1 //===- llvm/unittest/Support/KnownBitsTest.cpp - KnownBits tests ----------===//
2 //
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
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements unit tests for KnownBits functions.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/Support/KnownBits.h"
14 #include "KnownBitsTest.h"
15 #include "gtest/gtest.h"
16 
17 using namespace llvm;
18 
19 namespace {
20 
21 TEST(KnownBitsTest, AddCarryExhaustive) {
22   unsigned Bits = 4;
23   ForeachKnownBits(Bits, [&](const KnownBits &Known1) {
24     ForeachKnownBits(Bits, [&](const KnownBits &Known2) {
25       ForeachKnownBits(1, [&](const KnownBits &KnownCarry) {
26         // Explicitly compute known bits of the addition by trying all
27         // possibilities.
28         KnownBits Known(Bits);
29         Known.Zero.setAllBits();
30         Known.One.setAllBits();
31         ForeachNumInKnownBits(Known1, [&](const APInt &N1) {
32           ForeachNumInKnownBits(Known2, [&](const APInt &N2) {
33             ForeachNumInKnownBits(KnownCarry, [&](const APInt &Carry) {
34               APInt Add = N1 + N2;
35               if (Carry.getBoolValue())
36                 ++Add;
37 
38               Known.One &= Add;
39               Known.Zero &= ~Add;
40             });
41           });
42         });
43 
44         KnownBits KnownComputed = KnownBits::computeForAddCarry(
45             Known1, Known2, KnownCarry);
46         EXPECT_EQ(Known.Zero, KnownComputed.Zero);
47         EXPECT_EQ(Known.One, KnownComputed.One);
48       });
49     });
50   });
51 }
52 
53 static void TestAddSubExhaustive(bool IsAdd) {
54   unsigned Bits = 4;
55   ForeachKnownBits(Bits, [&](const KnownBits &Known1) {
56     ForeachKnownBits(Bits, [&](const KnownBits &Known2) {
57       KnownBits Known(Bits), KnownNSW(Bits);
58       Known.Zero.setAllBits();
59       Known.One.setAllBits();
60       KnownNSW.Zero.setAllBits();
61       KnownNSW.One.setAllBits();
62 
63       ForeachNumInKnownBits(Known1, [&](const APInt &N1) {
64         ForeachNumInKnownBits(Known2, [&](const APInt &N2) {
65           bool Overflow;
66           APInt Res;
67           if (IsAdd)
68             Res = N1.sadd_ov(N2, Overflow);
69           else
70             Res = N1.ssub_ov(N2, Overflow);
71 
72           Known.One &= Res;
73           Known.Zero &= ~Res;
74 
75           if (!Overflow) {
76             KnownNSW.One &= Res;
77             KnownNSW.Zero &= ~Res;
78           }
79         });
80       });
81 
82       KnownBits KnownComputed = KnownBits::computeForAddSub(
83           IsAdd, /*NSW*/false, Known1, Known2);
84       EXPECT_EQ(Known.Zero, KnownComputed.Zero);
85       EXPECT_EQ(Known.One, KnownComputed.One);
86 
87       // The NSW calculation is not precise, only check that it's
88       // conservatively correct.
