From: Artem Belevich Date: Fri, 12 Feb 2016 18:29:18 +0000 (+0000) Subject: [CUDA] Tweak attribute-based overload resolution to match nvcc behavior. X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=2721c4d7813b4e456bc2465cb487c729074fca1d;p=clang [CUDA] Tweak attribute-based overload resolution to match nvcc behavior. This is an artefact of split-mode CUDA compilation that we need to mimic. HD functions are sometimes allowed to call H or D functions. Due to split compilation mode device-side compilation will not see host-only function and thus they will not be considered at all. For clang both H and D variants will become function overloads visible to compiler. Normally target attribute is considered only if C++ rules can not determine which function is better. However in this case we need to ignore functions that would not be present during current compilation phase before we apply normal overload resolution rules. Changes: * introduced another level of call preference to better describe possible call combinations. * removed WrongSide functions from consideration if the set contains SameSide function. * disabled H->D, D->H and G->H calls. These combinations are not allowed by CUDA and we were reluctantly allowing them to work around device-side calls to math functions in std namespace. We no longer need it after r258880. Differential Revision: http://reviews.llvm.org/D16870 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@260697 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h index 7514373897..766bfa1e12 100644 --- a/include/clang/Sema/Sema.h +++ b/include/clang/Sema/Sema.h @@ -8794,12 +8794,18 @@ public: CUDAFunctionTarget IdentifyCUDATarget(const FunctionDecl *D); + // CUDA function call preference. Must be ordered numerically from + // worst to best. enum CUDAFunctionPreference { CFP_Never, // Invalid caller/callee combination. - CFP_LastResort, // Lowest priority. Only in effect if + CFP_WrongSide, // Calls from host-device to host or device + // function that do not match current compilation + // mode. Only in effect if // LangOpts.CUDADisableTargetCallChecks is true. - CFP_Fallback, // Low priority caller/callee combination - CFP_Best, // Preferred caller/callee combination + CFP_HostDevice, // Any calls to host/device functions. + CFP_SameSide, // Calls from host-device to host or device + // function matching current compilation mode. + CFP_Native, // host-to-host or device-to-device calls. }; /// Identifies relative preference of a given Caller/Callee diff --git a/lib/Sema/SemaCUDA.cpp b/lib/Sema/SemaCUDA.cpp index 84fccd5ef5..4e59a0a0aa 100644 --- a/lib/Sema/SemaCUDA.cpp +++ b/lib/Sema/SemaCUDA.cpp @@ -68,26 +68,26 @@ Sema::CUDAFunctionTarget Sema::IdentifyCUDATarget(const FunctionDecl *D) { // Ph - preference in host mode // Pd - preference in device mode // H - handled in (x) -// Preferences: b-best, f-fallback, l-last resort, n-never. +// Preferences: N:native, HD:host-device, SS:same side, WS:wrong side, --:never. // -// | F | T | Ph | Pd | H | -// |----+----+----+----+-----+ -// | d | d | b | b | (b) | -// | d | g | n | n | (a) | -// | d | h | l | l | (e) | -// | d | hd | f | f | (c) | -// | g | d | b | b | (b) | -// | g | g | n | n | (a) | -// | g | h | l | l | (e) | -// | g | hd | f | f | (c) | -// | h | d | l | l | (e) | -// | h | g | b | b | (b) | -// | h | h | b | b | (b) | -// | h | hd | f | f | (c) | -// | hd | d | l | f | (d) | -// | hd | g | f | n |(d/a)| -// | hd | h | f | l | (d) | -// | hd | hd | b | b | (b) | +// | F | T | Ph | Pd | H | +// |----+----+-----+-----+-----+ +// | d | d | N | N | (c) | +// | d | g | -- | -- | (a) | +// | d | h | -- | -- | (e) | +// | d | hd | HD | HD | (b) | +// | g | d | N | N | (c) | +// | g | g | -- | -- | (a) | +// | g | h | -- | -- | (e) | +// | g | hd | HD | HD | (b) | +// | h | d | -- | -- | (e) | +// | h | g | N | N | (c) | +// | h | h | N | N | (c) | +// | h | hd | HD | HD | (b) | +// | hd | d | WS | SS | (d) | +// | hd | g | SS | -- |(d/a)| +// | hd | h | SS | WS | (d) | +// | hd | hd | HD | HD | (b) | Sema::CUDAFunctionPreference Sema::IdentifyCUDAPreference(const FunctionDecl *Caller, @@ -112,39 +112,38 @@ Sema::IdentifyCUDAPreference(const FunctionDecl *Caller, (CallerTarget == CFT_HostDevice && getLangOpts().CUDAIsDevice))) return CFP_Never; - // (b) Best case scenarios + // (b) Calling HostDevice is OK for everyone. + if (CalleeTarget == CFT_HostDevice) + return CFP_HostDevice; + + // (c) Best case scenarios if (CalleeTarget == CallerTarget || (CallerTarget == CFT_Host && CalleeTarget == CFT_Global) || (CallerTarget == CFT_Global && CalleeTarget == CFT_Device)) - return CFP_Best; - - // (c) Calling HostDevice is OK as a fallback that works for everyone. - if (CalleeTarget == CFT_HostDevice) - return CFP_Fallback; - - // Figure out what should be returned 'last resort' cases. Normally - // those would not be allowed, but we'll consider them if - // CUDADisableTargetCallChecks is true. - CUDAFunctionPreference QuestionableResult = - getLangOpts().CUDADisableTargetCallChecks ? CFP_LastResort : CFP_Never; + return CFP_Native; // (d) HostDevice behavior depends on compilation mode. if (CallerTarget == CFT_HostDevice) { - // Calling a function that matches compilation mode is OK. - // Calling a function from the other side is frowned upon. - if (getLangOpts().CUDAIsDevice) - return CalleeTarget == CFT_Device ? CFP_Fallback : QuestionableResult; - else - return (CalleeTarget == CFT_Host || CalleeTarget == CFT_Global) - ? CFP_Fallback - : QuestionableResult; + // It's OK to call a compilation-mode matching function from an HD one. + if ((getLangOpts().CUDAIsDevice && CalleeTarget == CFT_Device) || + (!getLangOpts().CUDAIsDevice && + (CalleeTarget == CFT_Host || CalleeTarget == CFT_Global))) + return CFP_SameSide; + + // We'll allow calls to non-mode-matching functions if target call + // checks are disabled. This is needed to avoid complaining about + // HD->H calls when we compile for device side and vice versa. + if (getLangOpts().CUDADisableTargetCallChecks) + return CFP_WrongSide; + + return CFP_Never; } // (e) Calling across device/host boundary is not something you should do. if ((CallerTarget == CFT_Host && CalleeTarget == CFT_Device) || (CallerTarget == CFT_Device && CalleeTarget == CFT_Host) || (CallerTarget == CFT_Global && CalleeTarget == CFT_Host)) - return QuestionableResult; + return CFP_Never; llvm_unreachable("All cases should've been handled by now."); } diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp index d71b307d15..f190872f0a 100644 --- a/lib/Sema/SemaOverload.cpp +++ b/lib/Sema/SemaOverload.cpp @@ -8722,14 +8722,44 @@ OverloadingResult OverloadCandidateSet::BestViableFunction(Sema &S, SourceLocation Loc, iterator &Best, bool UserDefinedConversion) { + llvm::SmallVector Candidates; + 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 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 && S.getLangOpts().CUDATargetOverloads) { + const FunctionDecl *Caller = dyn_cast(S.CurContext); + bool ContainsSameSideCandidate = + llvm::any_of(Candidates, [&](OverloadCandidate *Cand) { + return Cand->Function && + S.IdentifyCUDAPreference(Caller, Cand->Function) == + Sema::CFP_SameSide; + }); + if (ContainsSameSideCandidate) { + auto IsWrongSideCandidate = [&](OverloadCandidate *Cand) { + return Cand->Function && + S.IdentifyCUDAPreference(Caller, Cand->Function) == + Sema::CFP_WrongSide; + }; + Candidates.erase(std::remove_if(Candidates.begin(), Candidates.end(), + IsWrongSideCandidate), + Candidates.end()); + } + } + // Find the best viable function. Best = end(); - for (iterator Cand = begin(); Cand != end(); ++Cand) { + for (auto *Cand : Candidates) if (Cand->Viable) if (Best == end() || isBetterOverloadCandidate(S, *Cand, *Best, Loc, UserDefinedConversion)) Best = Cand; - } // If