3 Commits

Author	SHA1	Message	Date
Noah Goldstein	4fcfff4f2d	Use analyzeKnownBitsFromAndXorOr in SimplifyDemandedUseBits for and/xor/or ... There are extra patterns that have for these three logic operations that aren't covered in `SimplifyDemandedUseBits`. To avoid duplicating the code, just use `analyzeKnownBitsFromAndXorOr` in `SimplifyDemandedUseBits` to get full coverage. Reviewed By: nikic Differential Revision: https://reviews.llvm.org/D142429	2023-02-23 19:52:17 -06:00
Noah Goldstein	9a8f517f57	[ValueTracking] Add KnownBits patterns xor(x, x - 1) and and(x, -x) for knowing upper bits to be zero ... These two BMI pattern will clear the upper bits of result past the first set bit. So if we know a single bit in `x` is set, we know that `results[bitwidth - 1, log2(x) + 1] = 0`. Alive2: blsmsk: https://alive2.llvm.org/ce/z/a397BS blsi: https://alive2.llvm.org/ce/z/tsbQhC Differential Revision: https://reviews.llvm.org/D142271	2023-02-18 13:31:17 -06:00
Noah Goldstein	c8fb2775ce	[ValueTracking] Add tests for known bits after common BMI pattern (blsmsk/blsi); NFC ... Differential Revision: https://reviews.llvm.org/D142270	2023-02-18 13:31:12 -06:00