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//===------ 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/StringExtras.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/AttributeMask.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/Module.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/TargetParser/Triple.h"
#include "llvm/Transforms/Utils/BuildLibCalls.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/SizeOpts.h"
#include <cmath>
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"));
// Enable conversion of operator new calls with a MemProf hot or cold hint
// to an operator new call that takes a hot/cold hint. Off by default since
// not all allocators currently support this extension.
static cl::opt<bool>
OptimizeHotColdNew("optimize-hot-cold-new", cl::Hidden, cl::init(false),
cl::desc("Enable hot/cold operator new library calls"));
static cl::opt<bool> OptimizeExistingHotColdNew(
"optimize-existing-hot-cold-new", cl::Hidden, cl::init(false),
cl::desc(
"Enable optimization of existing hot/cold operator new library calls"));
namespace {
// Specialized parser to ensure the hint is an 8 bit value (we can't specify
// uint8_t to opt<> as that is interpreted to mean that we are passing a char
// option with a specific set of values.
struct HotColdHintParser : public cl::parser<unsigned> {
HotColdHintParser(cl::Option &O) : cl::parser<unsigned>(O) {}
bool parse(cl::Option &O, StringRef ArgName, StringRef Arg, unsigned &Value) {
if (Arg.getAsInteger(0, Value))
return O.error("'" + Arg + "' value invalid for uint argument!");
if (Value > 255)
return O.error("'" + Arg + "' value must be in the range [0, 255]!");
return false;
}
};
} // end anonymous namespace
// Hot/cold operator new takes an 8 bit hotness hint, where 0 is the coldest
// and 255 is the hottest. Default to 1 value away from the coldest and hottest
// hints, so that the compiler hinted allocations are slightly less strong than
// manually inserted hints at the two extremes.
static cl::opt<unsigned, false, HotColdHintParser> ColdNewHintValue(
"cold-new-hint-value", cl::Hidden, cl::init(1),
cl::desc("Value to pass to hot/cold operator new for cold allocation"));
static cl::opt<unsigned, false, HotColdHintParser>
NotColdNewHintValue("notcold-new-hint-value", cl::Hidden, cl::init(128),
cl::desc("Value to pass to hot/cold operator new for "
"notcold (warm) allocation"));
static cl::opt<unsigned, false, HotColdHintParser> HotNewHintValue(
"hot-new-hint-value", cl::Hidden, cl::init(254),
cl::desc("Value to pass to hot/cold operator new for hot allocation"));
//===----------------------------------------------------------------------===//
// Helper Functions
//===----------------------------------------------------------------------===//
static bool ignoreCallingConv(LibFunc Func) {
return Func == LibFunc_abs || Func == LibFunc_labs ||
Func == LibFunc_llabs || Func == LibFunc_strlen;
}
/// 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();
});
}
// Convert the entire string Str representing an integer in Base, up to
// the terminating nul if present, to a constant according to the rules
// of strtoul[l] or, when AsSigned is set, of strtol[l]. On success
// return the result, otherwise null.
// The function assumes the string is encoded in ASCII and carefully
// avoids converting sequences (including "") that the corresponding
// library call might fail and set errno for.
static Value *convertStrToInt(CallInst *CI, StringRef &Str, Value *EndPtr,
uint64_t Base, bool AsSigned, IRBuilderBase &B) {
if (Base < 2 || Base > 36)
if (Base != 0)
// Fail for an invalid base (required by POSIX).
return nullptr;
// Current offset into the original string to reflect in EndPtr.
size_t Offset = 0;
// Strip leading whitespace.
for ( ; Offset != Str.size(); ++Offset)
if (!isSpace((unsigned char)Str[Offset])) {
Str = Str.substr(Offset);
break;
}
if (Str.empty())
// Fail for empty subject sequences (POSIX allows but doesn't require
// strtol[l]/strtoul[l] to fail with EINVAL).
return nullptr;
// Strip but remember the sign.
bool Negate = Str[0] == '-';
if (Str[0] == '-' || Str[0] == '+') {
Str = Str.drop_front();
if (Str.empty())
// Fail for a sign with nothing after it.
return nullptr;
++Offset;
}
// Set Max to the absolute value of the minimum (for signed), or
// to the maximum (for unsigned) value representable in the type.
Type *RetTy = CI->getType();
unsigned NBits = RetTy->getPrimitiveSizeInBits();
uint64_t Max = AsSigned && Negate ? 1 : 0;
Max += AsSigned ? maxIntN(NBits) : maxUIntN(NBits);
// Autodetect Base if it's zero and consume the "0x" prefix.
if (Str.size() > 1) {
if (Str[0] == '0') {
if (toUpper((unsigned char)Str[1]) == 'X') {
if (Str.size() == 2 || (Base && Base != 16))
// Fail if Base doesn't allow the "0x" prefix or for the prefix
// alone that implementations like BSD set errno to EINVAL for.
return nullptr;
Str = Str.drop_front(2);
Offset += 2;
Base = 16;
}
else if (Base == 0)
Base = 8;
} else if (Base == 0)
Base = 10;
}
else if (Base == 0)
Base = 10;
// Convert the rest of the subject sequence, not including the sign,
// to its uint64_t representation (this assumes the source character
// set is ASCII).
uint64_t Result = 0;
for (unsigned i = 0; i != Str.size(); ++i) {
unsigned char DigVal = Str[i];
if (isDigit(DigVal))
DigVal = DigVal - '0';
else {
DigVal = toUpper(DigVal);
if (isAlpha(DigVal))
DigVal = DigVal - 'A' + 10;
else
return nullptr;
}
if (DigVal >= Base)
// Fail if the digit is not valid in the Base.
return nullptr;
// Add the digit and fail if the result is not representable in
// the (unsigned form of the) destination type.
bool VFlow;
Result = SaturatingMultiplyAdd(Result, Base, (uint64_t)DigVal, &VFlow);
if (VFlow || Result > Max)
return nullptr;
}
if (EndPtr) {
// Store the pointer to the end.
Value *Off = B.getInt64(Offset + Str.size());
Value *StrBeg = CI->getArgOperand(0);
Value *StrEnd = B.CreateInBoundsGEP(B.getInt8Ty(), StrBeg, Off, "endptr");
B.CreateStore(StrEnd, EndPtr);
}
if (Negate)
// Unsigned negation doesn't overflow.