we didn't find any viable functions, abort. if (Best == end()) @@ -8739,7 +8769,7 @@ OverloadCandidateSet::BestViableFunction(Sema &S, SourceLocation Loc, // Make sure that this function is better than every other viable // function. If not, we have an ambiguity. - for (iterator Cand = begin(); Cand != end(); ++Cand) { + for (auto *Cand : Candidates) { if (Cand->Viable && Cand != Best && !isBetterOverloadCandidate(S, *Best, *Cand, Loc, diff --git a/test/CodeGenCUDA/function-overload.cu b/test/CodeGenCUDA/function-overload.cu index a12ef82773..3f8f930106 100644 --- a/test/CodeGenCUDA/function-overload.cu +++ b/test/CodeGenCUDA/function-overload.cu @@ -7,7 +7,8 @@ // RUN: | FileCheck -check-prefix=CHECK-BOTH -check-prefix=CHECK-HOST %s // RUN: %clang_cc1 -triple nvptx64-nvidia-cuda -fcuda-is-device \ // RUN: -fcuda-target-overloads -emit-llvm -o - %s \ -// RUN: | FileCheck -check-prefix=CHECK-BOTH -check-prefix=CHECK-DEVICE %s +// RUN: | FileCheck -check-prefix=CHECK-BOTH -check-prefix=CHECK-DEVICE \ +// RUN: -check-prefix=CHECK-DEVICE-STRICT %s // Check target overloads handling with disabled call target checks. // RUN: %clang_cc1 -DNOCHECKS -triple x86_64-unknown-linux-gnu -emit-llvm \ @@ -77,12 +78,112 @@ extern "C" __host__ int ch(void) {return 13;} extern "C" __host__ __device__ int chd(void) {return 14;} // CHECK-BOTH: ret i32 14 +// HD functions are sometimes allowed to call H or D functions -- this +// is an artifact of the source-to-source splitting performed by nvcc +// that we need to mimic. During device mode compilation in nvcc, host +// functions aren't present at all, so don't participate in +// overloading. But in clang, H and D functions are present in both +// compilation modes. Clang normally uses the target attribute as a +// tiebreaker between overloads with otherwise identical priority, but +// in order to match nvcc's behavior, we sometimes need to wholly +// discard overloads that would not be present during compilation +// under nvcc. + +template T template_vs_function(T arg) { return 15; } +__device__ float template_vs_function(float arg) { return 16; } + +// Here we expect to call the templated function during host +// compilation, even if -fcuda-disable-target-call-checks is passed, +// and even though C++ overload rules prefer the non-templated +// function. +// CHECK-BOTH-LABEL: define void @_Z5hd_tfv() +__host__ __device__ void hd_tf(void) { + template_vs_function(1.0f); + // CHECK-HOST: call float @_Z20template_vs_functionIfET_S0_(float + // CHECK-DEVICE: call float @_Z20template_vs_functionf(float + template_vs_function(2.0); + // CHECK-HOST: call double @_Z20template_vs_functionIdET_S0_(double + // CHECK-DEVICE: call float @_Z20template_vs_functionf(float +} + +// Calls from __host__ and __device__ functions should always call the +// overloaded function that matches their mode. +// CHECK-HOST-LABEL: define void @_Z4h_tfv() +__host__ void h_tf() { + template_vs_function(1.0f); + // CHECK-HOST: call float @_Z20template_vs_functionIfET_S0_(float + template_vs_function(2.0); + // CHECK-HOST: call double @_Z20template_vs_functionIdET_S0_(double +} + +// CHECK-DEVICE-LABEL: define void @_Z4d_tfv() +__device__ void d_tf() { + template_vs_function(1.0f); + // CHECK-DEVICE: call float @_Z20template_vs_functionf(float + template_vs_function(2.0); + // CHECK-DEVICE: call float @_Z20template_vs_functionf(float +} + +// In case 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 T template_vs_hd_function(T arg) { return 15; } +__host__ __device__ float template_vs_hd_function(float arg) { return 16; } + +// CHECK-BOTH-LABEL: define void @_Z7hd_thdfv() +__host__ __device__ void hd_thdf() { + template_vs_hd_function(1.0f); + // CHECK-HOST: call float @_Z23template_vs_hd_functionf(float + // CHECK-DEVICE: call float @_Z23template_vs_hd_functionf(float + template_vs_hd_function(1); + // CHECK-HOST: call i32 @_Z23template_vs_hd_functionIiET_S0_(i32 + // CHECK-DEVICE-STRICT: call float @_Z23template_vs_hd_functionf(float + // CHECK-DEVICE-NC: call i32 @_Z23template_vs_hd_functionIiET_S0_(i32 +} + +// CHECK-HOST-LABEL: define void @_Z6h_thdfv() +__host__ void h_thdf() { + template_vs_hd_function(1.0f); + // CHECK-HOST: call float @_Z23template_vs_hd_functionf(float + template_vs_hd_function(1); + // CHECK-HOST: call i32 @_Z23template_vs_hd_functionIiET_S0_(i32 +} + +// CHECK-DEVICE-LABEL: define void @_Z6d_thdfv() +__device__ void d_thdf() { + template_vs_hd_function(1.0f); + // CHECK-DEVICE: call float @_Z23template_vs_hd_functionf(float + template_vs_hd_function(1); + // Host-only function template is not callable with strict call checks, + // so for device side HD function will be the only choice. + // CHECK-DEVICE: call float @_Z23template_vs_hd_functionf(float +} + +// Check that overloads still work the same way on both host and +// device side when the overload set contains only functions from one +// side of compilation. +__device__ float device_only_function(int arg) { return 17; } +__device__ float device_only_function(float arg) { return 18; } + +__host__ float host_only_function(int arg) { return 19; } +__host__ float host_only_function(float arg) { return 20; } + +// CHECK-BOTH-LABEL: define void @_Z6hd_dofv() +__host__ __device__ void hd_dof() { +#ifdef NOCHECKS + device_only_function(1.0f); + // CHECK-BOTH-NC: call float @_Z20device_only_functionf(float + device_only_function(1); + // CHECK-BOTH-NC: call float @_Z20device_only_functioni(i32 + host_only_function(1.0f); + // CHECK-BOTH-NC: call float @_Z18host_only_functionf(float + host_only_function(1); + // CHECK-BOTH-NC: call float @_Z18host_only_functioni(i32 +#endif +} + + // CHECK-HOST-LABEL: define void @_Z5hostfv() __host__ void hostf(void) { -#if defined (NOCHECKS) - fp_t dp = d; // CHECK-HOST-NC: store {{.*}} @_Z1dv, {{.*}} %dp, - fp_t cdp = cd; // CHECK-HOST-NC: store {{.*}} @cd, {{.*}} %cdp, -#endif fp_t hp = h; // CHECK-HOST: store {{.*}} @_Z1hv, {{.*}} %hp, fp_t chp = ch; // CHECK-HOST: store {{.*}} @ch, {{.*}} %chp, fp_t dhp = dh; // CHECK-HOST: store {{.*}} @_Z2dhv, {{.*}} %dhp, @@ -91,10 +192,6 @@ __host__ void hostf(void) { fp_t chdp = chd; // CHECK-HOST: store {{.*}} @chd, {{.*}} %chdp, gp_t gp = g; // CHECK-HOST: store {{.*}} @_Z1gv, {{.*}} %gp, -#if defined (NOCHECKS) - d(); // CHECK-HOST-NC: call i32 @_Z1dv() - cd(); // CHECK-HOST-NC: call i32 @cd() -#endif h(); // CHECK-HOST: call i32 @_Z1hv() ch(); // CHECK-HOST: call i32 @ch() dh(); // CHECK-HOST: call i32 @_Z2dhv() @@ -106,10 +203,6 @@ __host__ void hostf(void) { __device__ void devicef(void) { fp_t dp = d; // CHECK-DEVICE: store {{.*}} @_Z1dv, {{.*}} %dp, fp_t cdp = cd; // CHECK-DEVICE: store {{.*}} @cd, {{.*}} %cdp, -#if defined (NOCHECKS) - fp_t hp = h; // CHECK-DEVICE-NC: store {{.*}} @_Z1hv, {{.*}} %hp, - fp_t chp = ch; // CHECK-DEVICE-NC: store {{.*}} @ch, {{.*}} %chp, -#endif fp_t dhp = dh; // CHECK-DEVICE: store {{.*}} @_Z2dhv, {{.*}} %dhp, fp_t cdhp = cdh; // CHECK-DEVICE: store {{.*}} @cdh, {{.*}} %cdhp, fp_t hdp = hd; // CHECK-DEVICE: store {{.*}} @_Z2hdv, {{.*}} %hdp, @@ -117,10 +210,6 @@ __device__ void devicef(void) { d(); // CHECK-DEVICE: call i32 @_Z1dv() cd(); // CHECK-DEVICE: call i32 @cd() -#if defined (NOCHECKS) - h(); // CHECK-DEVICE-NC: call i32 @_Z1hv() - ch(); // CHECK-DEVICE-NC: call i32 @ch() -#endif dh(); // CHECK-DEVICE: call i32 @_Z2dhv() cdh(); // CHECK-DEVICE: call i32 @cdh() } diff --git a/test/SemaCUDA/function-overload.cu b/test/SemaCUDA/function-overload.cu index bd3fb508bf..bc9fe2a1eb 100644 --- a/test/SemaCUDA/function-overload.cu +++ b/test/SemaCUDA/function-overload.cu @@ -70,13 +70,11 @@ extern "C" __host__ int ch(void) {return 11;} __host__ void hostf(void) { fp_t dp = d; - fp_t cdp = cd; -#if !defined(NOCHECKS) - // expected-error@-3 {{reference to __device__ function 'd' in __host__ function}} + // expected-error@-1 {{reference to __device__ function 'd' in __host__ function}} // expected-note@65 {{'d' declared here}} - // expected-error@-4 {{reference to __device__ function 'cd' in __host__ function}} + fp_t cdp = cd; + // expected-error@-1 {{reference to __device__ function 'cd' in __host__ function}} // expected-note@68 {{'cd' declared here}} -#endif fp_t hp = h; fp_t chp = ch; fp_t dhp = dh; @@ -84,13 +82,11 @@ __host__ void hostf(void) { gp_t gp = g; d(); - cd(); -#if !defined(NOCHECKS) - // expected-error@-3 {{no matching function for call to 'd'}} + // expected-error@-1 {{no matching function for call to 'd'}} // expected-note@65 {{candidate function not viable: call to __device__ function from __host__ function}} - // expected-error@-4 {{no matching function for call to 'cd'}} + cd(); + // expected-error@-1 {{no matching function for call to 'cd'}} // expected-note@68 {{candidate function not viable: call to __device__ function from __host__ function}} -#endif h(); ch(); dh(); @@ -104,13 +100,11 @@ __device__ void devicef(void) { fp_t dp = d; fp_t cdp = cd; fp_t hp = h; - fp_t chp = ch; -#if !defined(NOCHECKS) - // expected-error@-3 {{reference to __host__ function 'h' in __device__ function}} + // expected-error@-1 {{reference to __host__ function 'h' in __device__ function}} // expected-note@66 {{'h' declared here}} - // expected-error@-4 {{reference to __host__ function 'ch' in __device__ function}} + fp_t chp = ch; + // expected-error@-1 {{reference to __host__ function 'ch' in __device__ function}} // expected-note@69 {{'ch' declared here}} -#endif fp_t dhp = dh; fp_t cdhp = cdh; gp_t gp = g; // expected-error {{reference to __global__ function 'g' in __device__ function}} @@ -118,14 +112,10 @@ __device__ void devicef(void) { d(); cd(); - h(); - ch(); -#if !defined(NOCHECKS) - // expected-error@-3 {{no matching function for call to 'h'}} + h(); // expected-error {{no matching function for call to 'h'}} // expected-note@66 {{candidate function not viable: call to __host__ function from __device__ function}} - // expected-error@-4 {{no matching function for call to 'ch'}} + ch(); // expected-error {{no matching function for call to 'ch'}} // expected-note@69 {{candidate function not viable: call to __host__ function from __device__ function}} -#endif dh(); cdh(); g(); // expected-error {{no matching function for call to 'g'}} @@ -138,28 +128,25 @@ __global__ void globalf(void) { fp_t dp = d; fp_t cdp = cd; fp_t hp = h; - fp_t chp = ch; -#if !defined(NOCHECKS) - // expected-error@-3 {{reference to __host__ function 'h' in __global__ function}} + // expected-error@-1 {{reference to __host__ function 'h' in __global__ function}} // expected-note@66 {{'h' declared here}} - // expected-error@-4 {{reference to __host__ function 'ch' in __global__ function}} + fp_t chp = ch; + // expected-error@-1 {{reference to __host__ function 'ch' in __global__ function}} // expected-note@69 {{'ch' declared here}} -#endif fp_t dhp = dh; fp_t cdhp = cdh; - gp_t gp = g; // expected-error {{reference to __global__ function 'g' in __global__ function}} - // expected-note@67 {{'g' declared here}} + gp_t gp = g; + // expected-error@-1 {{reference to __global__ function 'g' in __global__ function}} + // expected-note@67 {{'g' declared here}} d(); cd(); h(); - ch(); -#if !defined(NOCHECKS) - // expected-error@-3 {{no matching function for call to 'h'}} + // expected-error@-1 {{no matching function for call to 'h'}} // expected-note@66 {{candidate function not viable: call to __host__ function from __global__ function}} - // expected-error@-4 {{no matching function for call to 'ch'}} + ch(); + // expected-error@-1 {{no matching function for call to 'ch'}} // expected-note@69 {{candidate function not viable: call to __host__ function from __global__ function}} -#endif dh(); cdh(); g(); // expected-error {{no matching function for call to 'g'}}