Differential D130224 Diff 447993 clang/lib/CodeGen/CGCall.cpp

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clang/lib/CodeGen/CGCall.cpp

Show First 20 Lines • Show All 2,040 Lines • ▼ Show 20 Lines if (const MatrixType *Matrix = dyn_cast<MatrixType>(QTy))

return DetermineNoUndef(Matrix->getElementType(), Types, DL, AI, false); return DetermineNoUndef(Matrix->getElementType(), Types, DL, AI, false);

if (const ArrayType *Array = dyn_cast<ArrayType>(QTy)) if (const ArrayType *Array = dyn_cast<ArrayType>(QTy))

return DetermineNoUndef(Array->getElementType(), Types, DL, AI, false); return DetermineNoUndef(Array->getElementType(), Types, DL, AI, false);

// TODO: Some structs may be `noundef`, in specific situations. // TODO: Some structs may be `noundef`, in specific situations.

return false; return false;

} }

/// Check if the argument of a function has maybe_undef attribute.

static bool IsArgumentMaybeUndef(const Decl *TargetDecl,

unsigned NumRequiredArgs, unsigned ArgNo) {

const auto *FD = dyn_cast_or_null<FunctionDecl>(TargetDecl);

if (!FD)

return false;

// Assume variadic arguments do not have maybe_undef attribute.

if (ArgNo >= NumRequiredArgs)

return false;

// Check if argument has maybe_undef attribute.

if (ArgNo < FD->getNumParams()) {

jdoerfertUnsubmitted

Not Done

Early exists please.

if (!TargetDecl)

return false

no ArgHasMayBeUndefAttr is needed, just return true/false, etc.

jdoerfert: Early exists please. if (!TargetDecl) return false no ArgHasMayBeUndefAttr is needed, just…

const ParmVarDecl *Param = FD->getParamDecl(ArgNo);

if (Param && Param->hasAttr<MaybeUndefAttr>()) {

return true;

}

aaron.ballmanUnsubmitted

Not Done

const ParmVarDecl *Param = FD->getParamDecl(ArgNo);

- if (Param && Param->hasAttr<MaybeUndefAttr>()) {

+ if (Param && Param->hasAttr<MaybeUndefAttr>())

return true;

- }

+ }

return false;

aaron.ballman:

}

aaron.ballmanUnsubmitted

Not Done

/// Check if the argument of a function has maybe_undef attribute.

static bool IsArgumentMayBeUndef(const Decl *TargetDecl, unsigned ArgNo) {

- if (!TargetDecl)

+ const auto *FD = dyn_cast_or_null<FunctionDecl>(TargetDecl);

+ if (!FD)

return false;

- bool ArgHasMayBeUndefAttr = false;

- if (TargetDecl) {

- if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(TargetDecl)) {

- if (FD && (ArgNo < FD->getNumParams())) {

- const ParmVarDecl *Param = FD->getParamDecl(ArgNo);

- if (Param && Param->hasAttr<MayBeUndefAttr>()) {

- ArgHasMayBeUndefAttr = true;

- }

- return ArgHasMayBeUndefAttr;

+ if (ArgNo < FD->getNumParams()) {

+ const ParmVarDecl *Param = FD->getParamDecl(ArgNo);

+ if (Param && Param->hasAttr<MayBeUndefAttr>())

+ return true;

+ }

+ return false;

}

/// Construct the IR attribute list of a function or call.

One question I have is whether you ever need to mark the variadic arguments as being maybe undef. e.g., void func(int i, ...); do you need to signal that arguments passed to ... are maybe undef?

aaron.ballman: One question I have is whether you ever need to mark the variadic arguments as being maybe…

skc7AuthorUnsubmitted

Not Done

Current change assumes variadic arguments will not have "maybe_undef" attribute. If its a function attribute, variadic arguments can inherit them (Have seen such cases in clang codebase). But "maybe_undef" is function argument attribute and I'm not sure on how to add it to variadic arguments.

skc7: Current change assumes variadic arguments will not have "maybe_undef" attribute. If its a…

aaron.ballmanUnsubmitted

Not Done

Current change assumes variadic arguments will not have "maybe_undef" attribute. If its a function attribute, variadic arguments can inherit them (Have seen such cases in clang codebase). But "maybe_undef" is function argument attribute and I'm not sure on how to add it to variadic arguments.

