This fold is done in IR by instcombine, and we have a special
form of it already here in DAGCombiner, but we want the more
general transform too:
https://rise4fun.com/Alive/3jZm
Name: general
Pre: (C1 + zext(C2) < 64)
%s = lshr i64 %x, C1
%t = trunc i64 %s to i16
%r = lshr i16 %t, C2
=>
%s2 = lshr i64 %x, C1 + zext(C2)
%a = and i64 %s2, zext((1 << (16 - C2)) - 1)
%r = trunc %a to i16
Name: special
Pre: C1 == 48
%s = lshr i64 %x, C1
%t = trunc i64 %s to i16
%r = lshr i16 %t, C2
=>
%s2 = lshr i64 %x, C1 + zext(C2)
%r = trunc %s2 to i16
...because D58017 exposes a regression without this fold.
This is not quite NFC because I changed the SDLoc to use the more
standard 'N' (the starting node for the fold).
This transform is a special-case of a more general fold that we
do in IR, but it seems like the general fold is needed here too
to avoid a potential regression seen in D58017.
https://rise4fun.com/Alive/3jZm
Summary: This combine showed up as needed when exploring the regression when processing the DAG in topological order.
Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68195
MVE has a basic symmetry between it's normal loads/store operations and
the masked variants. This means that masked loads and stores can use
pre-inc and post-inc addressing modes, just like the standard loads and
stores already do.
To enable that, this patch adds all the relevant infrastructure for
treating masked loads/stores addressing modes in the same way as normal
loads/stores.
This involves:
- Adding an AddressingMode to MaskedLoadStoreSDNode, along with an extra
Offset operand that is added after the PtrBase.
- Extending the IndexedModeActions from 8bits to 16bits to store the
legality of masked operations as well as normal ones. This array is
fairly small, so doubling the size still won't make it very large.
Offset masked loads can then be controlled with
setIndexedMaskedLoadAction, similar to standard loads.
- The same methods that combine to indexed loads, such as
CombineToPostIndexedLoadStore, are adjusted to handle masked loads in
the same way.
- The ARM backend is then adjusted to make use of these indexed masked
loads/stores.
- The X86 backend is adjusted to hopefully be no functional changes.
Differential Revision: https://reviews.llvm.org/D70176
We already have this simplification at node-creation-time, but
the test from:
https://bugs.llvm.org/show_bug.cgi?id=44139
...shows that we can combine our way to an assert/crash too.
Summary:
Convert (uaddo (uaddo x, y), carryIn) into addcarry x, y, carryIn if-and-only-if the carry flags of the first two uaddo are merged via OR or XOR.
Work remaining: match ADD, etc.
Reviewers: craig.topper, RKSimon, spatel, niravd, jonpa, uweigand, deadalnix, nikic, lebedev.ri, dmgreen, chfast
Reviewed By: lebedev.ri
Subscribers: chfast, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70079
Cleanup handling of the denormal-fp-math attribute. Consolidate places
checking the allowed names in one place.
This is in preparation for introducing FP type specific variants of
the denormal-fp-mode attribute. AMDGPU will switch to using this in
place of the current hacky use of subtarget features for the denormal
mode.
Introduce a new header for dealing with FP modes. The constrained
intrinsic classes define related enums that should also be moved into
this header for uses in other contexts.
The verifier could use a check to make sure the denorm-fp-mode
attribute is sane, but there currently isn't one.
Currently, DAGCombiner incorrectly asssumes non-IEEE behavior by
default in the one current user. Clang must be taught to start
emitting this attribute by default to avoid regressions when this is
switched to assume ieee behavior if the attribute isn't present.
AMDGPU needs to know the FP mode for the function to answer this
correctly when this is removed from the subtarget.
AArch64 had to make this more complicated by using this from an IR
hook, so add an IR typed overload.
* Implements scalable size queries for MVTs, split out from D53137.
* Contains a fix for FindMemType to avoid using scalable vector type
to contain non-scalable types.
* Explicit casts for several places where implicit integer sign
changes or promotion from 32 to 64 bits caused problems.
* CodeGenDAGPatterns will treat scalable and non-scalable vector types
as different.
Reviewers: greened, cameron.mcinally, sdesmalen, rovka
Reviewed By: rovka
Differential Revision: https://reviews.llvm.org/D66871
Summary:
Replaces
```
unsigned getShiftAmountThreshold(EVT VT)
```
by
```
bool shouldAvoidTransformToShift(EVT VT, unsigned amount)
```
thus giving more flexibility for targets to decide whether particular shift amounts must be considered expensive or not.
