Skip to content

Commit 520e3d6

Browse files
dsandersllvmdsandersllvm
committed
[gicombiner] Process the MatchDag such that every node is reachable from the roots
Summary: When we build the walk across these DAG's we need to be able to reach every node from the roots. Flip and traversal edges (so that use->def becomes def->uses) that make nodes unreachable. Note that early on we'll just error out on these flipped edges as def->uses edges are more complicated to match due to their one->many nature. Depends on D69077 Reviewers: volkan, bogner Subscribers: llvm-commits
1 parent 65f94b3 commit 520e3d6

File tree

6 files changed

+102
-4
lines changed

6 files changed

+102
-4
lines changed

‎llvm/include/llvm/ADT/iterator.h

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -333,6 +333,11 @@ make_pointer_range(RangeT &&Range) {
333333
PointerIteratorT(std::end(std::forward<RangeT>(Range))));
334334
}
335335

336+
template <typename WrappedIteratorT,
337+
typename T1 = typename std::remove_reference<decltype(**std::declval<WrappedIteratorT>())>::type,
338+
typename T2 = typename std::add_pointer<T1>::type>
339+
using raw_pointer_iterator = pointer_iterator<pointee_iterator<WrappedIteratorT, T1>, T2>;
340+
336341
// Wrapper iterator over iterator ItType, adding DataRef to the type of ItType,
337342
// to create NodeRef = std::pair<InnerTypeOfItType, DataRef>.
338343
template <typename ItType, typename NodeRef, typename DataRef>

‎llvm/test/TableGen/GICombinerEmitter/parse-match-pattern.td

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -132,8 +132,8 @@ def nonstandardroot : GICombineRule<
132132
// CHECK-NEXT: (MOV 0:dst<def>, 1:src1):$__anon3_0 // $s=getOperand(0), $s2=getOperand(1)
133133
// CHECK-NEXT: (MOV 0:dst<def>, 1:src1):$__anon3_2 // $d1=getOperand(0), $s=getOperand(1)
134134
// CHECK-NEXT: (MOV 0:dst<def>, 1:src1):$__anon3_4 // $d2=getOperand(0), $s=getOperand(1)
135-
// CHECK-NEXT: __anon3_2[src1] --[s]--> __anon3_0[dst]
136-
// CHECK-NEXT: __anon3_4[src1] --[s]--> __anon3_0[dst]
135+
// CHECK-NEXT: __anon3_0[dst] --[s]--> __anon3_2[src1]
136+
// CHECK-NEXT: __anon3_0[dst] --[s]--> __anon3_4[src1]
137137
// CHECK-NEXT: <<$mi.getOpcode() == MOV>>:$__anonpred3_1
138138
// CHECK-NEXT: <<$mi.getOpcode() == MOV>>:$__anonpred3_3
139139
// CHECK-NEXT: <<$mi.getOpcode() == MOV>>:$__anonpred3_5
@@ -150,8 +150,8 @@ def nonstandardroot : GICombineRule<
150150
// CHECK-NEXT: Node[[N1:0x[0-9a-f]+]] [shape=record,label="{{[{]{}}<s0>#0 $dst|<s1>#1 $src1}|__anon3_0|MOV|Match starts here|$s=getOperand(0), $s2=getOperand(1)|{{0x[0-9a-f]+}}|{<d0>#0 $dst|<d1>#1 $src1}}",color=red]
151151
// CHECK-NEXT: Node[[N2:0x[0-9a-f]+]] [shape=record,label="{{[{]{}}<s0>#0 $dst|<s1>#1 $src1}|__anon3_2|MOV|$d1=getOperand(0), $s=getOperand(1)|{{0x[0-9a-f]+}}|{<d0>#0 $dst|<d1>#1 $src1}}"]
152152
// CHECK-NEXT: Node[[N3:0x[0-9a-f]+]] [shape=record,label="{{[{]{}}<s0>#0 $dst|<s1>#1 $src1}|__anon3_4|MOV|$d2=getOperand(0), $s=getOperand(1)|{{0x[0-9a-f]+}}|{<d0>#0 $dst|<d1>#1 $src1}}"]
153-
// CHECK-NEXT: Node[[N2]]:s1:n -> Node[[N1]]:d0:s [label="$s"]
154-
// CHECK-NEXT: Node[[N3]]:s1:n -> Node[[N1]]:d0:s [label="$s"]
153+
// CHECK-NEXT: Node[[N2]]:s1:n -> Node[[N1]]:d0:s [label="$s",dir=back,arrowtail=crow]
154+
// CHECK-NEXT: Node[[N3]]:s1:n -> Node[[N1]]:d0:s [label="$s",dir=back,arrowtail=crow]
155155
// CHECK-NEXT: Pred[[P1:0x[0-9a-f]+]] [shape=record,label="{{[{]{}}<s0>#0 $$|<s1>#1 $mi}|__anonpred3_1|$mi.getOpcode() == MOV|{{0x[0-9a-f]+}}|{<d0>#0 $$|<d1>#1 $mi}}",style=dotted]
156156
// CHECK-NEXT: Pred[[P2:0x[0-9a-f]+]] [shape=record,label="{{[{]{}}<s0>#0 $$|<s1>#1 $mi}|__anonpred3_3|$mi.getOpcode() == MOV|{{0x[0-9a-f]+}}|{<d0>#0 $$|<d1>#1 $mi}}",style=dotted]
157157
// CHECK-NEXT: Pred[[P3:0x[0-9a-f]+]] [shape=record,label="{{[{]{}}<s0>#0 $$|<s1>#1 $mi}|__anonpred3_5|$mi.getOpcode() == MOV|{{0x[0-9a-f]+}}|{<d0>#0 $$|<d1>#1 $mi}}",style=dotted]