That's why I was asking if there will be a need either now or in the future -- is making this a parameter attribute the right design, or should this be a function attribute with positional arguments? (Not that I particularly love that design, but this isn't a user-facing attribute so if it's hard to use, I'm not that worried. I just want to make sure we don't need to add additional attributes in the future in this same space.)

aaron.ballman: > Current change assumes variadic arguments will not have "maybe_undef" attribute. If its a…

return false;

}

/// Construct the IR attribute list of a function or call. /// Construct the IR attribute list of a function or call.

/// ///

/// When adding an attribute, please consider where it should be handled: /// When adding an attribute, please consider where it should be handled:

/// ///

/// - getDefaultFunctionAttributes is for attributes that are essentially /// - getDefaultFunctionAttributes is for attributes that are essentially

/// part of the global target configuration (but perhaps can be /// part of the global target configuration (but perhaps can be

/// overridden on a per-function basis). Adding attributes there /// overridden on a per-function basis). Adding attributes there

/// will cause them to also be set in frontends that build on Clang's /// will cause them to also be set in frontends that build on Clang's

▲ Show 20 Lines • Show All 2,754 Lines • ▼ Show 20 Lines for (CallArgList::const_iterator I = CallArgs.begin(), E = CallArgs.end();

// Insert a padding argument to ensure proper alignment. // Insert a padding argument to ensure proper alignment.

if (IRFunctionArgs.hasPaddingArg(ArgNo)) if (IRFunctionArgs.hasPaddingArg(ArgNo))

IRCallArgs[IRFunctionArgs.getPaddingArgNo(ArgNo)] = IRCallArgs[IRFunctionArgs.getPaddingArgNo(ArgNo)] =

llvm::UndefValue::get(ArgInfo.getPaddingType()); llvm::UndefValue::get(ArgInfo.getPaddingType());

unsigned FirstIRArg, NumIRArgs; unsigned FirstIRArg, NumIRArgs;

std::tie(FirstIRArg, NumIRArgs) = IRFunctionArgs.getIRArgs(ArgNo); std::tie(FirstIRArg, NumIRArgs) = IRFunctionArgs.getIRArgs(ArgNo);

bool ArgHasMaybeUndefAttr =

IsArgumentMaybeUndef(TargetDecl, CallInfo.getNumRequiredArgs(), ArgNo);

switch (ArgInfo.getKind()) { switch (ArgInfo.getKind()) {

case ABIArgInfo::InAlloca: { case ABIArgInfo::InAlloca: {

assert(NumIRArgs == 0); assert(NumIRArgs == 0);

assert(getTarget().getTriple().getArch() == llvm::Triple::x86); assert(getTarget().getTriple().getArch() == llvm::Triple::x86);

if (I->isAggregate()) { if (I->isAggregate()) {

Address Addr = I->hasLValue() Address Addr = I->hasLValue()

? I->getKnownLValue().getAddress(*this) ? I->getKnownLValue().getAddress(*this)

: I->getKnownRValue().getAggregateAddress(); : I->getKnownRValue().getAggregateAddress();

▲ Show 20 Lines • Show All 42 Lines • ▼ Show 20 Lines for (CallArgList::const_iterator I = CallArgs.begin(), E = CallArgs.end();

case ABIArgInfo::Indirect: case ABIArgInfo::Indirect:

case ABIArgInfo::IndirectAliased: { case ABIArgInfo::IndirectAliased: {

assert(NumIRArgs == 1); assert(NumIRArgs == 1);

if (!I->isAggregate()) { if (!I->isAggregate()) {

// Make a temporary alloca to pass the argument. // Make a temporary alloca to pass the argument.

Address Addr = CreateMemTempWithoutCast( Address Addr = CreateMemTempWithoutCast(

I->Ty, ArgInfo.getIndirectAlign(), "indirect-arg-temp"); I->Ty, ArgInfo.getIndirectAlign(), "indirect-arg-temp");

IRCallArgs[FirstIRArg] = Addr.getPointer();

llvm::Value *Val = Addr.getPointer();

if (ArgHasMaybeUndefAttr)

Val = Builder.CreateFreeze(Addr.getPointer());

IRCallArgs[FirstIRArg] = Val;

jdoerfertUnsubmitted

Not Done

Style: Val, also below.

jdoerfert: Style: `Val`, also below.

I->copyInto(*this, Addr); I->copyInto(*this, Addr);

} else { } else {

// We want to avoid creating an unnecessary temporary+copy here; // We want to avoid creating an unnecessary temporary+copy here;

// however, we need one in three cases: // however, we need one in three cases:

// 1. If the argument is not byval, and we are required to copy the // 1. If the argument is not byval, and we are required to copy the

// source. (This case doesn't occur on any common architecture.) // source. (This case doesn't occur on any common architecture.)

