Commit Graph

6 Commits

Author SHA1 Message Date
Matt Arsenault 71dfb7ec5c AMDGPU: Make s34 the FP register
Make the FP register callee saved.

This is tricky because now the FP needs to be spilled in the prolog
relative to the incoming SP register, rather than the frame register
used throughout the rest of the function. I don't like how this
bypassess the standard mechanism for CSR spills just to get the
correct insert point. I may look for a better solution, since all CSR
VGPRs may also need to have all lanes activated. Another option might
be to make getFrameIndexReference change the base register if the
frame index is a CSR, and then try to figure out the right insertion
point in emitProlog.

If there is a free VGPR lane available for SGPR spilling, try to use
it for the FP. If that would require intrtoducing a new VGPR spill,
try to use a free call clobbered SGPR. Only fallback to introducing a
new VGPR spill as a last resort.

This also doesn't attempt to handle SGPR spilling with scalar stores.

llvm-svn: 365372
2019-07-08 19:03:38 +00:00
Matt Arsenault d88db6d7fc AMDGPU: Always use s33 for global scratch wave offset
Every called function could possibly need this to calculate the
absolute address of stack objectst, and this avoids inserting a copy
around every call site in the kernel. It's also somewhat cleaner to
keep this in a callee saved SGPR.

llvm-svn: 363990
2019-06-20 21:58:24 +00:00
Matt Arsenault 34c8b835b1 AMDGPU: Don't fix emergency stack slot at offset 0
This forced the caller to be aware of this, which is an ugly ABI
feature.

Partially reverts r295877. The original reasons for doing this are
mostly fixed. Alloca is now in a non-0 address space, so it should be
OK to have 0 as a valid pointer. Since we treat the absolute address
as the pointer value, this part only really needed to apply to
kernels.

Since r357093, we avoid the need to increment/decrement the offset
register in more cases, and since r354816 the scavenger can fail
without spilling, so it's less critical that we try to avoid an offset
that fits in the MUBUF offset.

Restrict to callable functions for now to split this into 2 steps to
limit thte number of test updates and in case anything breaks.

llvm-svn: 362665
2019-06-05 22:37:50 +00:00
Matt Arsenault 3d59e388ca AMDGPU: Activate all lanes when spilling CSR VGPR for SGPR spills
If some lanes weren't active on entry to the function, this could
clobber their VGPR values.

llvm-svn: 361655
2019-05-24 18:18:51 +00:00
Scott Linder afc24ed21a [AMDGPU] Mark test functions with hidden visibility
Prepare for future patch which affects codegen for calls to preemptible
functions.

Differential Revision: https://reviews.llvm.org/D57605

llvm-svn: 352920
2019-02-01 21:23:28 +00:00
Matt Arsenault 167601e629 DAG: Don't use ABI copies in some contexts
If an ABI-like value is used in a different block,
the type split used is not necessarily the same as
the call's ABI. The value is used through an intermediate
copy virtual registers from the other block. This
resulted in copies with inconsistent sizes later.

Fixes regressions since r338197 when AMDGPU started
splitting vector types for calls.

llvm-svn: 341018
2018-08-30 05:49:28 +00:00