[Clang][OpenMP] Allow host call to nohost function with host variant

[doru1004]

Summary

In OpenMP 5.2 when a nohost function is called from the host, the host variant of that function is called if one is declared.

[ABataev]

clang/lib/Sema/SemaOpenMP.cpp

2709–2718

It is recommended to implement such loops as functions/lauto &ambdas:

auto HasHostAttr = []() {
  for (const OMPDeclareVariantAttr *A :
    Callee->specific_attrs<OMPDeclareVariantAttr>()) {
    auto *DeclRefVariant = cast<DeclRefExpr>(A->getVariantFuncRef());
    auto *VariantFD = cast<FunctionDecl>(DeclRefVariant->getDecl());
    Optional<OMPDeclareTargetDeclAttr::DevTypeTy> DevTy =
        OMPDeclareTargetDeclAttr::getDeviceType(
            VariantFD->getMostRecentDecl());
    if (!DevTy || *DevTy == OMPDeclareTargetDeclAttr::DT_Host)
      return true;
  }
  return false;
};
if (HasHostAttr())
  return;

2715

Why the most recent decl?

2716

Isuppose it must be DevTy && *DevTy == OMPDeclareTargetDeclAttr::DT_Host, no?

[doru1004]

clang/lib/Sema/SemaOpenMP.cpp

2715

I believe that would retrieve the full information about the function since that's where the function is defined?

2716

Correct me if I'm wrong but if there's no device type associated with the function then it is a host function? For the second part of the condition, if there exists a DevTy associated with the function then it has to be DT_Host.

[doru1004]

clang/lib/Sema/SemaOpenMP.cpp

2709–2718

I will rewrite this.

[ABataev]

clang/lib/Sema/SemaOpenMP.cpp

2716

Ah, I missed it. Can we have just declare variant without device type? Can you add a test for this case?

[doru1004]

clang/lib/Sema/SemaOpenMP.cpp

2716

You mean when the variant function definition does not have a device type declared? That's the case that's currently tested:

#pragma omp declare variant(host_function) match(device={kind(host)})
void fun() {}
void host_function() {}

But I think you're right I should add another test which tests the other part of the condition when the host_function has a device type.

[ABataev]

clang/lib/Sema/SemaOpenMP.cpp

2683

Do you have a test for !DevTy case? Maybe I'm missing it.

[doru1004]

clang/lib/Sema/SemaOpenMP.cpp

2683

Yes it was the first test I added. The second one tests the second part of the condition.

[ABataev]

clang/lib/Sema/SemaOpenMP.cpp

2683

Hmm, but in this test we have *DevTy == OMPDeclareTargetDeclAttr::DT_Host, no?

[doru1004]

clang/lib/Sema/SemaOpenMP.cpp

2683

I added a positive check of that condition too. No error messages to check for in that case.

[ABataev]

clang/test/OpenMP/declare_target_nohost_variant_messages.cpp

16

You mean this test case? But it still has kind(host).

[doru1004]

clang/test/OpenMP/declare_target_nohost_variant_messages.cpp

16

The condition checks the attribute of the host_function which in this case is host. In the test above the condition is false because the not_a_host_function has a nohost attribute.

[doru1004]

clang/test/OpenMP/declare_target_nohost_variant_messages.cpp

16

It should always have host there because we are trying to fix the case where we have a nohost function that needs a host variant.

[ABataev]

LG

clang/test/OpenMP/declare_target_nohost_variant_messages.cpp

16

Ah, I missed that the check was for declare target attribute.

[doru1004]

Commit 658ed9547cdd6657895339a6c390c31aa77a5698

[mgorny]

In D140155#4004505, @doru1004 wrote:

Commit 658ed9547cdd6657895339a6c390c31aa77a5698

The added test fails on 32-bit platforms:

FAIL: Clang :: OpenMP/declare_target_nohost_variant_messages.cpp (10230 of 16135)
******************** TEST 'Clang :: OpenMP/declare_target_nohost_variant_messages.cpp' FAILED ********************
Script:
--
: 'RUN: at line 3';   /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/clang -cc1 -internal-isystem /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/../../../../lib/clang/16/include -nostdsysteminc -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -fopenmp-version=52 -DVERBOSE_MODE=1 -verify=omp52 -fnoopenmp-use-tls -ferror-limit 100 -fopenmp-targets=amdgcn-amd-amdhsa -o - /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/clang/test/OpenMP/declare_target_nohost_variant_messages.cpp
--
Exit Code: 1