89       KnownBits KnownNSWComputed = KnownBits::computeForAddSub(
90           IsAdd, /*NSW*/true, Known1, Known2);
91       EXPECT_TRUE(KnownNSWComputed.Zero.isSubsetOf(KnownNSW.Zero));
92       EXPECT_TRUE(KnownNSWComputed.One.isSubsetOf(KnownNSW.One));
93     });
94   });
95 }
96 
97 TEST(KnownBitsTest, AddSubExhaustive) {
98   TestAddSubExhaustive(true);
99   TestAddSubExhaustive(false);
100 }
101 
102 TEST(KnownBitsTest, BinaryExhaustive) {
103   unsigned Bits = 4;
104   ForeachKnownBits(Bits, [&](const KnownBits &Known1) {
105     ForeachKnownBits(Bits, [&](const KnownBits &Known2) {
106       KnownBits KnownAnd(Bits);
107       KnownAnd.Zero.setAllBits();
108       KnownAnd.One.setAllBits();
109       KnownBits KnownOr(KnownAnd);
110       KnownBits KnownXor(KnownAnd);
111       KnownBits KnownUMax(KnownAnd);
112       KnownBits KnownUMin(KnownAnd);
113       KnownBits KnownSMax(KnownAnd);
114       KnownBits KnownSMin(KnownAnd);
115       KnownBits KnownMul(KnownAnd);
116       KnownBits KnownMulHS(KnownAnd);
117       KnownBits KnownMulHU(KnownAnd);
118       KnownBits KnownUDiv(KnownAnd);
119       KnownBits KnownURem(KnownAnd);
120       KnownBits KnownSRem(KnownAnd);
121       KnownBits KnownShl(KnownAnd);
122       KnownBits KnownLShr(KnownAnd);
123       KnownBits KnownAShr(KnownAnd);
124 
125       ForeachNumInKnownBits(Known1, [&](const APInt &N1) {
126         ForeachNumInKnownBits(Known2, [&](const APInt &N2) {
127           APInt Res;
128 
129           Res = N1 & N2;
130           KnownAnd.One &= Res;
131           KnownAnd.Zero &= ~Res;
132 
133           Res = N1 | N2;
134           KnownOr.One &= Res;
135           KnownOr.Zero &= ~Res;
136 
137           Res = N1 ^ N2;
138           KnownXor.One &= Res;
139           KnownXor.Zero &= ~Res;
140 
141           Res = APIntOps::umax(N1, N2);
142           KnownUMax.One &= Res;
143           KnownUMax.Zero &= ~Res;
144 
145           Res = APIntOps::umin(N1, N2);
146           KnownUMin.One &= Res;
147           KnownUMin.Zero &= ~Res;
148 
149           Res = APIntOps::smax(N1, N2);
150           KnownSMax.One &= Res;
151           KnownSMax.Zero &= ~Res;
152 
153           Res = APIntOps::smin(N1, N2);
154           KnownSMin.One &= Res;
155           KnownSMin.Zero &= ~Res;
156 
157           Res = N1 * N2;
158           KnownMul.One &= Res;
159           KnownMul.Zero &= ~Res;
160 
161           Res = (N1.sext(2 * Bits) * N2.sext(2 * Bits)).extractBits(Bits, Bits);
162           KnownMulHS.One &= Res;
163           KnownMulHS.Zero &= ~Res;
164 
165           Res = (N1.zext(2 * Bits) * N2.zext(2 * Bits)).extractBits(Bits, Bits);
166           KnownMulHU.One &= Res;
167           KnownMulHU.Zero &= ~Res;
168 
169           if (!N2.isNullValue()) {
170             Res = N1.udiv(N2);
171             KnownUDiv.One &= Res;
172             KnownUDiv.Zero &= ~Res;
173 
174             Res = N1.urem(N2);
175             KnownURem.One &= Res;
176             KnownURem.Zero &= ~Res;
177 
178             Res = N1.srem(N2);
