Commit Graph

9 Commits

Author SHA1 Message Date
Matt Arsenault caf1316f71 IR: Add immarg attribute
This indicates an intrinsic parameter is required to be a constant,
and should not be replaced with a non-constant value.

Add the attribute to all AMDGPU and generic intrinsics that comments
indicate it should apply to. I scanned other target intrinsics, but I
don't see any obvious comments indicating which arguments are intended
to be only immediates.

This breaks one questionable testcase for the autoupgrade. I'm unclear
on whether the autoupgrade is supposed to really handle declarations
which were never valid. The verifier fails because the attributes now
refer to a parameter past the end of the argument list.

llvm-svn: 355981
2019-03-12 21:02:54 +00:00
Alexander Timofeev db7ee7660a [AMDGPU] Preliminary patch for divergence driven instruction selection. Immediate selection predicate changed
Differential revision: https://reviews.llvm.org/D51734
Reviewers: rampitec

llvm-svn: 341928
2018-09-11 11:56:50 +00:00
Matt Arsenault 8c4a35237a AMDGPU: Add pass to lower kernel arguments to loads
This replaces most argument uses with loads, but for
now not all.

The code in SelectionDAG for calling convention lowering
is actively harmful for amdgpu_kernel. It attempts to
split the argument types into register legal types, which
results in low quality code for arbitary types. Since
all kernel arguments are passed in memory, we just want the
raw types.

I've tried a couple of methods of mitigating this in SelectionDAG,
but it's easier to just bypass this problem alltogether. It's
possible to hack around the problem in the initial lowering,
but the real problem is the DAG then expects to be able to use
CopyToReg/CopyFromReg for uses of the arguments outside the block.

Exposing the argument loads in the IR also has the advantage
that the LoadStoreVectorizer can merge them.

I'm not sure the best approach to dealing with the IR
argument list is. The patch as-is just leaves the IR arguments
in place, so all the existing code will still compute the same
kernarg size and pointlessly lowers the arguments.

Arguably the frontend should emit kernels with an empty argument
list in the first place. Alternatively a dummy array could be
inserted as a single argument just to reserve space.

This does have some disadvantages. Local pointer kernel arguments can
no longer have AssertZext placed  on them as the equivalent !range
metadata is not valid on pointer  typed loads. This is mostly bad
for SI which needs to know about the known bits in order to use the
DS instruction offset, so in this case this is not done.

More importantly, this skips noalias arguments since this pass
does not yet convert this to the equivalent !alias.scope and !noalias
metadata. Producing this metadata correctly seems to be tricky,
although this logically is the same as inlining into a function which
doesn't exist. Additionally, exposing these loads to the vectorizer
may result in degraded aliasing information if a pointer load is
merged with another argument load.

I'm also not entirely sure this is preserving the current clover
ABI, although I would greatly prefer if it would stop widening
arguments and match the HSA ABI. As-is I think it is extending
< 4-byte arguments to 4-bytes but doesn't align them to 4-bytes.

llvm-svn: 335650
2018-06-26 19:10:00 +00:00
Matt Arsenault 206f826348 AMDGPU: Fix handling of div_scale with undef inputs
The src0 register must match src1 or src2, but if these
were undefined they could end up using different implicit_defed
virtual registers. Force these to use one undef vreg or pick the
defined other register.

Also fixes producing invalid nodes without the right number of
inputs when src2 is undef.

llvm-svn: 309743
2017-08-01 20:49:41 +00:00
Matt Arsenault 3dbeefa978 AMDGPU: Mark all unspecified CC functions in tests as amdgpu_kernel
Currently the default C calling convention functions are treated
the same as compute kernels. Make this explicit so the default
calling convention can be changed to a non-kernel.

Converted with perl -pi -e 's/define void/define amdgpu_kernel void/'
on the relevant test directories (and undoing in one place that actually
wanted a non-kernel).

llvm-svn: 298444
2017-03-21 21:39:51 +00:00
Matt Arsenault 3b99f12a4e AMDGPU: Remove modifiers from v_div_scale_*
They seem to produce nonsense results when used.

This should be applied to the release branch.

llvm-svn: 292472
2017-01-19 06:04:12 +00:00
Matt Arsenault 44e5483ada AMDGPU: Add volatile to test loads and stores
When the memory vectorizer is enabled, these tests break.
These tests don't really care about the memory instructions,
and it's easier to write check lines with the unmerged loads.

llvm-svn: 266071
2016-04-12 13:38:18 +00:00
Matt Arsenault 9c47dd583a AMDGPU: Remove some old intrinsic uses from tests
llvm-svn: 260493
2016-02-11 06:02:01 +00:00
Matt Arsenault bef34e21c7 AMDGPU: Rename intrinsics to use amdgcn prefix
The intrinsic target prefix should match the target name
as it appears in the triple.

This is not yet complete, but gets most of the important ones.
llvm.AMDGPU.* intrinsics used by mesa and libclc are still handled
for compatability for now.

llvm-svn: 258557
2016-01-22 21:30:34 +00:00