[HashRecognize] Fix big-endian CRC tables (#144754)

artagnon · web-flow · commit a94eb27a29ef · 2025-06-18T20:18:22.000+01:00
Big-endian CRC tables are incorrect due to the initial value of CRC in
genSarwateTable being hard-coded for CRC-8. 128 is the signed-min value
for CRC-8, but it should be generalized to APInt::getSignedMinValue. The
issue was found when writing CRC verification tests for llvm-test-suite.
diff --git a/llvm/lib/Analysis/HashRecognize.cpp b/llvm/lib/Analysis/HashRecognize.cpp
@@ -478,7 +478,7 @@ CRCTable HashRecognize::genSarwateTable(const APInt &GenPoly,
   Table[0] = APInt::getZero(BW);
 
   if (ByteOrderSwapped) {
-    APInt CRCInit(BW, 128);
+    APInt CRCInit = APInt::getSignedMinValue(BW);
     for (unsigned I = 1; I < 256; I <<= 1) {
       CRCInit = CRCInit.shl(1) ^
                 (CRCInit.isSignBitSet() ? GenPoly : APInt::getZero(BW));
diff --git a/llvm/test/Analysis/HashRecognize/cyclic-redundancy-check.ll b/llvm/test/Analysis/HashRecognize/cyclic-redundancy-check.ll
@@ -151,22 +151,22 @@ define i16 @crc16.be.tc8.crc.init.li(i16 %checksum, i8 %msg) {
 ; CHECK-NEXT:    Generating polynomial: 4129
 ; CHECK-NEXT:    Computed CRC: %crc.next = select i1 %check.sb, i16 %crc.xor, i16 %crc.shl
 ; CHECK-NEXT:    Computed CRC lookup table:
-; CHECK-NEXT:  0 256 512 768 1024 1280 1536 1792 2048 2304 2560 2816 3072 3328 3584 3840
-; CHECK-NEXT:  4096 4352 4608 4864 5120 5376 5632 5888 6144 6400 6656 6912 7168 7424 7680 7936
-; CHECK-NEXT:  8192 8448 8704 8960 9216 9472 9728 9984 10240 10496 10752 11008 11264 11520 11776 12032
-; CHECK-NEXT:  12288 12544 12800 13056 13312 13568 13824 14080 14336 14592 14848 15104 15360 15616 15872 16128
-; CHECK-NEXT:  16384 16640 16896 17152 17408 17664 17920 18176 18432 18688 18944 19200 19456 19712 19968 20224
-; CHECK-NEXT:  20480 20736 20992 21248 21504 21760 22016 22272 22528 22784 23040 23296 23552 23808 24064 24320
-; CHECK-NEXT:  24576 24832 25088 25344 25600 25856 26112 26368 26624 26880 27136 27392 27648 27904 28160 28416
-; CHECK-NEXT:  28672 28928 29184 29440 29696 29952 30208 30464 30720 30976 31232 31488 31744 32000 32256 32512
-; CHECK-NEXT:  32768 33024 33280 33536 33792 34048 34304 34560 34816 35072 35328 35584 35840 36096 36352 36608
-; CHECK-NEXT:  36864 37120 37376 37632 37888 38144 38400 38656 38912 39168 39424 39680 39936 40192 40448 40704
-; CHECK-NEXT:  40960 41216 41472 41728 41984 42240 42496 42752 43008 43264 43520 43776 44032 44288 44544 44800
-; CHECK-NEXT:  45056 45312 45568 45824 46080 46336 46592 46848 47104 47360 47616 47872 48128 48384 48640 48896
-; CHECK-NEXT:  49152 49408 49664 49920 50176 50432 50688 50944 51200 51456 51712 51968 52224 52480 52736 52992
-; CHECK-NEXT:  53248 53504 53760 54016 54272 54528 54784 55040 55296 55552 55808 56064 56320 56576 56832 57088
-; CHECK-NEXT:  57344 57600 57856 58112 58368 58624 58880 59136 59392 59648 59904 60160 60416 60672 60928 61184
-; CHECK-NEXT:  61440 61696 61952 62208 62464 62720 62976 63232 63488 63744 64000 64256 64512 64768 65024 65280
+; CHECK-NEXT:  0 4129 8258 12387 16516 20645 24774 28903 33032 37161 41290 45419 49548 53677 57806 61935