179             KnownSRem.One &= Res;
180             KnownSRem.Zero &= ~Res;
181           }
182 
183           if (N2.ult(1ULL << N1.getBitWidth())) {
184             Res = N1.shl(N2);
185             KnownShl.One &= Res;
186             KnownShl.Zero &= ~Res;
187 
188             Res = N1.lshr(N2);
189             KnownLShr.One &= Res;
190             KnownLShr.Zero &= ~Res;
191 
192             Res = N1.ashr(N2);
193             KnownAShr.One &= Res;
194             KnownAShr.Zero &= ~Res;
195           } else {
196             KnownShl.resetAll();
197             KnownLShr.resetAll();
198             KnownAShr.resetAll();
199           }
200         });
201       });
202 
203       KnownBits ComputedAnd = Known1 & Known2;
204       EXPECT_EQ(KnownAnd.Zero, ComputedAnd.Zero);
205       EXPECT_EQ(KnownAnd.One, ComputedAnd.One);
206 
207       KnownBits ComputedOr = Known1 | Known2;
208       EXPECT_EQ(KnownOr.Zero, ComputedOr.Zero);
209       EXPECT_EQ(KnownOr.One, ComputedOr.One);
210 
211       KnownBits ComputedXor = Known1 ^ Known2;
212       EXPECT_EQ(KnownXor.Zero, ComputedXor.Zero);
213       EXPECT_EQ(KnownXor.One, ComputedXor.One);
214 
215       KnownBits ComputedUMax = KnownBits::umax(Known1, Known2);
216       EXPECT_EQ(KnownUMax.Zero, ComputedUMax.Zero);
217       EXPECT_EQ(KnownUMax.One, ComputedUMax.One);
218 
219       KnownBits ComputedUMin = KnownBits::umin(Known1, Known2);
220       EXPECT_EQ(KnownUMin.Zero, ComputedUMin.Zero);
221       EXPECT_EQ(KnownUMin.One, ComputedUMin.One);
222 
223       KnownBits ComputedSMax = KnownBits::smax(Known1, Known2);
224       EXPECT_EQ(KnownSMax.Zero, ComputedSMax.Zero);
225       EXPECT_EQ(KnownSMax.One, ComputedSMax.One);
226 
227       KnownBits ComputedSMin = KnownBits::smin(Known1, Known2);
228       EXPECT_EQ(KnownSMin.Zero, ComputedSMin.Zero);
229       EXPECT_EQ(KnownSMin.One, ComputedSMin.One);
230 
231       // The following are conservatively correct, but not guaranteed to be
232       // precise.
233       KnownBits ComputedMul = KnownBits::computeForMul(Known1, Known2);
234       EXPECT_TRUE(ComputedMul.Zero.isSubsetOf(KnownMul.Zero));
235       EXPECT_TRUE(ComputedMul.One.isSubsetOf(KnownMul.One));
236 
237       KnownBits ComputedMulHS = KnownBits::mulhs(Known1, Known2);
238       EXPECT_TRUE(ComputedMulHS.Zero.isSubsetOf(KnownMulHS.Zero));
239       EXPECT_TRUE(ComputedMulHS.One.isSubsetOf(KnownMulHS.One));
240 
241       KnownBits ComputedMulHU = KnownBits::mulhu(Known1, Known2);
242       EXPECT_TRUE(ComputedMulHU.Zero.isSubsetOf(KnownMulHU.Zero));
243       EXPECT_TRUE(ComputedMulHU.One.isSubsetOf(KnownMulHU.One));
244 
245       KnownBits ComputedUDiv = KnownBits::udiv(Known1, Known2);
246       EXPECT_TRUE(ComputedUDiv.Zero.isSubsetOf(KnownUDiv.Zero));
247       EXPECT_TRUE(ComputedUDiv.One.isSubsetOf(KnownUDiv.One));
248 
249       KnownBits ComputedURem = KnownBits::urem(Known1, Known2);
250       EXPECT_TRUE(ComputedURem.Zero.isSubsetOf(KnownURem.Zero));
251       EXPECT_TRUE(ComputedURem.One.isSubsetOf(KnownURem.One));
252 
