Also renamed Zbe instructions to resolve name conflict even though
that change is in the 0.94 draft.
Reviewed By: asb, frasercrmck
Differential Revision: https://reviews.llvm.org/D94653
This recommits 71ed4b6ce5 with
the polarity of some of the pattern corrected.
Original commit message:
The custom expansion of select operations in the RISC-V backend
interferes with the matching of cmov instructions. Legalizing
select when the Zbt extension is available solves that problem.
Reviewed By: luismarques, craig.topper
Differential Revision: https://reviews.llvm.org/D93767
The first parameter should be selected if the condition is true and
the last parameter if the condition is false. Prior to this change
it was the other way round which was confusing.
Differential Revision: https://reviews.llvm.org/D94729
The custom expansion of select operations in the RISC-V backend
interferes with the matching of cmov instructions. Legalizing
select when the Zbt extension is available solves that problem.
Reviewed By: lenary, craig.topper
Differential Revision: https://reviews.llvm.org/D93767
One or more cmov instructions could be generated for these functions
when the Zbt extension is present.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D93768
We can use these instructions for single bit immediates that are too large for ANDI/ORI/CLRI.
The _10 test cases are to make sure that we still use ANDI/ORI/CLRI for small immediates.
Differential Revision: https://reviews.llvm.org/D92262
The fshl and fshr intrinsics are defined to modulo their shift amount by the bitwidth of one of their inputs. The FSR/FSL instructions read one extra bit from the shift amount. If that bit is set the inputs are swapped. In order to preserve the semantics of the llvm intrinsics we need to make sure that the extra bit isn't set. DAG combine or instcombine may have removed any mask that was originally present.
We could be smarter here and try to use computeKnownBits to check if the bit is known zero, but wanted to start with correctness.
Differential Revision: https://reviews.llvm.org/D90905
There is no FSLI instruction, but we can emulate it using FSRI by swapping operands and subtracting the immediate from the bitwidth.
Differential Revision: https://reviews.llvm.org/D90826
fsl/fsr take their shift amount in $rs2 or an immediate. The
sources are $rs1 and $rs3.
fshl/fshr ISD opcodes both concatenate operand 0 in the high bits and
operand 1 in the lower bits. fshl returns the high bits after
shifting and fshr returns the low bits. So a shift amount of 0
returns operand 0 for fshl and operand 1 for fshr.
fsl/fsr concatenate their operands in different orders such that
$rs1 will be returned for a shift amount of 0. So $rs1 needs to
come from operand 0 of fshl and operand 1 of fshr.
Differential Revision: https://reviews.llvm.org/D90735
In SelectionDAGBuilder always translate the fshl and fshr intrinsics to
FSHL and FSHR (or ROTL and ROTR) instead of lowering them to shifts and
ORs. Improve the legalization of FSHL and FSHR to avoid code quality
regressions.
Differential Revision: https://reviews.llvm.org/D77152
This patch provides optimization of bit manipulation operations by
enabling the +experimental-b target feature.
It adds matching of single block patterns of instructions to specific
bit-manip instructions from the ternary subset (zbt subextension) of the
experimental B extension of RISC-V.
It adds also the correspondent codegen tests.
This patch is based on Claire Wolf's proposal for the bit manipulation
extension of RISCV:
https://github.com/riscv/riscv-bitmanip/blob/master/bitmanip-0.92.pdf
Differential Revision: https://reviews.llvm.org/D79875
Craig Topper