[CUDA] Assume the latest known CUDA version if we've found an unknown one.

[tra]

Summary

This makes clang somewhat forward-compatible with new CUDA releases without
having to patch it for every minor release without adding any new functionality.

If an unknown version is found, clang issues a warning (can be disabled with -Wno-cuda-unknown-version)
and assumes that it has detected the latest known version. CUDA releases are usually supersets
of older ones feature-wise, so it should be sufficient to keep released clang versions
working with minor CUDA updates without having to upgrade clang, too.

[yaxunl]

LGTM. Thanks.

[tra]

Use std::string instead of Twine which can't be stored.

[yaxunl]

LGTM

[tra]

@hans : that's another candidate for 10.x cherry-pick, if you're OK with it.

[hans]

In D73231#1845096, @tra wrote:

@hans : that's another candidate for 10.x cherry-pick, if you're OK with it.

Sounds good to me. Cherry-picked in 5777899f146aaa53f598e6978702a7a2725200d7

[yaxunl]

clang/lib/Driver/ToolChains/Cuda.cpp

56

We got some issue with this warning.

Basically CudaInstallationDetector is a member of GNU and other host toolchain and this check is done in the ctor.

If a user has latest CUDA SDK installed, clang will always emit a warning. If the user has -Werror set, which is quite common, compilation will always fail.

Is it possible only do this check for CUDA compilation?

Thanks.

[tra]

clang/lib/Driver/ToolChains/Cuda.cpp

56

Agreed. Clang should not warn about this unless it's a CUDA compilation. I'll get it fixed.

[tra]

This patch should fix it: https://reviews.llvm.org/D76030

clang/include/clang/Basic/Cuda.h

 //===--- Cuda.h - Utilities for compiling CUDA code  ------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_BASIC_CUDA_H
 #define LLVM_CLANG_BASIC_CUDA_H
 
 namespace llvm {
 class StringRef;
+class Twine;
 class VersionTuple;
 } // namespace llvm
 
 namespace clang {
 
 enum class CudaVersion {
   UNKNOWN,
   CUDA_70,
   CUDA_75,
   CUDA_80,
   CUDA_90,
   CUDA_91,
   CUDA_92,
   CUDA_100,
   CUDA_101,
   LATEST = CUDA_101,
 };
 const char *CudaVersionToString(CudaVersion V);
 // Input is "Major.Minor"
-CudaVersion CudaStringToVersion(llvm::StringRef S);
+CudaVersion CudaStringToVersion(const llvm::Twine &S);
 
 enum class CudaArch {
   UNKNOWN,
   SM_20,
   SM_21,
   SM_30,
   SM_32,
   SM_35,

clang/include/clang/Basic/DiagnosticDriverKinds.td

 def err_drv_no_cuda_libdevice : Error<
   "cannot find libdevice for %0. Provide path to different CUDA installation "
   "via --cuda-path, or pass -nocudalib to build without linking with libdevice.">;
 def err_drv_cuda_version_unsupported : Error<
   "GPU arch %0 is supported by CUDA versions between %1 and %2 (inclusive), "
   "but installation at %3 is %4.  Use --cuda-path to specify a different CUDA "
   "install, pass a different GPU arch with --cuda-gpu-arch, or pass "
   "--no-cuda-version-check.">;
+def warn_drv_unknown_cuda_version: Warning<
+  "Unknown CUDA version %0. Assuming the latest supported version %1">,
+  InGroup<CudaUnknownVersion>;
 def err_drv_cuda_host_arch : Error<"unsupported architecture '%0' for host compilation.">;
 def err_drv_mix_cuda_hip : Error<"Mixed Cuda and HIP compilation is not supported.">;
 def err_drv_invalid_thread_model_for_target : Error<
   "invalid thread model '%0' in '%1' for this target">;
 def err_drv_invalid_linker_name : Error<
   "invalid linker name in argument '%0'">;
 def err_drv_invalid_pgo_instrumentor : Error<
   "invalid PGO instrumentor in argument '%0'">;

clang/include/clang/Basic/DiagnosticGroups.td

 
 // Issues with serialized diagnostics.
 def SerializedDiagnostics : DiagGroup<"serialized-diagnostics">;
 
 // A warning group for warnings about code that clang accepts when
 // compiling CUDA C/C++ but which is not compatible with the CUDA spec.
 def CudaCompat : DiagGroup<"cuda-compat">;
 
