The post-index matcher, before it queries the target legality, walks uses
of some instructions which in pathological cases can be massive. Since
no targets actually support indexed loads yet, disable this to stop wasting
compile time on something which is going to fail anyway.
This is needed for an upcoming change to how we translate conditional branches
which might generate these.
Differential Revision: https://reviews.llvm.org/D86383
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
AArch64, X86 and Mips currently directly consumes these and custom
lowering to produce a libcall, but really these should follow the
normal legalization process through the libcall/lower action.
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.
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.
If we have a mask, and a value x, where (x & mask) == x, we can drop the AND
and just use x.
This is about a 0.4% geomean code size improvement on CTMark at -O3 for AArch64.
In AArch64, this is most useful post-legalization. Patterns like this often
show up when legalizing s1s, which must be extended to larger types.
e.g.
```
%cmp:_(s32) = G_ICMP ...
%and:_(s32) = G_AND %cmp, 1
```
Since G_ICMP only produces a single bit, there's no reason to mask it with the
G_AND.
Differential Revision: https://reviews.llvm.org/D85463
This is restricted to single use loads, which if we fold to sextloads we can
find more optimal addressing modes on AArch64.
This also fixes an overload the MachineFunction::getMachineMemOperand() method
which was incorrectly using the MF alignment instead of the MMO alignment.
Differential Revision: https://reviews.llvm.org/D85966
By detecting this sign extend pattern early, we can uncover opportunities for
more optimizations.
Differential Revision: https://reviews.llvm.org/D85965
This implements
```
(logic_op (op x...), (op y...)) -> (op (logic_op x, y))
```
when `op` is an extend, a shift, or an and.
This is similar to `DAGCombiner::hoistLogicOpWithSameOpcodeHands`
(with a bunch of missing cases, e.g. G_TRUNC, G_BITCAST, etc.)
This is implemented so it works both pre and post-legalization.
This also adds a general way to add a series of instructions in a combine.
(`applyBuildInstructionSteps`).
Differential Revision: https://reviews.llvm.org/D85050
https://reviews.llvm.org/D84909
Patch adds two new GICombinerRules, one for G_INTTOPTR and one for
G_PTRTOINT. The G_INTTOPTR elides ptr2int(int2ptr(x)) to a copy of x, if
the cast is within the same address space. The G_PTRTOINT elides
int2ptr(ptr2int(x)) to a copy of x. Patch additionally adds new combiner
tests for the AArch64 target to test these new combiner rules.
Patch by mkitzan
It's possible to end up with a zext or something in the way of a G_CONSTANT,
even pre-legalization. This can happen with memsets.
e.g.
https://godbolt.org/z/Bjc8cw
To make sure we can catch these cases, use `getConstantVRegValWithLookThrough`
instead of `mi_match`.
Differential Revision: https://reviews.llvm.org/D81875
This implements the following combines:
((0-A) + B) -> B-A
(A + (0-B)) -> A-B
Porting over the basic algebraic combines from the DAGCombiner. There are
several combines which fold adds away into subtracts. This is just the simplest
one.
I noticed that add combines are some of the most commonly hit across CTMark,
(via print statements when they fire), so I'm porting over some of the obvious
ones.
This gives some minor code size improvements on CTMark at -O3 on AArch64.
Differential Revision: https://reviews.llvm.org/D77453
Summary:
Note to downstream target maintainers: this might silently change the semantics of your code if you override `TargetLowering::allowsMisalignedMemoryAccesses` without marking it override.
This patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790
Reviewers: courbet
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D81374
During legalization we can end up with extends of loads, which in the case of
zexts causes us to not hit tablegen imported patterns.
The caveat here is that we don't want anyext load forming, since some variants
are illegal. This change also prevents the combine from creating any illegal
loads.
Differential Revision: https://reviews.llvm.org/D80458
If we have a memory instruction (e.g. a load), we shouldn't combine it away in
some trivial combine.
It's possible that, say, a call lives between the instructions. This could
modify the value loaded, making the load instructions not safe to fold.
Differential Revision: https://reviews.llvm.org/D80053
(This patch is by Jessica, I'm just committing it on her behalf because I need
a post-legalizer combiner for something else).
This supersedes D77250, which did equivalent work in the selector. This can be
done pre-legalization or post-legalization. Post-legalization is more likely to
hit, since G_IMPLICIT_DEFs tend to appear during legalization. There's no reason
to not do it pre-legalization though-- if it can be caught earlier, great.
