[CUDA] Bump CUDA version to 11.5

[carlosgalvezp]

Summary

Following the pattern used for 11.4:
https://github.com/llvm/llvm-project/commit/49d982d8cbbbb6e01b6f8e4f173ed6325beab08b

[Hahnfeld]

I'm not sure if it's actually correct to advertise full support for CUDA 11.5, but I didn't look into exact changes since 11.4

[carlosgalvezp]

In D113249#3110954, @Hahnfeld wrote:

I'm not sure if it's actually correct to advertise full support for CUDA 11.5, but I didn't look into exact changes since 11.4

Good point. I was confused about the fact that 11.4 is both FULLY_SUPPORTED and PARTIALLY_SUPPORTED, so I thought to just follow the existing pattern. I didn't find any extra tests added for the bump 11.2 -> 11.4. Do we have infrastructure in place to test this, or how does it work?

[tra]

I think we're missing few more changes here:

• The driver needs to enable ptx75 when it constructs cc1 command line in clang/lib/Driver/ToolChains/Cuda.cpp
• We also need to handle PTX75 in clang/include/clang/Basic/BuiltinsNVPTX.def

In D113249#3110954, @Hahnfeld wrote:

I'm not sure if it's actually correct to advertise full support for CUDA 11.5, but I didn't look into exact changes since 11.4

Technically we never support all the features supported by NVCC, so for clang it essentially means "works well enough". I.e. no known regressions vs previous clang and CUDA versions. Usually it boils down to being able to compile CUDA headers.
"Partially supported" happens when we can compile code compileable with the older CUDA versions, but are missing something critical introduced by the new CUDA version. E.g. a new GPU variant. Or new compiler builtins/functions that a user may expect from the new CUDA version. Or some CUDA headers may use new instructions in inline asm that would not compile with ptxas unless we generate PTX output using the new PTX version.

AFAICT from the CUDA-11.5 release notes, it didn't introduce anything particularly interesting. We've been using clang with CUDA-11.5 for a few weeks w/o any issues, so I think it's fine to stamp it as supported, once the missing bits are in place.

[Hahnfeld]

Experimental support for __int128 is new in CUDA 11.5, not sure if Clang enables this for CUDA. The release notes also specify

builtin_assume can now be used to specify address space to allow for efficient loads and stores.

The docs are very scarce on this, I could only find void __builtin_assume(bool exp) which I think is not what they are talking about...

[tra]

In D113249#3112279, @Hahnfeld wrote:

Experimental support for __int128 is new in CUDA 11.5, not sure if Clang enables this for CUDA.

I think we've added support for i128 a while back: https://godbolt.org/z/18bEbhMYb

The release notes also specify

builtin_assume can now be used to specify address space to allow for efficient loads and stores.

The docs are very scarce on this, I could only find void __builtin_assume(bool exp) which I think is not what they are talking about...

AMD folks have D112041 under review which will have builtin_assume help AS inference. In any case, we've already been doing it reasonably well automatically.

[carlosgalvezp]

Updated BuilintsNVPTX.def

[carlosgalvezp]

• The driver needs to enable ptx75 when it constructs cc1 command line in clang/lib/Driver/ToolChains/Cuda.cpp

@tra Haven't I already done it in line 712? Or where should I enable it?

[carlosgalvezp]

Update release notes

[tra]

In D113249#3113666, @carlosgalvezp wrote:

• The driver needs to enable ptx75 when it constructs cc1 command line in clang/lib/Driver/ToolChains/Cuda.cpp

@tra Haven't I already done it in line 712? Or where should I enable it?

You're right. I've missed that.

[carlosgalvezp]

@Hahnfeld Are you satisfied with the replies to your questions? If so I can go ahead and merge.

[Hahnfeld]

In D113249#3117541, @carlosgalvezp wrote:

@Hahnfeld Are you satisfied with the replies to your questions? If so I can go ahead and merge.

Yes yes, I'm happy if @tra is happy :)

[carlosgalvezp]

Awesome, thanks a lot for the reviews!

clang/include/clang/Basic/Cuda.h

enum class CudaVersion {
   CUDA_100,
   CUDA_101,
   CUDA_102,
   CUDA_110,
   CUDA_111,
   CUDA_112,
   CUDA_113,
   CUDA_114,
-  FULLY_SUPPORTED = CUDA_114,
+  CUDA_115,
+  FULLY_SUPPORTED = CUDA_115,
   PARTIALLY_SUPPORTED =
-      CUDA_114, // Partially supported. Proceed with a warning.
+      CUDA_115, // Partially supported. Proceed with a warning.
   NEW = 10000,  // Too new. Issue a warning, but allow using it.
 };
 const char *CudaVersionToString(CudaVersion V);
 // Input is "Major.Minor"
 CudaVersion CudaStringToVersion(const llvm::Twine &S);
 
 enum class CudaArch {
   UNUSED,

clang/lib/Basic/Cuda.cpp

const char *CudaVersionToString(CudaVersion V) {
   case CudaVersion::CUDA_111:
     return "11.1";
   case CudaVersion::CUDA_112:
     return "11.2";
   case CudaVersion::CUDA_113:
     return "11.3";
   case CudaVersion::CUDA_114:
     return "11.4";
+  case CudaVersion::CUDA_115:
+    return "11.5";
   case CudaVersion::NEW:
     return "";
   }
   llvm_unreachable("invalid enum");
 }
 