253       KnownBits ComputedSRem = KnownBits::srem(Known1, Known2);
254       EXPECT_TRUE(ComputedSRem.Zero.isSubsetOf(KnownSRem.Zero));
255       EXPECT_TRUE(ComputedSRem.One.isSubsetOf(KnownSRem.One));
256 
257       KnownBits ComputedShl = KnownBits::shl(Known1, Known2);
258       EXPECT_TRUE(ComputedShl.Zero.isSubsetOf(KnownShl.Zero));
259       EXPECT_TRUE(ComputedShl.One.isSubsetOf(KnownShl.One));
260 
261       KnownBits ComputedLShr = KnownBits::lshr(Known1, Known2);
262       EXPECT_TRUE(ComputedLShr.Zero.isSubsetOf(KnownLShr.Zero));
263       EXPECT_TRUE(ComputedLShr.One.isSubsetOf(KnownLShr.One));
264 
265       KnownBits ComputedAShr = KnownBits::ashr(Known1, Known2);
266       EXPECT_TRUE(ComputedAShr.Zero.isSubsetOf(KnownAShr.Zero));
267       EXPECT_TRUE(ComputedAShr.One.isSubsetOf(KnownAShr.One));
268     });
269   });
270 }
271 
272 TEST(KnownBitsTest, UnaryExhaustive) {
273   unsigned Bits = 4;
274   ForeachKnownBits(Bits, [&](const KnownBits &Known) {
275     KnownBits KnownAbs(Bits);
276     KnownAbs.Zero.setAllBits();
277     KnownAbs.One.setAllBits();
278     KnownBits KnownAbsPoison(KnownAbs);
279 
280     ForeachNumInKnownBits(Known, [&](const APInt &N) {
281       APInt Res = N.abs();
282       KnownAbs.One &= Res;
283       KnownAbs.Zero &= ~Res;
284 
285       if (!N.isMinSignedValue()) {
286         KnownAbsPoison.One &= Res;
287         KnownAbsPoison.Zero &= ~Res;
288       }
289     });
290 
291     // abs() is conservatively correct, but not guaranteed to be precise.
292     KnownBits ComputedAbs = Known.abs();
293     EXPECT_TRUE(ComputedAbs.Zero.isSubsetOf(KnownAbs.Zero));
294     EXPECT_TRUE(ComputedAbs.One.isSubsetOf(KnownAbs.One));
295 
296     KnownBits ComputedAbsPoison = Known.abs(true);
297     EXPECT_TRUE(ComputedAbsPoison.Zero.isSubsetOf(KnownAbsPoison.Zero));
298     EXPECT_TRUE(ComputedAbsPoison.One.isSubsetOf(KnownAbsPoison.One));
299   });
300 }
301 
302 TEST(KnownBitsTest, ICmpExhaustive) {
303   unsigned Bits = 4;
304   ForeachKnownBits(Bits, [&](const KnownBits &Known1) {
305     ForeachKnownBits(Bits, [&](const KnownBits &Known2) {
306       bool AllEQ = true, NoneEQ = true;
307       bool AllNE = true, NoneNE = true;
308       bool AllUGT = true, NoneUGT = true;
309       bool AllUGE = true, NoneUGE = true;
310       bool AllULT = true, NoneULT = true;
311       bool AllULE = true, NoneULE = true;
312       bool AllSGT = true, NoneSGT = true;
313       bool AllSGE = true, NoneSGE = true;
314       bool AllSLT = true, NoneSLT = true;
315       bool AllSLE = true, NoneSLE = true;
316 
317       ForeachNumInKnownBits(Known1, [&](const APInt &N1) {
318         ForeachNumInKnownBits(Known2, [&](const APInt &N2) {
319           AllEQ &= N1.eq(N2);
320           AllNE &= N1.ne(N2);
321           AllUGT &= N1.ugt(N2);
322           AllUGE &= N1.uge(N2);
323           AllULT &= N1.ult(N2);
324           AllULE &= N1.ule(N2);
325           AllSGT &= N1.sgt(N2);
326           AllSGE &= N1.sge(N2);
327           AllSLT &= N1.slt(N2);
328           AllSLE &= N1.sle(N2);
