOperand(1) });
}
Value *LibCallSimplifier::optimizeLog(CallInst *Log, IRBuilderBase &B) {
Function *LogFn = Log->getCalledFunction();
AttributeList Attrs; // Attributes are only meaningful on the original call
StringRef LogNm = LogFn->getName();
Intrinsic::ID LogID = LogFn->getIntrinsicID();
Module *Mod = Log->getModule();
Type *Ty = Log->getType();
Value *Ret = nullptr;
if (UnsafeFPShrink && hasFloatVersion(LogNm))
Ret = optimizeUnaryDoubleFP(Log, B, true);
// The earlier call must also be 'fast' in order to do these transforms.
CallInst *Arg = dyn_cast<CallInst>(Log->getArgOperand(0));
if (!Log->isFast() || !Arg || !Arg->isFast() || !Arg->hasOneUse())
return Ret;
LibFunc LogLb, ExpLb, Exp2Lb, Exp10Lb, PowLb;
// This is only applicable to log(), log2(), log10().
if (TLI->getLibFunc(LogNm, LogLb))
switch (LogLb) {
case LibFunc_logf:
LogID = Intrinsic::log;
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
break;
case LibFunc_log:
LogID = Intrinsic::log;
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
break;
case LibFunc_logl:
LogID = Intrinsic::log;
ExpLb = LibFunc_expl;
Exp2Lb = LibFunc_exp2l;
Exp10Lb = LibFunc_exp10l;
PowLb = LibFunc_powl;
break;
case LibFunc_log2f:
LogID = Intrinsic::log2;
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
break;
case LibFunc_log2:
LogID = Intrinsic::log2;
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
break;
case LibFunc_log2l:
LogID = Intrinsic::log2;
ExpLb = LibFunc_expl;
Exp2Lb = LibFunc_exp2l;
Exp10Lb = LibFunc_exp10l;
PowLb = LibFunc_powl;
break;
case LibFunc_log10f:
LogID = Intrinsic::log10;
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
break;
case LibFunc_log10:
LogID = Intrinsic::log10;
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
break;
case LibFunc_log10l:
LogID = Intrinsic::log10;
ExpLb = LibFunc_expl;
Exp2Lb = LibFunc_exp2l;
Exp10Lb = LibFunc_exp10l;
PowLb = LibFunc_powl;
break;
default:
return Ret;
}
else if (LogID == Intrinsic::log || LogID == Intrinsic::log2 ||
LogID == Intrinsic::log10) {
if (Ty->getScalarType()->isFloatTy()) {
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
} else if (Ty->getScalarType()->isDoubleTy()) {
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
} else
return Ret;
} else
return Ret;
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(FastMathFlags::getFast());
Intrinsic::ID ArgID = Arg->getIntrinsicID();
LibFunc ArgLb = NotLibFunc;
TLI->getLibFunc(*Arg, ArgLb);
// log(pow(x,y)) -> y*log(x)
if (ArgLb == PowLb || ArgID == Intrinsic::pow) {
Value *LogX =
Log->doesNotAccessMemory()
? B.CreateCall(Intrinsic::getDeclaration(Mod, LogID, Ty),
Arg->getOperand(0), "log")
: emitUnaryFloatFnCall(Arg->getOperand(0), LogNm, B, Attrs);
Value *MulY = B.CreateFMul(Arg->getArgOperand(1), LogX, "mul");
// Since pow() may have side effects, e.g. errno,
// dead code elimination may not be trusted to remove it.
substituteInParent(Arg, MulY);
return MulY;
}
// log(exp{,2,10}(y)) -> y*log({e,2,10})
// TODO: There is no exp10() intrinsic yet.
if (ArgLb == ExpLb || ArgLb == Exp2Lb || ArgLb == Exp10Lb ||
ArgID == Intrinsic::exp || ArgID == Intrinsic::exp2) {
Constant *Eul;
if (ArgLb == ExpLb || ArgID == Intrinsic::exp)
// FIXME: Add more precise value of e for long double.