Result = -Result;
return ConstantInt::get(RetTy, 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->getParamDereferenceableOrNullBytes(ArgNo),
DereferenceableBytes);
if (CI->getParamDereferenceableBytes(ArgNo) < 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)) {
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);
}
}
}
// Copy CallInst "flags" like musttail, notail, and tail. Return New param for
// easier chaining. Calls to emit* and B.createCall should probably be wrapped
// in this function when New is created to replace Old. Callers should take
// care to check Old.isMustTailCall() if they aren't replacing Old directly
// with New.
static Value *copyFlags(const CallInst &Old, Value *New) {
assert(!Old.isMustTailCall() && "do not copy musttail call flags");
assert(!Old.isNoTailCall() && "do not copy notail call flags");
if (auto *NewCI = dyn_cast_or_null<CallInst>(New))
NewCI->setTailCallKind(Old.getTailCallKind());
return New;
}
static Value *mergeAttributesAndFlags(CallInst *NewCI, const CallInst &Old) {
NewCI->setAttributes(AttributeList::get(
NewCI->getContext(), {NewCI->getAttributes(), Old.getAttributes()}));
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
return copyFlags(Old, NewCI);
}
// Helper to avoid truncating the length if size_t is 32-bits.
static StringRef substr(StringRef Str, uint64_t Len) {
return Len >= Str.size() ? Str : Str.substr(0, Len);
}
//===----------------------------------------------------------------------===//
// 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 copyFlags(*CI, 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.CreateInBoundsGEP(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 copyFlags(*CI, emitStrLenMemCpy(Src, Dst, SrcLen, B));
}
// Helper to transform memchr(S, C, N) == S to N && *S == C and, when
// NBytes is null, strchr(S, C) to *S == C. A precondition of the function
// is that either S is dereferenceable or the value of N is nonzero.
static Value* memChrToCharCompare(CallInst *CI, Value *NBytes,
IRBuilderBase &B, const DataLayout &DL)
{
Value *Src = CI->getArgOperand(0);
Value *CharVal = CI->getArgOperand(1);
// Fold memchr(A, C, N) == A to N && *A == C.
Type *CharTy = B.getInt8Ty();
Value *Char0 = B.CreateLoad(CharTy, Src);
CharVal = B.CreateTrunc(CharVal, CharTy);
Value *Cmp = B.CreateICmpEQ(Char0, CharVal, "char0cmp");
if (NBytes) {
Value *Zero = ConstantInt::get(NBytes->getType(), 0);
Value *And = B.CreateICmpNE(NBytes, Zero);
Cmp = B.CreateLogicalAnd(And, Cmp);
}
Value *NullPtr = Constant::getNullValue(CI->getType());
return B.CreateSelect(Cmp, Src, NullPtr);
}
Value *LibCallSimplifier::optimizeStrChr(CallInst *CI, IRBuilderBase &B) {
Value *SrcStr = CI->getArgOperand(0);
Value *CharVal = CI->getArgOperand(1);
annotateNonNullNoUndefBasedOnAccess(CI, 0);
if (isOnlyUsedInEqualityComparison(CI, SrcStr))
return memChrToCharCompare(CI, nullptr, B, DL);
// 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>(CharVal);
if (!CharC) {
uint64_t Len = GetStringLength(SrcStr);
if (Len)
annotateDereferenceableBytes(CI, 0, Len);
else
return nullptr;
Function *Callee = CI->getCalledFunction();
FunctionType *FT = Callee->getFunctionType();
unsigned IntBits = TLI->getIntSize();
if (!FT->getParamType(1)->isIntegerTy(IntBits)) // memchr needs 'int'.
return nullptr;
unsigned SizeTBits = TLI->getSizeTSize(*CI->getModule());
Type *SizeTTy = IntegerType::get(CI->getContext(), SizeTBits);
return copyFlags(*CI,
emitMemChr(SrcStr, CharVal, // include nul.
ConstantInt::get(SizeTTy, Len), B,
DL, TLI));
}
if (CharC->isZero()) {
Value *NullPtr = Constant::getNullValue(CI->getType());
if (isOnlyUsedInEqualityComparison(CI, NullPtr))
// Pre-empt the transformation to strlen below and fold
// strchr(A, '\0') == null to false.
return B.CreateIntToPtr(B.getTrue(), CI->getType());
}
// 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.CreateInBoundsGEP(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.CreateInBoundsGEP(B.getInt8Ty(), SrcStr, B.getInt64(I), "strchr");
}
Value *LibCallSimplifier::optimizeStrRChr(CallInst *CI, IRBuilderBase &B) {
Value *SrcStr = CI->getArgOperand(0);
Value *CharVal = CI->getArgOperand(1);
ConstantInt *CharC = dyn_cast<ConstantInt>(CharVal);
annotateNonNullNoUndefBasedOnAccess(CI, 0);
StringRef Str;
if (!getConstantStringInfo(SrcStr, Str)) {
// strrchr(s, 0) -> strchr(s, 0)
if (CharC && CharC->isZero())
return copyFlags(*CI, emitStrChr(SrcStr, '\0', B, TLI));
return nullptr;
}
unsigned SizeTBits = TLI->getSizeTSize(*CI->getModule());
Type *SizeTTy = IntegerType::get(CI->getContext(), SizeTBits);
// Try to expand strrchr to the memrchr nonstandard extension if it's
// available, or simply fail otherwise.
uint64_t NBytes = Str.size() + 1; // Include the terminating nul.
Value *Size = ConstantInt::get(SizeTTy, NBytes);
return copyFlags(*CI, emitMemRChr(SrcStr, CharVal, Size, B, DL, TLI));
}
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(),
std::clamp(Str1.compare(Str2), -1, 1));
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 copyFlags(
*CI, 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 copyFlags(
*CI,
emitMemCmp(Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len2),
B, DL, TLI));
} else if (HasStr1 && !HasStr2) {
if (canTransformToMemCmp(CI, Str2P, Len1, DL))
return copyFlags(
*CI,
emitMemCmp(Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len1),
B, DL, TLI));
}
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
return nullptr;
}
// Optimize a memcmp or, when StrNCmp is true, strncmp call CI with constant
// arrays LHS and RHS and nonconstant Size.
static Value *optimizeMemCmpVarSize(CallInst *CI, Value *LHS, Value *RHS,
Value *Size, bool StrNCmp,
IRBuilderBase &B, const DataLayout &DL);
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 optimizeMemCmpVarSize(CI, Str1P, Str2P, Size, true, B, DL);
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 copyFlags(*CI, 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) {
// Avoid truncating the 64-bit Length to 32 bits in ILP32.
StringRef SubStr1 = substr(Str1, Length);
StringRef SubStr2 = substr(Str2, Length);
return ConstantInt::get(CI->getType(),
std::clamp(SubStr1.compare(SubStr2), -1, 1));
}
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 copyFlags(
*CI,
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 copyFlags(
*CI,
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 copyFlags(*CI, 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));
mergeAttributesAndFlags(NewCI, *CI);
return Dst;
}
Value *LibCallSimplifier::optimizeStpCpy(CallInst *CI, IRBuilderBase &B) {
Function *Callee = CI->getCalledFunction();
Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1);
// stpcpy(d,s) -> strcpy(d,s) if the result is not used.
if (CI->use_empty())
return copyFlags(*CI, emitStrCpy(Dst, Src, B, TLI));
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.CreateInBoundsGEP(
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);
mergeAttributesAndFlags(NewCI, *CI);
return DstEnd;
}
// Optimize a call to size_t strlcpy(char*, const char*, size_t).