329           NoneEQ &= !N1.eq(N2);
330           NoneNE &= !N1.ne(N2);
331           NoneUGT &= !N1.ugt(N2);
332           NoneUGE &= !N1.uge(N2);
333           NoneULT &= !N1.ult(N2);
334           NoneULE &= !N1.ule(N2);
335           NoneSGT &= !N1.sgt(N2);
336           NoneSGE &= !N1.sge(N2);
337           NoneSLT &= !N1.slt(N2);
338           NoneSLE &= !N1.sle(N2);
339         });
340       });
341 
342       Optional<bool> KnownEQ = KnownBits::eq(Known1, Known2);
343       Optional<bool> KnownNE = KnownBits::ne(Known1, Known2);
344       Optional<bool> KnownUGT = KnownBits::ugt(Known1, Known2);
345       Optional<bool> KnownUGE = KnownBits::uge(Known1, Known2);
346       Optional<bool> KnownULT = KnownBits::ult(Known1, Known2);
347       Optional<bool> KnownULE = KnownBits::ule(Known1, Known2);
348       Optional<bool> KnownSGT = KnownBits::sgt(Known1, Known2);
349       Optional<bool> KnownSGE = KnownBits::sge(Known1, Known2);
350       Optional<bool> KnownSLT = KnownBits::slt(Known1, Known2);
351       Optional<bool> KnownSLE = KnownBits::sle(Known1, Known2);
352 
353       EXPECT_EQ(AllEQ || NoneEQ, KnownEQ.hasValue());
354       EXPECT_EQ(AllNE || NoneNE, KnownNE.hasValue());
355       EXPECT_EQ(AllUGT || NoneUGT, KnownUGT.hasValue());
356       EXPECT_EQ(AllUGE || NoneUGE, KnownUGE.hasValue());
357       EXPECT_EQ(AllULT || NoneULT, KnownULT.hasValue());
358       EXPECT_EQ(AllULE || NoneULE, KnownULE.hasValue());
359       EXPECT_EQ(AllSGT || NoneSGT, KnownSGT.hasValue());
360       EXPECT_EQ(AllSGE || NoneSGE, KnownSGE.hasValue());
361       EXPECT_EQ(AllSLT || NoneSLT, KnownSLT.hasValue());
362       EXPECT_EQ(AllSLE || NoneSLE, KnownSLE.hasValue());
363 
364       EXPECT_EQ(AllEQ, KnownEQ.hasValue() && KnownEQ.getValue());
365       EXPECT_EQ(AllNE, KnownNE.hasValue() && KnownNE.getValue());
366       EXPECT_EQ(AllUGT, KnownUGT.hasValue() && KnownUGT.getValue());
367       EXPECT_EQ(AllUGE, KnownUGE.hasValue() && KnownUGE.getValue());
368       EXPECT_EQ(AllULT, KnownULT.hasValue() && KnownULT.getValue());
369       EXPECT_EQ(AllULE, KnownULE.hasValue() && KnownULE.getValue());
370       EXPECT_EQ(AllSGT, KnownSGT.hasValue() && KnownSGT.getValue());
371       EXPECT_EQ(AllSGE, KnownSGE.hasValue() && KnownSGE.getValue());
372       EXPECT_EQ(AllSLT, KnownSLT.hasValue() && KnownSLT.getValue());
373       EXPECT_EQ(AllSLE, KnownSLE.hasValue() && KnownSLE.getValue());
374 
375       EXPECT_EQ(NoneEQ, KnownEQ.hasValue() && !KnownEQ.getValue());
376       EXPECT_EQ(NoneNE, KnownNE.hasValue() && !KnownNE.getValue());
377       EXPECT_EQ(NoneUGT, KnownUGT.hasValue() && !KnownUGT.getValue());
378       EXPECT_EQ(NoneUGE, KnownUGE.hasValue() && !KnownUGE.getValue());
379       EXPECT_EQ(NoneULT, KnownULT.hasValue() && !KnownULT.getValue());
380       EXPECT_EQ(NoneULE, KnownULE.hasValue() && !KnownULE.getValue());
381       EXPECT_EQ(NoneSGT, KnownSGT.hasValue() && !KnownSGT.getValue());
382       EXPECT_EQ(NoneSGE, KnownSGE.hasValue() && !KnownSGE.getValue());