Command Output (stderr):
--
+ : 'RUN: at line 3'
+ /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/clang -cc1 -internal-isystem /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/../../../../lib/clang/16/include -nostdsysteminc -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -fopenmp-version=52 -DVERBOSE_MODE=1 -verify=omp52 -fnoopenmp-use-tls -ferror-limit 100 -fopenmp-targets=amdgcn-amd-amdhsa -o - /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/clang/test/OpenMP/declare_target_nohost_variant_messages.cpp
error: 'error' diagnostics seen but not expected: 
  (frontend): OpenMP target architecture 'amdgcn-amd-amdhsa' pointer size is incompatible with host 'i686-pc-linux-gnu'

--

********************

Please fix, or ideally revert, fix and then commit properly linking to the diff.

[jhuber6]

In D140155#4016274, @mgorny wrote:

In D140155#4004505, @doru1004 wrote:

Commit 658ed9547cdd6657895339a6c390c31aa77a5698

The added test fails on 32-bit platforms:

FAIL: Clang :: OpenMP/declare_target_nohost_variant_messages.cpp (10230 of 16135)
******************** TEST 'Clang :: OpenMP/declare_target_nohost_variant_messages.cpp' FAILED ********************
Script:
--
: 'RUN: at line 3';   /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/clang -cc1 -internal-isystem /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/../../../../lib/clang/16/include -nostdsysteminc -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -fopenmp-version=52 -DVERBOSE_MODE=1 -verify=omp52 -fnoopenmp-use-tls -ferror-limit 100 -fopenmp-targets=amdgcn-amd-amdhsa -o - /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/clang/test/OpenMP/declare_target_nohost_variant_messages.cpp
--
Exit Code: 1

Command Output (stderr):
--
+ : 'RUN: at line 3'
+ /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/clang -cc1 -internal-isystem /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/../../../../lib/clang/16/include -nostdsysteminc -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -fopenmp-version=52 -DVERBOSE_MODE=1 -verify=omp52 -fnoopenmp-use-tls -ferror-limit 100 -fopenmp-targets=amdgcn-amd-amdhsa -o - /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/clang/test/OpenMP/declare_target_nohost_variant_messages.cpp
error: 'error' diagnostics seen but not expected: 
  (frontend): OpenMP target architecture 'amdgcn-amd-amdhsa' pointer size is incompatible with host 'i686-pc-linux-gnu'

--

********************

Please fix, or ideally revert, fix and then commit properly linking to the diff.

Should be a simple fix, someone needs to provide --triple= in the test line. A lot of the old tests used 64-bit PowerPC but it's not really important.

[jhuber6]

In D140155#4016274, @mgorny wrote:

In D140155#4004505, @doru1004 wrote:

Commit 658ed9547cdd6657895339a6c390c31aa77a5698

The added test fails on 32-bit platforms:

FAIL: Clang :: OpenMP/declare_target_nohost_variant_messages.cpp (10230 of 16135)
******************** TEST 'Clang :: OpenMP/declare_target_nohost_variant_messages.cpp' FAILED ********************
Script:
--
: 'RUN: at line 3';   /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/clang -cc1 -internal-isystem /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/../../../../lib/clang/16/include -nostdsysteminc -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -fopenmp-version=52 -DVERBOSE_MODE=1 -verify=omp52 -fnoopenmp-use-tls -ferror-limit 100 -fopenmp-targets=amdgcn-amd-amdhsa -o - /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/clang/test/OpenMP/declare_target_nohost_variant_messages.cpp
--
Exit Code: 1

Command Output (stderr):
--
+ : 'RUN: at line 3'
+ /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/clang -cc1 -internal-isystem /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/../../../../lib/clang/16/include -nostdsysteminc -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -fopenmp-version=52 -DVERBOSE_MODE=1 -verify=omp52 -fnoopenmp-use-tls -ferror-limit 100 -fopenmp-targets=amdgcn-amd-amdhsa -o - /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/clang/test/OpenMP/declare_target_nohost_variant_messages.cpp
error: 'error' diagnostics seen but not expected: 
  (frontend): OpenMP target architecture 'amdgcn-amd-amdhsa' pointer size is incompatible with host 'i686-pc-linux-gnu'

--

********************

Please fix, or ideally revert, fix and then commit properly linking to the diff.