Updates the MSP430 target with a custom implementation.
This continues D69116, D69120, D69326 and updates them, so all of them must be committed before this.
Existing tests apply, a few more have been added.
Reviewers: asl, spatel
Reviewed By: spatel
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70042
This is a partial fix for the issues described in commit message of 027aa27 (the revert of G24609). Unfortunately, I can't provide test coverage for it on it's own as the only (known) wrong example is still wrong, but due to a separate issue.
These fixes are cases where when performing unrelated DAG combines, we were dropping the atomicity flags entirely.
Summary:
Functions replaceStoreOfFPConstant() and OptimizeFloatStore() both
replace store of float by a store of an integer unconditionally. However
this generates wrong code when the store that is replaced is an indexed
or truncating store. This commit solves this issue by adding an early
return in these functions when the store being considered is not a
normal store.
Bug was only observed on out of tree targets, hence the lack of testcase
in this commit.
Reviewers: efriedma
Subscribers: hiraditya, arphaman, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68420
Continuation of:
D69116
Contributes to a fix for PR43559:
https://bugs.llvm.org/show_bug.cgi?id=43559
See also D69099 and D69116
Use the TLI hook in DAGCombine.cpp to guard against creating
shift nodes that are not optimal for a target.
Patch by: @joanlluch (Joan LLuch)
Differential Revision: https://reviews.llvm.org/D69120
For AMDGPU this depends on whether denormals are enabled in the
default FP mode for the function. Currently this is treated as a
subtarget feature, so FMAD is selectively legal based on that. I want
to move this out of the subtarget features so this can be controlled
with a denormal mode attribute. Additionally, this will allow folding
based on a future ftz fast math flag.
This enhances D69127 (rGe6c145e0548e3b3de6eab27e44e1504387cf6b53)
to handle the looser "any_extend" cast in addition to zext.
This is a prerequisite step for canonicalizing in the other direction
(narrow the popcount) in IR - PR43688:
https://bugs.llvm.org/show_bug.cgi?id=43688
Similar to:
rG4c47617627fb
This makes the DAG behavior consistent with IR's insertelement.
https://bugs.llvm.org/show_bug.cgi?id=42689
I've tried to maintain test intent for AArch64 and WebAssembly
by replacing undef index operands with something else.
zext (ctpop X) --> ctpop (zext X)
This is a prerequisite step for canonicalizing in the other direction (narrow the popcount) in IR - PR43688:
https://bugs.llvm.org/show_bug.cgi?id=43688
I'm not sure if any other targets are affected, but I found a missing fold for PPC, so added tests based on that.
The reason we widen all the way to 64-bit in these tests is because the initial DAG looks something like this:
t5: i8 = ctpop t4
t6: i32 = zero_extend t5 <-- created based on IR, but unused node?
t7: i64 = zero_extend t5
Differential Revision: https://reviews.llvm.org/D69127
Adds a new ISD node to replicate a scalar value across all elements of
a vector. This is needed for scalable vectors, since BUILD_VECTOR cannot
be used.
Fixes up default type legalization for scalable vectors after the
new MVT type ranges were introduced.
At present I only use this node for scalable vectors. A DAGCombine has
been added to transform a BUILD_VECTOR into a SPLAT_VECTOR if all
elements are the same, but only if the default operation action of
Expand has been overridden by the target.
I've only added result promotion legalization for scalable vector
i8/i16/i32/i64 types in AArch64 for now.
Reviewers: t.p.northover, javed.absar, greened, cameron.mcinally, jmolloy
Reviewed By: jmolloy
Differential Revision: https://reviews.llvm.org/D47775
llvm-svn: 375222
Add generic DAG combine for extending masked loads.
Allow us to generate sext/zext masked loads which can access v4i8,
v8i8 and v4i16 memory to produce v4i32, v8i16 and v4i32 respectively.
Differential Revision: https://reviews.llvm.org/D68337
llvm-svn: 375085
Examples:
i32 X > -1 ? C1 : -1 --> (X >>s 31) | C1
i8 X < 0 ? C1 : 0 --> (X >>s 7) & C1
This is a small generalization of a fold requested in PR43650:
https://bugs.llvm.org/show_bug.cgi?id=43650
The sign-bit of the condition operand can be used as a mask for the true operand:
https://rise4fun.com/Alive/paT
Note that we already handle some of the patterns (isNegative + scalar) because
there's an over-specialized, yet over-reaching fold for that in foldSelectCCToShiftAnd().
