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[SimplifyLibCalls] Factor out fortified libcall handling.

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This lets us remove CGP duplicate.

Differential Revision: http://reviews.llvm.org/D6541


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225640 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ahmed Bougacha 2015-01-12 17:22:43 +00:00
parent fe2d64e0f6
commit 2cec3e9c11
5 changed files with 236 additions and 391 deletions
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14
include/llvm/Transforms/Utils/BuildLibCalls.h
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@ -115,20 +115,6 @@ namespace llvm {
/// a pointer, Size is an 'intptr_t', and File is a pointer to FILE.
Value *EmitFWrite(Value *Ptr, Value *Size, Value *File, IRBuilder<> &B,
const DataLayout *TD, const TargetLibraryInfo *TLI);
/// SimplifyFortifiedLibCalls - Helper class for folding checked library
/// calls (e.g. __strcpy_chk) into their unchecked counterparts.
class SimplifyFortifiedLibCalls {
protected:
CallInst *CI;
virtual void replaceCall(Value *With) = 0;
virtual bool isFoldable(unsigned SizeCIOp, unsigned SizeArgOp,
bool isString) const = 0;
public:
virtual ~SimplifyFortifiedLibCalls();
bool fold(CallInst *CI, const DataLayout *TD, const TargetLibraryInfo *TLI);
};
}
#endif

43
include/llvm/Transforms/Utils/SimplifyLibCalls.h
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@ -27,11 +27,46 @@ class TargetLibraryInfo;
class BasicBlock;
class Function;
/// \brief This class implements simplifications for calls to fortified library
/// functions (__st*cpy_chk, __memcpy_chk, __memmove_chk, __memset_chk), to,
/// when possible, replace them with their non-checking counterparts.
/// Other optimizations can also be done, but it's possible to disable them and
/// only simplify needless use of the checking versions (when the object size
/// is unknown) by passing true for OnlyLowerUnknownSize.
class FortifiedLibCallSimplifier {
private:
const DataLayout *DL;
const TargetLibraryInfo *TLI;
bool OnlyLowerUnknownSize;
public:
FortifiedLibCallSimplifier(const DataLayout *DL, const TargetLibraryInfo *TLI,
bool OnlyLowerUnknownSize = false);
/// \brief Take the given call instruction and return a more
/// optimal value to replace the instruction with or 0 if a more
/// optimal form can't be found.
Value *optimizeCall(CallInst *CI);
private:
Value *optimizeMemCpyChk(CallInst *CI, IRBuilder<> &B);
Value *optimizeMemMoveChk(CallInst *CI, IRBuilder<> &B);
Value *optimizeMemSetChk(CallInst *CI, IRBuilder<> &B);
Value *optimizeStrCpyChk(CallInst *CI, IRBuilder<> &B);
Value *optimizeStrNCpyChk(CallInst *CI, IRBuilder<> &B);
/// \brief Checks whether the call \p CI to a fortified libcall is foldable
/// to the non-fortified version.
bool isFortifiedCallFoldable(CallInst *CI, unsigned ObjSizeOp,
unsigned SizeOp, bool isString);
};
/// LibCallSimplifier - This class implements a collection of optimizations
/// that replace well formed calls to library functions with a more optimal
/// form. For example, replacing 'printf("Hello!")' with 'puts("Hello!")'.