Should be fixed in rGf74e3d2f81d2.

[mgorny]

Thank you. I'm going to try if the same solution helps with D139723 too.

[doru1004]

In D140155#4016333, @jhuber6 wrote:

In D140155#4016274, @mgorny wrote:

In D140155#4004505, @doru1004 wrote:

Commit 658ed9547cdd6657895339a6c390c31aa77a5698

The added test fails on 32-bit platforms:

FAIL: Clang :: OpenMP/declare_target_nohost_variant_messages.cpp (10230 of 16135)
******************** TEST 'Clang :: OpenMP/declare_target_nohost_variant_messages.cpp' FAILED ********************
Script:
--
: 'RUN: at line 3';   /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/clang -cc1 -internal-isystem /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/../../../../lib/clang/16/include -nostdsysteminc -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -fopenmp-version=52 -DVERBOSE_MODE=1 -verify=omp52 -fnoopenmp-use-tls -ferror-limit 100 -fopenmp-targets=amdgcn-amd-amdhsa -o - /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/clang/test/OpenMP/declare_target_nohost_variant_messages.cpp
--
Exit Code: 1

Command Output (stderr):
--
+ : 'RUN: at line 3'
+ /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/clang -cc1 -internal-isystem /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/x/y/clang-abi_x86_32.x86/bin/../../../../lib/clang/16/include -nostdsysteminc -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -fopenmp-version=52 -DVERBOSE_MODE=1 -verify=omp52 -fnoopenmp-use-tls -ferror-limit 100 -fopenmp-targets=amdgcn-amd-amdhsa -o - /var/tmp/portage/sys-devel/clang-16.0.0_pre20221225/work/clang/test/OpenMP/declare_target_nohost_variant_messages.cpp
error: 'error' diagnostics seen but not expected: 
  (frontend): OpenMP target architecture 'amdgcn-amd-amdhsa' pointer size is incompatible with host 'i686-pc-linux-gnu'

--

********************

Please fix, or ideally revert, fix and then commit properly linking to the diff.

Should be fixed in rGf74e3d2f81d2.

Thank you for pushing a fix!

clang/lib/Sema/SemaOpenMP.cpp

 
 void Sema::finalizeOpenMPDelayedAnalysis(const FunctionDecl *Caller,
                                          const FunctionDecl *Callee,
                                          SourceLocation Loc) {
   assert(LangOpts.OpenMP && "Expected OpenMP compilation mode.");
   Optional<OMPDeclareTargetDeclAttr::DevTypeTy> DevTy =
       OMPDeclareTargetDeclAttr::getDeviceType(Caller->getMostRecentDecl());
   // Ignore host functions during device analyzis.
   if (LangOpts.OpenMPIsDevice &&
       (!DevTy || *DevTy == OMPDeclareTargetDeclAttr::DT_Host))
     return;
   // Ignore nohost functions during host analyzis.
   if (!LangOpts.OpenMPIsDevice && DevTy &&
       *DevTy == OMPDeclareTargetDeclAttr::DT_NoHost)
     return;
   const FunctionDecl *FD = Callee->getMostRecentDecl();
   DevTy = OMPDeclareTargetDeclAttr::getDeviceType(FD);
   if (LangOpts.OpenMPIsDevice && DevTy &&
       *DevTy == OMPDeclareTargetDeclAttr::DT_Host) {
     // Diagnose host function called during device codegen.
     StringRef HostDevTy =
         getOpenMPSimpleClauseTypeName(OMPC_device_type, OMPC_DEVICE_TYPE_host);
     Diag(Loc, diag::err_omp_wrong_device_function_call) << HostDevTy << 0;
     Diag(*OMPDeclareTargetDeclAttr::getLocation(FD),
          diag::note_omp_marked_device_type_here)
         << HostDevTy;
     return;
   }
   if (!LangOpts.OpenMPIsDevice && !LangOpts.OpenMPOffloadMandatory && DevTy &&
       *DevTy == OMPDeclareTargetDeclAttr::DT_NoHost) {
+    // In OpenMP 5.2 or later, if the function has a host variant then allow
+    // that to be called instead
+    auto &&HasHostAttr = [](const FunctionDecl *Callee) {
+      for (OMPDeclareVariantAttr *A :
+           Callee->specific_attrs<OMPDeclareVariantAttr>()) {
+        auto *DeclRefVariant = cast<DeclRefExpr>(A->getVariantFuncRef());
+        auto *VariantFD = cast<FunctionDecl>(DeclRefVariant->getDecl());
+        Optional<OMPDeclareTargetDeclAttr::DevTypeTy> DevTy =
+            OMPDeclareTargetDeclAttr::getDeviceType(
+                VariantFD->getMostRecentDecl());
+        if (!DevTy || *DevTy == OMPDeclareTargetDeclAttr::DT_Host)
+          return true;
+      }
+      return false;
+    };
+    if (getLangOpts().OpenMP >= 52 &&
+        Callee->hasAttr<OMPDeclareVariantAttr>() && HasHostAttr(Callee))
+      return;
     // Diagnose nohost function called during host codegen.
     StringRef NoHostDevTy = getOpenMPSimpleClauseTypeName(
         OMPC_device_type, OMPC_DEVICE_TYPE_nohost);
     Diag(Loc, diag::err_omp_wrong_device_function_call) << NoHostDevTy << 1;
     Diag(*OMPDeclareTargetDeclAttr::getLocation(FD),
          diag::note_omp_marked_device_type_here)
         << NoHostDevTy;
   }

