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recommit c77a4078e0

This commit is contained in:
Yaxun (Sam) Liu 2020-04-24 16:41:24 -04:00
parent a8e5dcb072
commit b46b1a916d
2 changed files with 122 additions and 56 deletions
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126
clang/lib/Sema/SemaOverload.cpp
View File

@ -9374,16 +9374,22 @@ static Comparison compareEnableIfAttrs(const Sema &S, const FunctionDecl *Cand1,
return Comparison::Equal;
}
static bool isBetterMultiversionCandidate(const OverloadCandidate &Cand1,
static Comparison
isBetterMultiversionCandidate(const OverloadCandidate &Cand1,
const OverloadCandidate &Cand2) {
if (!Cand1.Function || !Cand1.Function->isMultiVersion() || !Cand2.Function ||
!Cand2.Function->isMultiVersion())
return false;
return Comparison::Equal;
// If Cand1 is invalid, it cannot be a better match, if Cand2 is invalid, this
// is obviously better.
if (Cand1.Function->isInvalidDecl()) return false;
if (Cand2.Function->isInvalidDecl()) return true;
// If both are invalid, they are equal. If one of them is invalid, the other
// is better.
if (Cand1.Function->isInvalidDecl()) {
if (Cand2.Function->isInvalidDecl())
return Comparison::Equal;
return Comparison::Worse;
}
if (Cand2.Function->isInvalidDecl())
return Comparison::Better;
// If this is a cpu_dispatch/cpu_specific multiversion situation, prefer
// cpu_dispatch, else arbitrarily based on the identifiers.
@ -9393,16 +9399,18 @@ static bool isBetterMultiversionCandidate(const OverloadCandidate &Cand1,
const auto *Cand2CPUSpec = Cand2.Function->getAttr<CPUSpecificAttr>();
if (!Cand1CPUDisp && !Cand2CPUDisp && !Cand1CPUSpec && !Cand2CPUSpec)
return false;
return Comparison::Equal;
if (Cand1CPUDisp && !Cand2CPUDisp)
return true;
return Comparison::Better;
if (Cand2CPUDisp && !Cand1CPUDisp)
return false;
return Comparison::Worse;
if (Cand1CPUSpec && Cand2CPUSpec) {
if (Cand1CPUSpec->cpus_size() != Cand2CPUSpec->cpus_size())
return Cand1CPUSpec->cpus_size() < Cand2CPUSpec->cpus_size();
return Cand1CPUSpec->cpus_size() < Cand2CPUSpec->cpus_size()
? Comparison::Better
: Comparison::Worse;
std::pair<CPUSpecificAttr::cpus_iterator, CPUSpecificAttr::cpus_iterator>
FirstDiff = std::mismatch(
@ -9415,7 +9423,9 @@ static bool isBetterMultiversionCandidate(const OverloadCandidate &Cand1,
assert(FirstDiff.first != Cand1CPUSpec->cpus_end() &&
"Two different cpu-specific versions should not have the same "
"identifier list, otherwise they'd be the same decl!");
return (*FirstDiff.first)->getName() < (*FirstDiff.second)->getName();
return (*FirstDiff.first)->getName() < (*FirstDiff.second)->getName()
? Comparison::Better
: Comparison::Worse;
}
llvm_unreachable("No way to get here unless both had cpu_dispatch");
}
@ -9475,6 +9485,50 @@ bool clang::isBetterOverloadCandidate(
else if (!Cand1.Viable)
return false;
// [CUDA] A function with 'never' preference is marked not viable, therefore
// is never shown up here. The worst preference shown up here is 'wrong side',
// e.g. a host function called by a device host function in device
// compilation. This is valid AST as long as the host device function is not
// emitted, e.g. it is an inline function which is called only by a host
// function. A deferred diagnostic will be triggered if it is emitted.
// However a wrong-sided function is still a viable candidate here.
//
// If Cand1 can be emitted and Cand2 cannot be emitted in the current
// context, Cand1 is better than Cand2. If Cand1 can not be emitted and Cand2
// can be emitted, Cand1 is not better than Cand2. This rule should have
// precedence over other rules.
//
// If both Cand1 and Cand2 can be emitted, or neither can be emitted, then
// other rules should be used to determine which is better. This is because
// host/device based overloading resolution is mostly for determining
// viability of a function. If two functions are both viable, other factors
// should take precedence in preference, e.g. the standard-defined preferences
// like argument conversion ranks or enable_if partial-ordering. The
// preference for pass-object-size parameters is probably most similar to a
// type-based-overloading decision and so should take priority.
