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<p>Ah, I think that's the difference. Statepoint's MMOs are
referencing stack objects and I hadn't consider that was possible
special. Oh well.</p>
<p>Philip<br>
</p>
<div class="moz-cite-prefix">On 3/18/20 5:41 PM, Craig Topper wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAF7ks-N+QK_yRwBLe7Oy-L=rx7tH5wDL4oV=v3HHFcn9zdcOVw@mail.gmail.com">
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<div dir="ltr">Isn't what's stored in the PointerInfo of a MMO
usually a Value * from IR? Except when its a stack reference or
a constant pool or one of the other PseudoSources?
<div><br clear="all">
<div>
<div dir="ltr" class="gmail_signature"
data-smartmail="gmail_signature">~Craig</div>
</div>
<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, Mar 18, 2020 at 5:32
PM Philip Reames <<a
href="mailto:listmail@philipreames.com"
moz-do-not-send="true">listmail@philipreames.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<p>I wasn't talking about the IR representation at all. At
MC, we can provide multiple MMO on a single instruction.
Given the semantics of a gather, we could encode each
implied memory access separate with it's own {base,
offset} information. So a single gather instruction would
have MMOs: {base, offset1}, {base, offset2}, ....</p>
<p>I hadn't considered the SDAG representation. We handle
that for STATEPOINT (one user of multiple MMOs I happen to
be familiar with) by placing them directly on a target
specific STATEPOINT node. So, yes, we'd probably want to
either allow MemSDNode to have multiple MMOs or split the
usage.</p>
<p>Philip<br>
</p>
<div>On 3/18/20 4:28 PM, Craig Topper wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>There's probably something we can do there. We'd
need a scalar pointer in IR to refer to though right?
We likely have a vector GEP and none of the underlying
APIs know what to do with that. Or we need to change
those APIs to refer to a specific element of the
vector?</div>
<div><br>
</div>
<div>We'd also need a new base class for the gather and
scatter nodes in SelectionDAG other than MemSDNode or
we'd need to change MemSDNode to have more than just a
single MemOperand pointer.</div>
<br clear="all">
<div>
<div dir="ltr">~Craig</div>
</div>
<br>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, Mar 18, 2020
at 4:16 PM Philip Reames via llvm-commits <<a
href="mailto:llvm-commits@lists.llvm.org"
target="_blank" moz-do-not-send="true">llvm-commits@lists.llvm.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px
0px 0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">Just curious, we
have the ability to describe multiple memory locations
<br>
for a single instruction. Why not simply track each
lane independently <br>
and keep the right locations on each half?<br>
<br>
Philip<br>
<br>
On 3/18/20 4:12 PM, Craig Topper via llvm-commits
wrote:<br>
> Author: Craig Topper<br>
> Date: 2020-03-18T16:07:15-07:00<br>
> New Revision:
c69a4d6bef0a1350f509f35beb450dccc2a6c5e2<br>
><br>
> URL: <a
href="https://github.com/llvm/llvm-project/commit/c69a4d6bef0a1350f509f35beb450dccc2a6c5e2"
rel="noreferrer" target="_blank"
moz-do-not-send="true">https://github.com/llvm/llvm-project/commit/c69a4d6bef0a1350f509f35beb450dccc2a6c5e2</a><br>
> DIFF: <a
href="https://github.com/llvm/llvm-project/commit/c69a4d6bef0a1350f509f35beb450dccc2a6c5e2.diff"
rel="noreferrer" target="_blank"
moz-do-not-send="true">https://github.com/llvm/llvm-project/commit/c69a4d6bef0a1350f509f35beb450dccc2a6c5e2.diff</a><br>
><br>
> LOG: [SelectionDAG] When splitting
gathers/scatters in type legalization, set MMO size to
UnknownSize<br>
><br>
> Gather/scatter don't access one memory location,
they access multiple disjoint locations. So using a
fixed size isn't accurate. But we don't have a way to
represent the true behavior so just use UnknownSize.<br>
><br>
> Previously we "split" the memory VT and use that
size for the MMO of each half. But the memory VT is
scalar so splitting usually just returned the original
scalar VT, but on 32-bit X86 if the scalar VT was i64
it probably returned i32?<br>
><br>
> Differential Revision: <a
href="https://reviews.llvm.org/D76388"
rel="noreferrer" target="_blank"