class LibCallSimplifier {
private:
FortifiedLibCallSimplifier FortifiedSimplifier;
const DataLayout *DL;
const TargetLibraryInfo *TLI;
bool UnsafeFPShrink;
@ -56,14 +91,6 @@ public:
virtual void replaceAllUsesWith(Instruction *I, Value *With) const;
private:
// Fortified Library Call Optimizations
Value *optimizeMemCpyChk(CallInst *CI, IRBuilder<> &B);
Value *optimizeMemMoveChk(CallInst *CI, IRBuilder<> &B);
Value *optimizeMemSetChk(CallInst *CI, IRBuilder<> &B);
Value *optimizeStrCpyChk(CallInst *CI, IRBuilder<> &B);
Value *optimizeStpCpyChk(CallInst *CI, IRBuilder<> &B);
Value *optimizeStrNCpyChk(CallInst *CI, IRBuilder<> &B);
// String and Memory Library Call Optimizations
Value *optimizeStrCat(CallInst *CI, IRBuilder<> &B);
Value *optimizeStrNCat(CallInst *CI, IRBuilder<> &B);

30
lib/CodeGen/CodeGenPrepare.cpp
View File

@ -45,6 +45,7 @@
#include "llvm/Transforms/Utils/BuildLibCalls.h"
#include "llvm/Transforms/Utils/BypassSlowDivision.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
using namespace llvm;
using namespace llvm::PatternMatch;
@ -847,22 +848,6 @@ static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
return MadeChange;
}
namespace {
class CodeGenPrepareFortifiedLibCalls : public SimplifyFortifiedLibCalls {
protected:
void replaceCall(Value *With) override {
CI->replaceAllUsesWith(With);
CI->eraseFromParent();
}
bool isFoldable(unsigned SizeCIOp, unsigned, bool) const override {
if (ConstantInt *SizeCI =
dyn_cast<ConstantInt>(CI->getArgOperand(SizeCIOp)))
return SizeCI->isAllOnesValue();
return false;
}
};
} // end anonymous namespace
// ScalarizeMaskedLoad() translates masked load intrinsic, like
// <16 x i32 > @llvm.masked.load( <16 x i32>* %addr, i32 align,
// <16 x i1> %mask, <16 x i32> %passthru)
@ -1152,10 +1137,15 @@ bool CodeGenPrepare::OptimizeCallInst(CallInst *CI, bool& ModifiedDT) {
// Lower all default uses of _chk calls. This is very similar
// to what InstCombineCalls does, but here we are only lowering calls
// that have the default "don't know" as the objectsize. Anything else
// should be left alone.
CodeGenPrepareFortifiedLibCalls Simplifier;
return Simplifier.fold(CI, TD, TLInfo);
// to fortified library functions (e.g. __memcpy_chk) that have the default
// "don't know" as the objectsize. Anything else should be left alone.
FortifiedLibCallSimplifier Simplifier(TD, TLInfo, true);
if (Value *V = Simplifier.optimizeCall(CI)) {
CI->replaceAllUsesWith(V);
CI->eraseFromParent();
return true;
}
return false;
}
/// DupRetToEnableTailCallOpts - Look for opportunities to duplicate return

132
lib/Transforms/Utils/BuildLibCalls.cpp
View File

@ -486,135 +486,3 @@ Value *llvm::EmitFWrite(Value *Ptr, Value *Size, Value *File,
CI->setCallingConv(Fn->getCallingConv());
return CI;
}
SimplifyFortifiedLibCalls::~SimplifyFortifiedLibCalls() { }
bool SimplifyFortifiedLibCalls::fold(CallInst *CI, const DataLayout *TD,
const TargetLibraryInfo *TLI) {
// We really need DataLayout for later.
if (!TD) return false;
this->CI = CI;
Function *Callee = CI->getCalledFunction();
StringRef Name = Callee->getName();
FunctionType *FT = Callee->getFunctionType();
LLVMContext &Context = CI->getParent()->getContext();
IRBuilder<> B(CI);
if (Name == "__memcpy_chk") {
// Check if this has the right signature.
if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
!FT->getParamType(0)->isPointerTy() ||
!FT->getParamType(1)->isPointerTy() ||
FT->getParamType(2) != TD->getIntPtrType(Context) ||
FT->getParamType(3) != TD->getIntPtrType(Context))
return false;
if (isFoldable(3, 2, false)) {
B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), 1);
replaceCall(CI->getArgOperand(0));
return true;
}
return false;
}
// Should be similar to memcpy.
if (Name == "__mempcpy_chk") {
return false;
}
if (Name == "__memmove_chk") {
// Check if this has the right signature.
if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
!FT->getParamType(0)->isPointerTy() ||
!FT->getParamType(1)->isPointerTy() ||
FT->getParamType(2) != TD->getIntPtrType(Context) ||
FT->getParamType(3) != TD->getIntPtrType(Context))
return false;
if (isFoldable(3, 2, false)) {
B.CreateMemMove(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), 1);
replaceCall(CI->getArgOperand(0));
return true;
}
return false;
}
if (Name == "__memset_chk") {
// Check if this has the right signature.
