From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 7905) id 3D1923874152; Tue, 13 Dec 2022 13:18:33 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 3D1923874152 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1670937513; bh=OEeXigR+yNPPHCRjpG2n0RhEzBz11wkrIXYR3x4IgjE=; h=From:To:Subject:Date:From; b=A7X94PywCK0xXrB6Qo4BJl2BiYeQ+Wr9EwqFQE9D2Gsw6fgaQXcae3GGhwdIsjo/p BOnAWQn0tSjllphHVqNdc8e4olgy4aHcCODJd0RpA4FQv9oRVLhSeJrePGlTamrQYG FwDqmzNQgZMRHd9lA4uB7FPjES/oBOGmLB48jc8s= MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Arthur Cohen To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-4651] gccrs: Add port of FNV hash used during legacy symbol mangling X-Act-Checkin: gcc X-Git-Author: Philip Herron X-Git-Refname: refs/heads/master X-Git-Oldrev: b32b1b1576a6df965cb3fcbed3780b9f045286b2 X-Git-Newrev: c7f8347e83caf8a66fb71e411415ae869c6e6a5c Message-Id: <20221213131833.3D1923874152@sourceware.org> Date: Tue, 13 Dec 2022 13:18:33 +0000 (GMT) List-Id: https://gcc.gnu.org/g:c7f8347e83caf8a66fb71e411415ae869c6e6a5c commit r13-4651-gc7f8347e83caf8a66fb71e411415ae869c6e6a5c Author: Philip Herron Date: Tue Aug 23 16:22:47 2022 +0100 gccrs: Add port of FNV hash used during legacy symbol mangling This hash was ported from the Go runtime, as we needed a hash for the legacy symbol mangling system. All symbols in Rust contain a hash of some metadata for uniqueness on generic functions. gcc/rust/ * util/fnv-hash.h: New. Diff: --- gcc/rust/util/fnv-hash.h | 95 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 95 insertions(+) diff --git a/gcc/rust/util/fnv-hash.h b/gcc/rust/util/fnv-hash.h new file mode 100644 index 00000000000..78e54c99411 --- /dev/null +++ b/gcc/rust/util/fnv-hash.h @@ -0,0 +1,95 @@ +// Copyright (C) 2020-2022 Free Software Foundation, Inc. + +// This file is part of GCC. + +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. + +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. + +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +#ifndef RUST_FNV_HASH_H +#define RUST_FNV_HASH_H + +namespace Rust { +namespace Hash { + +const uint64_t offset128Lower = 0x62b821756295c58d; +const uint64_t offset128Higher = 0x6c62272e07bb0142; +const uint64_t prime128Lower = 0x13b; +const uint64_t prime128Shift = 24; + +// ported from https://github.com/golang/go/blob/master/src/hash/fnv/fnv.go +class FNV128 +{ +public: + FNV128 () { reset (); } + + void reset () + { + buf[0] = offset128Higher; + buf[1] = offset128Lower; + } + + void write (const unsigned char *in, size_t len) + { + for (size_t i = 0; i < len; i++) + { + unsigned char c = in[i]; + + // https://stackoverflow.com/questions/28868367/getting-the-high-part-of-64-bit-integer-multiplication + uint64_t a = prime128Lower; + uint64_t b = buf[1]; + + uint64_t a_lo = (uint32_t) a; + uint64_t a_hi = a >> 32; + uint64_t b_lo = (uint32_t) b; + uint64_t b_hi = b >> 32; + + uint64_t a_x_b_hi = a_hi * b_hi; + uint64_t a_x_b_mid = a_hi * b_lo; + uint64_t b_x_a_mid = b_hi * a_lo; + uint64_t a_x_b_lo = a_lo * b_lo; + + uint64_t carry_bit + = ((uint64_t) (uint32_t) a_x_b_mid + (uint64_t) (uint32_t) b_x_a_mid + + (a_x_b_lo >> 32)) + >> 32; + + uint64_t multhi + = a_x_b_hi + (a_x_b_mid >> 32) + (b_x_a_mid >> 32) + carry_bit; + + uint64_t s0 = multhi; // high + uint64_t s1 = prime128Lower * buf[1]; // low + + s0 += buf[1] << (prime128Shift + prime128Lower * buf[0]); + + // Update the values + buf[1] = s1; + buf[0] = s0; + buf[1] ^= (uint64_t) c; + } + } + + void sum (uint64_t *hi, uint64_t *lo) const + { + *hi = buf[0]; + *lo = buf[1]; + } + +private: + uint64_t buf[2]; +}; + +} // namespace Hash +} // namespace Rust + +#endif // RUST_FNV_HASH_H