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Merge pull request #21999 from jrose-apple/from-exponential-expletives-to-quadratic-quality (#22045)
Cut down on exponential growth in checking switch exhaustivity. rdar://problem/47365349 (cherry picked from commit 37c30b1)
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+259
-19
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2 files changed

+259
-19
lines changed

‎lib/Sema/TypeCheckSwitchStmt.cpp

Lines changed: 47 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -506,12 +506,35 @@ namespace {
506506
PAIRCASE (SpaceKind::Disjunct, SpaceKind::UnknownCase): {
507507
SmallVector<Space, 4> smallSpaces;
508508
for (auto s : this->getSpaces()) {
509-
if (auto diff = s.minus(other, TC, DC, minusCount))
510-
smallSpaces.push_back(*diff);
511-
else
509+
auto diff = s.minus(other, TC, DC, minusCount);
510+
if (!diff)
512511
return None;
512+
if (diff->getKind() == SpaceKind::Disjunct) {
513+
smallSpaces.append(diff->getSpaces().begin(),
514+
diff->getSpaces().end());
515+
} else {
516+
smallSpaces.push_back(*diff);
517+
}
513518
}
514-
return Space::forDisjunct(smallSpaces);
519+
520+
// Remove any of the later spaces that are contained entirely in an
521+
// earlier one. Since we're not sorting by size, this isn't
522+
// guaranteed to give us a minimal set, but it'll still reduce the
523+
// general (A, B, C) - ((.a1, .b1, .c1) | (.a1, .b1, .c2)) problem.
524+
// This is a quadratic operation but it saves us a LOT of work
525+
// overall.
526+
SmallVector<Space, 4> usefulSmallSpaces;
527+
for (const Space &space : smallSpaces) {
528+
bool alreadyHandled = llvm::any_of(usefulSmallSpaces,
529+
[&](const Space &previousSpace) {
530+
return space.isSubspace(previousSpace, TC, DC);
531+
});
532+
if (alreadyHandled)
533+
continue;
534+
usefulSmallSpaces.push_back(space);
535+
}
536+
537+
return Space::forDisjunct(usefulSmallSpaces);
515538
}
516539
PAIRCASE (SpaceKind::Constructor, SpaceKind::Type):
517540
return Space();
@@ -923,26 +946,31 @@ namespace {
923946

924947
Space projection = projectPattern(TC, caseItem.getPattern());
925948

926-
if (!projection.isEmpty() &&
927-
projection.isSubspace(Space::forDisjunct(spaces), TC, DC)) {
949+
bool isRedundant = !projection.isEmpty() &&
950+
llvm::any_of(spaces, [&](const Space &handled) {
951+
return projection.isSubspace(handled, TC, DC);
952+
});
953+
if (isRedundant) {
928954
TC.diagnose(caseItem.getStartLoc(),
929955
diag::redundant_particular_case)
930956
.highlight(caseItem.getSourceRange());
931957
continue;
932-
} else {
933-
Expr *cachedExpr = nullptr;
934-
if (checkRedundantLiteral(caseItem.getPattern(), cachedExpr)) {
935-
assert(cachedExpr && "Cache found hit but no expr?");
936-
TC.diagnose(caseItem.getStartLoc(),
937-
diag::redundant_particular_literal_case)
938-
.highlight(caseItem.getSourceRange());
939-
TC.diagnose(cachedExpr->getLoc(),
940-
diag::redundant_particular_literal_case_here)
941-
.highlight(cachedExpr->getSourceRange());
942-
continue;
943-
}
944958
}
945-
spaces.push_back(projection);
959+
960+
Expr *cachedExpr = nullptr;
961+
if (checkRedundantLiteral(caseItem.getPattern(), cachedExpr)) {
962+
assert(cachedExpr && "Cache found hit but no expr?");
963+
TC.diagnose(caseItem.getStartLoc(),
964+
diag::redundant_particular_literal_case)
965+
.highlight(caseItem.getSourceRange());
966+
TC.diagnose(cachedExpr->getLoc(),
967+
diag::redundant_particular_literal_case_here)
968+
.highlight(cachedExpr->getSourceRange());
969+
continue;
970+
}
971+
972+
if (!projection.isEmpty())
973+
spaces.push_back(projection);
946974
}
947975
}
948976

