r323239 - [CUDA] CUDA has no device-side library builtins.

[Artem Belevich via cfe-commits]

Author: tra
Date: Tue Jan 23 11:08:18 2018
New Revision: 323239

URL: http://llvm.org/viewvc/llvm-project?rev=323239&view=rev
Log:
[CUDA] CUDA has no device-side library builtins.

We should (almost) never consider a device-side declaration to match a
library builtin functio.  Otherwise clang may ignore the implementation
provided by the CUDA headers and emit clang's idea of the builtin.

Differential Revision: https://reviews.llvm.org/D42319

Added:
    cfe/trunk/test/CodeGenCUDA/library-builtin.cu
Modified:
    cfe/trunk/lib/AST/Decl.cpp

Modified: cfe/trunk/lib/AST/Decl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Decl.cpp?rev=323239&r1=323238&r2=323239&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Decl.cpp (original)
+++ cfe/trunk/lib/AST/Decl.cpp Tue Jan 23 11:08:18 2018
@@ -2901,6 +2901,13 @@ unsigned FunctionDecl::getBuiltinID() co
       Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID))
     return 0;
 
+  // CUDA does not have device-side standard library. printf and malloc are the
+  // only special cases that are supported by device-side runtime.
+  if (Context.getLangOpts().CUDA && hasAttr<CUDADeviceAttr>() &&
+      !hasAttr<CUDAHostAttr>() &&
+      !(BuiltinID == Builtin::BIprintf || BuiltinID == Builtin::BImalloc))
+    return 0;
+
   return BuiltinID;
 }
 

Added: cfe/trunk/test/CodeGenCUDA/library-builtin.cu
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCUDA/library-builtin.cu?rev=323239&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenCUDA/library-builtin.cu (added)
+++ cfe/trunk/test/CodeGenCUDA/library-builtin.cu Tue Jan 23 11:08:18 2018
@@ -0,0 +1,22 @@
+// REQUIRES: x86-registered-target
+// REQUIRES: nvptx-registered-target
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -o - %s | \
+// RUN:  FileCheck --check-prefixes=HOST,BOTH %s
+// RUN: %clang_cc1 -fcuda-is-device -triple nvptx64-nvidia-cuda \
+// RUN:   -emit-llvm -o - %s | FileCheck %s --check-prefixes=DEVICE,BOTH
+
+// BOTH-LABEL: define float @logf(float
+
+// logf() should be calling itself recursively as we don't have any standard
+// library on device side.
+// DEVICE: call float @logf(float
+extern "C" __attribute__((device)) float logf(float __x) { return logf(__x); }
+
+// NOTE: this case is to illustrate the expected differences in behavior between
+// the host and device. In general we do not mess with host-side standard
+// library.
+//
+// Host is assumed to have standard library, so logf() calls LLVM intrinsic.
+// HOST: call float @llvm.log.f32(float
+extern "C" float logf(float __x) { return logf(__x); }