+; CHECK-NEXT:  4657 528 12915 8786 21173 17044 29431 25302 37689 33560 45947 41818 54205 50076 62463 58334
+; CHECK-NEXT:  9314 13379 1056 5121 25830 29895 17572 21637 42346 46411 34088 38153 58862 62927 50604 54669
+; CHECK-NEXT:  13907 9842 5649 1584 30423 26358 22165 18100 46939 42874 38681 34616 63455 59390 55197 51132
+; CHECK-NEXT:  18628 22757 26758 30887 2112 6241 10242 14371 51660 55789 59790 63919 35144 39273 43274 47403
+; CHECK-NEXT:  23285 19156 31415 27286 6769 2640 14899 10770 56317 52188 64447 60318 39801 35672 47931 43802
+; CHECK-NEXT:  27814 31879 19684 23749 11298 15363 3168 7233 60846 64911 52716 56781 44330 48395 36200 40265
+; CHECK-NEXT:  32407 28342 24277 20212 15891 11826 7761 3696 65439 61374 57309 53244 48923 44858 40793 36728
+; CHECK-NEXT:  37256 33193 45514 41451 53516 49453 61774 57711 4224 161 12482 8419 20484 16421 28742 24679
+; CHECK-NEXT:  33721 37784 41979 46042 49981 54044 58239 62302 689 4752 8947 13010 16949 21012 25207 29270
+; CHECK-NEXT:  46570 42443 38312 34185 62830 58703 54572 50445 13538 9411 5280 1153 29798 25671 21540 17413
+; CHECK-NEXT:  42971 47098 34713 38840 59231 63358 50973 55100 9939 14066 1681 5808 26199 30326 17941 22068
+; CHECK-NEXT:  55628 51565 63758 59695 39368 35305 47498 43435 22596 18533 30726 26663 6336 2273 14466 10403
+; CHECK-NEXT:  52093 56156 60223 64286 35833 39896 43963 48026 19061 23124 27191 31254 2801 6864 10931 14994
+; CHECK-NEXT:  64814 60687 56684 52557 48554 44427 40424 36297 31782 27655 23652 19525 15522 11395 7392 3265
+; CHECK-NEXT:  61215 65342 53085 57212 44955 49082 36825 40952 28183 32310 20053 24180 11923 16050 3793 7920
 ;
 entry:
   %msg.ext = zext i8 %msg to i16
@@ -196,22 +196,22 @@ define i16 @crc16.be.tc8.crc.init.arg(i16 %crc.init) {
 ; CHECK-NEXT:    Generating polynomial: 4129
 ; CHECK-NEXT:    Computed CRC: %crc.next = select i1 %check.sb, i16 %crc.xor, i16 %crc.shl
 ; CHECK-NEXT:    Computed CRC lookup table:
-; CHECK-NEXT:  0 256 512 768 1024 1280 1536 1792 2048 2304 2560 2816 3072 3328 3584 3840
-; CHECK-NEXT:  4096 4352 4608 4864 5120 5376 5632 5888 6144 6400 6656 6912 7168 7424 7680 7936
-; CHECK-NEXT:  8192 8448 8704 8960 9216 9472 9728 9984 10240 10496 10752 11008 11264 11520 11776 12032
-; CHECK-NEXT:  12288 12544 12800 13056 13312 13568 13824 14080 14336 14592 14848 15104 15360 15616 15872 16128
-; CHECK-NEXT:  16384 16640 16896 17152 17408 17664 17920 18176 18432 18688 18944 19200 19456 19712 19968 20224
-; CHECK-NEXT:  20480 20736 20992 21248 21504 21760 22016 22272 22528 22784 23040 23296 23552 23808 24064 24320
-; CHECK-NEXT:  24576 24832 25088 25344 25600 25856 26112 26368 26624 26880 27136 27392 27648 27904 28160 28416
-; CHECK-NEXT:  28672 28928 29184 29440 29696 29952 30208 30464 30720 30976 31232 31488 31744 32000 32256 32512
-; CHECK-NEXT:  32768 33024 33280 33536 33792 34048 34304 34560 34816 35072 35328 35584 35840 36096 36352 36608
-; CHECK-NEXT:  36864 37120 37376 37632 37888 38144 38400 38656 38912 39168 39424 39680 39936 40192 40448 40704
