optimizeEndCF removes EXEC restoring instruction case this instruction is the only one except the branch to the single successor and that successor contains EXEC mask restoring instruction that was lowered from END_CF belonging to IF_ELSE.
As a result of such optimization we get the basic block with the only one instruction that is a branch to the single successor.
In case the control flow can reach such an empty block from S_CBRANCH_EXEZ/EXECNZ it might happen that spill/reload instructions that were inserted later by register allocator are placed under exec == 0 condition and never execute.
Removing empty block solves the problem.
This change require further work to re-implement LIS updates. Recently, LIS is always nullptr in this pass. To enable it we need another patch to fix many places across the codegen.
Reviewed By: rampitec
Differential Revision: https://reviews.llvm.org/D86634
During the PEI pass, the dead TargetStackID::SGPRSpill spill slots
are not being removed while spilling the FP/BP to memory.
Fixes: SWDEV-250393
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D87032
This is a followup to 1ccfb52a61, which made a number of changes
including the apparently innocuous reordering of required passes in
MemCpyOptimizer. This however altered the creation order of BasicAA vs
Phi Values analysis, meaning BasicAA did not pick up PhiValues as a
cached result. Instead if we require MemoryDependence first it will
require PhiValuesAnalysis allowing BasicAA to use it for better results.
I don't claim this is an excellent design, but it fixes a nasty little
regressions where a query later in JumpThreading was getting worse
results.
Differential Revision: https://reviews.llvm.org/D87027
The addend in a REL32 reloc needs to be adjusted to account for the
offset from the PC value returned by the s_getpc instruction to the
point where the reloc is applied. This was being done correctly for
(GOTPC)REL32_LO but not for (GOTPC)REL32_HI. This will only make a
difference if the target symbol happens to get loaded almost exactly
a multiple of 4G away from the relocated instructions.
Differential Revision: https://reviews.llvm.org/D86938
Summary:
Analyses are preserved in MemCpyOptimizer.
Get analyses before running the pass and store the pointers, instead of
using lambdas and getting them every time on demand.
Reviewers: lenary, deadalnix, mehdi_amini, nikic, efriedma
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D74494
This is needed for an upcoming change to how we translate conditional branches
which might generate these.
Differential Revision: https://reviews.llvm.org/D86383
Unmerges have the same fundamental problem as G_TRUNC, and G_TRUNC
could be implemented in terms of G_UNMERGE_VALUES. Reducing the number
of elements in unmerge results ends up producing the original unmerge
type profile, so the artifact combiner needs to eliminate the
intermediate illegal registers. This avoids infinite looping in the
legalizer in a future change.
Assuming an unmerge has each result unmerged the same way, this ends
up producing a new unmerge of the source for every definition. I'm not
sure if the artifact combiner should either insert temporary merges
here and erase the original merge, or if the combiner should look at
uses from defs rather than defs from uses for unmerges.
In a few cases this regresses from using 16-bit shifts for 8-bit
values to using 32-bit shifts, but I think these can be legalized
later (the other legalization rules don't try very hard to use 16-bit
shifts either).
Currently the dbg_value ends up in the relaxed branch block. A future
commit will push the dbg_value out of this block, and I'm not sure how
to coax the IR into producing the same MIR at the relevant point.
For an instruction in the basic block BB, SinkingPass enumerates basic blocks
dominated by BB and BB's successors. For each enumerated basic block,
SinkingPass uses `AllUsesDominatedByBlock` to check whether the basic
block dominates all of the instruction's users. This is inefficient.
Use the nearest common dominator of all users to avoid enumerating the
candidate. The nearest common dominator may be in a parent loop which is
not beneficial. In that case, find the ancestors in the dominator tree.
In the case that the instruction has no user, with this change we will
not perform unnecessary move. This causes some amdgpu test changes.
A stage-2 x86-64 clang is a byte identical with this change.
The implicit def of the super register would appear to kill any live
uses of components before the spill, and would be deleted by
MachineCopyPropagation. We need to add implicit uses of the super
register, similarly to what copyPhysReg does. VGPR tuples appear to be
correctly handled already. I need to double check the SGPR->memory
path.
https://reviews.llvm.org/D83833
Patch adds two new GICombinerRules for G_SELECT. The rules include:
combining selects with undef comparisons into their first selectee value,
and to combine away selects with constant comparisons. Patch additionally
adds a new combiner test for the AArch64 target to test these new G_SELECT
combiner rules and the existing select_same_val combiner rule.
Patch by mkitzan
This is the first of a set of DAGCombiner changes enabling strictfp
optimizations. I want to test to waters with this to make sure changes
like these are acceptable for the strictfp case- this particular change
should preserve exception ordering and result precision perfectly, and
many other possible changes appear to be able to as well.
Copied from regular fadd combines but modified to preserve ordering via
the chain, this change allows strict_fadd x, (fneg y) to become
struct_fsub x, y and strict_fadd (fneg x), y to become strict_fsub y, x.
Differential Revision: https://reviews.llvm.org/D85548
There is no justification for changing vcc_lo to vcc
when shrinking V_CNDMASK, and such a change could
later confuse live variable analysis.
Make sure the original register is preserved.
Differential Revision: https://reviews.llvm.org/D86541
This would assert with unaligned DS access enabled. The offset may not
be aligned. Theoretically the pattern predicate should check the
memory alignment, although it is possible to have the memory be
aligned but not the immediate offset.
In this case I would expect it to use ds_{read|write}_b64 with
unaligned access, but am not clear if there's a reason it doesn't.
If the condition output is negated, swap the branch targets. This is
similar to what SelectionDAG does for when SelectionDAGBuilder
decides to invert the condition and swap the branches.
