Currently the return address ABI registers s[30:31], which fall in the call
clobbered register range, are added as a live-in on the function entry to
preserve its value when we have calls so that it gets saved and restored
around the calls.
But the DWARF unwind information (CFI) needs to track where the return address
resides in a frame and the above approach makes it difficult to track the
return address when the CFI information is emitted during the frame lowering,
due to the involvment of understanding the control flow.
This patch moves the return address ABI registers s[30:31] into callee saved
registers range and stops adding live-in for return address registers, so that
the CFI machinery will know where the return address resides when CSR
save/restore happen during the frame lowering.
And doing the above poses an issue that now the return instruction uses undefined
register `sgpr30_sgpr31`. This is resolved by hiding the return address register
use by the return instruction through the `SI_RETURN` pseudo instruction, which
doesn't take any input operands, until the `SI_RETURN` pseudo gets lowered to the
`S_SETPC_B64_return` during the `expandPostRAPseudo()`.
As an added benefit, this patch simplifies overall return instruction handling.
Note: The AMDGPU CFI changes are there only in the downstream code and another
version of this patch will be posted for review for the downstream code.
Reviewed By: arsenm, ronlieb
Differential Revision: https://reviews.llvm.org/D114652
Currently the return address ABI registers s[30:31], which fall in the call
clobbered register range, are added as a live-in on the function entry to
preserve its value when we have calls so that it gets saved and restored
around the calls.
But the DWARF unwind information (CFI) needs to track where the return address
resides in a frame and the above approach makes it difficult to track the
return address when the CFI information is emitted during the frame lowering,
due to the involvment of understanding the control flow.
This patch moves the return address ABI registers s[30:31] into callee saved
registers range and stops adding live-in for return address registers, so that
the CFI machinery will know where the return address resides when CSR
save/restore happen during the frame lowering.
And doing the above poses an issue that now the return instruction uses undefined
register `sgpr30_sgpr31`. This is resolved by hiding the return address register
use by the return instruction through the `SI_RETURN` pseudo instruction, which
doesn't take any input operands, until the `SI_RETURN` pseudo gets lowered to the
`S_SETPC_B64_return` during the `expandPostRAPseudo()`.
As an added benefit, this patch simplifies overall return instruction handling.
Note: The AMDGPU CFI changes are there only in the downstream code and another
version of this patch will be posted for review for the downstream code.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D114652
This patch changes the AMDGPU_Gfx calling convention. It defines the SGPR registers s[4:29] as callee-save and leaves some SGPRs usable for callers. The intention is to avoid unneccessary s_mov instructions for arguments the caller would otherwise save and restore in these registers.
Reviewed By: sebastian-ne
Differential Revision: https://reviews.llvm.org/D111637
This makes them consistent with all the other return convention
handling. If we don't do this, we lose the sext/zext flag if treated
as a full assignment, which complicates a future GlobalISel patch.
Returning in memory is not supported, so fall back to sret.
Also, extend i1 and i16 to i32. Otherwise, they would be passed through
memory.
Differential Revision: https://reviews.llvm.org/D100543
The generated calling convention code shouldn't see these types since
we split large types into 32-bit chunks before the calling convention
code is triggered.
GlobalISel ends up directly calls the generated CC code before
checking for the register count breakdown. Arguably this difference is
a bug, but this was dead code for the DAG anyway.
Add a calling convention called amdgpu_gfx for real function calls
within graphics shaders. For the moment, this uses the same calling
convention as other calls in amdgpu, with registers excluded for return
address, stack pointer and stack buffer descriptor.
Differential Revision: https://reviews.llvm.org/D88540
The AMDGPU target has a convention that defined all VGPRs
(execept the initial 32 argument registers) as callee-saved.
This convention is not efficient always, esp. when the callee
requiring more registers, ended up emitting a large number of
spills, even though its caller requires only a few.
This patch revises the ABI by introducing more scratch registers
that a callee can freely use.
The 256 vgpr registers now become:
32 argument registers
112 scratch registers and
112 callee saved registers.
The scratch registers and the CSRs are intermixed at regular
intervals (a split boundary of 8) to obtain a better occupancy.
Reviewers: arsenm, t-tye, rampitec, b-sumner, mjbedy, tpr
Reviewed By: arsenm, t-tye
Differential Revision: https://reviews.llvm.org/D76356
This reduces the number of SGPRs due to some concerns about running
out of SGPRs if you make all the SGPRs that aren't reserved available
for the calling convention.