if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
!FT->getParamType(0)->isPointerTy() ||
!FT->getParamType(1)->isIntegerTy() ||
FT->getParamType(2) != TD->getIntPtrType(Context) ||
FT->getParamType(3) != TD->getIntPtrType(Context))
return false;
if (isFoldable(3, 2, false)) {
Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(),
false);
B.CreateMemSet(CI->getArgOperand(0), Val, CI->getArgOperand(2), 1);
replaceCall(CI->getArgOperand(0));
return true;
}
return false;
}
if (Name == "__strcpy_chk" || Name == "__stpcpy_chk") {
// Check if this has the right signature.
if (FT->getNumParams() != 3 ||
FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
FT->getParamType(2) != TD->getIntPtrType(Context))
return 0;
// If a) we don't have any length information, or b) we know this will
// fit then just lower to a plain st[rp]cpy. Otherwise we'll keep our
// st[rp]cpy_chk call which may fail at runtime if the size is too long.
// TODO: It might be nice to get a maximum length out of the possible
// string lengths for varying.
if (isFoldable(2, 1, true)) {
Value *Ret = EmitStrCpy(CI->getArgOperand(0), CI->getArgOperand(1), B, TD,
TLI, Name.substr(2, 6));
if (!Ret)
return false;
replaceCall(Ret);
return true;
}
return false;
}
if (Name == "__strncpy_chk" || Name == "__stpncpy_chk") {
// Check if this has the right signature.
if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
!FT->getParamType(2)->isIntegerTy() ||
FT->getParamType(3) != TD->getIntPtrType(Context))
return false;
if (isFoldable(3, 2, false)) {
Value *Ret = EmitStrNCpy(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), B, TD, TLI,
Name.substr(2, 7));
if (!Ret)
return false;
replaceCall(Ret);
return true;
}
return false;
}
if (Name == "__strcat_chk") {
return false;
}
if (Name == "__strncat_chk") {
return false;
}
return false;
}

408
lib/Transforms/Utils/SimplifyLibCalls.cpp
View File

@ -180,209 +180,6 @@ static bool checkStringCopyLibFuncSignature(Function *F, LibFunc::Func Func,
return true;
}
//===----------------------------------------------------------------------===//
// Fortified Library Call Optimizations
//===----------------------------------------------------------------------===//
static bool isFortifiedCallFoldable(CallInst *CI, unsigned SizeCIOp, unsigned SizeArgOp,
bool isString) {
if (CI->getArgOperand(SizeCIOp) == CI->getArgOperand(SizeArgOp))
return true;
if (ConstantInt *SizeCI =
dyn_cast<ConstantInt>(CI->getArgOperand(SizeCIOp))) {
if (SizeCI->isAllOnesValue())
return true;
if (isString) {
uint64_t Len = GetStringLength(CI->getArgOperand(SizeArgOp));
// If the length is 0 we don't know how long it is and so we can't
// remove the check.
if (Len == 0)
return false;
return SizeCI->getZExtValue() >= Len;
}
if (ConstantInt *Arg = dyn_cast<ConstantInt>(CI->getArgOperand(SizeArgOp)))
return SizeCI->getZExtValue() >= Arg->getZExtValue();
}
return false;
}
Value *LibCallSimplifier::optimizeMemCpyChk(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
FunctionType *FT = Callee->getFunctionType();
LLVMContext &Context = CI->getContext();
// Check if this has the right signature.
if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
!FT->getParamType(0)->isPointerTy() ||
!FT->getParamType(1)->isPointerTy() ||
FT->getParamType(2) != DL->getIntPtrType(Context) ||
FT->getParamType(3) != DL->getIntPtrType(Context))
return nullptr;
if (isFortifiedCallFoldable(CI, 3, 2, false)) {
B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), 1);
return CI->getArgOperand(0);
}
return nullptr;
}
Value *LibCallSimplifier::optimizeMemMoveChk(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
FunctionType *FT = Callee->getFunctionType();
LLVMContext &Context = CI->getContext();
// Check if this has the right signature.
