Revert #5609

.gitignore

@@ -5,10 +5,6 @@ bin
 build
 .lintbin
 
-# Project-local LLVM installation (created by following prerequisite validation instructions)
-.llvm/
-llvm.sh
-
 nvfuser_common/version.py
 nvfuser_common/include
 nvfuser_comon/lib

CMakeLists.txt

@@ -41,13 +41,6 @@ endif()
 
 message(STATUS "Setting NVFUSER_DISTRIBUTED=${NVFUSER_DISTRIBUTED}")
 
-# NCCL include directory for distributed builds
-# This can be set by the Python build system when using pip-bundled NCCL
-set(NCCL_INCLUDE_DIR "" CACHE PATH "Directory containing nccl.h header")
-if(NVFUSER_DISTRIBUTED AND NCCL_INCLUDE_DIR)
-  message(STATUS "Using NCCL include dir: ${NCCL_INCLUDE_DIR}")
-endif()
-
 # We try to update which C++ standard we use together in lockstep across all
 # built libraries, and these variables control which that is. Generally we are
 # on C++20, but we still support a version of CUDA (11) that does not recognize
@@ -443,29 +436,6 @@ list(APPEND NVFUSER_SRCS
 
 # Add LLVM JIT related dependencies
 set(LLVM_MINIMUM_VERSION "18.1")
-
-# Check for project-local LLVM installations first (no sudo required)
-# This searches .llvm/ directory for version-specific installations
-if(NOT LLVM_DIR)
-  file(GLOB LLVM_CANDIDATES
-    "${CMAKE_SOURCE_DIR}/.llvm/*/lib/cmake/llvm"
-    "${CMAKE_SOURCE_DIR}/third_party/llvm/*/lib/cmake/llvm"
-  )
-  # Sort to get highest version first (assumes version numbers in paths)
-  list(SORT LLVM_CANDIDATES COMPARE NATURAL ORDER DESCENDING)
-  foreach(CANDIDATE ${LLVM_CANDIDATES})
-    if(EXISTS "${CANDIDATE}/LLVMConfig.cmake")
-      # Extract version from path to check if it meets minimum
-      string(REGEX MATCH "([0-9]+\\.[0-9]+\\.[0-9]+)" CANDIDATE_VERSION "${CANDIDATE}")
-      if(CANDIDATE_VERSION VERSION_GREATER_EQUAL LLVM_MINIMUM_VERSION)
-        set(LLVM_DIR "${CANDIDATE}" CACHE PATH "Path to LLVM CMake config")
-        message(STATUS "Found project-local LLVM ${CANDIDATE_VERSION} at ${LLVM_DIR}")
-        break()
-      endif()
-    endif()
-  endforeach()
-endif()
-
 find_package(LLVM REQUIRED CONFIG)
 if(${LLVM_VERSION} VERSION_LESS ${LLVM_MINIMUM_VERSION})
   message(FATAL_ERROR "LLVM ${LLVM_VERSION} does not meet the minimum version required: ${LLVM_MINIMUM_VERSION}")
@@ -558,10 +528,6 @@ target_include_directories(codegen_internal SYSTEM PUBLIC
   PRIVATE
   ${CUDA_INCLUDE_DIRS}
 )
-# Add NCCL include path for distributed builds (from pip-bundled nvidia-nccl-cu*)
-if(NVFUSER_DISTRIBUTED AND NCCL_INCLUDE_DIR)
-  target_include_directories(codegen_internal SYSTEM PRIVATE ${NCCL_INCLUDE_DIR})
-endif()
 target_include_directories(codegen_internal PUBLIC
   "$<BUILD_INTERFACE:${NVFUSER_SRCS_DIR}>"
   "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/nvfuser>"

README.md

@@ -55,33 +55,20 @@ pip install -r python/requirements.txt
 pip install --no-build-isolation -e python -v
 ```
 
-### Prerequisite Validation
-
-Prerequisites are automatically validated before building. If validation fails, follow the error message instructions.
-
-**Validated**: Python, CMake, Ninja, pybind11, PyTorch (CUDA), System CUDA toolkit, Git submodules, GCC, LLVM
-
-**Skip validation** (for CI or custom setups):
-```bash
-NVFUSER_BUILD_SKIP_VALIDATION=1 pip install --no-build-isolation -e python -v
-```
-
-See `python/setup.py` for all build environment variables.
-
 Supported compilers:
 
 **GCC:**
 
-GCC 13+ is required (C++20 `<format>` header support). Recommended versions:
+We support all "supported releases" of gcc as specified in [the official site](https://gcc.gnu.org/).
+As of 3/2/2025, they are:
 
+- gcc 12.4
 - gcc 13.3
 - gcc 14.2
 
-Note: GCC 12 is not supported due to missing `<format>` header in libstdc++.
-
 **Clang:**
 
-- clang 19+
+- clang 16+
 
 Supported C++ standard:
 

python/pyproject.toml

@@ -1,3 +1,3 @@
 [build-system]
-requires = ["setuptools>=42", "wheel", "ninja", "cmake>=3.18", "pybind11[global]>=2.0"]
+requires = ["setuptools>=42", "wheel", "ninja", "cmake>=3.18"]
 build-backend = "setuptools.build_meta:__legacy__"

python/setup.py

@@ -66,12 +66,7 @@
 #   NVFUSER_BUILD_CPP_STANDARD=STANDARD
 #     Specify the C++ standard to use for building nvfuser. The default is C++20.
 #
-#   NVFUSER_BUILD_SKIP_VALIDATION
-#     Skip prerequisite validation checks. Use this for CI or when you know
-#     all prerequisites are satisfied. Validation will still run if not set.
-#
 
-import os
 import sys
 
 from utils import (
@@ -101,24 +96,6 @@ def main():
     # Override build config from environment variables
     override_build_config_from_env(config)
 
-    # Prerequisite validation (can be skipped with NVFUSER_BUILD_SKIP_VALIDATION)
-    if not os.environ.get("NVFUSER_BUILD_SKIP_VALIDATION"):
-        try:
-            from tools.prereqs import validate_prerequisites
-
-            validate_prerequisites()
-        except ImportError as e:
-            # Prerequisite validation not available (shouldn't happen in dev)
-            print(f"WARNING: Could not import prerequisite validation: {e}")
-        except Exception as e:
-            # Prerequisite check failed
-            print(f"\n{e}\n", file=sys.stderr)
-            sys.exit(1)
-    else:
-        print(
-            "[nvFuser] Skipping prerequisite validation (NVFUSER_BUILD_SKIP_VALIDATION set)"
-        )
-
     if "clean" in sys.argv:
         # only disables BUILD_SETUP, but keep the argument for setuptools
         config.build_setup = False