It doesn't use any TLI hooks, so I can't easily rip out that code even though we're
duplicating part of it here. This fold is guarded by TLI.convertSelectOfConstantsToMath(),
so it should not cause problems for targets that prefer select over shift.
Also worth noting: I thought we could generalize this further to include the case where
the true operand of the select is not constant, but Alive says that may allow poison to
pass through where it does not in the original select form of the code.
Differential Revision: https://reviews.llvm.org/D68949
llvm-svn: 374902
The diffs suggest that we are missing some more basic
analysis/transforms, but this keeps the vector path in
sync with the scalar (rL374397). This is again a
preliminary step for introducing the reverse transform
in IR as proposed in D63382.
llvm-svn: 374555
This reverses the scalar canonicalization proposed in D63382.
Pre: isPowerOf2(C1)
%r = select i1 %cond, i32 C1, i32 0
=>
%z = zext i1 %cond to i32
%r = shl i32 %z, log2(C1)
https://rise4fun.com/Alive/Z50
x86 already tries to fold this pattern, but it isn't done
uniformly, so we still see a diff. AArch64 probably should
enable the TLI hook to benefit too, but that's a follow-on.
llvm-svn: 374397
Summary: It ensures that the bswap is generated even when a part of the subtree already matches a bswap transform.
Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68250
llvm-svn: 374340
As background, starting in D66309, I'm working on support unordered atomics analogous to volatile flags on normal LoadSDNode/StoreSDNodes for X86.
As part of that, I spent some time going through usages of LoadSDNode and StoreSDNode looking for cases where we might have missed a volatility check or need an atomic check. I couldn't find any cases that clearly miscompile - i.e. no test cases - but a couple of pieces in code loop suspicious though I can't figure out how to exercise them.
This patch adds defensive checks and asserts in the places my manual audit found. If anyone has any ideas on how to either a) disprove any of the checks, or b) hit the bug they might be fixing, I welcome suggestions.
Differential Revision: https://reviews.llvm.org/D68419
llvm-svn: 374261
If a fp scalar is loaded and then used as both a scalar and a vector broadcast, perform the load as a broadcast and then extract the scalar for 'free' from the 0th element.
This involved switching the order of the X86ISD::BROADCAST combines so we only convert to X86ISD::BROADCAST_LOAD once all other canonicalizations have been attempted.
Adds a DAGCombinerInfo::recursivelyDeleteUnusedNodes wrapper.
Fixes PR43217
Differential Revision: https://reviews.llvm.org/D68544
llvm-svn: 373871
Summary: It ensures that the bswap is generated even when a part of the subtree already matches a bswap transform.
Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68250
llvm-svn: 373850
As discussed on llvm-dev and:
https://bugs.llvm.org/show_bug.cgi?id=43542
...we have transforms that assume shift operations are legal and transforms to
use them are profitable, but that may not hold for simple targets.
In this case, the MSP430 target custom lowers shifts by repeating (many)
simpler/fixed ops. That can be avoided by keeping this code as setcc/select.
Differential Revision: https://reviews.llvm.org/D68397
llvm-svn: 373666
This patch converts the DAGCombine isNegatibleForFree/GetNegatedExpression into overridable TLI hooks.
The intention is to let us extend existing FNEG combines to work more generally with negatible float ops, allowing it work with target specific combines and opcodes (e.g. X86's FMA variants).
Unlike the SimplifyDemandedBits, we can't just handle target nodes through a Target callback, we need to do this as an override to allow targets to handle generic opcodes as well. This does mean that the target implementations has to duplicate some checks (recursion depth etc.).
Partial reversion of rL372756 - I've identified the infinite loop issue inside the X86 override but haven't fixed it yet so I've only (re)committed the common TargetLowering refactoring part of the patch.
Differential Revision: https://reviews.llvm.org/D67557
llvm-svn: 373343
Rename old function to explicitly show that it cares only about alignment.
The new allowsMemoryAccess call the function related to alignment by default
and can be overridden by target to inform whether the memory access is legal or
not.
Differential Revision: https://reviews.llvm.org/D67121
llvm-svn: 372935
We might be able to do better on the example in the test,
but in general, we should not scalarize a splatted vector
binop if there are other uses of the binop. Otherwise, we
can end up with code as we had - a scalar op that is
redundant with a vector op.
llvm-svn: 372886
This patch converts the DAGCombine isNegatibleForFree/GetNegatedExpression into overridable TLI hooks and includes a demonstration X86 implementation.