Value *LibCallSimplifier::optimizeStrLCpy(CallInst *CI, IRBuilderBase &B) {
Value *Size = CI->getArgOperand(2);
if (isKnownNonZero(Size, DL))
// Like snprintf, the function stores into the destination only when
// the size argument is nonzero.
annotateNonNullNoUndefBasedOnAccess(CI, 0);
// The function reads the source argument regardless of Size (it returns
// its length).
annotateNonNullNoUndefBasedOnAccess(CI, 1);
uint64_t NBytes;
if (ConstantInt *SizeC = dyn_cast<ConstantInt>(Size))
NBytes = SizeC->getZExtValue();
else
return nullptr;
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
if (NBytes <= 1) {
if (NBytes == 1)
// For a call to strlcpy(D, S, 1) first store a nul in *D.
B.CreateStore(B.getInt8(0), Dst);
// Transform strlcpy(D, S, 0) to a call to strlen(S).
return copyFlags(*CI, emitStrLen(Src, B, DL, TLI));
}
// Try to determine the length of the source, substituting its size
// when it's not nul-terminated (as it's required to be) to avoid
// reading past its end.
StringRef Str;
if (!getConstantStringInfo(Src, Str, /*TrimAtNul=*/false))
return nullptr;
uint64_t SrcLen = Str.find('\0');
// Set if the terminating nul should be copied by the call to memcpy
// below.
bool NulTerm = SrcLen < NBytes;
if (NulTerm)
// Overwrite NBytes with the number of bytes to copy, including
// the terminating nul.
NBytes = SrcLen + 1;
else {
// Set the length of the source for the function to return to its
// size, and cap NBytes at the same.
SrcLen = std::min(SrcLen, uint64_t(Str.size()));
NBytes = std::min(NBytes - 1, SrcLen);
}
if (SrcLen == 0) {
// Transform strlcpy(D, "", N) to (*D = '\0, 0).
B.CreateStore(B.getInt8(0), Dst);
return ConstantInt::get(CI->getType(), 0);
}
Function *Callee = CI->getCalledFunction();
Type *PT = Callee->getFunctionType()->getParamType(0);
// Transform strlcpy(D, S, N) to memcpy(D, S, N') where N' is the lower
// bound on strlen(S) + 1 and N, optionally followed by a nul store to
// D[N' - 1] if necessary.
CallInst *NewCI = B.CreateMemCpy(Dst, Align(1), Src, Align(1),
ConstantInt::get(DL.getIntPtrType(PT), NBytes));
mergeAttributesAndFlags(NewCI, *CI);
if (!NulTerm) {
Value *EndOff = ConstantInt::get(CI->getType(), NBytes);
Value *EndPtr = B.CreateInBoundsGEP(B.getInt8Ty(), Dst, EndOff);
B.CreateStore(B.getInt8(0), EndPtr);
}
// Like snprintf, strlcpy returns the number of nonzero bytes that would
// have been copied if the bound had been sufficiently big (which in this
// case is strlen(Src)).
return ConstantInt::get(CI->getType(), SrcLen);
}
// Optimize a call CI to either stpncpy when RetEnd is true, or to strncpy
// otherwise.
Value *LibCallSimplifier::optimizeStringNCpy(CallInst *CI, bool RetEnd,
IRBuilderBase &B) {
Function *Callee = CI->getCalledFunction();
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
if (isKnownNonZero(Size, DL)) {
// Both st{p,r}ncpy(D, S, N) access the source and destination arrays
// only when N is nonzero.
annotateNonNullNoUndefBasedOnAccess(CI, 0);
annotateNonNullNoUndefBasedOnAccess(CI, 1);
}
// If the "bound" argument is known set N to it. Otherwise set it to
// UINT64_MAX and handle it later.
uint64_t N = UINT64_MAX;
if (ConstantInt *SizeC = dyn_cast<ConstantInt>(Size))
N = SizeC->getZExtValue();
if (N == 0)
// Fold st{p,r}ncpy(D, S, 0) to D.
return Dst;
if (N == 1) {
Type *CharTy = B.getInt8Ty();
Value *CharVal = B.CreateLoad(CharTy, Src, "stxncpy.char0");
B.CreateStore(CharVal, Dst);
if (!RetEnd)
// Transform strncpy(D, S, 1) to return (*D = *S), D.
return Dst;
// Transform stpncpy(D, S, 1) to return (*D = *S) ? D + 1 : D.
Value *ZeroChar = ConstantInt::get(CharTy, 0);
Value *Cmp = B.CreateICmpEQ(CharVal, ZeroChar, "stpncpy.char0cmp");
Value *Off1 = B.getInt32(1);
Value *EndPtr = B.CreateInBoundsGEP(CharTy, Dst, Off1, "stpncpy.end");
return B.CreateSelect(Cmp, Dst, EndPtr, "stpncpy.sel");
}
// If the length of the input string is known set SrcLen to it.
uint64_t SrcLen = GetStringLength(Src);
if (SrcLen)
annotateDereferenceableBytes(CI, 1, SrcLen);
else
return nullptr;
--SrcLen; // Unbias length.
if (SrcLen == 0) {
// Transform st{p,r}ncpy(D, "", N) to memset(D, '\0', N) for any N.
Align MemSetAlign =
CI->getAttributes().getParamAttrs(0).getAlignment().valueOrOne();
CallInst *NewCI = B.CreateMemSet(Dst, B.getInt8('\0'), Size, MemSetAlign);
AttrBuilder ArgAttrs(CI->getContext(), CI->getAttributes().getParamAttrs(0));
NewCI->setAttributes(NewCI->getAttributes().addParamAttributes(
CI->getContext(), 0, ArgAttrs));
copyFlags(*CI, NewCI);
return Dst;
}
if (N > SrcLen + 1) {
if (N > 128)
// Bail if N is large or unknown.
return nullptr;
// st{p,r}ncpy(D, "a", N) -> memcpy(D, "a\0\0\0", N) for N <= 128.
StringRef Str;
if (!getConstantStringInfo(Src, Str))
return nullptr;
std::string SrcStr = Str.str();
// Create a bigger, nul-padded array with the same length, SrcLen,
// as the original string.
SrcStr.resize(N, '\0');
Src = B.CreateGlobalString(SrcStr, "str");
}
Type *PT = Callee->getFunctionType()->getParamType(0);
// st{p,r}ncpy(D, S, N) -> memcpy(align 1 D, align 1 S, N) when both
// S and N are constant.
CallInst *NewCI = B.CreateMemCpy(Dst, Align(1), Src, Align(1),
ConstantInt::get(DL.getIntPtrType(PT), N));
mergeAttributesAndFlags(NewCI, *CI);
if (!RetEnd)
return Dst;
// stpncpy(D, S, N) returns the address of the first null in D if it writes
// one, otherwise D + N.