383       EXPECT_EQ(NoneSLT, KnownSLT.hasValue() && !KnownSLT.getValue());
384       EXPECT_EQ(NoneSLE, KnownSLE.hasValue() && !KnownSLE.getValue());
385     });
386   });
387 }
388 
389 TEST(KnownBitsTest, GetMinMaxVal) {
390   unsigned Bits = 4;
391   ForeachKnownBits(Bits, [&](const KnownBits &Known) {
392     APInt Min = APInt::getMaxValue(Bits);
393     APInt Max = APInt::getMinValue(Bits);
394     ForeachNumInKnownBits(Known, [&](const APInt &N) {
395       Min = APIntOps::umin(Min, N);
396       Max = APIntOps::umax(Max, N);
397     });
398     EXPECT_EQ(Min, Known.getMinValue());
399     EXPECT_EQ(Max, Known.getMaxValue());
400   });
401 }
402 
403 TEST(KnownBitsTest, GetSignedMinMaxVal) {
404   unsigned Bits = 4;
405   ForeachKnownBits(Bits, [&](const KnownBits &Known) {
406     APInt Min = APInt::getSignedMaxValue(Bits);
407     APInt Max = APInt::getSignedMinValue(Bits);
408     ForeachNumInKnownBits(Known, [&](const APInt &N) {
409       Min = APIntOps::smin(Min, N);
410       Max = APIntOps::smax(Max, N);
411     });
412     EXPECT_EQ(Min, Known.getSignedMinValue());
413     EXPECT_EQ(Max, Known.getSignedMaxValue());
414   });
415 }
416 
417 TEST(KnownBitsTest, SExtOrTrunc) {
418   const unsigned NarrowerSize = 4;
419   const unsigned BaseSize = 6;
420   const unsigned WiderSize = 8;
421   APInt NegativeFitsNarrower(BaseSize, -4, /*isSigned*/ true);
422   APInt NegativeDoesntFitNarrower(BaseSize, -28, /*isSigned*/ true);
423   APInt PositiveFitsNarrower(BaseSize, 14);
424   APInt PositiveDoesntFitNarrower(BaseSize, 36);
425   auto InitKnownBits = [&](KnownBits &Res, const APInt &Input) {
426     Res = KnownBits(Input.getBitWidth());
427     Res.One = Input;
428     Res.Zero = ~Input;
429   };
430 
431   for (unsigned Size : {NarrowerSize, BaseSize, WiderSize}) {
432     for (const APInt &Input :
433          {NegativeFitsNarrower, NegativeDoesntFitNarrower, PositiveFitsNarrower,
434           PositiveDoesntFitNarrower}) {
435       KnownBits Test;
436       InitKnownBits(Test, Input);
437       KnownBits Baseline;
438       InitKnownBits(Baseline, Input.sextOrTrunc(Size));
439       Test = Test.sextOrTrunc(Size);
440       EXPECT_EQ(Test.One, Baseline.One);
441       EXPECT_EQ(Test.Zero, Baseline.Zero);
442     }
443   }
444 }
445 
446 TEST(KnownBitsTest, SExtInReg) {
447   unsigned Bits = 4;
448   for (unsigned FromBits = 1; FromBits <= Bits; ++FromBits) {
449     ForeachKnownBits(Bits, [&](const KnownBits &Known) {
450       APInt CommonOne = APInt::getAllOnesValue(Bits);
451       APInt CommonZero = APInt::getAllOnesValue(Bits);
452       unsigned ExtBits = Bits - FromBits;
453       ForeachNumInKnownBits(Known, [&](const APInt &N) {
454         APInt Ext = N << ExtBits;
455         Ext.ashrInPlace(ExtBits);
456         CommonOne &= Ext;
457         CommonZero &= ~Ext;
458       });
459       KnownBits KnownSExtInReg = Known.sextInReg(FromBits);
460       EXPECT_EQ(CommonOne, KnownSExtInReg.One);
461       EXPECT_EQ(CommonZero, KnownSExtInReg.Zero);
462     });
463   }
464 }
465 
466 } // end anonymous namespace
467