clang/test/OpenMP/declare_target_messages.cpp

 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp45 -fopenmp -fopenmp-version=45 -fnoopenmp-use-tls -ferror-limit 100 -o - %s
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp5,host5 -fopenmp -fopenmp-targets=x86_64-apple-macos10.7.0 -fnoopenmp-use-tls -ferror-limit 100 -o - %s
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp5,dev5 -fopenmp -fopenmp-is-device -fopenmp-targets=x86_64-apple-macos10.7.0 -aux-triple x86_64-apple-macos10.7.0 -fnoopenmp-use-tls -ferror-limit 100 -o - %s
 
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp5,host5 -fopenmp-simd -fopenmp-targets=x86_64-apple-macos10.7.0 -fnoopenmp-use-tls -ferror-limit 100 -o - %s
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp5,host5 -fopenmp-simd -fopenmp-is-device -fopenmp-targets=x86_64-apple-macos10.7.0 -fnoopenmp-use-tls -ferror-limit 100 -o - %s
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp45 -fopenmp-version=45 -fopenmp-simd -fnoopenmp-use-tls -ferror-limit 100 -o - %s
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp51 -fopenmp -fopenmp-version=51 -fnoopenmp-use-tls -ferror-limit 100 -o - %s
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp51 -fopenmp -fopenmp-version=51 -fnoopenmp-use-tls -ferror-limit 100 -DTESTEND=1 -o - %s
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp51 -fopenmp -fopenmp-version=51 -fnoopenmp-use-tls -ferror-limit 100 -I%S/Inputs -DTESTENDINC=1 -o - %s
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp51 -fopenmp-version=51 -fopenmp-simd -fnoopenmp-use-tls -ferror-limit 100 -o - %s
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp51 -fopenmp-version=51 -fopenmp-simd -fnoopenmp-use-tls -ferror-limit 100 -o - %s
 
+// RUN: %clang_cc1 -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -fopenmp-version=52 -DVERBOSE_MODE=1 -verify=expected,omp52 -fnoopenmp-use-tls -ferror-limit 100 -o - %s
+
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify=expected,omp5 -fopenmp -fnoopenmp-use-tls -ferror-limit 100 -o - %s
 #pragma omp end declare target // expected-error {{unexpected OpenMP directive '#pragma omp end declare target'}}
 
-int a, b, z; // omp5-error {{variable captured in declare target region must appear in a to clause}} // omp51-error {{variable captured in declare target region must appear in a to clause}}
+int a, b, z; // omp5-error {{variable captured in declare target region must appear in a to clause}} // omp51-error {{variable captured in declare target region must appear in a to clause}} omp52-error {{variable captured in declare target region must appear in a to clause}}
 __thread int t; // expected-note {{defined as threadprivate or thread local}}
 