‎llvm/utils/TableGen/GICombinerEmitter.cpp

Lines changed: 58 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -11,6 +11,7 @@
1111
///
1212
//===----------------------------------------------------------------------===//
1313

14+
#include "llvm/ADT/SmallSet.h"
1415
#include "llvm/ADT/Statistic.h"
1516
#include "llvm/ADT/StringSet.h"
1617
#include "llvm/Support/CommandLine.h"
@@ -137,6 +138,60 @@ class CombineRule {
137138
iterator_range<const_root_iterator> roots() const {
138139
return llvm::make_range(Roots.begin(), Roots.end());
139140
}
141+
142+
/// The matcher will begin from the roots and will perform the match by
143+
/// traversing the edges to cover the whole DAG. This function reverses DAG
144+
/// edges such that everything is reachable from a root. This is part of the
145+
/// preparation work for flattening the DAG into a tree.
146+
void reorientToRoots() {
147+
SmallSet<const GIMatchDagInstr *, 5> Roots;
148+
SmallSet<const GIMatchDagInstr *, 5> Visited;
149+
SmallSet<GIMatchDagEdge *, 20> EdgesRemaining;
150+
151+
for (auto &I : MatchDag.roots()) {
152+
Roots.insert(I);
153+
Visited.insert(I);
154+
}
155+
for (auto &I : MatchDag.edges())
156+
EdgesRemaining.insert(I);
157+
158+
bool Progressed = false;
159+
SmallSet<GIMatchDagEdge *, 20> EdgesToRemove;
160+
while (!EdgesRemaining.empty()) {
161+
for (auto EI = EdgesRemaining.begin(), EE = EdgesRemaining.end();
162+
EI != EE; ++EI) {
163+
if (Visited.count((*EI)->getFromMI())) {
164+
if (Roots.count((*EI)->getToMI()))
165+
PrintError(TheDef.getLoc(), "One or more roots are unnecessary");
166+
Visited.insert((*EI)->getToMI());
167+
EdgesToRemove.insert(*EI);
168+
Progressed = true;
169+
}
170+
}
171+
for (GIMatchDagEdge *ToRemove : EdgesToRemove)
172+
EdgesRemaining.erase(ToRemove);
173+
EdgesToRemove.clear();
174+
175+
for (auto EI = EdgesRemaining.begin(), EE = EdgesRemaining.end();
176+
EI != EE; ++EI) {
177+
if (Visited.count((*EI)->getToMI())) {
178+
(*EI)->reverse();
179+
Visited.insert((*EI)->getToMI());
180+
EdgesToRemove.insert(*EI);
181+
Progressed = true;
182+
}
183+
for (GIMatchDagEdge *ToRemove : EdgesToRemove)
184+
EdgesRemaining.erase(ToRemove);
185+
EdgesToRemove.clear();
186+
}
187+
188+
if (!Progressed) {
189+
LLVM_DEBUG(dbgs() << "No progress\n");
190+
return;
191+
}
192+
Progressed = false;
193+
}
194+
}
140195
};
141196