if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
!FT->getParamType(0)->isPointerTy() ||
!FT->getParamType(1)->isPointerTy() ||
FT->getParamType(2) != DL->getIntPtrType(Context) ||
FT->getParamType(3) != DL->getIntPtrType(Context))
return nullptr;
if (isFortifiedCallFoldable(CI, 3, 2, false)) {
B.CreateMemMove(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), 1);
return CI->getArgOperand(0);
}
return nullptr;
}
Value *LibCallSimplifier::optimizeMemSetChk(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
FunctionType *FT = Callee->getFunctionType();
LLVMContext &Context = CI->getContext();
// Check if this has the right signature.
if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
!FT->getParamType(0)->isPointerTy() ||
!FT->getParamType(1)->isIntegerTy() ||
FT->getParamType(2) != DL->getIntPtrType(Context) ||
FT->getParamType(3) != DL->getIntPtrType(Context))
return nullptr;
if (isFortifiedCallFoldable(CI, 3, 2, false)) {
Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(), false);
B.CreateMemSet(CI->getArgOperand(0), Val, CI->getArgOperand(2), 1);
return CI->getArgOperand(0);
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStrCpyChk(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
StringRef Name = Callee->getName();
FunctionType *FT = Callee->getFunctionType();
LLVMContext &Context = CI->getContext();
// Check if this has the right signature.
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
FT->getParamType(2) != DL->getIntPtrType(Context))
return nullptr;
Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1);
if (Dst == Src) // __strcpy_chk(x,x) -> x
return Src;
// If a) we don't have any length information, or b) we know this will
// fit then just lower to a plain strcpy. Otherwise we'll keep our
// strcpy_chk call which may fail at runtime if the size is too long.
// TODO: It might be nice to get a maximum length out of the possible
// string lengths for varying.
if (isFortifiedCallFoldable(CI, 2, 1, true)) {
Value *Ret = EmitStrCpy(Dst, Src, B, DL, TLI, Name.substr(2, 6));
return Ret;
} else {
// Maybe we can stil fold __strcpy_chk to __memcpy_chk.
uint64_t Len = GetStringLength(Src);
if (Len == 0)
return nullptr;
// This optimization require DataLayout.
if (!DL)
return nullptr;
Value *Ret = EmitMemCpyChk(
Dst, Src, ConstantInt::get(DL->getIntPtrType(Context), Len),
CI->getArgOperand(2), B, DL, TLI);
return Ret;
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStpCpyChk(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
StringRef Name = Callee->getName();
FunctionType *FT = Callee->getFunctionType();
LLVMContext &Context = CI->getContext();
// Check if this has the right signature.
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
FT->getParamType(2) != DL->getIntPtrType(FT->getParamType(0)))
return nullptr;
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(Dst, StrLen) : nullptr;
}
// If a) we don't have any length information, or b) we know this will
// fit then just lower to a plain stpcpy. Otherwise we'll keep our
// stpcpy_chk call which may fail at runtime if the size is too long.
// TODO: It might be nice to get a maximum length out of the possible
// string lengths for varying.
if (isFortifiedCallFoldable(CI, 2, 1, true)) {
Value *Ret = EmitStrCpy(Dst, Src, B, DL, TLI, Name.substr(2, 6));
return Ret;
} else {
// Maybe we can stil fold __stpcpy_chk to __memcpy_chk.
uint64_t Len = GetStringLength(Src);
if (Len == 0)
return nullptr;
// This optimization require DataLayout.
if (!DL)
return nullptr;
Type *PT = FT->getParamType(0);
Value *LenV = ConstantInt::get(DL->getIntPtrType(PT), Len);
Value *DstEnd =
B.CreateGEP(Dst, ConstantInt::get(DL->getIntPtrType(PT), Len - 1));
if (!EmitMemCpyChk(Dst, Src, LenV, CI->getArgOperand(2), B, DL, TLI))
return nullptr;
return DstEnd;
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStrNCpyChk(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
StringRef Name = Callee->getName();
FunctionType *FT = Callee->getFunctionType();
LLVMContext &Context = CI->getContext();
// Check if this has the right signature.
