An extension of D19978, this patch replaces the default BITREVERSE evaluation of individual bit masks+shifts with block mask+shifts when we have integer elements of power-of-2 bits in size.
After calling BSWAP to reverse the order of the constituent bytes (which typically follows a similar approach), every neighbouring 4-bits, 2-bits and finally 1-bit pairs are masked off and swapped over with shifts.
In doing so we can significantly reduce the number of operations required.
Differential Revision: https://reviews.llvm.org/D21578
llvm-svn: 276432
In bidirectional scheduling this gives more stable results than just
comparing the "reason" fields of the top/bottom node because the reason
field may be higher depending on what other nodes are in the queue.
Differential Revision: http://reviews.llvm.org/D19401
llvm-svn: 273755
Most immediates are printed in Aarch64InstPrinter using 'formatImm' macro,
but not all of them.
Implementation contains following rules:
- floating point immediates are always printed as decimal
- signed integer immediates are printed depends on flag settings
(for negative values 'formatImm' macro prints the value as i.e -0x01
which may be convenient when imm is an address or offset)
- logical immediates are always printed as hex
- the 64-bit immediate for advSIMD, encoded in "a🅱️c:d:e:f:g:h" is always printed as hex
- the 64-bit immedaite in exception generation instructions like:
brk, dcps1, dcps2, dcps3, hlt, hvc, smc, svc is always printed as hex
- the rest of immediates is printed depends on availability
of -print-imm-hex
Signed-off-by: Maciej Gabka <maciej.gabka@arm.com>
Signed-off-by: Paul Osmialowski <pawel.osmialowski@arm.com>
Differential Revision: http://reviews.llvm.org/D16929
llvm-svn: 269446
For BITREVERSE, bit shifting/masking every bit in a vector element is a very lengthy procedure.
If the input vector type is a whole multiple of bytes wide then we can split this into a BSWAP shuffle stage (to reverse at the byte level) and then a BITREVERSE stage applied to each byte. Most vector capable targets can efficiently BSWAP using shuffles resulting in a considerable reduction in instructions.
With this patch targets would only need to implement a target specific vXi8 BITREVERSE implementation to efficiently reverse most legal vector types.
Differential Revision: http://reviews.llvm.org/D19978
llvm-svn: 269290
Something I missed from Hal's review, rightly pointed out by Ben Kramer - we should make sure the expansion is properly checked as it can be easy for bugs to creep in.
I've checked the scalar i8 expansion here and the vector i8 expansion in a previous commit.
llvm-svn: 253024
Richard Trieu noted that UBSan detected an overflowing shift, and the obvious fix caused a crash.
What was happening was that the shiftee (1U) was indeed too small for the possible range of shifts it had to handle, but also we were using "VT.getSizeInBits()" to get the maximum type bitwidth, but we wanted "VT.getScalarSizeInBits()" to get the vector lane size instead of the entire vector size.
Use an APInt for the shift and VT.getScalarSizeInBits().
llvm-svn: 253023
Several backends have instructions to reverse the order of bits in an integer. Conceptually matching such patterns is similar to @llvm.bswap, and it was mentioned in http://reviews.llvm.org/D14234 that it would be best if these patterns were matched in InstCombine instead of reimplemented in every different target.
This patch introduces an intrinsic @llvm.bitreverse.i* that operates similarly to @llvm.bswap. For plumbing purposes there is also a new ISD node ISD::BITREVERSE, with simple expansion and promotion support.
The intention is that InstCombine's BSWAP detection logic will be extended to support BITREVERSE too, and @llvm.bitreverse intrinsics emitted (if the backend supports lowering it efficiently).
llvm-svn: 252878
Chad Rosier