1 //===--- RDFDeadCode.h ----------------------------------------------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // RDF-based generic dead code elimination.
11 // The main interface of this class are functions "collect" and "erase".
12 // This allows custom processing of the function being optimized by a
13 // particular consumer. The simplest way to use this class would be to
14 // instantiate an object, and then simply call "collect" and "erase",
15 // passing the result of "getDeadInstrs()" to it.
16 // A more complex scenario would be to call "collect" first, then visit
17 // all post-increment instructions to see if the address update is dead
18 // or not, and if it is, convert the instruction to a non-updating form.
19 // After that "erase" can be called with the set of nodes including both,
20 // dead defs from the updating instructions and the nodes corresponding
21 // to the dead instructions.
23 #ifndef RDF_DEADCODE_H
24 #define RDF_DEADCODE_H
26 #include "llvm/CodeGen/RDFGraph.h"
27 #include "llvm/CodeGen/RDFLiveness.h"
28 #include "llvm/ADT/SetVector.h"
31 class MachineRegisterInfo
;
34 struct DeadCodeElimination
{
35 DeadCodeElimination(DataFlowGraph
&dfg
, MachineRegisterInfo
&mri
)
36 : Trace(false), DFG(dfg
), MRI(mri
), LV(mri
, dfg
) {}
39 bool erase(const SetVector
<NodeId
> &Nodes
);
40 void trace(bool On
) { Trace
= On
; }
41 bool trace() const { return Trace
; }
43 SetVector
<NodeId
> getDeadNodes() { return DeadNodes
; }
44 SetVector
<NodeId
> getDeadInstrs() { return DeadInstrs
; }
45 DataFlowGraph
&getDFG() { return DFG
; }
49 SetVector
<NodeId
> LiveNodes
;
50 SetVector
<NodeId
> DeadNodes
;
51 SetVector
<NodeId
> DeadInstrs
;
53 MachineRegisterInfo
&MRI
;
56 template<typename T
> struct SetQueue
;
58 bool isLiveInstr(NodeAddr
<StmtNode
*> S
) const;
59 void scanInstr(NodeAddr
<InstrNode
*> IA
, SetQueue
<NodeId
> &WorkQ
);
60 void processDef(NodeAddr
<DefNode
*> DA
, SetQueue
<NodeId
> &WorkQ
);
61 void processUse(NodeAddr
<UseNode
*> UA
, SetQueue
<NodeId
> &WorkQ
);