0caa8f42be
This change is inspired by a case in facerec benchmark, where performance of scalar code may improve by about 6%@aarch64 due to getting rid of redundant loads from Fortran descriptors. These descriptors are corresponding to subroutine local ALLOCATABLE, SAVE variables. The scalar loop nest in LocalMove subroutine contains call to Fortran runtime IO functions, and LLVM globals-aa analysis cannot prove that these calls do not modify the globalized descriptors with internal linkage. This patch sets and propagates llvm.memory_effects attribute for fir.call operations calling Fortran runtime functions. In particular, it tries to set the Other memory effect to NoModRef. The Other memory effect includes accesses to globals and captured pointers, so we cannot set it for functions taking Fortran descriptors with one exception for calls where the Fortran descriptor arguments are all null. As long as different calls to the same Fortran runtime function may have different attributes, I decided to attach the attributes to the calls rather than functions. Moreover, attaching the attributes to func.func will require propagating these attributes to llvm.func, which is not happening right now. In addition to llvm.memory_effects, the new pass sets llvm.nosync and llvm.nocallback attributes that may also help LLVM alias analysis (e.g. see #127707). These attributes are ignored currently. I will support them in LLVM IR dialect in a separate patch. I also added another pass for developers to be able to print declarations/calls of all Fortran runtime functions that are recognized by the attributes setting pass. It should help with maintenance of the LIT tests.
82 lines
2.6 KiB
Python
Executable File
82 lines
2.6 KiB
Python
Executable File
#!/usr/bin/env python3
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"""A script to generate FileCheck statements for Fortran runtime funcs.
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This script can be used to update
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flang/test/Transforms/verify-known-runtime-functions.fir
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whenever new recognized Fortran runtime functions are added
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into flang/Optimizer/Transforms/RuntimeFunctions.inc
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or any of the recognized functions changes its signature.
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"""
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# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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# See https://llvm.org/LICENSE.txt for license information.
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# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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import argparse
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import os
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import re
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import sys
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ADVERT_BEGIN = "// NOTE: Assertions have been autogenerated by "
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ADVERT_END = """
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// The script allows updating Flang LIT test
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// flang/test/Transforms/verify-known-runtime-functions.fir,
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// which is intended to verify signatures of Fortran runtime
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// functions recognized in flang/Optimizer/Transforms/RuntimeFunctions.inc
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// table. If new function is added into the table or
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// an existing function changes its signature,
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// the SetRuntimeCallAttributesPass may need to be updated
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// to properly handle it. Once the pass is verified to work,
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// one can update this test using the following output:
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// echo "module {}" | fir-opt --gen-runtime-calls-for-test | \\
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// generate-checks-for-runtime-funcs.py
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"""
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CHECK_RE_STR = "func.func.*@_Fortran.*"
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CHECK_RE = re.compile(CHECK_RE_STR)
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CHECK_NOT_STR = "// CHECK-NOT: func.func"
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CHECK_STR = "// CHECK:"
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CHECK_NEXT_STR = "// CHECK-NEXT:"
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def main():
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parser = argparse.ArgumentParser(
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description=__doc__, formatter_class=argparse.RawTextHelpFormatter
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)
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parser.add_argument(
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"input", nargs="?", type=argparse.FileType("r"), default=sys.stdin
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)
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args = parser.parse_args()
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input_lines = [l.rstrip() for l in args.input]
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args.input.close()
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repo_path = os.path.join(os.path.dirname(__file__), "..", "..", "..")
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script_name = os.path.relpath(__file__, repo_path)
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autogenerated_note = ADVERT_BEGIN + script_name + "\n" + ADVERT_END
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output = sys.stdout
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output.write(autogenerated_note + "\n")
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output_lines = []
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output_lines.append(CHECK_NOT_STR)
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check_prefix = CHECK_STR
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for input_line in input_lines:
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if not input_line:
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continue
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m = CHECK_RE.match(input_line.lstrip())
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if m:
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output_lines.append(check_prefix + " " + input_line.lstrip())
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check_prefix = CHECK_NEXT_STR
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output_lines.append(CHECK_NOT_STR)
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for line in output_lines:
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output.write(line + "\n")
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output.close()
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if __name__ == "__main__":
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main()
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