We currently miss a number of opportunities to emit single-instruction
VMRG[LH][BHW] instructions for shuffles on little endian subtargets. Although
this in itself is not a huge performance opportunity since loading the permute
vector for a VPERM can always be pulled out of loops, producing such merge
instructions is useful to downstream optimizations.
Since VPERM is essentially opaque to all subsequent optimizations, we want to
avoid it as much as possible. Other permute instructions have semantics that can
be reasoned about much more easily in later optimizations.
This patch does the following:
- Canonicalize shuffles so that the first element comes from the first vector
(since that's what most of the mask matching functions want)
- Switch the elements that come from splat vectors so that they match the
corresponding elements from the other vector (to allow for merges)
- Adds debugging messages for when a shuffle is matched to a VPERM so that
anyone interested in improving this further can get the info for their code
Differential revision: https://reviews.llvm.org/D77448
There are a few patterns where we use a superclass for inputs to this
instruction rather than the correct class. This can sometimes lead to
unncessary copies.
If the arch is P8, we will select XFLOAD to load the floating point, and then, expand it to vsx and non-vsx X-form instruction post RA. This patch is trying to convert the X-form to D-form if it meets the requirement that one operand of the x-form inst is the special Zero register, and another operand fed by add inst. i.e.
y = add imm, reg
LFDX. 0, y
-->
LFD imm(reg)
Reviewers: Nemanjai
Differential Revision: https://reviews.llvm.org/D49007
llvm-svn: 340149
This patch aims to improve the codegen for vector loads involving the
scalar_to_vector (load X) sequence. Initially, ld->mv instructions were used
for scalar_to_vector (load X), so this patch allows scalar_to_vector (load X)
to utilize:
LXSD and LXSDX for i64 and f64
LXSIWAX for i32 (sign extension to i64)
LXSIWZX for i32 and f64
Committing on behalf of Amy Kwan.
Differential Revision: https://reviews.llvm.org/D48950
llvm-svn: 339260
