[CUDA][HIP] Use the same default language std as C++

[yaxunl]

Summary

Currently CUDA/HIP defines their own language standards in LanguageStandards.def but they are redundant. They are the same as stdc++14. The fact that CUDA/HIP uses c++* in option -std= indicates that they have the same language standards as C++. The CUDA/HIP specific language features are conveyed through language options, not language standards features. It makes sense to let CUDA/HIP uses the same default language standard as C++.

[scchan]

LGTM thanks

[tra]

We should probably update documentation that C++ standard version for CUDA/HIP compilation now matches C++ default instead of previously used c++14.

[yaxunl]

update release note

[dyung]

Hi @yaxunl, your change appears to have broken the LLDB build. Can you take a look and revert if you time to investigate?

https://lab.llvm.org/buildbot/#/builders/243/builds/9581

FAILED: tools/lldb/source/Plugins/TypeSystem/Clang/CMakeFiles/lldbPluginTypeSystemClang.dir/TypeSystemClang.cpp.o 
/opt/ccache/bin/g++ -DGTEST_HAS_RTTI=0 -DHAVE_ROUND -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D_LIBCPP_ENABLE_ASSERTIONS -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/tools/lldb/source/Plugins/TypeSystem/Clang -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/lldb/source/Plugins/TypeSystem/Clang -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/lldb/include -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/tools/lldb/include -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/include -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/llvm/include -I/usr/include/python3.10 -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/llvm/../clang/include -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/tools/lldb/../clang/include -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/lldb/source -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/tools/lldb/source -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -fno-lifetime-dse -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -Wno-deprecated-declarations -Wno-unknown-pragmas -Wno-strict-aliasing -Wno-stringop-truncation -O3 -DNDEBUG  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -std=c++17 -MD -MT tools/lldb/source/Plugins/TypeSystem/Clang/CMakeFiles/lldbPluginTypeSystemClang.dir/TypeSystemClang.cpp.o -MF tools/lldb/source/Plugins/TypeSystem/Clang/CMakeFiles/lldbPluginTypeSystemClang.dir/TypeSystemClang.cpp.o.d -o tools/lldb/source/Plugins/TypeSystem/Clang/CMakeFiles/lldbPluginTypeSystemClang.dir/TypeSystemClang.cpp.o -c /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp: In function ‘void ParseLangArgs(clang::LangOptions&, clang::InputKind, const char*)’:
/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:489:31: error: ‘lang_cuda’ is not a member of ‘clang::LangStandard’
  489 |       LangStd = LangStandard::lang_cuda;
      |                               ^~~~~~~~~
/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:501:31: error: ‘lang_hip’ is not a member of ‘clang::LangStandard’
  501 |       LangStd = LangStandard::lang_hip;
      |                               ^~~~~~~~

Other failing buildbots:

• https://lab.llvm.org/buildbot/#/builders/96/builds/42305
• https://lab.llvm.org/buildbot/#/builders/17/builds/40545
• https://lab.llvm.org/buildbot/#/builders/68/builds/56513

[sylvestre.ledru]

I reverted the patch for causing https://github.com/llvm/llvm-project/issues/63974
https://github.com/llvm/llvm-project/commit/443f490b6aac4af28500f4b09b68a13260f4fba9

[yaxunl]

In D155539#4517882, @sylvestre.ledru wrote:

I reverted the patch for causing https://github.com/llvm/llvm-project/issues/63974
https://github.com/llvm/llvm-project/commit/443f490b6aac4af28500f4b09b68a13260f4fba9

Thanks. I will fix it.

[probinson]

This change to lang-std.cpp causes it not to verify _which_ language standard is the default. It only verifies that cuda and hip don't _change_ it.
If you run FileCheck on one of those output files, it would preserve that property.

[yaxunl]

In D155539#4524189, @probinson wrote:

This change to lang-std.cpp causes it not to verify _which_ language standard is the default. It only verifies that cuda and hip don't _change_ it.
If you run FileCheck on one of those output files, it would preserve that property.

It is intentional since we just want to make sure CUDA/HIP uses the same default language standard as C++. We do not want to update the test when C++ changes its default language standard.

