[libcu++] Replace cudaStreamPerThread with cudaStream{} in PSTL

[davebayer]

Fixes #9213.

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between 9a8f7f6 and 99ac5ff.

📒 Files selected for processing (7)

• libcudacxx/include/cuda/std/__pstl/cuda/shift_left.h
• libcudacxx/include/cuda/std/__pstl/cuda/shift_right.h
• libcudacxx/include/cuda/std/__pstl/cuda/sort.h
• libcudacxx/include/cuda/std/__pstl/cuda/stable_partition.h
• libcudacxx/include/cuda/std/__pstl/cuda/temporary_storage.h
• libcudacxx/test/libcudacxx/cuda/execution/execution_policy/get_memory_resource.pass.cpp
• libcudacxx/test/libcudacxx/cuda/execution/execution_policy/get_stream.pass.cpp

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📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes
  • Fixed CUDA stream handling in parallel algorithms (sort, shift, and partition operations) to properly acquire default execution streams instead of using deprecated stream settings.
  • Updated corresponding test expectations to reflect corrected stream behavior.

Walkthrough

This PR updates CUDA PSTL algorithm backends to use a default-initialized null stream (::cudaStream_t{}) as the fallback stream reference instead of the per-thread stream (cudaStreamPerThread). The change applies consistently across shift_left, shift_right, sort, stable_partition implementations and temporary storage, with corresponding test updates to validate the new behavior.

Changes

Stream fallback unification

Layer / File(s)	Summary
Algorithm stream fallback updates libcudacxx/include/cuda/std/__pstl/cuda/shift_left.h, shift_right.h, sort.h, stable_partition.h, temporary_storage.h	shift_left, shift_right, sort (radix and merge paths), stable_partition, and temporary_storage all replace ::cuda::stream_ref{cudaStreamPerThread} with ::cuda::stream_ref{::cudaStream_t{}} as the fallback stream reference passed to __call_or(::cuda::get_stream, ...).
Test updates for stream fallback libcudacxx/test/libcudacxx/cuda/execution/execution_policy/get_stream.pass.cpp, get_memory_resource.pass.cpp	Test baseline expectations and assertions for ::cuda::get_stream are updated to use the new cuda::stream_ref{::cudaStream_t{}} reference, and get_memory_resource.pass.cpp adds a stream check after resource overwrite.

Assessment against linked issues

Objective	Addressed	Explanation
Unify PSTL algorithm stream fallback behavior [#9213]	✅

Suggested reviewers

• pciolkosz
• ericniebler

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 Infer (1.2.0)

libcudacxx/test/libcudacxx/cuda/execution/execution_policy/get_memory_resource.pass.cpp

libcudacxx/test/libcudacxx/cuda/execution/execution_policy/get_memory_resource.pass.cpp:17:10: fatal error: 'cuda/functional' file not found
17 | #include <cuda/functional>
| ^~~~~~~~~~~~~~~~~
1 error generated.
Error: the following clang command did not run successfully:
/opt/infer-linux-x86_64-v1.2.0/lib/infer/facebook-clang-plugins/clang/install/bin/clang-18
@/tmp/coderabbit-infer/99ac5ffcbfbf1b032774007601fba90593699d39-592ecba06aa173d3/tmp/clang_command_.tmp.115228.txt
++Contents of '/tmp/coderabbit-infer/99ac5ffcbfbf1b032774007601fba90593699d39-592ecba06aa173d3/tmp/clang_command_.tmp.115228.txt':
"-cc1" "-load"
"/opt/infer-linux-x86_64-v1.2.0/lib/infer/infer/bin/../../facebook-clang-plugins/libtooling/build/FacebookClangPlugin.dylib"
"-add-plugin" "BiniouASTExporter" "-plugin-arg-BiniouASTExporter" "-"
"-plugin-arg-BiniouASTExporter" "PREPEND_CURRENT_DIR=1"
"-plugin-arg-BiniouASTExporter" "MAX_STRING_SIZE=65535" "-cc1" "-triple"