142197
/// A convenience function to check that an Init refers to a specific def. This
@@ -450,6 +505,9 @@ GICombinerEmitter::makeCombineRule(const Record &TheDef) {
450505
return nullptr;
451506
if (!Rule->parseMatcher(Target))
452507
return nullptr;
508+
509+
Rule->reorientToRoots();
510+
453511
LLVM_DEBUG({
454512
dbgs() << "Parsed rule defs/match for '" << Rule->getName() << "'\n";
455513
Rule->getMatchDag().dump();

‎llvm/utils/TableGen/GlobalISel/GIMatchDag.h

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -53,6 +53,9 @@ class GIMatchDag {
5353
public:
5454
using InstrNodesVec = std::vector<std::unique_ptr<GIMatchDagInstr>>;
5555
using EdgesVec = std::vector<std::unique_ptr<GIMatchDagEdge>>;
56+
using edge_iterator = raw_pointer_iterator<EdgesVec::iterator>;
57+
using const_edge_iterator = raw_pointer_iterator<EdgesVec::const_iterator>;
58+
5659
using PredicateNodesVec = std::vector<std::unique_ptr<GIMatchDagPredicate>>;
5760

5861
using PredicateDependencyEdgesVec =
@@ -73,6 +76,30 @@ class GIMatchDag {
7376
GIMatchDag(const GIMatchDag &) = delete;
7477

7578
GIMatchDagContext &getContext() const { return Ctx; }
79+
edge_iterator edges_begin() {
80+
return raw_pointer_iterator<EdgesVec::iterator>(Edges.begin());
81+
}
82+
edge_iterator edges_end() {
83+
return raw_pointer_iterator<EdgesVec::iterator>(Edges.end());
84+
}
85+
const_edge_iterator edges_begin() const {
86+
return raw_pointer_iterator<EdgesVec::const_iterator>(Edges.begin());
87+
}
88+
const_edge_iterator edges_end() const {
89+
return raw_pointer_iterator<EdgesVec::const_iterator>(Edges.end());
90+
}
91+
iterator_range<edge_iterator> edges() {
92+
return make_range(edges_begin(), edges_end());
93+
}
94+
iterator_range<const_edge_iterator> edges() const {
95+
return make_range(edges_begin(), edges_end());
96+
}
97+
iterator_range<std::vector<GIMatchDagInstr *>::iterator> roots() {
98+
return make_range(MatchRoots.begin(), MatchRoots.end());
99+
}
100+
iterator_range<std::vector<GIMatchDagInstr *>::const_iterator> roots() const {
101+
return make_range(MatchRoots.begin(), MatchRoots.end());
102+
}
76103

77104
template <class... Args> GIMatchDagInstr *addInstrNode(Args &&... args) {
78105
auto Obj =

‎llvm/utils/TableGen/GlobalISel/GIMatchDagEdge.cpp

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -18,3 +18,8 @@ LLVM_DUMP_METHOD void GIMatchDagEdge::print(raw_ostream &OS) const {
1818
<< "]";
1919
}
2020

21+
void GIMatchDagEdge::reverse() {
22+
std::swap(FromMI, ToMI);
23+
std::swap(FromMO, ToMO);
24+
}
25+

‎llvm/utils/TableGen/GlobalISel/GIMatchDagEdge.h

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -51,6 +51,9 @@ class GIMatchDagEdge {
5151
const GIMatchDagInstr *getToMI() const { return ToMI; }
5252
const GIMatchDagOperand *getToMO() const { return ToMO; }
5353

54+
/// Flip the direction of the edge.
55+
void reverse();
56+
5457
LLVM_DUMP_METHOD void print(raw_ostream &OS) const;
5558

5659
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

0 commit comments

Comments
 (0)