//
// If other rules cannot determine which is better, CUDA preference will be
// used again to determine which is better.
//
// TODO: Currently IdentifyCUDAPreference does not return correct values
// for functions called in global variable initializers due to missing
// correct context about device/host. Therefore we can only enforce this
// rule when there is a caller. We should enforce this rule for functions
// in global variable initializers once proper context is added.
if (S.getLangOpts().CUDA && Cand1.Function && Cand2.Function) {
if (FunctionDecl *Caller = dyn_cast<FunctionDecl>(S.CurContext)) {
auto P1 = S.IdentifyCUDAPreference(Caller, Cand1.Function);
auto P2 = S.IdentifyCUDAPreference(Caller, Cand2.Function);
assert(P1 != Sema::CFP_Never && P2 != Sema::CFP_Never);
auto Cand1Emittable = P1 > Sema::CFP_WrongSide;
auto Cand2Emittable = P2 > Sema::CFP_WrongSide;
if (Cand1Emittable && !Cand2Emittable)
return true;
if (!Cand1Emittable && Cand2Emittable)
return false;
}
}
// C++ [over.match.best]p1:
//
// -- if F is a static member function, ICS1(F) is defined such
@ -9709,12 +9763,6 @@ bool clang::isBetterOverloadCandidate(
return Cmp == Comparison::Better;
}
if (S.getLangOpts().CUDA && Cand1.Function && Cand2.Function) {
FunctionDecl *Caller = dyn_cast<FunctionDecl>(S.CurContext);
return S.IdentifyCUDAPreference(Caller, Cand1.Function) >
S.IdentifyCUDAPreference(Caller, Cand2.Function);
}
bool HasPS1 = Cand1.Function != nullptr &&
functionHasPassObjectSizeParams(Cand1.Function);
bool HasPS2 = Cand2.Function != nullptr &&
@ -9722,7 +9770,22 @@ bool clang::isBetterOverloadCandidate(
if (HasPS1 != HasPS2 && HasPS1)
return true;
return isBetterMultiversionCandidate(Cand1, Cand2);
auto MV = isBetterMultiversionCandidate(Cand1, Cand2);
if (MV == Comparison::Better)
return true;
if (MV == Comparison::Worse)
return false;
// If other rules cannot determine which is better, CUDA preference is used
// to determine which is better.
if (S.getLangOpts().CUDA && Cand1.Function && Cand2.Function) {
if (FunctionDecl *Caller = dyn_cast<FunctionDecl>(S.CurContext)) {
return S.IdentifyCUDAPreference(Caller, Cand1.Function) >
S.IdentifyCUDAPreference(Caller, Cand2.Function);
}
}
return false;
}
/// Determine whether two declarations are "equivalent" for the purposes of
@ -9808,33 +9871,6 @@ OverloadCandidateSet::BestViableFunction(Sema &S, SourceLocation Loc,
std::transform(begin(), end(), std::back_inserter(Candidates),
[](OverloadCandidate &Cand) { return &Cand; });
// [CUDA] HD->H or HD->D calls are technically not allowed by CUDA but
// are accepted by both clang and NVCC. However, during a particular
// compilation mode only one call variant is viable. We need to
// exclude non-viable overload candidates from consideration based
// only on their host/device attributes. Specifically, if one
// candidate call is WrongSide and the other is SameSide, we ignore
// the WrongSide candidate.
if (S.getLangOpts().CUDA) {
const FunctionDecl *Caller = dyn_cast<FunctionDecl>(S.CurContext);
bool ContainsSameSideCandidate =
llvm::any_of(Candidates, [&](OverloadCandidate *Cand) {
// Check viable function only.
return Cand->Viable && Cand->Function &&
S.IdentifyCUDAPreference(Caller, Cand->Function) ==
Sema::CFP_SameSide;
});
if (ContainsSameSideCandidate) {
auto IsWrongSideCandidate = [&](OverloadCandidate *Cand) {
// Check viable function only to avoid unnecessary data copying/moving.
return Cand->Viable && Cand->Function &&
S.IdentifyCUDAPreference(Caller, Cand->Function) ==
Sema::CFP_WrongSide;
};
llvm::erase_if(Candidates, IsWrongSideCandidate);
}
}
// Find the best viable function.