... [truncated 1214 characters] ...

l/include" "-internal-isystem"
"/usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include"
"-internal-externc-isystem" "/usr/include/x86_64-linux-gnu"
"-internal-externc-isystem" "/include" "-internal-externc-isystem"
"/usr/include" "-Wno-ignored-optimization-argument" "-Wno-everything"
"-fdeprecated-macro" "-ferror-limit" "19" "-fgnuc-version=4.2.1"
"-fskip-odr-check-in-gmf" "-fcxx-exceptions" "-fexceptions"
"-D__GCC_HAVE_DWARF2_CFI_ASM=1" "-o"
"/tmp/coderabbit-infer/592ecba06aa173d3/file.o" "-x" "c++"
"libcudacxx/test/libcudacxx/cuda/execution/execution_policy/get_memory_resource.pass.cpp"
"-O0" "-fno-builtin" "-include"
"/opt/infer-linux-x86_64-v1.2.0/lib/infer/infer/bin/../lib/clang_wrappers/global_defines.h"
"-Wno-everything"

libcudacxx/test/libcudacxx/cuda/execution/execution_policy/get_stream.pass.cpp

libcudacxx/test/libcudacxx/cuda/execution/execution_policy/get_stream.pass.cpp:17:10: fatal error: 'cuda/functional' file not found
17 | #include <cuda/functional>
| ^~~~~~~~~~~~~~~~~
1 error generated.
Error: the following clang command did not run successfully:
/opt/infer-linux-x86_64-v1.2.0/lib/infer/facebook-clang-plugins/clang/install/bin/clang-18
@/tmp/coderabbit-infer/99ac5ffcbfbf1b032774007601fba90593699d39-dcd2ecffd9fe1481/tmp/clang_command_.tmp.c583a6.txt
++Contents of '/tmp/coderabbit-infer/99ac5ffcbfbf1b032774007601fba90593699d39-dcd2ecffd9fe1481/tmp/clang_command_.tmp.c583a6.txt':
"-cc1" "-load"
"/opt/infer-linux-x86_64-v1.2.0/lib/infer/infer/bin/../../facebook-clang-plugins/libtooling/build/FacebookClangPlugin.dylib"
"-add-plugin" "BiniouASTExporter" "-plugin-arg-BiniouASTExporter" "-"
"-plugin-arg-BiniouASTExporter" "PREPEND_CURRENT_DIR=1"
"-plugin-arg-BiniouASTExporter" "MAX_STRING_SIZE=65535" "-cc1" "-triple"
"x86_64-

... [truncated 1187 characters] ...

/usr/local/include" "-internal-isystem"
"/usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include"
"-internal-externc-isystem" "/usr/include/x86_64-linux-gnu"
"-internal-externc-isystem" "/include" "-internal-externc-isystem"
"/usr/include" "-Wno-ignored-optimization-argument" "-Wno-everything"
"-fdeprecated-macro" "-ferror-limit" "19" "-fgnuc-version=4.2.1"
"-fskip-odr-check-in-gmf" "-fcxx-exceptions" "-fexceptions"
"-D__GCC_HAVE_DWARF2_CFI_ASM=1" "-o"
"/tmp/coderabbit-infer/dcd2ecffd9fe1481/file.o" "-x" "c++"
"libcudacxx/test/libcudacxx/cuda/execution/execution_policy/get_stream.pass.cpp"
"-O0" "-fno-builtin" "-include"
"/opt/infer-linux-x86_64-v1.2.0/lib/infer/infer/bin/../lib/clang_wrappers/global_defines.h"
"-Wno-everything"

---

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[github-actions]

Successfully created backport PR for branch/3.4.x:

• [Backport branch/3.4.x] [libcu++] Replace cudaStreamPerThread with cudaStream{} in PSTL #9217