-; CHECK-NEXT:  40960 41216 41472 41728 41984 42240 42496 42752 43008 43264 43520 43776 44032 44288 44544 44800
-; CHECK-NEXT:  45056 45312 45568 45824 46080 46336 46592 46848 47104 47360 47616 47872 48128 48384 48640 48896
-; CHECK-NEXT:  49152 49408 49664 49920 50176 50432 50688 50944 51200 51456 51712 51968 52224 52480 52736 52992
-; CHECK-NEXT:  53248 53504 53760 54016 54272 54528 54784 55040 55296 55552 55808 56064 56320 56576 56832 57088
-; CHECK-NEXT:  57344 57600 57856 58112 58368 58624 58880 59136 59392 59648 59904 60160 60416 60672 60928 61184
-; CHECK-NEXT:  61440 61696 61952 62208 62464 62720 62976 63232 63488 63744 64000 64256 64512 64768 65024 65280
+; CHECK-NEXT:  0 4129 8258 12387 16516 20645 24774 28903 33032 37161 41290 45419 49548 53677 57806 61935
+; CHECK-NEXT:  4657 528 12915 8786 21173 17044 29431 25302 37689 33560 45947 41818 54205 50076 62463 58334
+; CHECK-NEXT:  9314 13379 1056 5121 25830 29895 17572 21637 42346 46411 34088 38153 58862 62927 50604 54669
+; CHECK-NEXT:  13907 9842 5649 1584 30423 26358 22165 18100 46939 42874 38681 34616 63455 59390 55197 51132
+; CHECK-NEXT:  18628 22757 26758 30887 2112 6241 10242 14371 51660 55789 59790 63919 35144 39273 43274 47403
+; CHECK-NEXT:  23285 19156 31415 27286 6769 2640 14899 10770 56317 52188 64447 60318 39801 35672 47931 43802
+; CHECK-NEXT:  27814 31879 19684 23749 11298 15363 3168 7233 60846 64911 52716 56781 44330 48395 36200 40265
+; CHECK-NEXT:  32407 28342 24277 20212 15891 11826 7761 3696 65439 61374 57309 53244 48923 44858 40793 36728
+; CHECK-NEXT:  37256 33193 45514 41451 53516 49453 61774 57711 4224 161 12482 8419 20484 16421 28742 24679
+; CHECK-NEXT:  33721 37784 41979 46042 49981 54044 58239 62302 689 4752 8947 13010 16949 21012 25207 29270
+; CHECK-NEXT:  46570 42443 38312 34185 62830 58703 54572 50445 13538 9411 5280 1153 29798 25671 21540 17413
+; CHECK-NEXT:  42971 47098 34713 38840 59231 63358 50973 55100 9939 14066 1681 5808 26199 30326 17941 22068
+; CHECK-NEXT:  55628 51565 63758 59695 39368 35305 47498 43435 22596 18533 30726 26663 6336 2273 14466 10403
+; CHECK-NEXT:  52093 56156 60223 64286 35833 39896 43963 48026 19061 23124 27191 31254 2801 6864 10931 14994
+; CHECK-NEXT:  64814 60687 56684 52557 48554 44427 40424 36297 31782 27655 23652 19525 15522 11395 7392 3265
+; CHECK-NEXT:  61215 65342 53085 57212 44955 49082 36825 40952 28183 32310 20053 24180 11923 16050 3793 7920
 ;
 entry:
   br label %loop
@@ -238,22 +238,22 @@ define i16 @crc16.be.tc8.crc.init.arg.flipped.sb.check(i16 %crc.init) {
 ; CHECK-NEXT:    Generating polynomial: 4129
 ; CHECK-NEXT:    Computed CRC: %crc.next = select i1 %check.sb, i16 %crc.shl, i16 %crc.xor
 ; CHECK-NEXT:    Computed CRC lookup table:
-; CHECK-NEXT:  0 256 512 768 1024 1280 1536 1792 2048 2304 2560 2816 3072 3328 3584 3840
-; CHECK-NEXT:  4096 4352 4608 4864 5120 5376 5632 5888 6144 6400 6656 6912 7168 7424 7680 7936
-; CHECK-NEXT:  8192 8448 8704 8960 9216 9472 9728 9984 10240 10496 10752 11008 11264 11520 11776 12032
-; CHECK-NEXT:  12288 12544 12800 13056 13312 13568 13824 14080 14336 14592 14848 15104 15360 15616 15872 16128