 #pragma omp declare target . // expected-error {{expected '(' after 'declare target'}}
 
 #pragma omp declare target
 void f();
 #pragma omp end declare target shared(a) // expected-warning {{extra tokens at the end of '#pragma omp end declare target' are ignored}}
 
-#pragma omp declare target map(a) // omp45-error {{expected at least one 'to' or 'link' clause}} omp5-error {{expected at least one 'to' or 'link' clause}} omp51-error {{expected at least one 'to', 'link' or 'indirect' clause}} omp45-error {{unexpected 'map' clause, only 'to' or 'link' clauses expected}} omp5-error {{unexpected 'map' clause, only 'to', 'link' or 'device_type' clauses expected}} omp51-error {{unexpected 'map' clause, only 'to', 'link', 'device_type' or 'indirect' clauses expected}}
+#pragma omp declare target map(a) // omp45-error {{expected at least one 'to' or 'link' clause}} omp5-error {{expected at least one 'to' or 'link' clause}} omp51-error {{expected at least one 'to', 'link' or 'indirect' clause}} omp45-error {{unexpected 'map' clause, only 'to' or 'link' clauses expected}} omp5-error {{unexpected 'map' clause, only 'to', 'link' or 'device_type' clauses expected}} omp51-error {{unexpected 'map' clause, only 'to', 'link', 'device_type' or 'indirect' clauses expected}} omp52-error {{unexpected 'map' clause, only 'enter', 'link', 'device_type' or 'indirect' clauses expected}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 
-#pragma omp declare target to(foo1) // expected-error {{use of undeclared identifier 'foo1'}}
+#pragma omp declare target to(foo1) // omp45-error {{use of undeclared identifier 'foo1'}} omp5-error {{use of undeclared identifier 'foo1'}} omp51-error {{use of undeclared identifier 'foo1'}} omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 
 #pragma omp declare target link(foo2) // expected-error {{use of undeclared identifier 'foo2'}}
 
-#pragma omp declare target to(f) device_type(host) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} dev5-note {{marked as 'device_type(host)' here}}
+#pragma omp declare target to(f) device_type(host) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} dev5-note {{marked as 'device_type(host)' here}} omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 
 void q();
-#pragma omp declare target to(q) device_type(any) device_type(any) device_type(host) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} omp5-warning {{more than one 'device_type' clause is specified}} // omp51-warning {{more than one 'device_type' clause is specified}}
+#pragma omp declare target to(q) device_type(any) device_type(any) device_type(host) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} omp5-warning {{more than one 'device_type' clause is specified}} // omp51-warning {{more than one 'device_type' clause is specified}} omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 
 #if _OPENMP == 202011
 // omp51-error@+1 {{directive '#pragma omp declare target' cannot contain more than one 'indirect' clause}}
 #pragma omp declare target to(q) indirect(true) indirect(false)
 
 int xxx; //expected-note {{declared here}}
 // omp51-error@+2 {{expression is not an integral constant expression}}
 // omp51-note@+1 {{read of non-const variable 'xxx' is not allowed in a constant expression}}

 void bar();
 #pragma omp end declare target
 #endif  // _OPENMP
 
 void c();
 
 void func() {} // expected-note {{'func' defined here}}
 
-#pragma omp declare target link(func) allocate(a) // expected-error {{function name is not allowed in 'link' clause}} omp45-error {{unexpected 'allocate' clause, only 'to' or 'link' clauses expected}} omp5-error {{unexpected 'allocate' clause, only 'to', 'link' or 'device_type' clauses expected}} omp51-error {{unexpected 'allocate' clause, only 'to', 'link', 'device_type' or 'indirect' clauses expected}}
+#pragma omp declare target link(func) allocate(a) // expected-error {{function name is not allowed in 'link' clause}} omp45-error {{unexpected 'allocate' clause, only 'to' or 'link' clauses expected}} omp5-error {{unexpected 'allocate' clause, only 'to', 'link' or 'device_type' clauses expected}} omp51-error {{unexpected 'allocate' clause, only 'to', 'link', 'device_type' or 'indirect' clauses expected}} omp52-error {{unexpected 'allocate' clause, only 'enter', 'link', 'device_type' or 'indirect' clauses expected}}
 