Eul = ConstantFP::get(Log->getType(), numbers::e);
else if (ArgLb == Exp2Lb || ArgID == Intrinsic::exp2)
Eul = ConstantFP::get(Log->getType(), 2.0);
else
Eul = ConstantFP::get(Log->getType(), 10.0);
Value *LogE = Log->doesNotAccessMemory()
? B.CreateCall(Intrinsic::getDeclaration(Mod, LogID, Ty),
Eul, "log")
: emitUnaryFloatFnCall(Eul, LogNm, B, Attrs);
Value *MulY = B.CreateFMul(Arg->getArgOperand(0), LogE, "mul");
// Since exp() may have side effects, e.g. errno,
// dead code elimination may not be trusted to remove it.
substituteInParent(Arg, MulY);
return MulY;
}
return Ret;
}
Value *LibCallSimplifier::optimizeSqrt(CallInst *CI, IRBuilderBase &B) {
Function *Callee = CI->getCalledFunction();
Value *Ret = nullptr;
// TODO: Once we have a way (other than checking for the existince of the
// libcall) to tell whether our target can lower @llvm.sqrt, relax the
// condition below.
if (TLI->has(LibFunc_sqrtf) && (Callee->getName() == "sqrt" ||
Callee->getIntrinsicID() == Intrinsic::sqrt))
Ret = optimizeUnaryDoubleFP(CI, B, true);
if (!CI->isFast())
return Ret;
Instruction *I = dyn_cast<Instruction>(CI->getArgOperand(0));
if (!I || I->getOpcode() != Instruction::FMul || !I->isFast())
return Ret;
// We're looking for a repeated factor in a multiplication tree,
// so we can do this fold: sqrt(x * x) -> fabs(x);
// or this fold: sqrt((x * x) * y) -> fabs(x) * sqrt(y).
Value *Op0 = I->getOperand(0);
Value *Op1 = I->getOperand(1);
Value *RepeatOp = nullptr;
Value *OtherOp = nullptr;
if (Op0 == Op1) {
// Simple match: the operands of the multiply are identical.
RepeatOp = Op0;
} else {
// Look for a more complicated pattern: one of the operands is itself
// a multiply, so search for a common factor in that multiply.
// Note: We don't bother looking any deeper than this first level or for
// variations of this pattern because instcombine's visitFMUL and/or the
// reassociation pass should give us this form.
Value *OtherMul0, *OtherMul1;
if (match(Op0, m_FMul(m_Value(OtherMul0), m_Value(OtherMul1)))) {
// Pattern: sqrt((x * y) * z)
if (OtherMul0 == OtherMul1 && cast<Instruction>(Op0)->isFast()) {
// Matched: sqrt((x * x) * z)
RepeatOp = OtherMul0;
OtherOp = Op1;
}
}
}
if (!RepeatOp)
return Ret;
// Fast math flags for any created instructions should match the sqrt
// and multiply.
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(I->getFastMathFlags());
// If we found a repeated factor, hoist it out of the square root and
// replace it with the fabs of that factor.
Module *M = Callee->getParent();
Type *ArgType = I->getType();
Function *Fabs = Intrinsic::getDeclaration(M, Intrinsic::fabs, ArgType);
Value *FabsCall = B.CreateCall(Fabs, RepeatOp, "fabs");
if (OtherOp) {
// If we found a non-repeated factor, we still need to get its square
// root. We then multiply that by the value that was simplified out
// of the square root calculation.
Function *Sqrt = Intrinsic::getDeclaration(M, Intrinsic::sqrt, ArgType);
Value *SqrtCall = B.CreateCall(Sqrt, OtherOp, "sqrt");
return B.CreateFMul(FabsCall, SqrtCall);
}
return FabsCall;
}
// TODO: Generalize to handle any trig function and its inverse.