Change-Id: Idb4ca4dc72f5b6808cb524ff7270915a8de5b4c1
llvm-svn: 370215
This is the more natural lowering, and presents more opportunities to
reduce 64-bit ops to 32-bit.
This should also help avoid issues graphics shaders have had with
64-bit values, and simplify argument lowering in globalisel.
llvm-svn: 366578
This is split out from my patches to split register allocation into a
separate SGPR and VGPR phase, and has some parts that aren't yet used
(like maintaining LiveIntervals).
This simplifies making the frame pointer register callee saved. As it
is now, the code to determine callee saves needs to predict all the
possible SGPR spills and how many callee saved VGPRs are needed. By
handling this before PrologEpilogInserter, it's possible to just check
the spill objects that already exist.
Change-Id: I29e6df4034afcf949e06f8ef44206acb94696f04
llvm-svn: 365095
Summary:
SGPR in CC can be either hw initialized or set by other chained shaders
and so this increases the SGPR count availalbe to CC to 105.
Change-Id: I3dfadc750fe4a3e2bd07117a2899fd13f3e2fef3
Subscribers: arsenm, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D61261
llvm-svn: 360778
They are not used by anything yet, but a subsequent commit will start
using them for image ops that return 5 dwords.
Differential Revision: https://reviews.llvm.org/D58903
Change-Id: I63e1904081e39a6d66e4eb96d51df25ad399d271
llvm-svn: 356735
Added support for dwordx3 for most load/store types, but not DS, and not
intrinsics yet.
SI (gfx6) does not have dwordx3 instructions, so they are not enabled
there.
Some of this patch is from Matt Arsenault, also of AMD.
Differential Revision: https://reviews.llvm.org/D58902
Change-Id: I913ef54f1433a7149da8d72f4af54dbb13436bd9
llvm-svn: 356659
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Summary:
This is a follow-up to r335942.
- Merge SISubtarget into AMDGPUSubtarget and rename to GCNSubtarget
- Rename AMDGPUCommonSubtarget to AMDGPUSubtarget
- Merge R600Subtarget::Generation and GCNSubtarget::Generation into
AMDGPUSubtarget::Generation.
Reviewers: arsenm, jvesely
Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, javed.absar, llvm-commits
Differential Revision: https://reviews.llvm.org/D49037
llvm-svn: 336851
Avoid using allocateKernArg / AssignFn. We do not want any
of the type splitting properties of normal calling convention
lowering.
For now at least this exists alongside the IR argument lowering
pass. This is necessary to handle struct padding correctly while
some arguments are still skipped by the IR argument lowering
pass.
llvm-svn: 336373
Summary:
We now have two sets of generated TableGen files, one for R600 and one
for GCN, so each sub-target now has its own tables of instructions,
registers, ISel patterns, etc. This should help reduce compile time
since each sub-target now only has to consider information that
is specific to itself. This will also help prevent the R600
sub-target from slowing down new features for GCN, like disassembler
support, GlobalISel, etc.
Reviewers: arsenm, nhaehnle, jvesely
Reviewed By: arsenm
Subscribers: MatzeB, kzhuravl, wdng, mgorny, yaxunl, dstuttard, tpr, t-tye, javed.absar, llvm-commits
Differential Revision: https://reviews.llvm.org/D46365
llvm-svn: 335942
Includes a hack to fix the type selected for
the GlobalAddress of the function, which will be
fixed by changing the default datalayout to use
generic pointers for 0.
llvm-svn: 309732
Partially implement callee-side for arguments and return values.
byval doesn't work properly, and most likely sret or other on-stack
return values most as well.
llvm-svn: 303308
Don't use AllocateStack because kernel arguments have nothing
to do with the stack. The ensureMaxAlignment call was still
changing the stack alignment.
llvm-svn: 273080
This makes it possible to distinguish between mesa shaders
and other kernels even in the presence of compute shaders.
Patch By: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Differential Revision: http://reviews.llvm.org/D18559
llvm-svn: 265589
Summary:
Return values can be stored in SGPRs (i32) and VGPRs (f32).
This will be used by functions which expect some bytecode or other binary to
be appended at the end. It allows defining in which registers the return
values will be stored.
v2: don't do this for compute shaders
Reviewers: tstellarAMD, arsenm
Subscribers: arsenm
Differential Revision: http://reviews.llvm.org/D16033
llvm-svn: 257621