 void bar();
 void baz() {bar();}
-#pragma omp declare target(bar) // omp5-warning {{declaration marked as declare target after first use, it may lead to incorrect results}} // omp51-warning {{declaration marked as declare target after first use, it may lead to incorrect results}}
+#pragma omp declare target(bar) // omp5-warning {{declaration marked as declare target after first use, it may lead to incorrect results}} // omp51-warning {{declaration marked as declare target after first use, it may lead to incorrect results}} omp52-warning {{declaration marked as declare target after first use, it may lead to incorrect results}}
 
 extern int b;
 
 struct NonT {
   int a;
 };
 
 typedef int sint;
void foo(int p) {
   g += object.method1();
   g += object1.method() + p;
   f(); // dev5-error {{function with 'device_type(host)' is not available on device}}
   q();
   c();
 }
 #pragma omp declare target
 void foo1() {
-  [&](){ (void)(b+z);}(); // omp5-note {{variable 'z' is captured here}} //omp51-note {{variable 'z' is captured here}}
+  [&](){ (void)(b+z);}(); // omp5-note {{variable 'z' is captured here}} //omp51-note {{variable 'z' is captured here}} omp52-note {{variable 'z' is captured here}}
 }
 #pragma omp end declare target
 
 #pragma omp end declare target
 #pragma omp end declare target
 #pragma omp end declare target // expected-error {{unexpected OpenMP directive '#pragma omp end declare target'}}
 
 int C::method() {

 #pragma omp declare target
   int x;
 }
 #pragma omp end declare target
 
 #pragma omp declare target link(S) // expected-error {{'S' used in declare target directive is not a variable or a function name}}
 
 #pragma omp declare target (x, x) // expected-error {{'x' appears multiple times in clauses on the same declare target directive}}
-#pragma omp declare target to(x) to(x) // expected-error {{'x' appears multiple times in clauses on the same declare target directive}}
+#pragma omp declare target to(x) to(x) // omp45-error {{'x' appears multiple times in clauses on the same declare target directive}} omp5-error {{'x' appears multiple times in clauses on the same declare target directive}} omp51-error {{'x' appears multiple times in clauses on the same declare target directive}} omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 #pragma omp declare target link(x) // expected-error {{'x' must not appear in both clauses 'to' and 'link'}}
 
 void bazz() {}
-#pragma omp declare target to(bazz) device_type(nohost) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} host5-note 3{{marked as 'device_type(nohost)' here}}
+#pragma omp declare target to(bazz) device_type(nohost) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} host5-note 3{{marked as 'device_type(nohost)' here}} omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 void bazzz() {bazz();}
-#pragma omp declare target to(bazzz) device_type(nohost) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}}
+#pragma omp declare target to(bazzz) device_type(nohost) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 void any() {bazz();} // host5-error {{function with 'device_type(nohost)' is not available on host}}
 void host1() {bazz();} // host5-error {{function with 'device_type(nohost)' is not available on host}}
-#pragma omp declare target to(host1) device_type(host) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} dev5-note 3 {{marked as 'device_type(host)' here}}
+#pragma omp declare target to(host1) device_type(host) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} dev5-note 3 {{marked as 'device_type(host)' here}} omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 void host2() {bazz();} //host5-error {{function with 'device_type(nohost)' is not available on host}}
-#pragma omp declare target to(host2)
+#pragma omp declare target to(host2) // omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 void device() {host1();} // dev5-error {{function with 'device_type(host)' is not available on device}}
-#pragma omp declare target to(device) device_type(nohost) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} host5-note 2 {{marked as 'device_type(nohost)' here}}
+#pragma omp declare target to(device) device_type(nohost) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} host5-note 2 {{marked as 'device_type(nohost)' here}} omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 void host3() {host1();} // dev5-error {{function with 'device_type(host)' is not available on device}}
-#pragma omp declare target to(host3)
+#pragma omp declare target to(host3) // omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 
 #pragma omp declare target
 void any1() {any();}
 void any2() {host1();} // dev5-error {{function with 'device_type(host)' is not available on device}}
 void any3() {device();} // host5-error {{function with 'device_type(nohost)' is not available on host}}
 void any4() {any2();}
 #pragma omp end declare target
 