// 2. If the argument is byval, RV is not sufficiently aligned, and // 2. If the argument is byval, RV is not sufficiently aligned, and

▲ Show 20 Lines • Show All 41 Lines • ▼ Show 20 Lines case ABIArgInfo::IndirectAliased: {

NeedCopy = true; NeedCopy = true;

} }

if (NeedCopy) { if (NeedCopy) {

// Create an aligned temporary, and copy to it. // Create an aligned temporary, and copy to it.

Address AI = CreateMemTempWithoutCast( Address AI = CreateMemTempWithoutCast(

I->Ty, ArgInfo.getIndirectAlign(), "byval-temp"); I->Ty, ArgInfo.getIndirectAlign(), "byval-temp");

IRCallArgs[FirstIRArg] = AI.getPointer(); llvm::Value *Val = AI.getPointer();

if (ArgHasMaybeUndefAttr)

Val = Builder.CreateFreeze(AI.getPointer());

IRCallArgs[FirstIRArg] = Val;

// Emit lifetime markers for the temporary alloca. // Emit lifetime markers for the temporary alloca.

llvm::TypeSize ByvalTempElementSize = llvm::TypeSize ByvalTempElementSize =

CGM.getDataLayout().getTypeAllocSize(AI.getElementType()); CGM.getDataLayout().getTypeAllocSize(AI.getElementType());

llvm::Value *LifetimeSize = llvm::Value *LifetimeSize =

EmitLifetimeStart(ByvalTempElementSize, AI.getPointer()); EmitLifetimeStart(ByvalTempElementSize, AI.getPointer());

// Add cleanup code to emit the end lifetime marker after the call. // Add cleanup code to emit the end lifetime marker after the call.

if (LifetimeSize) // In case we disabled lifetime markers. if (LifetimeSize) // In case we disabled lifetime markers.

CallLifetimeEndAfterCall.emplace_back(AI, LifetimeSize); CallLifetimeEndAfterCall.emplace_back(AI, LifetimeSize);

// Generate the copy. // Generate the copy.

I->copyInto(*this, AI); I->copyInto(*this, AI);

} else { } else {

// Skip the extra memcpy call. // Skip the extra memcpy call.

auto *T = llvm::PointerType::getWithSamePointeeType( auto *T = llvm::PointerType::getWithSamePointeeType(

cast<llvm::PointerType>(V->getType()), cast<llvm::PointerType>(V->getType()),

CGM.getDataLayout().getAllocaAddrSpace()); CGM.getDataLayout().getAllocaAddrSpace());

IRCallArgs[FirstIRArg] = getTargetHooks().performAddrSpaceCast(

llvm::Value *Val = getTargetHooks().performAddrSpaceCast(

*this, V, LangAS::Default, CGM.getASTAllocaAddressSpace(), T, *this, V, LangAS::Default, CGM.getASTAllocaAddressSpace(), T,

true); true);

if (ArgHasMaybeUndefAttr)

Val = Builder.CreateFreeze(Val);

IRCallArgs[FirstIRArg] = Val;

} }

break; break;

} }

case ABIArgInfo::Ignore: case ABIArgInfo::Ignore:

assert(NumIRArgs == 0); assert(NumIRArgs == 0);

break; break;

Show All 37 Lines case ABIArgInfo::Direct: {

V = Builder.CreateZExt(V, ArgInfo.getCoerceToType()); V = Builder.CreateZExt(V, ArgInfo.getCoerceToType());

// If the argument doesn't match, perform a bitcast to coerce it. This // If the argument doesn't match, perform a bitcast to coerce it. This

// can happen due to trivial type mismatches. // can happen due to trivial type mismatches.

if (FirstIRArg < IRFuncTy->getNumParams() && if (FirstIRArg < IRFuncTy->getNumParams() &&

V->getType() != IRFuncTy->getParamType(FirstIRArg)) V->getType() != IRFuncTy->getParamType(FirstIRArg))

V = Builder.CreateBitCast(V, IRFuncTy->getParamType(FirstIRArg)); V = Builder.CreateBitCast(V, IRFuncTy->getParamType(FirstIRArg));

if (ArgHasMaybeUndefAttr)

V = Builder.CreateFreeze(V);

IRCallArgs[FirstIRArg] = V; IRCallArgs[FirstIRArg] = V;

break; break;

} }

// FIXME: Avoid the conversion through memory if possible. // FIXME: Avoid the conversion through memory if possible.