[probinson]

In D155539#4524543, @yaxunl wrote:

In D155539#4524189, @probinson wrote:

This change to lang-std.cpp causes it not to verify _which_ language standard is the default. It only verifies that cuda and hip don't _change_ it.
If you run FileCheck on one of those output files, it would preserve that property.

It is intentional since we just want to make sure CUDA/HIP uses the same default language standard as C++. We do not want to update the test when C++ changes its default language standard.

I agree you don't want to change the CUDA/HIP part. But we do want to preserve the check for what the actual default is. That was the purpose when the test was introduced in D131465. As it stands, there is no test for the actual default; you have repurposed the test from "check language standard defaults" to "check that CUDA/HIP don't affect the default" and that's losing test coverage.

If you want to extract the CUDA/HIP part into a separate test, that's fine. But please don't lose the coverage that we had.

[yaxunl]

In D155539#4528094, @probinson wrote:

In D155539#4524543, @yaxunl wrote:

In D155539#4524189, @probinson wrote:

This change to lang-std.cpp causes it not to verify _which_ language standard is the default. It only verifies that cuda and hip don't _change_ it.
If you run FileCheck on one of those output files, it would preserve that property.

It is intentional since we just want to make sure CUDA/HIP uses the same default language standard as C++. We do not want to update the test when C++ changes its default language standard.

I agree you don't want to change the CUDA/HIP part. But we do want to preserve the check for what the actual default is. That was the purpose when the test was introduced in D131465. As it stands, there is no test for the actual default; you have repurposed the test from "check language standard defaults" to "check that CUDA/HIP don't affect the default" and that's losing test coverage.

If you want to extract the CUDA/HIP part into a separate test, that's fine. But please don't lose the coverage that we had.

Sorry, I misunderstood the purpose of this test. I will add the check back and create a review for that. Thanks.

[yaxunl]

In D155539#4528137, @yaxunl wrote:

In D155539#4528094, @probinson wrote:

In D155539#4524543, @yaxunl wrote:

In D155539#4524189, @probinson wrote:

This change to lang-std.cpp causes it not to verify _which_ language standard is the default. It only verifies that cuda and hip don't _change_ it.
If you run FileCheck on one of those output files, it would preserve that property.

It is intentional since we just want to make sure CUDA/HIP uses the same default language standard as C++. We do not want to update the test when C++ changes its default language standard.

I agree you don't want to change the CUDA/HIP part. But we do want to preserve the check for what the actual default is. That was the purpose when the test was introduced in D131465. As it stands, there is no test for the actual default; you have repurposed the test from "check language standard defaults" to "check that CUDA/HIP don't affect the default" and that's losing test coverage.

If you want to extract the CUDA/HIP part into a separate test, that's fine. But please don't lose the coverage that we had.

Sorry, I misunderstood the purpose of this test. I will add the check back and create a review for that. Thanks.

https://reviews.llvm.org/D156127

clang/docs/ReleaseNotes.rst

- Added ``attribute(riscv_rvv_vector_bits(__riscv_v_fixed_vlen))`` to allow
   the size of a RVV (RISC-V Vector) scalable type to be specified. This allows
   RVV scalable vector types to be used in structs or in global variables.
 - The rules for ordering of extensions in ``-march`` strings were relaxed. A
   canonical ordering is no longer enforced on ``z*``, ``s*``, and ``x*``
   prefixed extensions.
 
 CUDA/HIP Language Changes
 ^^^^^^^^^^^^^^^^^^^^^^^^^
+- Clang has been updated to align its default language standard for CUDA/HIP with
+  that of C++. The standard has now been enhanced to gnu++17, supplanting the
+  previously used c++14.
 