This is leaving behind a dead constant def for some reason.
This produces less work for addressing mode matching. I think this is
safe since I don't think machine IR is supposed to give the same
aliasing properties as getelementptr in the IR.
If a workgroup size is known to be not greater than wavefront size
the s_barrier instruction is not needed since all threads are guaranteed
to come to the same point at the same time.
This is the same optimization that was implemented for SelectionDAG in
D31731.
Differential Revision: https://reviews.llvm.org/D86609
Before calling target hook to determine if two loads/stores are clusterable,
we put them into different groups to avoid fake cluster due to dependency.
For now, we are putting the loads/stores into the same group if they have
the same predecessor. We assume that, if two loads/stores have the same
predecessor, it is likely that, they didn't have dependency for each other.
However, one SUnit might have several predecessors and for now, we just
pick up the first predecessor that has non-data/non-artificial dependency,
which is too arbitrary. And we are struggling to fix it.
So, I am proposing some better implementation.
1. Collect all the loads/stores that has memory info first to reduce the complexity.
2. Sort these loads/stores so that we can stop the seeking as early as possible.
3. For each load/store, seeking for the first non-dependency instruction with the
sorted order, and check if they can cluster or not.
Reviewed By: Jay Foad
Differential Revision: https://reviews.llvm.org/D85517
Most notably, we were incorrectly reporting <3 x s16> as a legal type
for these. Make sure these aren't legal to help make progress on
fixing the artifact combiner and vector legalizer
rules. Unfortunately, this means spreading the -global-isel-abort=0
hack, although this doesn't change the legalizer result in any
situation.
Implicit uses of non-register value types places impossible to satisfy
constraints on the legalizer / artifact combiner. These prevent
writing sensible legalize rules for the artifacts without triggering
infinite loops in the legalizer.
The verifier really needs to enforce this, but I'm not sure what the
exact conditions would look like yet.
SelectionDAG and GlobalISel take different failure paths for these and
end up producing different failure errors. Check both so the test
passes when the default is switched.
This interferes with GlobalISel's much better handling of the
situation.
This should really be disable for GlobalISel. However, the fallback
only re-runs the selection passes, and doesn't go back and rerun any
codegen IR passes. I haven't come up with a good solution to this
problem.
This is to initially handleg immAllOnesV, which should match
G_BUILD_VECTOR or G_BUILD_VECTOR_TRUNC. In the future, it could be
used for other patterns cases that map to multiple G_* instructions,
such as G_ADD and G_PTR_ADD.
D77152 tried to do this but got it wrong in the shift-by-zero case.
D86430 reverted the wrong code. Reimplement the optimization with
different code depending on whether the shift amount is known to be
non-zero (modulo bitwidth).
This improves code quality for fshl tests on AMDGPU, which only has an
fshr instruction.
Differential Revision: https://reviews.llvm.org/D86438
Handle workitem intrinsics. There isn't really away to adequately test
this right now, since none of the known bits users are fine grained
enough to test the edge conditions. This triggers a number of
instances of the new 64-bit to 32-bit shift combine in the existing
tests.
shl ([sza]ext x, y) => zext (shl x, y).
Turns expensive 64 bit shifts into 32 bit if it does not overflow the
source type:
This is a port of an AMDGPU DAG combine added in
5fa289f0d8. InstCombine does this
already, but we need to do it again here to apply it to shifts
introduced for lowered getelementptrs. This will help matching
addressing modes that use 32-bit offsets in a future patch.
TableGen annoyingly assumes only a single match data operand, so
introduce a reusable struct. However, this still requires defining a
separate GIMatchData for every combine which is still annoying.
Adds a morally equivalent function to the existing
getShiftAmountTy. Without this, we would have to do try to repeatedly
query the legalizer info and guess at what type to use for the shift.
This is a fixup of commit 0819a6416f (D77152) which could
result in miscompiles. The miscompile could only happen for targets
where isOperationLegalOrCustom could return different values for
FSHL and FSHR.
The commit mentioned above added logic in expandFunnelShift to
convert between FSHL and FSHR by swapping direction of the
funnel shift. However, that transform is only legal if we know
that the shift count (modulo bitwidth) isn't zero.
Basically, since fshr(-1,0,0)==0 and fshl(-1,0,0)==-1 then doing a
rewrite such as fshr(X,Y,Z) => fshl(X,Y,0-Z) would be incorrect if
Z modulo bitwidth, could be zero.
```
$ ./alive-tv /tmp/test.ll
----------------------------------------
define i32 @src(i32 %x, i32 %y, i32 %z) {
%0:
%t0 = fshl i32 %x, i32 %y, i32 %z
ret i32 %t0
}
=>
define i32 @tgt(i32 %x, i32 %y, i32 %z) {
%0:
%t0 = sub i32 32, %z
%t1 = fshr i32 %x, i32 %y, i32 %t0
ret i32 %t1
}
Transformation doesn't verify!
ERROR: Value mismatch
Example:
i32 %x = #x00000000 (0)
i32 %y = #x00000400 (1024)
i32 %z = #x00000000 (0)
Source:
i32 %t0 = #x00000000 (0)
Target:
i32 %t0 = #x00000020 (32)
i32 %t1 = #x00000400 (1024)
Source value: #x00000000 (0)
Target value: #x00000400 (1024)
```
It could be possible to add back the transform, given that logic
is added to check that (Z % BW) can't be zero. Since there were
no test cases proving that such a transform actually would be useful
I decided to simply remove the faulty code in this patch.
Reviewed By: foad, lebedev.ri
Differential Revision: https://reviews.llvm.org/D86430
Ronak Chauhan