2 Commits

Author	SHA1	Message	Date
Kang Zhang	86e3abc9e6	[PowerPC] Add some InstAlias definitions ... Summary: This patch add the InstAlias definitions for below instructions. ADDI ADDIS ADDI8 ADDIS8 RLWINM8 ISEL ISEL8 OR OR_rec ORI ORI8 XORI8 CNTLZW8 CNTLZW8_rec TEND TSR RFEBB NOR NOR_rec MTCRF SUBF SUBF_rec SUBFC SUBFC_rec RLDICL_32_64 TW Reviewed By: steven.zhang Differential Revision: https://reviews.llvm.org/D77559	2020-05-24 14:05:28 +00:00
Zi Xuan Wu	1445b77e8c	[PowerPC] Strength reduction of multiply by a constant by shift and add/sub in place ... A shift and add/sub sequence combination is faster in place of a multiply by constant. Because the cycle or latency of multiply is not huge, we only consider such following worthy patterns. ``` (mul x, 2^N + 1) => (add (shl x, N), x) (mul x, -(2^N + 1)) => -(add (shl x, N), x) (mul x, 2^N - 1) => (sub (shl x, N), x) (mul x, -(2^N - 1)) => (sub x, (shl x, N)) ``` And the cycles or latency is subtarget-dependent so that we need consider the subtarget to determine to do or not do such transformation. Also data type is considered for different cycles or latency to do multiply. Differential Revision: https://reviews.llvm.org/D58950 llvm-svn: 357233	2019-03-29 03:08:39 +00:00