(I also think that it might be worth reimplementing D78769 using a
target-specific post-legalization combine too after thinking about it for a
while.)
Differential Revision: https://reviews.llvm.org/D78852
Summary:
Fix an issue which could result in ElideBrByInvertingCond or
CombineIndexedLoadStore being missed when debug info is present. In both
cases the fix is s/hasOneUse/hasOneNonDbgUse/.
Reviewers: aemerson, dsanders
Subscribers: hiraditya, aprantl, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D78254
Summary:
This fixes several issues where the presence of debug instructions could
disable certain combines, due to dominance queries finding uses/defs that
don't actually exist.
Reviewers: dsanders, fhahn, paquette, aemerson
Subscribers: hiraditya, arphaman, aprantl, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D78253
When we have
```
a = G_OR x, x
```
or
```
b = G_AND y, y
```
We can drop the G_OR/G_AND and just use x/y respectively.
Also update arm64-fallback.ll because there was an or in there which hits this
transformation.
Differential Revision: https://reviews.llvm.org/D77105
Implement identity combines for operations like the following:
```
%a = G_SUB %b, 0
```
This can just be replaced with %b.
Over CTMark, this gives some minor size improvements at -O3.
Differential Revision: https://reviews.llvm.org/D76640
When we see this:
```
%a = COPY $physreg
...
SOMETHING implicit-def $physreg
...
%b = COPY $physreg
```
The two copies are not equivalent, and so we shouldn't perform any folding
on them.
When we have two instructions which use a physical register check that they
define the same virtual register(s) as well.
e.g., if we run into this case
```
%a = COPY $physreg
...
%b = COPY %a
```
we can say that the two copies are the same, and can be folded.
Differential Revision: https://reviews.llvm.org/D76890
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790
Reviewers: courbet
Subscribers: arsenm, dschuff, sdardis, nemanjai, jvesely, nhaehnle, sbc100, jgravelle-google, hiraditya, aheejin, kbarton, jrtc27, atanasyan, jfb, kerbowa, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76925
When we find something like this:
```
%a:_(s32) = G_SOMETHING ...
...
%select:_(s32) = G_SELECT %cond(s1), %a, %a
```
We can remove the select and just replace it entirely with `%a` because it's
always going to result in `%a`.
Same if we have
```
%select:_(s32) = G_SELECT %cond(s1), %a, %b
```
where we can deduce that `%a == %b`.
This implements the following cases:
- `%select:_(s32) = G_SELECT %cond(s1), %a, %a` -> `%a`
- `%select:_(s32) = G_SELECT %cond(s1), %a, %some_copy_from_a` -> `%a`
- `%select:_(s32) = G_SELECT %cond(s1), %a, %b` -> `%a` when `%a` and `%b`
are defined by identical instructions
This gives a few minor code size improvements on CTMark at -O3 for AArch64.
Differential Revision: https://reviews.llvm.org/D76523
Port over the following:
- shuffle undef, undef, any_mask -> undef
- shuffle anything, anything, undef_mask -> undef
This sort of thing shows up a lot when you try to bugpoint code containing
shufflevector.
Differential Revision: https://reviews.llvm.org/D76382
This ports some combines from DAGCombiner.cpp which perform some trivial
transformations on instructions with undef operands.
Not having these can make it extremely annoying to find out where we differ
from SelectionDAG by looking at existing lit tests. Without them, we tend to
produce pretty bad code generation when we run into instructions which use
undef operands.
Also remove the nonpow2_store_narrowing testcase from arm64-fallback.ll, since
we no longer fall back on the add.
Differential Revision: https://reviews.llvm.org/D76339
Produce an unmerge to a narrower type and introduce a narrower shift
if needed. I wasn't sure if there was a better way to parameterize the
target's preferred shift type for the GICombineRule, so manually call
the combine helper.
Like COPY instructions explained in D70616, we don't check the constraints
when combining G_UNMERGE_VALUES. Use the same logic used in D70616 to check
if registers can be replaced, or a COPY instruction needs to be built.
https://reviews.llvm.org/D70564
Summary: This patch introduces an API for MemOp in order to simplify and tighten the client code.
Reviewers: courbet
Subscribers: arsenm, nemanjai, jvesely, nhaehnle, hiraditya, kbarton, jsji, kerbowa, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73964
Volkan Keles