Address Src = Address::invalid(); Address Src = Address::invalid();

if (!I->isAggregate()) { if (!I->isAggregate()) {

Src = CreateMemTemp(I->Ty, "coerce"); Src = CreateMemTemp(I->Ty, "coerce");

Show All 28 Lines case ABIArgInfo::Direct: {

} else { } else {

Src = Builder.CreateElementBitCast(Src, STy); Src = Builder.CreateElementBitCast(Src, STy);

} }

assert(NumIRArgs == STy->getNumElements()); assert(NumIRArgs == STy->getNumElements());

for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {

Address EltPtr = Builder.CreateStructGEP(Src, i); Address EltPtr = Builder.CreateStructGEP(Src, i);

llvm::Value *LI = Builder.CreateLoad(EltPtr); llvm::Value *LI = Builder.CreateLoad(EltPtr);

if (ArgHasMaybeUndefAttr)

LI = Builder.CreateFreeze(LI);

IRCallArgs[FirstIRArg + i] = LI; IRCallArgs[FirstIRArg + i] = LI;

} }

} else { } else {

// In the simple case, just pass the coerced loaded value. // In the simple case, just pass the coerced loaded value.

assert(NumIRArgs == 1); assert(NumIRArgs == 1);

llvm::Value *Load = llvm::Value *Load =

CreateCoercedLoad(Src, ArgInfo.getCoerceToType(), *this); CreateCoercedLoad(Src, ArgInfo.getCoerceToType(), *this);

if (CallInfo.isCmseNSCall()) { if (CallInfo.isCmseNSCall()) {

// For certain parameter types, clear padding bits, as they may reveal // For certain parameter types, clear padding bits, as they may reveal

// sensitive information. // sensitive information.

// Small struct/union types are passed as integer arrays. // Small struct/union types are passed as integer arrays.

auto *ATy = dyn_cast<llvm::ArrayType>(Load->getType()); auto *ATy = dyn_cast<llvm::ArrayType>(Load->getType());

if (ATy != nullptr && isa<RecordType>(I->Ty.getCanonicalType())) if (ATy != nullptr && isa<RecordType>(I->Ty.getCanonicalType()))

Load = EmitCMSEClearRecord(Load, ATy, I->Ty); Load = EmitCMSEClearRecord(Load, ATy, I->Ty);

} }

if (ArgHasMaybeUndefAttr)

Load = Builder.CreateFreeze(Load);

IRCallArgs[FirstIRArg] = Load; IRCallArgs[FirstIRArg] = Load;

} }

break; break;

} }

case ABIArgInfo::CoerceAndExpand: { case ABIArgInfo::CoerceAndExpand: {

auto coercionType = ArgInfo.getCoerceAndExpandType(); auto coercionType = ArgInfo.getCoerceAndExpandType();

Show All 29 Lines case ABIArgInfo::CoerceAndExpand: {

addr = Builder.CreateElementBitCast(addr, coercionType); addr = Builder.CreateElementBitCast(addr, coercionType);

unsigned IRArgPos = FirstIRArg; unsigned IRArgPos = FirstIRArg;

for (unsigned i = 0, e = coercionType->getNumElements(); i != e; ++i) { for (unsigned i = 0, e = coercionType->getNumElements(); i != e; ++i) {

llvm::Type *eltType = coercionType->getElementType(i); llvm::Type *eltType = coercionType->getElementType(i);

if (ABIArgInfo::isPaddingForCoerceAndExpand(eltType)) continue; if (ABIArgInfo::isPaddingForCoerceAndExpand(eltType)) continue;

Address eltAddr = Builder.CreateStructGEP(addr, i); Address eltAddr = Builder.CreateStructGEP(addr, i);

llvm::Value *elt = Builder.CreateLoad(eltAddr); llvm::Value *elt = Builder.CreateLoad(eltAddr);

if (ArgHasMaybeUndefAttr)

elt = Builder.CreateFreeze(elt);

IRCallArgs[IRArgPos++] = elt; IRCallArgs[IRArgPos++] = elt;

} }

assert(IRArgPos == FirstIRArg + NumIRArgs); assert(IRArgPos == FirstIRArg + NumIRArgs);

if (tempSize) { if (tempSize) {

EmitLifetimeEnd(tempSize, AllocaAddr.getPointer()); EmitLifetimeEnd(tempSize, AllocaAddr.getPointer());

} }

▲ Show 20 Lines • Show All 494 Lines • Show Last 20 Lines