moz-do-not-send="true">https://reviews.llvm.org/D76388</a><br>
><br>
> Added:<br>
> <br>
><br>
> Modified:<br>
>
llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp<br>
><br>
> Removed:<br>
> <br>
><br>
><br>
>
################################################################################<br>
> diff --git
a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp<br>
> index 5a4b4c615bc0..09934bbb29fe 100644<br>
> ---
a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp<br>
> +++
b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp<br>
> @@ -20,10 +20,11 @@<br>
>
//===----------------------------------------------------------------------===//<br>
> <br>
> #include "LegalizeTypes.h"<br>
> +#include "llvm/Analysis/MemoryLocation.h"<br>
> #include "llvm/IR/DataLayout.h"<br>
> #include "llvm/Support/ErrorHandling.h"<br>
> -#include "llvm/Support/raw_ostream.h"<br>
> #include "llvm/Support/TypeSize.h"<br>
> +#include "llvm/Support/raw_ostream.h"<br>
> using namespace llvm;<br>
> <br>
> #define DEBUG_TYPE "legalize-types"<br>
> @@ -1627,11 +1628,6 @@ void
DAGTypeLegalizer::SplitVecRes_MGATHER(MaskedGatherSDNode
*MGT,<br>
> std::tie(MaskLo, MaskHi) =
DAG.SplitVector(Mask, dl);<br>
> }<br>
> <br>
> - EVT MemoryVT = MGT->getMemoryVT();<br>
> - EVT LoMemVT, HiMemVT;<br>
> - // Split MemoryVT<br>
> - std::tie(LoMemVT, HiMemVT) =
DAG.GetSplitDestVTs(MemoryVT);<br>
> -<br>
> SDValue PassThruLo, PassThruHi;<br>
> if (getTypeAction(PassThru.getValueType()) ==
TargetLowering::TypeSplitVector)<br>
> GetSplitVector(PassThru, PassThruLo,
PassThruHi);<br>
> @@ -1644,10 +1640,10 @@ void
DAGTypeLegalizer::SplitVecRes_MGATHER(MaskedGatherSDNode
*MGT,<br>
> else<br>
> std::tie(IndexLo, IndexHi) =
DAG.SplitVector(Index, dl);<br>
> <br>
> - MachineMemOperand *MMO =
DAG.getMachineFunction().<br>
> -
getMachineMemOperand(MGT->getPointerInfo(),<br>
> -
MachineMemOperand::MOLoad, LoMemVT.getStoreSize(),<br>
> - Alignment,
MGT->getAAInfo(), MGT->getRanges());<br>
> + MachineMemOperand *MMO =
DAG.getMachineFunction().getMachineMemOperand(<br>
> + MGT->getPointerInfo(),
MachineMemOperand::MOLoad,<br>
> + MemoryLocation::UnknownSize, Alignment,
MGT->getAAInfo(),<br>
> + MGT->getRanges());<br>
> <br>
> SDValue OpsLo[] = {Ch, PassThruLo, MaskLo,
Ptr, IndexLo, Scale};<br>
> Lo = DAG.getMaskedGather(DAG.getVTList(LoVT,
MVT::Other), LoVT, dl, OpsLo,<br>
> @@ -2376,13 +2372,10 @@ SDValue
DAGTypeLegalizer::SplitVecOp_MSCATTER(MaskedScatterSDNode
*N,<br>
> SDValue Index = N->getIndex();<br>
> SDValue Scale = N->getScale();<br>
> SDValue Data = N->getValue();<br>
> - EVT MemoryVT = N->getMemoryVT();<br>
> unsigned Alignment =
N->getOriginalAlignment();<br>
> SDLoc DL(N);<br>
> <br>
> // Split all operands<br>
> - EVT LoMemVT, HiMemVT;<br>
> - std::tie(LoMemVT, HiMemVT) =
DAG.GetSplitDestVTs(MemoryVT);<br>
> <br>
> SDValue DataLo, DataHi;<br>
> if (getTypeAction(Data.getValueType()) ==
TargetLowering::TypeSplitVector)<br>
> @@ -2409,20 +2402,14 @@ SDValue
DAGTypeLegalizer::SplitVecOp_MSCATTER(MaskedScatterSDNode
*N,<br>
> std::tie(IndexLo, IndexHi) =
DAG.SplitVector(Index, DL);<br>
> <br>
> SDValue Lo;<br>
> - MachineMemOperand *MMO =
DAG.getMachineFunction().<br>
> - getMachineMemOperand(N->getPointerInfo(),<br>
> -
MachineMemOperand::MOStore, LoMemVT.getStoreSize(),<br>
> - Alignment,
N->getAAInfo(), N->getRanges());<br>
> + MachineMemOperand *MMO =
DAG.getMachineFunction().getMachineMemOperand(<br>
> + N->getPointerInfo(),
MachineMemOperand::MOStore,<br>
> + MemoryLocation::UnknownSize, Alignment,
N->getAAInfo(), N->getRanges());<br>
> <br>
> SDValue OpsLo[] = {Ch, DataLo, MaskLo, Ptr,
IndexLo, Scale};<br>
> Lo =
DAG.getMaskedScatter(DAG.getVTList(MVT::Other),
DataLo.getValueType(),<br>
> DL, OpsLo, MMO,
N->getIndexType());<br>
> <br>
> - MMO = DAG.getMachineFunction().<br>
> - getMachineMemOperand(N->getPointerInfo(),<br>
> -
MachineMemOperand::MOStore, HiMemVT.getStoreSize(),<br>
> - Alignment,
N->getAAInfo(), N->getRanges());<br>
> -<br>
> // The order of the Scatter operation after
split is well defined. The "Hi"<br>
> // part comes after the "Lo". So these two
operations should be chained one<br>
> // after another.<br>
><br>
><br>
> <br>
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