 CUDA Support
 ^^^^^^^^^^^^
 - Clang now supports CUDA SDK up to 12.1
 
 AIX Support
 ^^^^^^^^^^^
 - Add an AIX-only link-time option, `-mxcoff-build-id=0xHEXSTRING`, to allow users

clang/include/clang/Basic/LangStandards.def

 LANGSTANDARD_ALIAS_DEPR(opencl11, "CL1.1")
 LANGSTANDARD_ALIAS_DEPR(opencl12, "CL1.2")
 LANGSTANDARD_ALIAS_DEPR(opencl20, "CL2.0")
 LANGSTANDARD_ALIAS_DEPR(opencl30, "CL3.0")
 LANGSTANDARD_ALIAS_DEPR(openclcpp10, "CLC++")
 LANGSTANDARD_ALIAS_DEPR(openclcpp10, "CLC++1.0")
 LANGSTANDARD_ALIAS_DEPR(openclcpp2021, "CLC++2021")
 
-// CUDA
-LANGSTANDARD(cuda, "cuda", CUDA, "NVIDIA CUDA(tm)",
-             LineComment | CPlusPlus | CPlusPlus11 | CPlusPlus14 | Digraphs)
-
-// HIP
-LANGSTANDARD(hip, "hip", HIP, "HIP",
-             LineComment | CPlusPlus | CPlusPlus11 | CPlusPlus14 | Digraphs)
-
 // HLSL
 LANGSTANDARD(hlsl, "hlsl",
              HLSL, "High Level Shader Language",
              LineComment | HLSL | CPlusPlus )
 
 LANGSTANDARD(hlsl2015, "hlsl2015",
              HLSL, "High Level Shader Language 2015",
              LineComment | HLSL | CPlusPlus )

clang/lib/Basic/LangStandards.cpp

LangStandard::Kind clang::getDefaultLanguageStandard(clang::Language Lang,
   switch (Lang) {
   case Language::Unknown:
   case Language::LLVM_IR:
     llvm_unreachable("Invalid input kind!");
   case Language::OpenCL:
     return LangStandard::lang_opencl12;
   case Language::OpenCLCXX:
     return LangStandard::lang_openclcpp10;
-  case Language::CUDA:
-    return LangStandard::lang_cuda;
   case Language::Asm:
   case Language::C:
     // The PS4 uses C99 as the default C standard.
     if (T.isPS4())
       return LangStandard::lang_gnu99;
     return LangStandard::lang_gnu17;
   case Language::ObjC:
     return LangStandard::lang_gnu11;
   case Language::CXX:
   case Language::ObjCXX:
+  case Language::CUDA:
+  case Language::HIP:
     if (T.isPS())
       return LangStandard::lang_gnucxx14;
     return LangStandard::lang_gnucxx17;
   case Language::RenderScript:
     return LangStandard::lang_c99;
-  case Language::HIP:
-    return LangStandard::lang_hip;
   case Language::HLSL:
     return LangStandard::lang_hlsl2021;
   }
   llvm_unreachable("unhandled Language kind!");
 }

clang/test/CodeGenCUDA/long-double.cu

 // RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -target-cpu gfx906 \
 // RUN:   -aux-triple x86_64-unknown-gnu-linux -fcuda-is-device \
 // RUN:   -emit-llvm -o - -x hip %s 2>&1 | FileCheck %s
 
 // RUN: %clang_cc1 -triple nvptx \
 // RUN:   -aux-triple x86_64-unknown-gnu-linux -fcuda-is-device \
 // RUN:   -emit-llvm -o - %s 2>&1 | FileCheck %s
 
-// CHECK: @_ZN15infinity_helperIeE5valueE = {{.*}} double 0x47EFFFFFD586B834, align 8
+// CHECK: @_ZN15infinity_helperIeE5valueE = {{.*}} double 0x47EFFFFFD586B834,{{.*}} align 8
 // CHECK: @size = {{.*}} i32 8
 
 #include "Inputs/cuda.h"
 
 template <class> struct infinity_helper {};
 template <> struct infinity_helper<long double> { static constexpr long double value = 3.4028234e38L; };
 constexpr long double infinity_helper<long double>::value;
 __device__ int size = sizeof(long double);

clang/test/Driver/unknown-std.cpp

 // This file checks output given when processing C++/ObjC++ files.
 // When user selects invalid language standard
 // print out supported values with short description.
 