The intention is to let us extend existing FNEG combines to work more generally with negatible float ops, allowing it work with target specific combines and opcodes (e.g. X86's FMA variants).
Unlike the SimplifyDemandedBits, we can't just handle target nodes through a Target callback, we need to do this as an override to allow targets to handle generic opcodes as well. This does mean that the target implementations has to duplicate some checks (recursion depth etc.).
I've only begun to replace X86's FNEG handling here, handling FMADDSUB/FMSUBADD negation and some low impact codegen changes (some FMA negatation propagation). We can build on this in future patches.
Differential Revision: https://reviews.llvm.org/D67557
llvm-svn: 372333
As commented on D67557 we have a lot of uses of depth checks all using magic numbers.
This patch adds the SelectionDAG::MaxRecursionDepth constant and moves over some general cases to use this explicitly.
Differential Revision: https://reviews.llvm.org/D67711
llvm-svn: 372315
Summary:
`DAGCombiner::visitADDLikeCommutative()` already has a sibling fold:
`(add X, Carry) -> (addcarry X, 0, Carry)`
This fold, as suggested by @efriedma, helps recover from //some//
of the regressions of D62266
Reviewers: efriedma, deadalnix
Subscribers: javed.absar, kristof.beyls, llvm-commits, efriedma
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62392
llvm-svn: 372259
This is the first sweep of generic code to add isAtomic bailouts where appropriate. The intention here is to have the switch from AtomicSDNode to LoadSDNode/StoreSDNode be close to NFC; that is, I'm not looking to allow additional optimizations at this time. That will come later. See D66309 for context.
Differential Revision: https://reviews.llvm.org/D66318
llvm-svn: 371786
The X86 decision assumes the compare will produce a result in an XMM
register, but that can't happen for an fp128 compare since those
go to a libcall the returns an i32. Pass the VT so X86 can check
the type.
llvm-svn: 371775
Current implementation of estimating divisions loses precision since it
estimates reciprocal first and does multiplication. This patch is to re-order
arithmetic operations in the last iteration in DAGCombiner to improve the
accuracy.
Reviewed By: Sanjay Patel, Jinsong Ji
Differential Revision: https://reviews.llvm.org/D66050
llvm-svn: 371713
Summary:
Add an intrinsic that takes 2 unsigned integers with
the scale of them provided as the third argument and
performs fixed point multiplication on them. The
result is saturated and clamped between the largest and
smallest representable values of the first 2 operands.
This is a part of implementing fixed point arithmetic
in clang where some of the more complex operations
will be implemented as intrinsics.
Patch by: leonardchan, bjope
Reviewers: RKSimon, craig.topper, bevinh, leonardchan, lebedev.ri, spatel
Reviewed By: leonardchan
Subscribers: ychen, wuzish, nemanjai, MaskRay, jsji, jdoerfert, Ka-Ka, hiraditya, rjmccall, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D57836
llvm-svn: 371308
The motivating bugs are:
https://bugs.llvm.org/show_bug.cgi?id=41340https://bugs.llvm.org/show_bug.cgi?id=42697
As discussed there, we could view this as a failure of IR canonicalization,
but then we would need to implement a backend fixup with target overrides
to get this right in all cases. Instead, we can just view this as a codegen
opportunity. It's not even clear for x86 exactly when we should favor
test+set; some CPUs have better theoretical throughput for the ALU ops than
bt/test.
This patch is made more complicated than I expected because there's an early
DAGCombine for 'and' that can change types of the intermediate ops via
trunc+anyext.
Differential Revision: https://reviews.llvm.org/D66687
llvm-svn: 370668
The motivating case for this is a long way from here:
https://bugs.llvm.org/show_bug.cgi?id=43146
...but I think this is where we have to start.
We need to canonicalize/optimize sequences of shift and logic to ease
pattern matching for things like bswap and improve perf in general.
But without the artificial limit of '!LegalTypes' (early combining),
there are a lot of test diffs, and not all are good.
In the minimal tests added for this proposal, x86 should have better
throughput in all cases. AArch64 is neutral for scalar tests because
it can fold shifts into bitwise logic ops.
There are 3 shift opcodes and 3 logic opcodes for a total of 9 possible patterns:
https://rise4fun.com/Alive/VlIhttps://rise4fun.com/Alive/n1mhttps://rise4fun.com/Alive/1Vn
Differential Revision: https://reviews.llvm.org/D67021
llvm-svn: 370617
Narrowing stores when the target doesn't support the narrow version
forces the target to expand into a load-modify-store sequence, which
is highly suboptimal. The information narrowing throws away (legality
of the inverse transform) is hard to re-analyze. If the target doesn't
support a store of the narrow type, don't narrow even in pre-legalize
mode.