Value *LibCallSimplifier::optimizeTan(CallInst *CI, IRBuilderBase &B) {
Function *Callee = CI->getCalledFunction();
Value *Ret = nullptr;
StringRef Name = Callee->getName();
if (UnsafeFPShrink && Name == "tan" && hasFloatVersion(Name))
Ret = optimizeUnaryDoubleFP(CI, B, true);
Value *Op1 = CI->getArgOperand(0);
auto *OpC = dyn_cast<CallInst>(Op1);
if (!OpC)
return Ret;
// Both calls must be 'fast' in order to remove them.
if (!CI->isFast() || !OpC->isFast())
return Ret;
// tan(atan(x)) -> x
// tanf(atanf(x)) -> x
// tanl(atanl(x)) -> x
LibFunc Func;
Function *F = OpC->getCalledFunction();
if (F && TLI->getLibFunc(F->getName(), Func) && TLI->has(Func) &&
((Func == LibFunc_atan && Callee->getName() == "tan") ||
(Func == LibFunc_atanf && Callee->getName() == "tanf") ||
(Func == LibFunc_atanl && Callee->getName() == "tanl")))
Ret = OpC->getArgOperand(0);
return Ret;
}
static bool isTrigLibCall(CallInst *CI) {
// We can only hope to do anything useful if we can ignore things like errno
// and floating-point exceptions.
// We already checked the prototype.
return CI->hasFnAttr(Attribute::NoUnwind) &&
CI->hasFnAttr(Attribute::ReadNone);
}
static void insertSinCosCall(IRBuilderBase &B, Function *OrigCallee, Value *Arg,
bool UseFloat, Value *&Sin, Value *&Cos,
Value *&SinCos) {
Type *ArgTy = Arg->getType();
Type *ResTy;
StringRef Name;
Triple T(OrigCallee->getParent()->getTargetTriple());
if (UseFloat) {
Name = "__sincospif_stret";
assert(T.getArch() != Triple::x86 && "x86 messy and unsupported for now");
// x86_64 can't use {float, float} since that would be returned in both
// xmm0 and xmm1, which isn't what a real struct would do.
ResTy = T.getArch() == Triple::x86_64
? static_cast<Type *>(FixedVectorType::get(ArgTy, 2))
: static_cast<Type *>(StructType::get(ArgTy, ArgTy));
} else {
Name = "__sincospi_stret";
ResTy = StructType::get(ArgTy, ArgTy);
}
Module *M = OrigCallee->getParent();
FunctionCallee Callee =
M->getOrInsertFunction(Name, OrigCallee->getAttributes(), ResTy, ArgTy);
if (Instruction *ArgInst = dyn_cast<Instruction>(Arg)) {
// If the argument is an instruction, it must dominate all uses so put our
// sincos call there.
B.SetInsertPoint(ArgInst->getParent(), ++ArgInst->getIterator());
} else {
// Otherwise (e.g. for a constant) the beginning of the function is as
// good a place as any.
BasicBlock &EntryBB = B.GetInsertBlock()->getParent()->getEntryBlock();
B.SetInsertPoint(&EntryBB, EntryBB.begin());
}
SinCos = B.CreateCall(Callee, Arg, "sincospi");
if (SinCos->getType()->isStructTy()) {
Sin = B.CreateExtractValue(SinCos, 0, "sinpi");
Cos = B.CreateExtractValue(SinCos, 1, "cospi");
} else {
Sin = B.CreateExtractElement(SinCos, ConstantInt::get(B.getInt32Ty(), 0),
"sinpi");
Cos = B.CreateExtractElement(SinCos, ConstantInt::get(B.getInt32Ty(), 1),
"cospi");
}
}
Value *LibCallSimplifier::optimizeSinCosPi(CallInst *CI, IRBuilderBase &B) {
// Make sure the prototype is as expected, otherwise the rest of the
// function is probably invalid and likely to abort.
if (!isTrigLibCall(CI))
return nullptr;
Value *Arg = CI->getArgOperand(0);
SmallVector<CallInst *, 1> SinCalls;
SmallVector<CallInst *, 1> CosCalls;
SmallVector<CallInst *, 1> SinCosCalls;
bool IsFloat = Arg->getType()->isFloatTy();
// Look for all compatible sinpi, cospi and sincospi calls with the same
// argument. If there are enough (in some sense) we can make the
// substitution.