 // RUN: not %clang %s -std=foobar -c 2>&1 | FileCheck --match-full-lines %s
 // RUN: not %clang -x objective-c++ %s -std=foobar -c 2>&1 | FileCheck --match-full-lines %s
-// RUN: not %clang -x cuda -nocudainc -nocudalib --cuda-path=%S/Inputs/CUDA/usr/local/cuda %s -std=foobar -c 2>&1 | FileCheck --match-full-lines --check-prefix=CHECK --check-prefix=CUDA %s
+// RUN: not %clang -x cuda -nocudainc -nocudalib --cuda-path=%S/Inputs/CUDA/usr/local/cuda \
+// RUN:   %s -std=foobar -c 2>&1 | FileCheck --match-full-lines %s
+// RUN: not %clang -x hip -nocudainc -nocudalib %s -std=foobar -c 2>&1 \
+// RUN:   | FileCheck --match-full-lines %s
 
 // CHECK: error: invalid value 'foobar' in '-std=foobar'
 // CHECK-NEXT: note: use 'c++98' or 'c++03' for 'ISO C++ 1998 with amendments' standard
 // CHECK-NEXT: note: use 'gnu++98' or 'gnu++03' for 'ISO C++ 1998 with amendments and GNU extensions' standard
 // CHECK-NEXT: note: use 'c++11' for 'ISO C++ 2011 with amendments' standard
 // CHECK-NEXT: note: use 'gnu++11' for 'ISO C++ 2011 with amendments and GNU extensions' standard
 // CHECK-NEXT: note: use 'c++14' for 'ISO C++ 2014 with amendments' standard
 // CHECK-NEXT: note: use 'gnu++14' for 'ISO C++ 2014 with amendments and GNU extensions' standard
 // CHECK-NEXT: note: use 'c++17' for 'ISO C++ 2017 with amendments' standard
 // CHECK-NEXT: note: use 'gnu++17' for 'ISO C++ 2017 with amendments and GNU extensions' standard
 // CHECK-NEXT: note: use 'c++20' for 'ISO C++ 2020 DIS' standard
 // CHECK-NEXT: note: use 'gnu++20' for 'ISO C++ 2020 DIS with GNU extensions' standard
 // CHECK-NEXT: note: use 'c++23' for 'ISO C++ 2023 DIS' standard
 // CHECK-NEXT: note: use 'gnu++23' for 'ISO C++ 2023 DIS with GNU extensions' standard
 // CHECK-NEXT: note: use 'c++2c' or 'c++26' for 'Working draft for C++2c' standard
 // CHECK-NEXT: note: use 'gnu++2c' or 'gnu++26' for 'Working draft for C++2c with GNU extensions' standard
-// CUDA-NEXT: note: use 'cuda' for 'NVIDIA CUDA(tm)' standard
 
 // Make sure that no other output is present.
 // CHECK-NOT: {{^.+$}}
 

clang/test/Preprocessor/lang-std.cpp

-// UNSUPPORTED: target={{.*-(ps4|ps5)}}
 /// Test default standards.
-/// PS4/PS5 default to gnu++14.
+/// CUDA/HIP uses the same default standards as C++.
 
-// RUN: %clang_cc1 -dM -E %s | FileCheck --check-prefix=CXX17 %s
-// RUN: %clang_cc1 -dM -E -x cuda %s | FileCheck --check-prefix=CXX14 %s
-// RUN: %clang_cc1 -dM -E -x hip %s | FileCheck --check-prefix=CXX14 %s
+// RUN: %clang_cc1 -dM -E %s | grep __cplusplus >%T-cpp-std.txt
+// RUN: %clang_cc1 -dM -E -x cuda %s | grep __cplusplus >%T-cuda-cuda.txt
+// RUN: %clang_cc1 -dM -E -x hip %s | grep __cplusplus >%T-hip-std.txt
+// RUN: diff %T-cpp-std.txt %T-cuda-cuda.txt
+// RUN: diff %T-cpp-std.txt %T-hip-std.txt
 
 // RUN: %clang_cc1 -dM -E -x cuda -std=c++14 %s | FileCheck --check-prefix=CXX14 %s
+// RUN: %clang_cc1 -dM -E -x cuda -std=c++17 %s | FileCheck --check-prefix=CXX17 %s
 // RUN: %clang_cc1 -dM -E -x hip -std=c++98 %s | FileCheck --check-prefix=CXX98 %s
 
 // CXX98: #define __cplusplus 199711L
 // CXX14: #define __cplusplus 201402L
 // CXX17: #define __cplusplus 201703L