+// Warning about unknown CUDA SDK version.
+def CudaUnknownVersion: DiagGroup<"unknown-cuda-version">;
+
 // A warning group for warnings about features supported by HIP but
 // ignored by CUDA.
 def HIPOnly : DiagGroup<"hip-only">;
 
 // Warnings which cause linking of the runtime libraries like
 // libc and the CRT to be skipped.
 def AVRRtlibLinkingQuirks : DiagGroup<"avr-rtlib-linking-quirks">;
 

clang/lib/Basic/Cuda.cpp

 #include "clang/Basic/Cuda.h"
 
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/Twine.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/VersionTuple.h"
 
 namespace clang {
 
 const char *CudaVersionToString(CudaVersion V) {
   switch (V) {
   case CudaVersion::UNKNOWN:
const char *CudaVersionToString(CudaVersion V) {
   case CudaVersion::CUDA_100:
     return "10.0";
   case CudaVersion::CUDA_101:
     return "10.1";
   }
   llvm_unreachable("invalid enum");
 }
 
-CudaVersion CudaStringToVersion(llvm::StringRef S) {
-  return llvm::StringSwitch<CudaVersion>(S)
+CudaVersion CudaStringToVersion(const llvm::Twine &S) {
+  return llvm::StringSwitch<CudaVersion>(S.str())
       .Case("7.0", CudaVersion::CUDA_70)
       .Case("7.5", CudaVersion::CUDA_75)
       .Case("8.0", CudaVersion::CUDA_80)
       .Case("9.0", CudaVersion::CUDA_90)
       .Case("9.1", CudaVersion::CUDA_91)
       .Case("9.2", CudaVersion::CUDA_92)
       .Case("10.0", CudaVersion::CUDA_100)
-      .Case("10.1", CudaVersion::CUDA_101);
+      .Case("10.1", CudaVersion::CUDA_101)
+      .Default(CudaVersion::UNKNOWN);
 }
 
 const char *CudaArchToString(CudaArch A) {
   switch (A) {
   case CudaArch::LAST:
     break;
   case CudaArch::UNKNOWN:
     return "unknown";

clang/lib/Driver/ToolChains/Cuda.cpp

 using namespace clang::driver;
 using namespace clang::driver::toolchains;
 using namespace clang::driver::tools;
 using namespace clang;
 using namespace llvm::opt;
 
 // Parses the contents of version.txt in an CUDA installation.  It should
 // contain one line of the from e.g. "CUDA Version 7.5.2".
-static CudaVersion ParseCudaVersionFile(llvm::StringRef V) {
+static CudaVersion ParseCudaVersionFile(const Driver &D, llvm::StringRef V) {
   if (!V.startswith("CUDA Version "))
     return CudaVersion::UNKNOWN;
   V = V.substr(strlen("CUDA Version "));
-  int Major = -1, Minor = -1;
-  auto First = V.split('.');
-  auto Second = First.second.split('.');
-  if (First.first.getAsInteger(10, Major) ||
-      Second.first.getAsInteger(10, Minor))
-    return CudaVersion::UNKNOWN;
-
-  if (Major == 7 && Minor == 0) {
-    // This doesn't appear to ever happen -- version.txt doesn't exist in the
-    // CUDA 7 installs I've seen.  But no harm in checking.
-    return CudaVersion::CUDA_70;
-  }
-  if (Major == 7 && Minor == 5)
-    return CudaVersion::CUDA_75;
-  if (Major == 8 && Minor == 0)
-    return CudaVersion::CUDA_80;
-  if (Major == 9 && Minor == 0)
-    return CudaVersion::CUDA_90;
-  if (Major == 9 && Minor == 1)
-    return CudaVersion::CUDA_91;
-  if (Major == 9 && Minor == 2)
-    return CudaVersion::CUDA_92;
-  if (Major == 10 && Minor == 0)
-    return CudaVersion::CUDA_100;
-  if (Major == 10 && Minor == 1)
-    return CudaVersion::CUDA_101;
+  SmallVector<StringRef,4> VersionParts;
+  V.split(VersionParts, '.');
+  if (VersionParts.size() < 2)
     return CudaVersion::UNKNOWN;
+  Twine MajorMinor = VersionParts[0] + "." + VersionParts[1];
+  CudaVersion Version = CudaStringToVersion(MajorMinor);
+  if (Version != CudaVersion::UNKNOWN)
+    return Version;
+
+  // Issue a warning and assume that the version we've found is compatible with
+  // the latest version we support.
+  D.Diag(diag::warn_drv_unknown_cuda_version)
+      << MajorMinor.str() << CudaVersionToString(CudaVersion::LATEST);
+  return CudaVersion::LATEST;
 }
 