 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("10.2", CudaVersion::CUDA_102)
       .Case("11.0", CudaVersion::CUDA_110)
       .Case("11.1", CudaVersion::CUDA_111)
       .Case("11.2", CudaVersion::CUDA_112)
       .Case("11.3", CudaVersion::CUDA_113)
       .Case("11.4", CudaVersion::CUDA_114)
+      .Case("11.5", CudaVersion::CUDA_115)
       .Default(CudaVersion::UNKNOWN);
 }
 
 namespace {
 struct CudaArchToStringMap {
   CudaArch arch;
   const char *arch_name;
   const char *virtual_arch_name;
CudaVersion ToCudaVersion(llvm::VersionTuple Version) {
   case 111:
     return CudaVersion::CUDA_111;
   case 112:
     return CudaVersion::CUDA_112;
   case 113:
     return CudaVersion::CUDA_113;
   case 114:
     return CudaVersion::CUDA_114;
+  case 115:
+    return CudaVersion::CUDA_115;
   default:
     return CudaVersion::UNKNOWN;
   }
 }
 
 bool CudaFeatureEnabled(llvm::VersionTuple  Version, CudaFeature Feature) {
   return CudaFeatureEnabled(ToCudaVersion(Version), Feature);
 }

clang/lib/Basic/Targets/NVPTX.cpp

NVPTXTargetInfo::NVPTXTargetInfo(const llvm::Triple &Triple,
   assert((TargetPointerWidth == 32 || TargetPointerWidth == 64) &&
          "NVPTX only supports 32- and 64-bit modes.");
 
   PTXVersion = 32;
   for (const StringRef Feature : Opts.FeaturesAsWritten) {
     if (!Feature.startswith("+ptx"))
       continue;
     PTXVersion = llvm::StringSwitch<unsigned>(Feature)
+                     .Case("+ptx75", 75)
                      .Case("+ptx74", 74)
                      .Case("+ptx73", 73)
                      .Case("+ptx72", 72)
                      .Case("+ptx71", 71)
                      .Case("+ptx70", 70)
                      .Case("+ptx65", 65)
                      .Case("+ptx64", 64)
                      .Case("+ptx63", 63)

clang/lib/Driver/ToolChains/Cuda.cpp

CudaVersion getCudaVersion(uint32_t raw_version) {
   if (raw_version < 11020)
     return CudaVersion::CUDA_111;
   if (raw_version < 11030)
     return CudaVersion::CUDA_112;
   if (raw_version < 11040)
     return CudaVersion::CUDA_113;
   if (raw_version < 11050)
     return CudaVersion::CUDA_114;
+  if (raw_version < 11060)
+    return CudaVersion::CUDA_115;
   return CudaVersion::NEW;
 }
 
 CudaVersion parseCudaHFile(llvm::StringRef Input) {
   // Helper lambda which skips the words if the line starts with them or returns
   // None otherwise.
   auto StartsWithWords =
       [](llvm::StringRef Line,
void CudaToolChain::addClangTargetOptions(
   // by new PTX version, so we need to raise PTX level to enable them in NVPTX
   // back-end.
   const char *PtxFeature = nullptr;
   switch (CudaInstallationVersion) {
 #define CASE_CUDA_VERSION(CUDA_VER, PTX_VER)                                   \
   case CudaVersion::CUDA_##CUDA_VER:                                           \
     PtxFeature = "+ptx" #PTX_VER;                                              \
     break;
+    CASE_CUDA_VERSION(115, 75);
     CASE_CUDA_VERSION(114, 74);
     CASE_CUDA_VERSION(113, 73);
     CASE_CUDA_VERSION(112, 72);
     CASE_CUDA_VERSION(111, 71);
     CASE_CUDA_VERSION(110, 70);
     CASE_CUDA_VERSION(102, 65);
     CASE_CUDA_VERSION(101, 64);
     CASE_CUDA_VERSION(100, 63);

llvm/docs/CompileCudaWithLLVM.rst

 
 Compiling CUDA Code
 ===================
 
 Prerequisites
 -------------
 
 CUDA is supported since llvm 3.9. Clang currently supports CUDA 7.0 through
-10.1. If clang detects a newer CUDA version, it will issue a warning and will
-attempt to use detected CUDA SDK it as if it were CUDA-10.1.
+11.5. If clang detects a newer CUDA version, it will issue a warning and will
+attempt to use detected CUDA SDK it as if it were CUDA 11.5.
 
 Before you build CUDA code, you'll need to have installed the CUDA SDK.  See
 `NVIDIA's CUDA installation guide
 <https://docs.nvidia.com/cuda/cuda-installation-guide-linux/index.html>`_ for
 details.  Note that clang `maynot support
 <https://bugs.llvm.org/show_bug.cgi?id=26966>`_ the CUDA toolkit as installed by
 some Linux package managers. Clang does attempt to deal with specific details of
 CUDA installation on a handful of common Linux distributions, but in general the

llvm/lib/Target/NVPTX/NVPTX.td

 def PTX71 : SubtargetFeature<"ptx71", "PTXVersion", "71",
                              "Use PTX version 7.1">;
 def PTX72 : SubtargetFeature<"ptx72", "PTXVersion", "72",
                              "Use PTX version 7.2">;
 def PTX73 : SubtargetFeature<"ptx73", "PTXVersion", "73",
                              "Use PTX version 7.3">;
 def PTX74 : SubtargetFeature<"ptx74", "PTXVersion", "74",
                              "Use PTX version 7.4">;
+def PTX75 : SubtargetFeature<"ptx75", "PTXVersion", "75",
+                             "Use PTX version 7.5">;
 
 //===----------------------------------------------------------------------===//
 // NVPTX supported processors.
 //===----------------------------------------------------------------------===//
 
 class Proc<string Name, list<SubtargetFeature> Features>
  : Processor<Name, NoItineraries, Features>;