Function *F = CI->getFunction();
for (User *U : Arg->users())
classifyArgUse(U, F, IsFloat, SinCalls, CosCalls, SinCosCalls);
// It's only worthwhile if both sinpi and cospi are actually used.
if (SinCalls.empty() || CosCalls.empty())
return nullptr;
Value *Sin, *Cos, *SinCos;
insertSinCosCall(B, CI->getCalledFunction(), Arg, IsFloat, Sin, Cos, SinCos);
auto replaceTrigInsts = [this](SmallVectorImpl<CallInst *> &Calls,
Value *Res) {
for (CallInst *C : Calls)
replaceAllUsesWith(C, Res);
};
replaceTrigInsts(SinCalls, Sin);
replaceTrigInsts(CosCalls, Cos);
replaceTrigInsts(SinCosCalls, SinCos);
return nullptr;
}
void LibCallSimplifier::classifyArgUse(
Value *Val, Function *F, bool IsFloat,
SmallVectorImpl<CallInst *> &SinCalls,
SmallVectorImpl<CallInst *> &CosCalls,
SmallVectorImpl<CallInst *> &SinCosCalls) {
CallInst *CI = dyn_cast<CallInst>(Val);
if (!CI || CI->use_empty())
return;
// Don't consider calls in other functions.
if (CI->getFunction() != F)
return;
Function *Callee = CI->getCalledFunction();
LibFunc Func;
if (!Callee || !TLI->getLibFunc(*Callee, Func) || !TLI->has(Func) ||
!isTrigLibCall(CI))
return;
if (IsFloat) {
if (Func == LibFunc_sinpif)
SinCalls.push_back(CI);
else if (Func == LibFunc_cospif)
CosCalls.push_back(CI);
else if (Func == LibFunc_sincospif_stret)
SinCosCalls.push_back(CI);
} else {
if (Func == LibFunc_sinpi)
SinCalls.push_back(CI);
else if (Func == LibFunc_cospi)
CosCalls.push_back(CI);
else if (Func == LibFunc_sincospi_stret)
SinCosCalls.push_back(CI);
}
}
//===----------------------------------------------------------------------===//
// Integer Library Call Optimizations
//===----------------------------------------------------------------------===//
Value *LibCallSimplifier::optimizeFFS(CallInst *CI, IRBuilderBase &B) {
// ffs(x) -> x != 0 ? (i32)llvm.cttz(x)+1 : 0
Value *Op = CI->getArgOperand(0);
Type *ArgType = Op->getType();
Function *F = Intrinsic::getDeclaration(CI->getCalledFunction()->getParent(),
Intrinsic::cttz, ArgType);
Value *V = B.CreateCall(F, {Op, B.getTrue()}, "cttz");
V = B.CreateAdd(V, ConstantInt::get(V->getType(), 1));
V = B.CreateIntCast(V, B.getInt32Ty(), false);
Value *Cond = B.CreateICmpNE(Op, Constant::getNullValue(ArgType));
return B.CreateSelect(Cond, V, B.getInt32(0));
}
Value *LibCallSimplifier::optimizeFls(CallInst *CI, IRBuilderBase &B) {
// fls(x) -> (i32)(sizeInBits(x) - llvm.ctlz(x, false))
Value *Op = CI->getArgOperand(0);
Type *ArgType = Op->getType();
Function *F = Intrinsic::getDeclaration(CI->getCalledFunction()->getParent(),
Intrinsic::ctlz, ArgType);
Value *V = B.CreateCall(F, {Op, B.getFalse()}, "ctlz");
V = B.CreateSub(ConstantInt::get(V->getType(), ArgType->getIntegerBitWidth()),
V);
return B.CreateIntCast(V, CI->getType(), false);
}
Value *LibCallSimplifier::optimizeAbs(CallInst *CI, IRBuilderBase &B) {