if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
!FT->getParamType(2)->isIntegerTy() ||
FT->getParamType(3) != DL->getIntPtrType(Context))
return nullptr;
if (isFortifiedCallFoldable(CI, 3, 2, false)) {
Value *Ret =
EmitStrNCpy(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), B, DL, TLI, Name.substr(2, 7));
return Ret;
}
return nullptr;
}
//===----------------------------------------------------------------------===//
// String and Memory Library Call Optimizations
//===----------------------------------------------------------------------===//
@ -2166,6 +1963,15 @@ Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
}
}
// Also try to simplify calls to fortified library functions.
if (Value *SimplifiedFortifiedCI = FortifiedSimplifier.optimizeCall(CI)) {
// Try to further simplify the result.
if (CallInst *SimplifiedCI = dyn_cast<CallInst>(SimplifiedFortifiedCI))
if (Value *V = optimizeStringMemoryLibCall(SimplifiedCI, Builder))
return V;
return SimplifiedFortifiedCI;
}
// Then check for known library functions.
if (TLI->getLibFunc(FuncName, Func) && TLI->has(Func)) {
// We never change the calling convention.
@ -2270,29 +2076,16 @@ Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
if (hasFloatVersion(FuncName))
return optimizeBinaryDoubleFP(CI, Builder);
return nullptr;
case LibFunc::memcpy_chk:
return optimizeMemCpyChk(CI, Builder);
case LibFunc::memmove_chk:
return optimizeMemMoveChk(CI, Builder);
case LibFunc::memset_chk:
return optimizeMemSetChk(CI, Builder);
case LibFunc::strcpy_chk:
return optimizeStrCpyChk(CI, Builder);
case LibFunc::stpcpy_chk:
return optimizeStpCpyChk(CI, Builder);
case LibFunc::stpncpy_chk:
case LibFunc::strncpy_chk:
return optimizeStrNCpyChk(CI, Builder);
default:
return nullptr;
}
}
return nullptr;
}
LibCallSimplifier::LibCallSimplifier(const DataLayout *DL,
const TargetLibraryInfo *TLI) :
FortifiedSimplifier(DL, TLI),
DL(DL),
TLI(TLI),
UnsafeFPShrink(false) {
@ -2350,3 +2143,184 @@ void LibCallSimplifier::replaceAllUsesWith(Instruction *I, Value *With) const {
// * trunc(cnst) -> cnst'
//
//
//===----------------------------------------------------------------------===//
// Fortified Library Call Optimizations
//===----------------------------------------------------------------------===//
bool FortifiedLibCallSimplifier::isFortifiedCallFoldable(CallInst *CI,
unsigned ObjSizeOp,
unsigned SizeOp,
bool isString) {
if (CI->getArgOperand(ObjSizeOp) == CI->getArgOperand(SizeOp))
return true;
if (ConstantInt *ObjSizeCI =
dyn_cast<ConstantInt>(CI->getArgOperand(ObjSizeOp))) {
if (ObjSizeCI->isAllOnesValue())
return true;
// If the object size wasn't -1 (unknown), bail out if we were asked to.
if (OnlyLowerUnknownSize)
return false;
if (isString) {
uint64_t Len = GetStringLength(CI->getArgOperand(SizeOp));
// If the length is 0 we don't know how long it is and so we can't
// remove the check.
if (Len == 0)
return false;
return ObjSizeCI->getZExtValue() >= Len;
}
if (ConstantInt *SizeCI = dyn_cast<ConstantInt>(CI->getArgOperand(SizeOp)))
return ObjSizeCI->getZExtValue() >= SizeCI->getZExtValue();
}
return false;
}
Value *FortifiedLibCallSimplifier::optimizeMemCpyChk(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
if (!checkStringCopyLibFuncSignature(Callee, LibFunc::memcpy_chk, DL))
return nullptr;
if (isFortifiedCallFoldable(CI, 3, 2, false)) {
B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), 1);
return CI->getArgOperand(0);
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeMemMoveChk(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
if (!checkStringCopyLibFuncSignature(Callee, LibFunc::memmove_chk, DL))
return nullptr;
if (isFortifiedCallFoldable(CI, 3, 2, false)) {
B.CreateMemMove(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), 1);
return CI->getArgOperand(0);
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeMemSetChk(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
if (!checkStringCopyLibFuncSignature(Callee, LibFunc::memset_chk, DL))
return nullptr;
if (isFortifiedCallFoldable(CI, 3, 2, false)) {
Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(), false);
B.CreateMemSet(CI->getArgOperand(0), Val, CI->getArgOperand(2), 1);
return CI->getArgOperand(0);
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeStrCpyChk(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
StringRef Name = Callee->getName();
LibFunc::Func Func =
Name.startswith("str") ? LibFunc::strcpy_chk : LibFunc::stpcpy_chk;
if (!checkStringCopyLibFuncSignature(Callee, Func, DL))
return nullptr;
Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1),
*ObjSize = CI->getArgOperand(2);
// __stpcpy_chk(x,x,...) -> x+strlen(x)
if (!OnlyLowerUnknownSize && Dst == Src) {
Value *StrLen = EmitStrLen(Src, B, DL, TLI);
return StrLen ? B.CreateInBoundsGEP(Dst, StrLen) : nullptr;
}
// If a) we don't have any length information, or b) we know this will
// fit then just lower to a plain st[rp]cpy. Otherwise we'll keep our
// st[rp]cpy_chk call which may fail at runtime if the size is too long.