 CudaInstallationDetector::CudaInstallationDetector(
     const Driver &D, const llvm::Triple &HostTriple,
     const llvm::opt::ArgList &Args)
     : D(D) {
   struct Candidate {
     std::string Path;
     bool StrictChecking;
 
     Candidate(std::string Path, bool StrictChecking = false)
for (const auto &Candidate : Candidates) {
 
     llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> VersionFile =
         FS.getBufferForFile(InstallPath + "/version.txt");
     if (!VersionFile) {
       // CUDA 7.0 doesn't have a version.txt, so guess that's our version if
       // version.txt isn't present.
       Version = CudaVersion::CUDA_70;
     } else {
-      Version = ParseCudaVersionFile((*VersionFile)->getBuffer());
+      Version = ParseCudaVersionFile(D, (*VersionFile)->getBuffer());
     }
 
     if (Version >= CudaVersion::CUDA_90) {
       // CUDA-9+ uses single libdevice file for all GPU variants.
       std::string FilePath = LibDevicePath + "/libdevice.10.bc";
       if (FS.exists(FilePath)) {
         for (const char *GpuArchName :
              {"sm_30", "sm_32", "sm_35", "sm_37", "sm_50", "sm_52", "sm_53",

clang/lib/Headers/__clang_cuda_runtime_wrapper.h

 #pragma push_macro("__CUDA_ARCH__")
 
 // WARNING: Preprocessor hacks below are based on specific details of
 // CUDA-7.x headers and are not expected to work with any other
 // version of CUDA headers.
 #include "cuda.h"
 #if !defined(CUDA_VERSION)
 #error "cuda.h did not define CUDA_VERSION"
-#elif CUDA_VERSION < 7000 || CUDA_VERSION > 10010
+#elif CUDA_VERSION < 7000
 #error "Unsupported CUDA version!"
 #endif
 
 #pragma push_macro("__CUDA_INCLUDE_COMPILER_INTERNAL_HEADERS__")
 #if CUDA_VERSION >= 10000
 #define __CUDA_INCLUDE_COMPILER_INTERNAL_HEADERS__
 #endif
 

clang/test/Driver/Inputs/CUDA-unknown/usr/local/cuda/version.txt

+CUDA Version 999.999.999

clang/test/Driver/cuda-version-check.cu

 // REQUIRES: clang-driver
 // REQUIRES: x86-registered-target
 // REQUIRES: nvptx-registered-target
 
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_20 --cuda-path=%S/Inputs/CUDA/usr/local/cuda 2>&1 %s | \
 // RUN:    FileCheck %s --check-prefix=OK
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_20 --cuda-path=%S/Inputs/CUDA_80/usr/local/cuda 2>&1 %s | \
 // RUN:    FileCheck %s --check-prefix=OK
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-path=%S/Inputs/CUDA_80/usr/local/cuda 2>&1 %s | \
 // RUN:    FileCheck %s --check-prefix=OK
+// RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-path=%S/Inputs/CUDA-unknown/usr/local/cuda 2>&1 %s | \
+// RUN:    FileCheck %s --check-prefix=UNKNOWN_VERSION
 
 // The installation at Inputs/CUDA is CUDA 7.0, which doesn't support sm_60.
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-path=%S/Inputs/CUDA/usr/local/cuda 2>&1 %s | \
 // RUN:    FileCheck %s --check-prefix=ERR_SM60
 
 // This should only complain about sm_60, not sm_35.
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-gpu-arch=sm_35 \
 // RUN:    --cuda-path=%S/Inputs/CUDA/usr/local/cuda 2>&1 %s | \

 // OK_SM35-NOT: error: GPU arch sm_35
 
 // We should only get one error per architecture.
 // ERR_SM60: error: GPU arch sm_60 {{.*}}
 // ERR_SM60-NOT: error: GPU arch sm_60
 
 // ERR_SM61: error: GPU arch sm_61 {{.*}}
 // ERR_SM61-NOT: error: GPU arch sm_61
+
+// UNKNOWN_VERSION: Unknown CUDA version 999.999. Assuming the latest supported version