Best = end();
for (auto *Cand : Candidates) {

50
clang/test/SemaCUDA/function-overload.cu
View File

@ -331,9 +331,6 @@ __device__ void test_device_calls_template_fn() {
// If we have a mix of HD and H-only or D-only candidates in the overload set,
// normal C++ overload resolution rules apply first.
template <typename T> TemplateReturnTy template_vs_hd_function(T arg)
#ifdef __CUDA_ARCH__
//expected-note@-2 {{declared here}}
#endif
{
return TemplateReturnTy();
}
@ -342,11 +339,13 @@ __host__ __device__ HostDeviceReturnTy template_vs_hd_function(float arg) {
}
__host__ __device__ void test_host_device_calls_hd_template() {
HostDeviceReturnTy ret1 = template_vs_hd_function(1.0f);
TemplateReturnTy ret2 = template_vs_hd_function(1);
#ifdef __CUDA_ARCH__
// expected-error@-2 {{reference to __host__ function 'template_vs_hd_function<int>' in __host__ __device__ function}}
typedef HostDeviceReturnTy ExpectedReturnTy;
#else
typedef TemplateReturnTy ExpectedReturnTy;
#endif
HostDeviceReturnTy ret1 = template_vs_hd_function(1.0f);
ExpectedReturnTy ret2 = template_vs_hd_function(1);
}
__host__ void test_host_calls_hd_template() {
@ -367,14 +366,14 @@ __device__ void test_device_calls_hd_template() {
__device__ DeviceReturnTy device_only_function(int arg) { return DeviceReturnTy(); }
__device__ DeviceReturnTy2 device_only_function(float arg) { return DeviceReturnTy2(); }
#ifndef __CUDA_ARCH__
// expected-note@-3 {{'device_only_function' declared here}}
// expected-note@-3 {{'device_only_function' declared here}}
// expected-note@-3 2{{'device_only_function' declared here}}
// expected-note@-3 2{{'device_only_function' declared here}}
#endif
__host__ HostReturnTy host_only_function(int arg) { return HostReturnTy(); }
__host__ HostReturnTy2 host_only_function(float arg) { return HostReturnTy2(); }
#ifdef __CUDA_ARCH__
// expected-note@-3 {{'host_only_function' declared here}}
// expected-note@-3 {{'host_only_function' declared here}}
// expected-note@-3 2{{'host_only_function' declared here}}
// expected-note@-3 2{{'host_only_function' declared here}}
#endif
__host__ __device__ void test_host_device_single_side_overloading() {
@ -392,6 +391,37 @@ __host__ __device__ void test_host_device_single_side_overloading() {
#endif
}
// wrong-sided overloading should not cause diagnostic unless it is emitted.
// This inline function is not emitted.
inline __host__ __device__ void test_host_device_wrong_side_overloading_inline_no_diag() {
DeviceReturnTy ret1 = device_only_function(1);
DeviceReturnTy2 ret2 = device_only_function(1.0f);
HostReturnTy ret3 = host_only_function(1);
HostReturnTy2 ret4 = host_only_function(1.0f);
}
// wrong-sided overloading should cause diagnostic if it is emitted.
// This inline function is emitted since it is called by an emitted function.
inline __host__ __device__ void test_host_device_wrong_side_overloading_inline_diag() {
DeviceReturnTy ret1 = device_only_function(1);
DeviceReturnTy2 ret2 = device_only_function(1.0f);
#ifndef __CUDA_ARCH__
// expected-error@-3 {{reference to __device__ function 'device_only_function' in __host__ __device__ function}}
// expected-error@-3 {{reference to __device__ function 'device_only_function' in __host__ __device__ function}}
#endif
HostReturnTy ret3 = host_only_function(1);
HostReturnTy2 ret4 = host_only_function(1.0f);
#ifdef __CUDA_ARCH__
// expected-error@-3 {{reference to __host__ function 'host_only_function' in __host__ __device__ function}}
// expected-error@-3 {{reference to __host__ function 'host_only_function' in __host__ __device__ function}}
#endif
}
__host__ __device__ void test_host_device_wrong_side_overloading_inline_diag_caller() {
test_host_device_wrong_side_overloading_inline_diag();
// expected-note@-1 {{called by 'test_host_device_wrong_side_overloading_inline_diag_caller'}}
}
// Verify that we allow overloading function templates.
template <typename T> __host__ T template_overload(const T &a) { return a; };
template <typename T> __device__ T template_overload(const T &a) { return a; };