Value *Off = B.getInt64(std::min(SrcLen, N));
return B.CreateInBoundsGEP(B.getInt8Ty(), Dst, Off, "endptr");
}
Value *LibCallSimplifier::optimizeStringLength(CallInst *CI, IRBuilderBase &B,
unsigned CharSize,
Value *Bound) {
Value *Src = CI->getArgOperand(0);
Type *CharTy = B.getIntNTy(CharSize);
if (isOnlyUsedInZeroEqualityComparison(CI) &&
(!Bound || isKnownNonZero(Bound, DL))) {
// Fold strlen:
// strlen(x) != 0 --> *x != 0
// strlen(x) == 0 --> *x == 0
// and likewise strnlen with constant N > 0:
// strnlen(x, N) != 0 --> *x != 0
// strnlen(x, N) == 0 --> *x == 0
return B.CreateZExt(B.CreateLoad(CharTy, Src, "char0"),
CI->getType());
}
if (Bound) {
if (ConstantInt *BoundCst = dyn_cast<ConstantInt>(Bound)) {
if (BoundCst->isZero())
// Fold strnlen(s, 0) -> 0 for any s, constant or otherwise.
return ConstantInt::get(CI->getType(), 0);
if (BoundCst->isOne()) {
// Fold strnlen(s, 1) -> *s ? 1 : 0 for any s.
Value *CharVal = B.CreateLoad(CharTy, Src, "strnlen.char0");
Value *ZeroChar = ConstantInt::get(CharTy, 0);
Value *Cmp = B.CreateICmpNE(CharVal, ZeroChar, "strnlen.char0cmp");
return B.CreateZExt(Cmp, CI->getType());
}
}
}
if (uint64_t Len = GetStringLength(Src, CharSize)) {
Value *LenC = ConstantInt::get(CI->getType(), Len - 1);
// Fold strlen("xyz") -> 3 and strnlen("xyz", 2) -> 2
// and strnlen("xyz", Bound) -> min(3, Bound) for nonconstant Bound.
if (Bound)
return B.CreateBinaryIntrinsic(Intrinsic::umin, LenC, Bound);
return LenC;
}
if (Bound)
// Punt for strnlen for now.
return nullptr;
// 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 CharSize elements. 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)) {
// TODO: Handle subobjects.
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);
uint64_t ArrSize =
cast<ArrayType>(GEP->getSourceElementType())->getNumElements();
// 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.isNonNegative() && Known.getMaxValue().ule(NullTermIdx)) ||
(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));
}
}
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::optimizeStrNLen(CallInst *CI, IRBuilderBase &B) {
Value *Bound = CI->getArgOperand(1);
if (Value *V = optimizeStringLength(CI, B, 8, Bound))
return V;
if (isKnownNonZero(Bound, DL))
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.CreateInBoundsGEP(B.getInt8Ty(), CI->getArgOperand(0),
B.getInt64(I), "strpbrk");
}
// strpbrk(s, "a") -> strchr(s, 'a')
if (HasS2 && S2.size() == 1)
return copyFlags(*CI, 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 copyFlags(*CI, 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 CI->getArgOperand(0);
// 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 CI->getArgOperand(0);
// 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)
return B.CreateConstInBoundsGEP1_64(B.getInt8Ty(), CI->getArgOperand(0),
Offset, "strstr");
}
// fold strstr(x, "y") -> strchr(x, 'y').
if (HasStr2 && ToFindStr.size() == 1) {
return emitStrChr(CI->getArgOperand(0), ToFindStr[0], B, TLI);
}
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
return nullptr;
}
Value *LibCallSimplifier::optimizeMemRChr(CallInst *CI, IRBuilderBase &B) {
Value *SrcStr = CI->getArgOperand(0);
Value *Size = CI->getArgOperand(2);
annotateNonNullAndDereferenceable(CI, 0, Size, DL);
Value *CharVal = CI->getArgOperand(1);
ConstantInt *LenC = dyn_cast<ConstantInt>(Size);
Value *NullPtr = Constant::getNullValue(CI->getType());
if (LenC) {
if (LenC->isZero())
// Fold memrchr(x, y, 0) --> null.
return NullPtr;
if (LenC->isOne()) {
// Fold memrchr(x, y, 1) --> *x == y ? x : null for any x and y,
// constant or otherwise.
Value *Val = B.CreateLoad(B.getInt8Ty(), SrcStr, "memrchr.char0");
// Slice off the character's high end bits.
CharVal = B.CreateTrunc(CharVal, B.getInt8Ty());
Value *Cmp = B.CreateICmpEQ(Val, CharVal, "memrchr.char0cmp");
return B.CreateSelect(Cmp, SrcStr, NullPtr, "memrchr.sel");
}
}
StringRef Str;
if (!getConstantStringInfo(SrcStr, Str, /*TrimAtNul=*/false))
return nullptr;
if (Str.size() == 0)
// If the array is empty fold memrchr(A, C, N) to null for any value
// of C and N on the basis that the only valid value of N is zero
// (otherwise the call is undefined).
return NullPtr;
uint64_t EndOff = UINT64_MAX;
if (LenC) {
EndOff = LenC->getZExtValue();
if (Str.size() < EndOff)
// Punt out-of-bounds accesses to sanitizers and/or libc.
return nullptr;
}
if (ConstantInt *CharC = dyn_cast<ConstantInt>(CharVal)) {
// Fold memrchr(S, C, N) for a constant C.
size_t Pos = Str.rfind(CharC->getZExtValue(), EndOff);
if (Pos == StringRef::npos)
// When the character is not in the source array fold the result
// to null regardless of Size.
return NullPtr;
if (LenC)
// Fold memrchr(s, c, N) --> s + Pos for constant N > Pos.
return B.CreateInBoundsGEP(B.getInt8Ty(), SrcStr, B.getInt64(Pos));
if (Str.find(Str[Pos]) == Pos) {
// When there is just a single occurrence of C in S, i.e., the one
// in Str[Pos], fold
// memrchr(s, c, N) --> N <= Pos ? null : s + Pos
// for nonconstant N.
Value *Cmp = B.CreateICmpULE(Size, ConstantInt::get(Size->getType(), Pos),
"memrchr.cmp");
Value *SrcPlus = B.CreateInBoundsGEP(B.getInt8Ty(), SrcStr,
B.getInt64(Pos), "memrchr.ptr_plus");
return B.CreateSelect(Cmp, NullPtr, SrcPlus, "memrchr.sel");
}
}
// Truncate the string to search at most EndOff characters.
Str = Str.substr(0, EndOff);
if (Str.find_first_not_of(Str[0]) != StringRef::npos)
return nullptr;
// If the source array consists of all equal characters, then for any
// C and N (whether in bounds or not), fold memrchr(S, C, N) to
// N != 0 && *S == C ? S + N - 1 : null
Type *SizeTy = Size->getType();
Type *Int8Ty = B.getInt8Ty();
Value *NNeZ = B.CreateICmpNE(Size, ConstantInt::get(SizeTy, 0));
// Slice off the sought character's high end bits.