// TODO: It might be nice to get a maximum length out of the possible
// string lengths for varying.
if (isFortifiedCallFoldable(CI, 2, 1, true)) {
Value *Ret = EmitStrCpy(Dst, Src, B, DL, TLI, Name.substr(2, 6));
return Ret;
} else if (!OnlyLowerUnknownSize) {
// Maybe we can stil fold __st[rp]cpy_chk to __memcpy_chk.
uint64_t Len = GetStringLength(Src);
if (Len == 0)
return nullptr;
// This optimization requires DataLayout.
if (!DL)
return nullptr;
Type *SizeTTy = DL->getIntPtrType(CI->getContext());
Value *LenV = ConstantInt::get(SizeTTy, Len);
Value *Ret = EmitMemCpyChk(Dst, Src, LenV, ObjSize, B, DL, TLI);
// If the function was an __stpcpy_chk, and we were able to fold it into
// a __memcpy_chk, we still need to return the correct end pointer.
if (Ret && Func == LibFunc::stpcpy_chk)
return B.CreateGEP(Dst, ConstantInt::get(SizeTTy, Len - 1));
return Ret;
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeStrNCpyChk(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
StringRef Name = Callee->getName();
LibFunc::Func Func =
Name.startswith("str") ? LibFunc::strncpy_chk : LibFunc::stpncpy_chk;
if (!checkStringCopyLibFuncSignature(Callee, Func, DL))
return nullptr;
if (isFortifiedCallFoldable(CI, 3, 2, false)) {
Value *Ret =
EmitStrNCpy(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), B, DL, TLI, Name.substr(2, 7));
return Ret;
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeCall(CallInst *CI) {
if (CI->isNoBuiltin())
return nullptr;
LibFunc::Func Func;
Function *Callee = CI->getCalledFunction();
StringRef FuncName = Callee->getName();
IRBuilder<> Builder(CI);
bool isCallingConvC = CI->getCallingConv() == llvm::CallingConv::C;
// First, check that this is a known library functions.
if (!TLI->getLibFunc(FuncName, Func) || !TLI->has(Func))
return nullptr;
// We never change the calling convention.
if (!ignoreCallingConv(Func) && !isCallingConvC)
return nullptr;
switch (Func) {
case LibFunc::memcpy_chk:
return optimizeMemCpyChk(CI, Builder);
case LibFunc::memmove_chk:
return optimizeMemMoveChk(CI, Builder);
case LibFunc::memset_chk:
return optimizeMemSetChk(CI, Builder);
case LibFunc::stpcpy_chk:
case LibFunc::strcpy_chk:
return optimizeStrCpyChk(CI, Builder);
case LibFunc::stpncpy_chk:
case LibFunc::strncpy_chk:
return optimizeStrNCpyChk(CI, Builder);
default:
break;
}
return nullptr;
}
FortifiedLibCallSimplifier::
FortifiedLibCallSimplifier(const DataLayout *DL, const TargetLibraryInfo *TLI,
bool OnlyLowerUnknownSize)
: DL(DL), TLI(TLI), OnlyLowerUnknownSize(OnlyLowerUnknownSize) {
}