This will prevent the `assert(!O.readsReg())` from firing in
SIOptimizeVGPRLiveRange::optimizeLiveRange
Fix for #64163
Reviewed By: arsenm, #amdgpu
Differential Revision: https://reviews.llvm.org/D156893
As the comment notes, the shader results in an INSERT_SUBREG with
"undef" (dead) operand in the Endif block. The same can happen with
REG_SEQUENCE. The register is considered dead from a liveness
analysis perspective. The correct thing to do seems to be nothing:
we keep the undef use of the register, the register allocator should
still be able to take the liveness into account correctly.
Differential Revision: https://reviews.llvm.org/D149161
If the CFG structure of a waterfall loop is not the expected shape
then gracefully abort traversing the IR for the given loop.
This applies to nest waterfall loops which are not supported by
the VGPR live range optimizer.
Reviewed By: ruiling
Differential Revision: https://reviews.llvm.org/D123480
Split waterfall loops into multiple blocks so that exec mask
manipulation (s_and_saveexec) does not occur in the middle of
a block.
VGPR live range optimizer is updated to handle waterfall loops
spanning multiple blocks.
Reviewed By: ruiling
Differential Revision: https://reviews.llvm.org/D122200
This was not removing the block from the live set depending on the
specific depth first visit order. Fixes a verifier error in the OpenCL
conformance tests.
The killed flag is not always set. E.g. when a variable is used in a
loop, it is never marked as killed, although it is unused in following
basic blocks. Also, we try to deprecate kill flags and not use them.
Check if the register is live in the endif block. If not, consider it
killed in the then and else blocks.
The vgpr-liverange tests have two new tests with loops
(pre-committed, so the diff is visible).
I also needed to change the subtarget to gfx10.1, otherwise calls
are not working.
Differential Revision: https://reviews.llvm.org/D106291
The loops are run exactly once per lane, so VGPRs do not need to be
saved. Use the SIOptimizeVGPRLiveRange pass to add phi nodes that take
undef when coming from the loop.
There is still a shortcoming:
Return values from a function call in the loop are copied because their
live range conflicts with the live range of arguments, even if arguments
are only IMPLICIT_DEF after the phi insertion.
Differential Revision: https://reviews.llvm.org/D105192
This pass aims to optimize VGPR live-range in a typical divergent if-else
control flow. For example:
def(a)
if(cond)
use(a)
... // A
else
use(a)
As AMDGPU access vgpr with respect to active-mask, we can mark `a` as
dead in region A. For details, please refer to the comments in
implementation file.
The pass is enabled by default, the frontend can disable it through
"-amdgpu-opt-vgpr-liverange=false".
Differential Revision: https://reviews.llvm.org/D102212