 void any5() {any();}
 void any6() {host1();}
 void any7() {device();} // host5-error {{function with 'device_type(nohost)' is not available on host}}
 void any8() {any2();}
 
 int MultiDevTy;
-#pragma omp declare target to(MultiDevTy) device_type(any)    // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}}
-#pragma omp declare target to(MultiDevTy) device_type(host)   // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} omp5-error {{'device_type(host)' does not match previously specified 'device_type(any)' for the same declaration}} omp51-error {{'device_type(host)' does not match previously specified 'device_type(any)' for the same declaration}}
-#pragma omp declare target to(MultiDevTy) device_type(nohost) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} omp5-error {{'device_type(nohost)' does not match previously specified 'device_type(any)' for the same declaration}} // omp51-error {{'device_type(nohost)' does not match previously specified 'device_type(any)' for the same declaration}}
+#pragma omp declare target to(MultiDevTy) device_type(any)    // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
+#pragma omp declare target to(MultiDevTy) device_type(host)   // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} omp5-error {{'device_type(host)' does not match previously specified 'device_type(any)' for the same declaration}} omp51-error {{'device_type(host)' does not match previously specified 'device_type(any)' for the same declaration}} omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
+#pragma omp declare target to(MultiDevTy) device_type(nohost) // omp45-error {{unexpected 'device_type' clause, only 'to' or 'link' clauses expected}} omp5-error {{'device_type(nohost)' does not match previously specified 'device_type(any)' for the same declaration}} // omp51-error {{'device_type(nohost)' does not match previously specified 'device_type(any)' for the same declaration}} omp52-error {{unexpected 'to' clause, use 'enter' instead}} omp52-error {{expected at least one 'enter', 'link' or 'indirect' clause}}
 
 #if TESTENDINC
 #include "unterminated_declare_target_include.h"
 #elif TESTEND
 // expected-warning@+1 {{expected '#pragma omp end declare target' at end of file to match '#pragma omp declare target'}}
 #pragma omp declare target
 #else
 // expected-warning@+1 {{expected '#pragma omp end declare target' at end of file to match '#pragma omp begin declare target'}}
 #pragma omp begin declare target
 #endif
+
+void fun();
+void host_function();
+#pragma omp declare target enter(fun) device_type(nohost) // omp45-error {{unexpected 'enter' clause, use 'to' instead}} omp45-error {{expected at least one 'to' or 'link' clause}} omp5-error {{unexpected 'enter' clause, use 'to' instead}} omp5-error {{expected at least one 'to' or 'link' clause}} omp51-error {{expected at least one 'to', 'link' or 'indirect' clause}} omp51-error {{unexpected 'enter' clause, use 'to' instead}}
+#pragma omp declare variant(host_function) match(device={kind(host)})
+void fun() {}
+void host_function() {}
+void call_host_function() { fun(); }

clang/test/OpenMP/declare_target_nohost_variant_messages.cpp

+// RUN: %clang_cc1 -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -fopenmp-version=52 -DVERBOSE_MODE=1 -verify=omp52 -fnoopenmp-use-tls -ferror-limit 100 -fopenmp-targets=amdgcn-amd-amdhsa -o - %s
+
+void fun();
+void not_a_host_function();
+#pragma omp declare target enter(fun) device_type(nohost) // omp52-note {{marked as 'device_type(nohost)' here}}
+#pragma omp declare variant(not_a_host_function) match(device={kind(host)}) // omp52-error {{function with 'device_type(nohost)' is not available on host}}
+void fun() {}
+#pragma omp begin declare target device_type(nohost) // omp52-note {{marked as 'device_type(nohost)' here}}
+void not_a_host_function() {}
+#pragma omp end declare target
+void failed_call_to_host_function() { fun(); } // omp52-error {{function with 'device_type(nohost)' is not available on host}}
+
+void fun2();
+void host_function();
+#pragma omp declare target enter(fun2) device_type(nohost)
+#pragma omp declare variant(host_function) match(device={kind(host)})
+void fun2() {}
+#pragma omp begin declare target device_type(host)
+void host_function() {}
+#pragma omp end declare target
+void call_to_host_function() { fun2(); }