[CUDA] Let NVPTX inherit the host's calling conventions.

Justin Lebar · Justin Lebar · commit 86c4e63ff974 · 2017-01-05T16:53:38.000Z
Summary: When compiling device code, we may still see host code with explicit calling conventions. NVPTX needs to claim that it supports these CCs, so that (a) we don't raise noisy warnings, and (b) we don't break existing code which relies on the existence of these CCs when specializing templates. (If a CC doesn't exist, clang ignores it, so two template specializations which are different only insofar as one specifies a CC are considered identical and therefore are an error if that CC is not supported.) Reviewers: tra Subscribers: cfe-commits Differential Revision: https://reviews.llvm.org/D28323 llvm-svn: 291136
diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
@@ -1962,6 +1962,16 @@ class NVPTXTargetInfo : public TargetInfo {
     Opts.support("cl_khr_local_int32_base_atomics");
     Opts.support("cl_khr_local_int32_extended_atomics");
   }
+
+  CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
+    // CUDA compilations support all of the host's calling conventions.
+    //
+    // TODO: We should warn if you apply a non-default CC to anything other than
+    // a host function.
+    if (HostTarget)
+      return HostTarget->checkCallingConvention(CC);
+    return CCCR_Warning;
+  }
 };
 
 const Builtin::Info NVPTXTargetInfo::BuiltinInfo[] = {
diff --git a/clang/test/SemaCUDA/cuda-inherits-calling-conv.cu b/clang/test/SemaCUDA/cuda-inherits-calling-conv.cu
@@ -0,0 +1,30 @@
+// RUN: %clang_cc1 -std=c++11 -triple i386-windows-msvc \
+// RUN:   -aux-triple nvptx-nvidia-cuda -fsyntax-only -verify %s
+
+// RUN: %clang_cc1 -std=c++11 -triple nvptx-nvidia-cuda \
+// RUN:   -aux-triple i386-windows-msvc -fsyntax-only \
+// RUN:   -fcuda-is-device -verify %s
+
+// RUN: %clang_cc1 -std=c++11 -triple nvptx-nvidia-cuda \
+// RUN:   -aux-triple x86_64-linux-gnu -fsyntax-only \
+// RUN:   -fcuda-is-device -verify -verify-ignore-unexpected=note \
+// RUN:   -DEXPECT_ERR %s
+
+// CUDA device code should inherit the host's calling conventions.
+
+template <class T>
+struct Foo;
+
+template <class T>
+struct Foo<T()> {};
+
+// On x86_64-linux-gnu, this is a redefinition of the template, because the
+// __fastcall calling convention doesn't exist (and is therefore ignored).
+#ifndef EXPECT_ERR
+// expected-no-diagnostics
+#else
+// expected-error@+4 {{redefinition of 'Foo}}
+// expected-warning@+3 {{calling convention '__fastcall' ignored}}
+#endif
+template <class T>
+struct Foo<T __fastcall()> {};
