Use clmul for CRC32.#28511
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timothytrippel merged 1 commit intolowRISC:earlgrey_1.0.0from Oct 20, 2025
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The crc32 instructions are non-standard and not supported by upstream clang. According to perftest, this only slows things down by a few cycles before: I00003 crc32_perftest.c:33] CRC32 computed in 11343 cycles. I00004 crc32_perftest.c:33] CRC32 computed in 11317 cycles. I00005 crc32_perftest.c:33] CRC32 computed in 11314 cycles. I00006 crc32_perftest.c:33] CRC32 computed in 11314 cycles. I00007 crc32_perftest.c:33] CRC32 computed in 11314 cycles. I00008 crc32_perftest.c:33] CRC32 computed in 11314 cycles. I00009 crc32_perftest.c:33] CRC32 computed in 11314 cycles. I00010 crc32_perftest.c:33] CRC32 computed in 11314 cycles. I00011 crc32_perftest.c:33] CRC32 computed in 11314 cycles. I00012 crc32_perftest.c:33] CRC32 computed in 11314 cycles. after: I00003 crc32_perftest.c:33] CRC32 computed in 11358 cycles. I00004 crc32_perftest.c:33] CRC32 computed in 11319 cycles. I00005 crc32_perftest.c:33] CRC32 computed in 11318 cycles. I00006 crc32_perftest.c:33] CRC32 computed in 11318 cycles. I00007 crc32_perftest.c:33] CRC32 computed in 11318 cycles. I00008 crc32_perftest.c:33] CRC32 computed in 11318 cycles. I00009 crc32_perftest.c:33] CRC32 computed in 11318 cycles. I00010 crc32_perftest.c:33] CRC32 computed in 11318 cycles. I00011 crc32_perftest.c:33] CRC32 computed in 11318 cycles. Signed-off-by: Kor Nielsen <kor@google.com>
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Overall LGTM. See the inline comment about zbc.
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I tried that, but it broke the "[Verilated English Breakfast]" test cases; you must not be using that compiler flag everywhere. I will put it back and re-run the tests. |
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The crc32 instructions are non-standard and not supported by upstream clang.
According to perftest, this only slows things down by a few cycles