Summary:
Truncating the result of a merge means that most likely we could have done without merge in the first place and just used the input merge inputs directly. This can be done in three cases:
1. If the truncation result is smaller than the merge source, we can use the source in the trunc directly
2. If the sizes are the same, we can replace the register or use a copy
3. If the truncation size is a multiple of the merge source size, we can build a smaller merge
This gets rid of most of the larger, hard-to-legalize merges.
Reviewers: qcolombet, aditya_nandakumar, aemerson, paquette, arsenm, Petar.Avramovic
Reviewed By: arsenm
Subscribers: sdardis, jvesely, wdng, nhaehnle, rovka, jrtc27, atanasyan, kerbowa, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75915
This was assuming the narrow target was the source type. Respect the
requested type when these don't match by using intermediate
merges. This avoids producing very wide, illegal shift expansions.
This is necessary for handling <3 x s16> on AMDGPU, assuming this
should be handled as 2 separate legalization actions. The alternative
would be for fewerElementsVector to handle 3->2.
llvm-svn: 369547
AMDGPU sometimes has legal s16 and <2 x s16> operations, but all
registers are really 32-bit. An unmerge destination really should ben
widened to a 32-bit register. If widening a scalarizing vector with a
target size that matches the vector size, bitcast to integer and
extract the relevant bits with shifts.
I'm not sure if this is the right place for this. This could arguably
be part of widenScalar for the result. I also have a growing feeling
that we're missing a bitcast legalize action.
llvm-svn: 367604
There are two main issues preventing us from generating immediate form shifts:
1) We have partial SelectionDAG imported support for G_ASHR and G_LSHR shift
immediate forms, but they currently don't work because the amount type is
expected to be an s64 constant, but we only legalize them to have homogenous
types.
To deal with this, first we introduce a custom legalizer to *only* custom legalize
s32 shifts which have a constant operand into a s64.
There is also an additional artifact combiner to fold zexts(g_constant) to a
larger G_CONSTANT if it's legal, a counterpart to the anyext version committed
in an earlier patch.
2) For G_SHL the importer can't cope with the pattern. For this I introduced an
early selection phase in the arm64 selector to select these forms manually
before the tablegen selector pessimizes it to a register-register variant.
Differential Revision: https://reviews.llvm.org/D63910
llvm-svn: 364994
There is a combine that was hiding these tests
not actually testing what they should be, although
they were producing the expected end result.
llvm-svn: 351698
As Roman Tereshin pointed out in https://reviews.llvm.org/D45541, the
-global-isel option is redundant when -run-pass is given. -global-isel sets up
the GlobalISel passes in the pass manager but -run-pass skips that entirely and
configures it's own pipeline.
llvm-svn: 331603
Matt Arsenault