This adds a special operand type that is allowed to be either
an immediate or register. By giving it a unique operand type the
machine verifier will ignore it.
This perturbs a lot of tests but mostly it is just slightly different
instruction orders. Something bad did happen to some min/max reduction
tests. We're spilling vector registers when we weren't before.
Reviewed By: khchen
Differential Revision: https://reviews.llvm.org/D101246
This modifies my previous patch to push the strided load formation
to isel. This gives us opportunity to fold the splat into a .vx
operation first. Using a scalar register and a .vx operation reduces
vector register pressure which can be important for larger LMULs.
If we can't fold the splat into a .vx operation, then it can make
sense to use a strided load to free up the vector arithmetic
ALU to do actual arithmetic rather than tying it up with vmv.v.x.
Reviewed By: khchen
Differential Revision: https://reviews.llvm.org/D101138
This patch extends the lowering of RVV fixed-length vector shuffles to
avoid the default stack expansion and instead lower to vrgather
instructions.
For "permute"-style shuffles where one vector is swizzled, we can lower
to one vrgather. For shuffles involving two vector operands, we lower to
one unmasked vrgather (or splat, where appropriate) followed by a masked
vrgather which blends in the second half.
On occasion, when it's not possible to create a legal BUILD_VECTOR for
the indices, we use vrgatherei16 instructions with 16-bit index types.
For 8-bit element vectors where we may have indices over 255, we have a
fairly blunt fallback to the stack expansion to avoid custom-splitting
of the vector types.
To enable the selection of masked vrgather instructions, this patch
extends the various RISCVISD::VRGATHER nodes to take a passthru operand.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D100549
This patch adds a small optimization for vector shuffle lowering,
detecting shuffles which can be re-expressed as vector selects.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D99270
Craig Topper