-; CHECK-NEXT:  16384 16640 16896 17152 17408 17664 17920 18176 18432 18688 18944 19200 19456 19712 19968 20224
-; CHECK-NEXT:  20480 20736 20992 21248 21504 21760 22016 22272 22528 22784 23040 23296 23552 23808 24064 24320
-; CHECK-NEXT:  24576 24832 25088 25344 25600 25856 26112 26368 26624 26880 27136 27392 27648 27904 28160 28416
-; CHECK-NEXT:  28672 28928 29184 29440 29696 29952 30208 30464 30720 30976 31232 31488 31744 32000 32256 32512
-; CHECK-NEXT:  32768 33024 33280 33536 33792 34048 34304 34560 34816 35072 35328 35584 35840 36096 36352 36608
-; CHECK-NEXT:  36864 37120 37376 37632 37888 38144 38400 38656 38912 39168 39424 39680 39936 40192 40448 40704
-; CHECK-NEXT:  40960 41216 41472 41728 41984 42240 42496 42752 43008 43264 43520 43776 44032 44288 44544 44800
-; CHECK-NEXT:  45056 45312 45568 45824 46080 46336 46592 46848 47104 47360 47616 47872 48128 48384 48640 48896
-; CHECK-NEXT:  49152 49408 49664 49920 50176 50432 50688 50944 51200 51456 51712 51968 52224 52480 52736 52992
-; CHECK-NEXT:  53248 53504 53760 54016 54272 54528 54784 55040 55296 55552 55808 56064 56320 56576 56832 57088
-; CHECK-NEXT:  57344 57600 57856 58112 58368 58624 58880 59136 59392 59648 59904 60160 60416 60672 60928 61184
-; CHECK-NEXT:  61440 61696 61952 62208 62464 62720 62976 63232 63488 63744 64000 64256 64512 64768 65024 65280
+; CHECK-NEXT:  0 4129 8258 12387 16516 20645 24774 28903 33032 37161 41290 45419 49548 53677 57806 61935
+; CHECK-NEXT:  4657 528 12915 8786 21173 17044 29431 25302 37689 33560 45947 41818 54205 50076 62463 58334
+; CHECK-NEXT:  9314 13379 1056 5121 25830 29895 17572 21637 42346 46411 34088 38153 58862 62927 50604 54669
+; CHECK-NEXT:  13907 9842 5649 1584 30423 26358 22165 18100 46939 42874 38681 34616 63455 59390 55197 51132
+; CHECK-NEXT:  18628 22757 26758 30887 2112 6241 10242 14371 51660 55789 59790 63919 35144 39273 43274 47403
+; CHECK-NEXT:  23285 19156 31415 27286 6769 2640 14899 10770 56317 52188 64447 60318 39801 35672 47931 43802
+; CHECK-NEXT:  27814 31879 19684 23749 11298 15363 3168 7233 60846 64911 52716 56781 44330 48395 36200 40265
+; CHECK-NEXT:  32407 28342 24277 20212 15891 11826 7761 3696 65439 61374 57309 53244 48923 44858 40793 36728
+; CHECK-NEXT:  37256 33193 45514 41451 53516 49453 61774 57711 4224 161 12482 8419 20484 16421 28742 24679
+; CHECK-NEXT:  33721 37784 41979 46042 49981 54044 58239 62302 689 4752 8947 13010 16949 21012 25207 29270
+; CHECK-NEXT:  46570 42443 38312 34185 62830 58703 54572 50445 13538 9411 5280 1153 29798 25671 21540 17413
+; CHECK-NEXT:  42971 47098 34713 38840 59231 63358 50973 55100 9939 14066 1681 5808 26199 30326 17941 22068
+; CHECK-NEXT:  55628 51565 63758 59695 39368 35305 47498 43435 22596 18533 30726 26663 6336 2273 14466 10403
+; CHECK-NEXT:  52093 56156 60223 64286 35833 39896 43963 48026 19061 23124 27191 31254 2801 6864 10931 14994
+; CHECK-NEXT:  64814 60687 56684 52557 48554 44427 40424 36297 31782 27655 23652 19525 15522 11395 7392 3265
+; CHECK-NEXT:  61215 65342 53085 57212 44955 49082 36825 40952 28183 32310 20053 24180 11923 16050 3793 7920
 ;
 entry:
   br label %loop