CharVal = B.CreateTrunc(CharVal, Int8Ty);
Value *CEqS0 = B.CreateICmpEQ(ConstantInt::get(Int8Ty, Str[0]), CharVal);
Value *And = B.CreateLogicalAnd(NNeZ, CEqS0);
Value *SizeM1 = B.CreateSub(Size, ConstantInt::get(SizeTy, 1));
Value *SrcPlus =
B.CreateInBoundsGEP(Int8Ty, SrcStr, SizeM1, "memrchr.ptr_plus");
return B.CreateSelect(And, SrcPlus, NullPtr, "memrchr.sel");
}
Value *LibCallSimplifier::optimizeMemChr(CallInst *CI, IRBuilderBase &B) {
Value *SrcStr = CI->getArgOperand(0);
Value *Size = CI->getArgOperand(2);
if (isKnownNonZero(Size, DL)) {
annotateNonNullNoUndefBasedOnAccess(CI, 0);
if (isOnlyUsedInEqualityComparison(CI, SrcStr))
return memChrToCharCompare(CI, Size, B, DL);
}
Value *CharVal = CI->getArgOperand(1);
ConstantInt *CharC = dyn_cast<ConstantInt>(CharVal);
ConstantInt *LenC = dyn_cast<ConstantInt>(Size);
Value *NullPtr = Constant::getNullValue(CI->getType());
// memchr(x, y, 0) -> null
if (LenC) {
if (LenC->isZero())
return NullPtr;
if (LenC->isOne()) {
// Fold memchr(x, y, 1) --> *x == y ? x : null for any x and y,
// constant or otherwise.
Value *Val = B.CreateLoad(B.getInt8Ty(), SrcStr, "memchr.char0");
// Slice off the character's high end bits.
CharVal = B.CreateTrunc(CharVal, B.getInt8Ty());
Value *Cmp = B.CreateICmpEQ(Val, CharVal, "memchr.char0cmp");
return B.CreateSelect(Cmp, SrcStr, NullPtr, "memchr.sel");
}
}
StringRef Str;
if (!getConstantStringInfo(SrcStr, Str, /*TrimAtNul=*/false))
return nullptr;
if (CharC) {
size_t Pos = Str.find(CharC->getZExtValue());
if (Pos == StringRef::npos)
// When the character is not in the source array fold the result
// to null regardless of Size.
return NullPtr;
// Fold memchr(s, c, n) -> n <= Pos ? null : s + Pos
// When the constant Size is less than or equal to the character
// position also fold the result to null.
Value *Cmp = B.CreateICmpULE(Size, ConstantInt::get(Size->getType(), Pos),
"memchr.cmp");
Value *SrcPlus = B.CreateInBoundsGEP(B.getInt8Ty(), SrcStr, B.getInt64(Pos),
"memchr.ptr");
return B.CreateSelect(Cmp, NullPtr, SrcPlus);
}
if (Str.size() == 0)
// If the array is empty fold memchr(A, C, N) to null for any value
// of C and N on the basis that the only valid value of N is zero
// (otherwise the call is undefined).
return NullPtr;
if (LenC)
Str = substr(Str, LenC->getZExtValue());
size_t Pos = Str.find_first_not_of(Str[0]);
if (Pos == StringRef::npos
|| Str.find_first_not_of(Str[Pos], Pos) == StringRef::npos) {
// If the source array consists of at most two consecutive sequences
// of the same characters, then for any C and N (whether in bounds or
// not), fold memchr(S, C, N) to
// N != 0 && *S == C ? S : null
// or for the two sequences to:
// N != 0 && *S == C ? S : (N > Pos && S[Pos] == C ? S + Pos : null)
// ^Sel2 ^Sel1 are denoted above.
// The latter makes it also possible to fold strchr() calls with strings
// of the same characters.
Type *SizeTy = Size->getType();
Type *Int8Ty = B.getInt8Ty();
// Slice off the sought character's high end bits.
CharVal = B.CreateTrunc(CharVal, Int8Ty);
Value *Sel1 = NullPtr;
if (Pos != StringRef::npos) {
// Handle two consecutive sequences of the same characters.
Value *PosVal = ConstantInt::get(SizeTy, Pos);
Value *StrPos = ConstantInt::get(Int8Ty, Str[Pos]);
Value *CEqSPos = B.CreateICmpEQ(CharVal, StrPos);
Value *NGtPos = B.CreateICmp(ICmpInst::ICMP_UGT, Size, PosVal);
Value *And = B.CreateAnd(CEqSPos, NGtPos);
Value *SrcPlus = B.CreateInBoundsGEP(B.getInt8Ty(), SrcStr, PosVal);
Sel1 = B.CreateSelect(And, SrcPlus, NullPtr, "memchr.sel1");
}
Value *Str0 = ConstantInt::get(Int8Ty, Str[0]);
Value *CEqS0 = B.CreateICmpEQ(Str0, CharVal);
Value *NNeZ = B.CreateICmpNE(Size, ConstantInt::get(SizeTy, 0));
Value *And = B.CreateAnd(NNeZ, CEqS0);
return B.CreateSelect(And, SrcStr, Sel1, "memchr.sel2");
}
if (!LenC) {
if (isOnlyUsedInEqualityComparison(CI, SrcStr))
// S is dereferenceable so it's safe to load from it and fold
// memchr(S, C, N) == S to N && *S == C for any C and N.
// TODO: This is safe even for nonconstant S.
return memChrToCharCompare(CI, Size, B, DL);
// From now on we need a constant length and constant array.
return nullptr;
}
bool OptForSize = CI->getFunction()->hasOptSize() ||
llvm::shouldOptimizeForSize(CI->getParent(), PSI, BFI,
PGSOQueryType::IRPass);
// 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 (OptForSize || Str.empty() || !isOnlyUsedInZeroEqualityComparison(CI))
return nullptr;
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)) {
// Build chain of ORs
// Transform:
// memchr("abcd", C, 4) != nullptr
// to:
// (C == 'a' || C == 'b' || C == 'c' || C == 'd') != 0
std::string SortedStr = Str.str();
llvm::sort(SortedStr);
// Compute the number of of non-contiguous ranges.
unsigned NonContRanges = 1;
for (size_t i = 1; i < SortedStr.size(); ++i) {
if (SortedStr[i] > SortedStr[i - 1] + 1) {
NonContRanges++;
}
}
// Restrict this optimization to profitable cases with one or two range
// checks.
if (NonContRanges > 2)
return nullptr;
SmallVector<Value *> CharCompares;
for (unsigned char C : SortedStr)
CharCompares.push_back(
B.CreateICmpEQ(CharVal, ConstantInt::get(CharVal->getType(), C)));
return B.CreateIntToPtr(B.CreateOr(CharCompares), CI->getType());
}
// 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(CharVal, 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.CreateLogicalAnd(Bounds, Bits, "memchr"),
CI->getType());
}
// Optimize a memcmp or, when StrNCmp is true, strncmp call CI with constant
// arrays LHS and RHS and nonconstant Size.
static Value *optimizeMemCmpVarSize(CallInst *CI, Value *LHS, Value *RHS,
Value *Size, bool StrNCmp,
IRBuilderBase &B, const DataLayout &DL) {
if (LHS == RHS) // memcmp(s,s,x) -> 0
return Constant::getNullValue(CI->getType());
StringRef LStr, RStr;
if (!getConstantStringInfo(LHS, LStr, /*TrimAtNul=*/false) ||
!getConstantStringInfo(RHS, RStr, /*TrimAtNul=*/false))
return nullptr;
// If the contents of both constant arrays are known, fold a call to
// memcmp(A, B, N) to
// N <= Pos ? 0 : (A < B ? -1 : B < A ? +1 : 0)
// where Pos is the first mismatch between A and B, determined below.
uint64_t Pos = 0;
Value *Zero = ConstantInt::get(CI->getType(), 0);
for (uint64_t MinSize = std::min(LStr.size(), RStr.size()); ; ++Pos) {
if (Pos == MinSize ||
(StrNCmp && (LStr[Pos] == '\0' && RStr[Pos] == '\0'))) {
// One array is a leading part of the other of equal or greater
// size, or for strncmp, the arrays are equal strings.