No test as this is DAGCombiner and depends on target bits.
llvm-svn: 370576
This is hidden behind a (scalar-only) isOneConstant(N1) check at the moment, but once we get around to adding vector support we need to ensure we're dealing with the scalar bitwidth, not the total.
llvm-svn: 370468
Return a proper zero vector, just in case some elements are undef.
Noticed by inspection after dealing with a similar issue in PR43159.
llvm-svn: 370460
Summary: This is beneficial when the shuffle is only used once and end up being generated in a few places when some node is combined into a shuffle.
Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66718
llvm-svn: 370326
Summary: There are at least 2 ways to express the same shuffle. Various pieces of code explicit check for both option, but other places do not when they would benefit from doing it. This patches refactor the codebase to use buildLegalVectorShuffle in order to make that behavior more consistent.
Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri
Subscribers: javed.absar, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66804
llvm-svn: 370190
(-X) * (-Y) + Z --> X * Y + Z
This is a missing optimization that shows up as a potential regression in D66050,
so we should solve it first. We appear to be partly missing this fold in IR as well.
We do handle the simpler case already:
(-X) * (-Y) --> X * Y
And it might be beneficial to make the constraint less conservative (eg, if both
operands are cheap, but not necessarily cheaper), but that causes infinite looping
for the existing fmul transform.
Differential Revision: https://reviews.llvm.org/D66755
llvm-svn: 370071
This change causes instrumented builds of Clang to have a fatal error in the
backend. https://reviews.llvm.org/D66537 has the details.
llvm-svn: 370006
This improves the combine I included in D66504 to handle constants in the upper operands of the concat. If we can constant fold them away we can pull the concat after the bin op. This helps with chains of madd reductions on X86 from loop unrolling. The loop madd reduction pattern creates pmaddwd with half the width of the add that follows it using zeroes to fill the upper bits. If we have two of these added together we can pull the zeroes through the accumulating add and then shrink it.
Differential Revision: https://reviews.llvm.org/D66680
llvm-svn: 369937
Summary:
This comes as a first step toward processing the DAG nodes in topological orders. Doing so ensure that arguments of a node are combined before the node itself is combined, which exposes ore opportunities for optimization and/or reduce the amount of patterns a node has to match for.
DAGCombiner adding nodes to the worklist is various places causes the nodes to be in a different order from what is expected. In addition, this is reduant because these nodes end up being added to the worklist anyways due to the machinery at line 1621.
Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66537
llvm-svn: 369927
Summary:
Concat_vectors is more canonical during early DAG combine. For example, its what's used by SelectionDAGBuilder when converting IR shuffles into SelectionDAG shuffles when element counts between inputs and mask don't match. We also have combines in DAGCombiner than can pull concat_vectors through a shuffle. See partitionShuffleOfConcats. So it seems like concat_vectors is a better operation to use here. I had to teach DAGCombiner's SimplifyVBinOp to also handle concat_vectors with undef. I haven't checked yet if we can remove the INSERT_SUBVECTOR version in there or not.
I didn't want to mess with the other caller of getShuffleHalfVectors that's used during shuffle lowering where insert_subvector probably is what we want to produce so I've enabled this via a boolean passed to the function.
Reviewers: spatel, RKSimon
Reviewed By: RKSimon
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66504
llvm-svn: 369872
These can turn up during multiplication legalization. In principle
these should also apply to smul_lohi, but I wasn't able to figure
out how to produce those with the necessary operands.
Differential Revision: https://reviews.llvm.org/D66380
llvm-svn: 369864
If the accumulator and either of the multiply operands are negatable then we can we negate the entire expression.
Differential Revision: https://reviews.llvm.org/D63141
llvm-svn: 369746
Summary: These nodes end up being processed regardless due to DAGCombiner ensuring arguments are processed. This changes the order in which nodes are processed, which fixes an issue on PowerPC.
Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri, mcberg2017, stefanp, hfinkel
Subscribers: nemanjai, MaskRay, jsji, steven.zhang, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66548
llvm-svn: 369662
Summary:
These calls change the order in which some nodes are processed and so have an effect on codegen.
The change in fixup-bw-copy.ll is due to (and (load anyext)) gets transformed into (load zext) while previously the and was removed by SimplifyDemandedBits, so the (load anyext) remained.
Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66543
llvm-svn: 369561
I also had to add a new combine to X86's combineExtractSubvector to prevent a regression.
This helps our vXi1 code see the full concat operation and allow it optimize undef to a zero if there is already a zero in the concat. This helped us use a movzx instead of an AND in some of the tests. In those tests, one concat comes from SelectionDAGBuilder and the second comes from type legalization of v4i1->i4 bitcasts which uses an additional concat. Though these changes weren't my original motivation.
I'm looking at making X86ISelLowering's narrowShuffle emit a concat_vectors instead of an insert_subvector since concat_vectors is more canonical during early DAG combine. This patch helps prevent a regression from my experiments with that.
Differential Revision: https://reviews.llvm.org/D66456
llvm-svn: 369459
Set the StartIdx type to size_t so that it matches the StoreNodes SmallVector size() and index types.
Silences the MSVC analyzer warning that unsigned increment might overflow before exceeding size_t on 64-bit targets - this isn't likely to happen but it means we use consistent types and reduces the warning "noise" a little.
llvm-svn: 368998
This is the codegen part of fixing:
https://bugs.llvm.org/show_bug.cgi?id=32939
Even with the optimal/canonical IR that is ideally created by D65954,
we would reverse that transform in DAGCombiner and end up with the same
asm on AArch64 or x86.
I see 2 options for trying to correct this:
1. Limit isNegatibleForFree() by special-casing the fmul pattern (this patch).
2. Avoid creating (fmul X, 2.0) in the 1st place by adding a special-case
transform to SelectionDAG::getNode() and/or SelectionDAGBuilder::visitFMul()
that matches the transform done by DAGCombiner.
This seems like the less intrusive patch, but if there's some other reason to
prefer 1 option over the other, we can change to the other option.
Differential Revision: https://reviews.llvm.org/D66016
llvm-svn: 368490
We may be able to look to how VSELECT is handled to further
improve this, but this appears to be neutral or an improvement
on the test cases we have.
llvm-svn: 368344
Summary:
Before this patch MGATHER/MSCATTER is capable of representing all
common addressing modes, but only when illegal types are used.
This patch adds an IndexType property so more representations
are available when using legal types only.
Original modes:
vector of bases
base + vector of signed scaled offsets
New modes:
base + vector of signed unscaled offsets
base + vector of unsigned scaled offsets
base + vector of unsigned unscaled offsets
The current behaviour of addressing modes for gather/scatter remains
unchanged.
Patch by Paul Walker.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D65636
llvm-svn: 368008
The test case is based on the example from the post-commit thread for:
https://reviews.llvm.org/rGc9171bd0a955
This replaces the x86-specific simple-type check from:
rL367766
with a check in the DAGCombiner. Adding the check isn't
strictly necessary after the fix from:
rL367768
...but it seems likely that we're heading for trouble if
we are creating weird types in this transform.
I combined the earlier legality check into the initial
clause to simplify the code.
So we should only try the trunc/sext transform at the
earliest combine stage, but we limit the transform to
simple types anyway because the TLI hook is probably
too lax about what it considers a free truncate.
llvm-svn: 367834
This is further fix for PR42880.
Sanjay already disabled the X86 TLI hook for non-simple types,
but we should really call isTypeLegal here if we're after type
legalization.
llvm-svn: 367768
This reverses a questionable IR canonicalization when a truncate
is free:
sra (add (shl X, N1C), AddC), N1C -->
sext (add (trunc X to (width - N1C)), AddC')
https://rise4fun.com/Alive/slRC
More details in PR42644:
https://bugs.llvm.org/show_bug.cgi?id=42644
I limited this to pre-legalization for code simplicity because that
should be enough to reverse the IR patterns. I don't have any
evidence (no regression test diffs) that we need to try this later.
Differential Revision: https://reviews.llvm.org/D65607
llvm-svn: 367710
If a type is larger than a legal type and needs to be split, we would previously allow the multiply to be decomposed even if the split multiply is legal. Since the shift + add/sub code would also need to be split, its not any better to decompose it.
This patch figures out what type the mul will eventually be legalized to and then uses that type for the query. I tried just returning false illegal types and letting them get handled after type legalization, but then we can't recognize and i64 constant splat on 32-bit targets since will be destroyed by type legalization. We could special case vectors of i64 to avoid that...
Differential Revision: https://reviews.llvm.org/D65533
llvm-svn: 367601
Sanjay Patel