tra updated the summary for this revision.
tra updated this revision to Diff 47335.
tra marked 3 inline comments as done.
tra added a comment.
Updated the way WrongSide functions are removed from consideration during
overload resolution.
Previous version could provide inconsistent results depending on the order of
candidates in the overload set.
This version removes WrongSide functions from the set before we perform
pair-wise comparison of candidates.
Added another test case to make sure HD->{H,H} or HD->{D,D} overloads are
resolved consistently during host and device compilation.
http://reviews.llvm.org/D16870
Files:
include/clang/Sema/Sema.h
lib/Sema/SemaCUDA.cpp
lib/Sema/SemaOverload.cpp
test/CodeGenCUDA/function-overload.cu
test/SemaCUDA/function-overload.cu
Index: test/SemaCUDA/function-overload.cu
===================================================================
--- test/SemaCUDA/function-overload.cu
+++ test/SemaCUDA/function-overload.cu
@@ -70,27 +70,23 @@
__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;
fp_t cdhp = cdh;
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();
@@ -104,28 +100,22 @@
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}}
// expected-note@67 {{'g' declared here}}
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 @@
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'}}
Index: test/CodeGenCUDA/function-overload.cu
===================================================================
--- test/CodeGenCUDA/function-overload.cu
+++ 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 \
@@ -77,24 +78,120 @@
extern "C" __host__ __device__ int chd(void) {return 14;}
// CHECK-BOTH: ret i32 14
+// NOTE: 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. Normally target attribute is considered only if
+// C++ rules can not determine which function is better. However in
+// this case we need to discard functions that would not be present
+// during current compilation phase before we apply normal overload
+// resolution rules.
+
+template <typename T> T template_vs_function(T arg) { return 15; }
+__device__ float template_vs_function(float arg) { return 16; }
+
+// In this case during host compilation we expect to call function
+// template even if __device__ function may be available and allowed
+// by -fcuda-disable-target-call-checks and, according to C++ overload
+// resolution rules, would be prefered over function template.
+// 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
+// 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 mix of HD and H-only or D-only candidates in the
+// overload set normal C++ overload resolution rules apply first.
+template <typename T> 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 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,
fp_t cdhp = cdh; // CHECK-HOST: store {{.*}} @cdh, {{.*}} %cdhp,
fp_t hdp = hd; // CHECK-HOST: store {{.*}} @_Z2hdv, {{.*}} %hdp,
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()
@@ -106,21 +203,13 @@
__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,
fp_t chdp = chd; // CHECK-DEVICE: store {{.*}} @chd, {{.*}} %chdp,
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()
}
Index: lib/Sema/SemaOverload.cpp
===================================================================
--- lib/Sema/SemaOverload.cpp
+++ lib/Sema/SemaOverload.cpp
@@ -8722,14 +8722,43 @@
OverloadCandidateSet::BestViableFunction(Sema &S, SourceLocation Loc,
iterator &Best,
bool UserDefinedConversion) {
+ llvm::SmallVector<OverloadCandidate *, 16> 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 particular
+ // compilation pass 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<FunctionDecl>(S.CurContext);
+ bool IgnoreWrongSideFunctions =
+ llvm::any_of(Candidates, [&](OverloadCandidate *Cand) {
+ return Cand->Function &&
+ S.IdentifyCUDAPreference(Caller, Cand->Function) ==
+ Sema::CFP_SameSide;
+ });
+ if (IgnoreWrongSideFunctions)
+ Candidates.erase(std::remove_if(Candidates.begin(), Candidates.end(),
+ [&](OverloadCandidate *Cand) {
+ return Cand->Function &&
+ S.IdentifyCUDAPreference(
+ Caller, Cand->Function) ==
+ Sema::CFP_WrongSide;
+ }),
+ 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 +8768,7 @@
// 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,
Index: lib/Sema/SemaCUDA.cpp
===================================================================
--- lib/Sema/SemaCUDA.cpp
+++ lib/Sema/SemaCUDA.cpp
@@ -68,26 +68,26 @@
// 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: +:native, *:host-device, o:same side, .: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) |
+// | d | d | + | + | (c) |
+// | d | g | - | - | (a) |
+// | d | h | - | - | (e) |
+// | d | hd | * | * | (b) |
+// | g | d | + | + | (c) |
+// | g | g | - | - | (a) |
+// | g | h | - | - | (e) |
+// | g | hd | * | * | (b) |
+// | h | d | - | - | (e) |
+// | h | g | + | + | (c) |
+// | h | h | + | + | (c) |
+// | h | hd | * | * | (b) |
+// | hd | d | . | o | (d) |
+// | hd | g | o | - |(d/a)|
+// | hd | h | o | . | (d) |
+// | hd | hd | * | * | (b) |
Sema::CUDAFunctionPreference
Sema::IdentifyCUDAPreference(const FunctionDecl *Caller,
@@ -112,39 +112,38 @@
(CallerTarget == CFT_HostDevice && getLangOpts().CUDAIsDevice)))
return CFP_Never;
- // (b) Best case scenarios
+ // (b) Calling HostDevice is OK as a fallback that works 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 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.");
}
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -8794,12 +8794,18 @@
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
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