// Fold the result to zero. Size is assumed to be in bounds, since
// otherwise the call would be undefined.
return Zero;
}
if (LStr[Pos] != RStr[Pos])
break;
}
// Normalize the result.
typedef unsigned char UChar;
int IRes = UChar(LStr[Pos]) < UChar(RStr[Pos]) ? -1 : 1;
Value *MaxSize = ConstantInt::get(Size->getType(), Pos);
Value *Cmp = B.CreateICmp(ICmpInst::ICMP_ULE, Size, MaxSize);
Value *Res = ConstantInt::get(CI->getType(), IRes);
return B.CreateSelect(Cmp, Zero, Res);
}
// Optimize a memcmp call CI with constant size Len.
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(), LHS, "lhsc"),
CI->getType(), "lhsv");
Value *RHSV = B.CreateZExt(B.CreateLoad(B.getInt8Ty(), RHS, "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);
Align PrefAlignment = DL.getPrefTypeAlign(IntType);
// First, see if we can fold either argument to a constant.
Value *LHSV = nullptr;
if (auto *LHSC = dyn_cast<Constant>(LHS))
LHSV = ConstantFoldLoadFromConstPtr(LHSC, IntType, DL);
Value *RHSV = nullptr;
if (auto *RHSC = dyn_cast<Constant>(RHS))
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)
LHSV = B.CreateLoad(IntType, LHS, "lhsv");
if (!RHSV)
RHSV = B.CreateLoad(IntType, RHS, "rhsv");
return B.CreateZExt(B.CreateICmpNE(LHSV, RHSV), CI->getType(), "memcmp");
}
}
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);
annotateNonNullAndDereferenceable(CI, {0, 1}, Size, DL);
if (Value *Res = optimizeMemCmpVarSize(CI, LHS, RHS, Size, false, B, DL))
return Res;
// Handle constant Size.
ConstantInt *LenC = dyn_cast<ConstantInt>(Size);
if (!LenC)
return nullptr;
return optimizeMemCmpConstantSize(CI, LHS, RHS, LenC->getZExtValue(), B, DL);
}
Value *LibCallSimplifier::optimizeMemCmp(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
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 (isLibFuncEmittable(M, TLI, LibFunc_bcmp) &&
isOnlyUsedInZeroEqualityComparison(CI)) {
Value *LHS = CI->getArgOperand(0);
Value *RHS = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
return copyFlags(*CI, 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);
mergeAttributesAndFlags(NewCI, *CI);
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, /*TrimAtNul=*/false) ||
// TODO: Handle zeroinitializer.
!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()) {
copyFlags(*CI, 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
copyFlags(*CI, 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?
mergeAttributesAndFlags(NewCI, *CI);
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);
mergeAttributesAndFlags(NewCI, *CI);
return CI->getArgOperand(0);
}
Value *LibCallSimplifier::optimizeMemSet(CallInst *CI, IRBuilderBase &B) {
Value *Size = CI->getArgOperand(2);
annotateNonNullAndDereferenceable(CI, 0, Size, DL);
if (isa<IntrinsicInst>(CI))
return nullptr;
// 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));
mergeAttributesAndFlags(NewCI, *CI);
return CI->getArgOperand(0);
}
Value *LibCallSimplifier::optimizeRealloc(CallInst *CI, IRBuilderBase &B) {
if (isa<ConstantPointerNull>(CI->getArgOperand(0)))
return copyFlags(*CI, emitMalloc(CI->getArgOperand(1), B, DL, TLI));
return nullptr;
}
// When enabled, replace operator new() calls marked with a hot or cold memprof
// attribute with an operator new() call that takes a __hot_cold_t parameter.
// Currently this is supported by the open source version of tcmalloc, see:
// https://github.com/google/tcmalloc/blob/master/tcmalloc/new_extension.h
Value *LibCallSimplifier::optimizeNew(CallInst *CI, IRBuilderBase &B,
LibFunc &Func) {
if (!OptimizeHotColdNew)
return nullptr;
uint8_t HotCold;
if (CI->getAttributes().getFnAttr("memprof").getValueAsString() == "cold")
HotCold = ColdNewHintValue;
else if (CI->getAttributes().getFnAttr("memprof").getValueAsString() ==
"notcold")
HotCold = NotColdNewHintValue;
else if (CI->getAttributes().getFnAttr("memprof").getValueAsString() == "hot")
HotCold = HotNewHintValue;
else
return nullptr;
// For calls that already pass a hot/cold hint, only update the hint if
// directed by OptimizeExistingHotColdNew. For other calls to new, add a hint
// if cold or hot, and leave as-is for default handling if "notcold" aka warm.
// Note that in cases where we decide it is "notcold", it might be slightly
// better to replace the hinted call with a non hinted call, to avoid the
// extra paramter and the if condition check of the hint value in the
// allocator. This can be considered in the future.
