This is the logically correct thing to do. But it generates worse
code for i32 umin/umax on the rv64 due to type legalize requesting
zext even though the arguments are sext. Maybe we can teach type
legalizer to use sext for umin/umax for RISCV.
It's also producing possibly worse code on i64 on RV32 since we
still end up with selects that become branches. But this seems
like something we could improve in type legalization or DAG combine.
Hopefully this makes D92095 work for RISCV with Zbb.
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
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 base subset (zbb 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/D79870
Craig Topper