‎validation-test/Sema/large-switch-rdar47365349.swift

Lines changed: 212 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,212 @@
1+
// RUN: %target-typecheck-verify-swift
2+
3+
enum NumericBase {
4+
case binary
5+
case ternary
6+
case quaternary
7+
case quinary
8+
case senary
9+
case septary
10+
case octal
11+
case nonary
12+
case decimal
13+
case undecimal
14+
case duodecimal
15+
}
16+
17+
enum Direction {
18+
case left
19+
case right
20+
}
21+
22+
enum WritingSystem {
23+
case logographic
24+
case alphabet(kind: Alphabet)
25+
case abjad
26+
case abugida
27+
case syllabary
28+
case other
29+
}
30+
31+
enum Alphabet {
32+
case roman
33+
case greek
34+
case cyrillic
35+
}
36+
37+
func test(base: NumericBase, direction: Direction, writingSystem: WritingSystem) {
38+
switch (base, direction, writingSystem) {
39+
case (.binary, .left, .logographic),
40+
(.binary, .left, .alphabet),
41+
(.binary, .left, .abugida):
42+
break
43+
44+
case (.binary, .right, .logographic),
45+
(.binary, .right, .alphabet),
46+
(.binary, .right, .abugida):
47+
break
48+
49+
case (.binary, _, .abjad):
50+
break
51+
52+
case (.binary, _, .syllabary):
53+
break
54+
55+
case (.ternary, .left, .logographic):
56+
break
57+
58+
case (.ternary, .left, .alphabet),
59+
(.ternary, .left, .abugida):
60+
break
61+
62+
case (.ternary, .right, .logographic),
63+
(.ternary, .right, .abugida):
64+
break
65+
66+
case (.ternary, .right, .alphabet):
67+
break
68+
69+
case (.ternary, _, .abjad):
70+
break
71+
72+
case (.ternary, _, .syllabary):
73+
break
74+
75+
case (.quaternary, .left, .logographic):
76+
break
77+
78+
case (.quaternary, .left, .alphabet),
79+
(.quaternary, .left, .abugida):
80+
break
81+
82+
case (.quaternary, .right, .logographic),
83+
(.quaternary, .right, .abugida):
84+
break
85+
86+
case (.quaternary, .right, .alphabet):
87+
break
88+
89+
case (.quaternary, _, .abjad):
90+
break
91+
92+
case (.quaternary, _, .syllabary):
93+
break
94+
95+
case (.quinary, .left, .logographic),
96+
(.senary, .left, .logographic):
97+
break
98+
99+
case (.quinary, .left, .alphabet),
100+
(.senary, .left, .alphabet),
101+
(.quinary, .left, .abugida),
102+
(.senary, .left, .abugida):
103+
break
104+
105+
case (.quinary, .right, .logographic),
106+
(.senary, .right, .logographic):
107+
break
108+
109+
case (.quinary, .right, .alphabet),
110+
(.senary, .right, .alphabet),
111+
(.quinary, .right, .abugida),
112+
(.senary, .right, .abugida):
113+
break
114+
115+
case (.quinary, _, .abjad),
116+
(.senary, _, .abjad):
117+
break
118+
119+
case (.quinary, _, .syllabary),
120+
(.senary, _, .syllabary):
121+
break
122+
123+
case (.septary, .left, .logographic):
124+
break
125+
126+
case (.septary, .left, .alphabet),
127+
(.septary, .left, .abugida):
128+
break
129+
130+
case (.septary, .right, .logographic):
131+
break
132+
133+
case (.septary, .right, .alphabet),
134+
(.septary, .right, .abugida):
135+
break
136+
137+
case (.septary, _, .abjad):
138+
break
139+
140+
case (.septary, _, .syllabary):
141+
break
142+
143+
case (.decimal, .left, .logographic):
144+
break
145+
146+
case (.decimal, .left, .alphabet),
147+
(.decimal, .left, .abugida):
148+
break
149+
150+
case (.decimal, .right, .logographic):
151+
break
152+
153+
case (.decimal, .right, .alphabet),
154+
(.decimal, .right, .abugida):
155+
break
156+
157+
case (.octal, .left, .logographic),
158+
(.nonary, .left, .logographic):
159+
break
160+
161+
case (.octal, .left, .alphabet),
162+
(.nonary, .left, .alphabet),
163+
(.octal, .left, .abugida),
164+
(.nonary, .left, .abugida):
165+
break
166+
167+
case (.octal, .right, .logographic),
168+
(.nonary, .right, .logographic):
169+
break
170+
171+
case (.octal, .right, .alphabet),
172+
(.nonary, .right, .alphabet),
173+
(.octal, .right, .abugida),
174+
(.nonary, .right, .abugida):
175+
break
176+
177+
case (.octal, _, .abjad),
178+
(.nonary, _, .abjad),
179+
(.decimal, _, .abjad):
180+
break
181+
182+
case (.octal, _, .syllabary),
183+
(.nonary, _, .syllabary),
184+
(.decimal, _, .syllabary):
185+
break
186+
187+
case (.undecimal, .left, .logographic):
188+
break
189+
190+
case (.undecimal, .left, .alphabet),
191+
(.undecimal, .left, .abugida):
192+
break
193+
194+
case (.undecimal, .right, .logographic):
195+
break
196+
197+
case (.undecimal, .right, .alphabet),
198+
(.undecimal, .right, .abugida):
199+
break
200+
201+
case (.undecimal, _, .abjad):
202+
break
203+
204+
case (.undecimal, _, .syllabary):
205+
break
206+
207+
case (.duodecimal, _, _):
208+
break
209+
case (_, _, .other):
210+
break
211+
}
212+
}

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