switch (Func) {
case LibFunc_Znwm12__hot_cold_t:
if (OptimizeExistingHotColdNew)
return emitHotColdNew(CI->getArgOperand(0), B, TLI,
LibFunc_Znwm12__hot_cold_t, HotCold);
break;
case LibFunc_Znwm:
if (HotCold != NotColdNewHintValue)
return emitHotColdNew(CI->getArgOperand(0), B, TLI,
LibFunc_Znwm12__hot_cold_t, HotCold);
break;
case LibFunc_Znam12__hot_cold_t:
if (OptimizeExistingHotColdNew)
return emitHotColdNew(CI->getArgOperand(0), B, TLI,
LibFunc_Znam12__hot_cold_t, HotCold);
break;
case LibFunc_Znam:
if (HotCold != NotColdNewHintValue)
return emitHotColdNew(CI->getArgOperand(0), B, TLI,
LibFunc_Znam12__hot_cold_t, HotCold);
break;
case LibFunc_ZnwmRKSt9nothrow_t12__hot_cold_t:
if (OptimizeExistingHotColdNew)
return emitHotColdNewNoThrow(
CI->getArgOperand(0), CI->getArgOperand(1), B, TLI,
LibFunc_ZnwmRKSt9nothrow_t12__hot_cold_t, HotCold);
break;
case LibFunc_ZnwmRKSt9nothrow_t:
if (HotCold != NotColdNewHintValue)
return emitHotColdNewNoThrow(
CI->getArgOperand(0), CI->getArgOperand(1), B, TLI,
LibFunc_ZnwmRKSt9nothrow_t12__hot_cold_t, HotCold);
break;
case LibFunc_ZnamRKSt9nothrow_t12__hot_cold_t:
if (OptimizeExistingHotColdNew)
return emitHotColdNewNoThrow(
CI->getArgOperand(0), CI->getArgOperand(1), B, TLI,
LibFunc_ZnamRKSt9nothrow_t12__hot_cold_t, HotCold);
break;
case LibFunc_ZnamRKSt9nothrow_t:
if (HotCold != NotColdNewHintValue)
return emitHotColdNewNoThrow(
CI->getArgOperand(0), CI->getArgOperand(1), B, TLI,
LibFunc_ZnamRKSt9nothrow_t12__hot_cold_t, HotCold);
break;
case LibFunc_ZnwmSt11align_val_t12__hot_cold_t:
if (OptimizeExistingHotColdNew)
return emitHotColdNewAligned(
CI->getArgOperand(0), CI->getArgOperand(1), B, TLI,
LibFunc_ZnwmSt11align_val_t12__hot_cold_t, HotCold);
break;
case LibFunc_ZnwmSt11align_val_t:
if (HotCold != NotColdNewHintValue)
return emitHotColdNewAligned(
CI->getArgOperand(0), CI->getArgOperand(1), B, TLI,
LibFunc_ZnwmSt11align_val_t12__hot_cold_t, HotCold);
break;
case LibFunc_ZnamSt11align_val_t12__hot_cold_t:
if (OptimizeExistingHotColdNew)
return emitHotColdNewAligned(
CI->getArgOperand(0), CI->getArgOperand(1), B, TLI,
LibFunc_ZnamSt11align_val_t12__hot_cold_t, HotCold);
break;
case LibFunc_ZnamSt11align_val_t:
if (HotCold != NotColdNewHintValue)
return emitHotColdNewAligned(
CI->getArgOperand(0), CI->getArgOperand(1), B, TLI,
LibFunc_ZnamSt11align_val_t12__hot_cold_t, HotCold);
break;
case LibFunc_ZnwmSt11align_val_tRKSt9nothrow_t12__hot_cold_t:
if (OptimizeExistingHotColdNew)
return emitHotColdNewAlignedNoThrow(
CI->getArgOperand(0), CI->getArgOperand(1), CI->getArgOperand(2), B,
TLI, LibFunc_ZnwmSt11align_val_tRKSt9nothrow_t12__hot_cold_t,
HotCold);
break;
case LibFunc_ZnwmSt11align_val_tRKSt9nothrow_t:
if (HotCold != NotColdNewHintValue)
return emitHotColdNewAlignedNoThrow(
CI->getArgOperand(0), CI->getArgOperand(1), CI->getArgOperand(2), B,
TLI, LibFunc_ZnwmSt11align_val_tRKSt9nothrow_t12__hot_cold_t,
HotCold);
break;
case LibFunc_ZnamSt11align_val_tRKSt9nothrow_t12__hot_cold_t:
if (OptimizeExistingHotColdNew)
return emitHotColdNewAlignedNoThrow(
CI->getArgOperand(0), CI->getArgOperand(1), CI->getArgOperand(2), B,
TLI, LibFunc_ZnamSt11align_val_tRKSt9nothrow_t12__hot_cold_t,
HotCold);
break;
case LibFunc_ZnamSt11align_val_tRKSt9nothrow_t:
if (HotCold != NotColdNewHintValue)
return emitHotColdNewAlignedNoThrow(
CI->getArgOperand(0), CI->getArgOperand(1), CI->getArgOperand(2), B,
TLI, LibFunc_ZnamSt11align_val_tRKSt9nothrow_t12__hot_cold_t,
HotCold);
break;
default:
return nullptr;
}
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) {
CallInst *NewCall = B.CreateUnaryIntrinsic(IID, CI->getArgOperand(0), CI);
NewCall->takeName(CI);
return copyFlags(*CI, 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, const TargetLibraryInfo *TLI,
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.starts_with(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], TLI, CalleeName, B,
CalleeAttrs)
: emitUnaryFloatFnCall(V[0], TLI, CalleeName, B, CalleeAttrs);
}
return B.CreateFPExt(R, B.getDoubleTy());
}
/// Shrink double -> float for unary functions.
static Value *optimizeUnaryDoubleFP(CallInst *CI, IRBuilderBase &B,
const TargetLibraryInfo *TLI,
bool isPrecise = false) {
return optimizeDoubleFP(CI, B, false, TLI, isPrecise);
}
/// Shrink double -> float for binary functions.
static Value *optimizeBinaryDoubleFP(CallInst *CI, IRBuilderBase &B,
const TargetLibraryInfo *TLI,
bool isPrecise = false) {
return optimizeDoubleFP(CI, B, true, TLI, 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->arg_size() == 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->arg_size() == 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);
return copyFlags(*CI, B.CreateUnaryIntrinsic(Intrinsic::sqrt,
B.CreateFAdd(RealReal, ImagImag),
nullptr, "cabs"));
}
// Return a properly extended integer (DstWidth bits wide) if the operation is
// an itofp.
static Value *getIntToFPVal(Value *I2F, IRBuilderBase &B, unsigned DstWidth) {
if (isa<SIToFPInst>(I2F) || isa<UIToFPInst>(I2F)) {
Value *Op = cast<Instruction>(I2F)->getOperand(0);
// Make sure that the exponent fits inside an "int" of size DstWidth,
// thus avoiding any range issues that FP has not.
unsigned BitWidth = Op->getType()->getScalarSizeInBits();
if (BitWidth < DstWidth || (BitWidth == DstWidth && isa<SIToFPInst>(I2F))) {
Type *IntTy = Op->getType()->getWithNewBitWidth(DstWidth);
return isa<SIToFPInst>(I2F) ? B.CreateSExt(Op, IntTy)
: B.CreateZExt(Op, IntTy);
}
}
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) {
Module *M = Pow->getModule();
Value *Base = Pow->getArgOperand(0), *Expo = Pow->getArgOperand(1);
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) &&
isLibFuncEmittable(M, TLI, 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.CreateUnaryIntrinsic(ID, FMul, nullptr, 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;
AttributeList NoAttrs; // Attributes are only meaningful on the original call
const bool UseIntrinsic = Pow->doesNotAccessMemory();
// pow(2.0, itofp(x)) -> ldexp(1.0, x)
if ((UseIntrinsic || !Ty->isVectorTy()) && match(Base, m_SpecificFP(2.0)) &&
(isa<SIToFPInst>(Expo) || isa<UIToFPInst>(Expo)) &&
hasFloatFn(M, TLI, Ty, LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl)) {
if (Value *ExpoI = getIntToFPVal(Expo, B, TLI->getIntSize())) {
Constant *One = ConstantFP::get(Ty, 1.0);
if (UseIntrinsic) {
return copyFlags(*Pow, B.CreateIntrinsic(Intrinsic::ldexp,
{Ty, ExpoI->getType()},
{One, ExpoI}, Pow, "exp2"));
}
return copyFlags(*Pow, emitBinaryFloatFnCall(
One, ExpoI, TLI, LibFunc_ldexp, LibFunc_ldexpf,
LibFunc_ldexpl, B, NoAttrs));
}
}
// pow(2.0 ** n, x) -> exp2(n * x)
if (hasFloatFn(M, 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 copyFlags(*Pow, B.CreateUnaryIntrinsic(Intrinsic::exp2, FMul,
nullptr, "exp2"));
else
return copyFlags(*Pow, emitUnaryFloatFnCall(FMul, TLI, LibFunc_exp2,
LibFunc_exp2f,
LibFunc_exp2l, B, NoAttrs));
}
}
// pow(10.0, x) -> exp10(x)
if (match(Base, m_SpecificFP(10.0)) &&
hasFloatFn(M, TLI, Ty, LibFunc_exp10, LibFunc_exp10f, LibFunc_exp10l)) {
if (Pow->doesNotAccessMemory()) {
CallInst *NewExp10 =
B.CreateIntrinsic(Intrinsic::exp10, {Ty}, {Expo}, Pow, "exp10");
return copyFlags(*Pow, NewExp10);
}
return copyFlags(*Pow, emitUnaryFloatFnCall(Expo, TLI, LibFunc_exp10,
LibFunc_exp10f, LibFunc_exp10l,
B, NoAttrs));
}
// 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 copyFlags(*Pow, B.CreateUnaryIntrinsic(Intrinsic::exp2, FMul,
nullptr, "exp2"));
else if (hasFloatFn(M, TLI, Ty, LibFunc_exp2, LibFunc_exp2f,
LibFunc_exp2l))
return copyFlags(*Pow, emitUnaryFloatFnCall(FMul, TLI, LibFunc_exp2,
LibFunc_exp2f,
LibFunc_exp2l, B, NoAttrs));
}
}
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)
return B.CreateUnaryIntrinsic(Intrinsic::sqrt, V, nullptr, "sqrt");
// Otherwise, use the libcall for sqrt().
if (hasFloatFn(M, 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);
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, 0,
SimplifyQuery(DL, TLI, /*DT=*/nullptr, AC, Pow)))
return nullptr;
Sqrt = getSqrtCall(Base, AttributeList(), Pow->doesNotAccessMemory(), Mod, B,
TLI);
if (!Sqrt)
return nullptr;
// Handle signed zero base by expanding to fabs(sqrt(x)).
if (!Pow->hasNoSignedZeros())
Sqrt = B.CreateUnaryIntrinsic(Intrinsic::fabs, Sqrt, nullptr, "abs");
Sqrt = copyFlags(*Pow, Sqrt);
// 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};
Type *Types[] = {Base->getType(), Expo->getType()};
return B.CreateIntrinsic(Intrinsic::powi, Types, 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;
// If we can approximate pow:
// pow(x, n) -> powi(x, n) * sqrt(x) if n has exactly a 0.5 fraction
// pow(x, n) -> powi(x, n) if n is a constant signed integer value
const APFloat *ExpoF;
if (AllowApprox && match(Expo, m_APFloat(ExpoF)) &&
!ExpoF->isExactlyValue(0.5) && !ExpoF->isExactlyValue(-0.5)) {
APFloat ExpoA(abs(*ExpoF));
APFloat ExpoI(*ExpoF);
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;
if (ExpoI.roundToIntegral(APFloat::rmTowardNegative) !=
APFloat::opInexact)
return nullptr;
if (!ExpoI.isInteger())
return nullptr;
ExpoF = &ExpoI;
Sqrt = getSqrtCall(Base, AttributeList(), Pow->doesNotAccessMemory(), M,
B, TLI);
if (!Sqrt)
return nullptr;
}
// 0.5 fraction is now optionally handled.
// Do pow -> powi for remaining integer exponent
APSInt IntExpo(TLI->getIntSize(), /*isUnsigned=*/false);
if (ExpoF->isInteger() &&
ExpoF->convertToInteger(IntExpo, APFloat::rmTowardZero, &Ignored) ==
APFloat::opOK) {
Value *PowI = copyFlags(
*Pow,
createPowWithIntegerExponent(
Base, ConstantInt::get(B.getIntNTy(TLI->getIntSize()), IntExpo),
M, B));
if (PowI && Sqrt)
return B.CreateFMul(PowI, Sqrt);
return PowI;
}
}
// powf(x, itofp(y)) -> powi(x, y)
if (AllowApprox && (isa<SIToFPInst>(Expo) || isa<UIToFPInst>(Expo))) {
if (Value *ExpoI = getIntToFPVal(Expo, B, TLI->getIntSize()))
return copyFlags(*Pow, 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(M, Name)) {
if (Value *Shrunk = optimizeBinaryDoubleFP(Pow, B, TLI, true))
return Shrunk;
}
return nullptr;
}
Value *LibCallSimplifier::optimizeExp2(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
Function *Callee = CI->getCalledFunction();
StringRef Name = Callee->getName();
Value *Ret = nullptr;
if (UnsafeFPShrink && Name == TLI->getName(LibFunc_exp2) &&
hasFloatVersion(M, Name))
Ret = optimizeUnaryDoubleFP(CI, B, TLI, true);
const bool UseIntrinsic = CI->doesNotAccessMemory();
// Bail out for vectors because the code below only expects scalars.
Type *Ty = CI->getType();
if (!UseIntrinsic && Ty->isVectorTy())
return Ret;
// exp2(sitofp(x)) -> ldexp(1.0, sext(x)) if sizeof(x) <= IntSize
// exp2(uitofp(x)) -> ldexp(1.0, zext(x)) if sizeof(x) < IntSize
Value *Op = CI->getArgOperand(0);
if ((isa<SIToFPInst>(Op) || isa<UIToFPInst>(Op)) &&
hasFloatFn(M, TLI, Ty, LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl)) {
if (Value *Exp = getIntToFPVal(Op, B, TLI->getIntSize())) {
Constant *One = ConstantFP::get(Ty, 1.0);
// TODO: Emitting the intrinsic should not depend on whether the libcall
// is available.
if (UseIntrinsic) {
return copyFlags(*CI, B.CreateIntrinsic(Intrinsic::ldexp,
{Ty, Exp->getType()},
{One, Exp}, CI));
}
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(CI->getFastMathFlags());
return copyFlags(*CI, emitBinaryFloatFnCall(
One, Exp, TLI, LibFunc_ldexp, LibFunc_ldexpf,
LibFunc_ldexpl, B, AttributeList()));
}
}
return Ret;
}
Value *LibCallSimplifier::optimizeFMinFMax(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
// 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(M, Name))
if (Value *Ret = optimizeBinaryDoubleFP(CI, B, TLI))
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().starts_with("fmin") ? Intrinsic::minnum
: Intrinsic::maxnum;
return copyFlags(*CI, B.CreateBinaryIntrinsic(IID, CI->getArgOperand(0),
CI->getArgOperand(1)));
}
Value *LibCallSimplifier::optimizeLog(CallInst *Log, IRBuilderBase &B) {
Function *LogFn = Log->getCalledFunction();
StringRef LogNm = LogFn->getName();
Intrinsic::ID LogID = LogFn->getIntrinsicID();
Module *Mod = Log->getModule();
Type *Ty = Log->getType();
Value *Ret = nullptr;
if (UnsafeFPShrink && hasFloatVersion(Mod, LogNm))
Ret = optimizeUnaryDoubleFP(Log, B, TLI, 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_e