xref: /llvm-project/llvm/test/Transforms/InstCombine/memcmp-4.ll (revision 90ba33099cbb17e7c159e9ebc5a512037db99d6d)
1; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
2; Verify that calls to memcmp with counts in excess of the array sizes are
3; either folded gracefully or expanded to library calls.
4;
5; RUN: opt < %s -passes=instcombine -S -data-layout="E" | FileCheck %s --check-prefixes=BE
6; RUN: opt < %s -passes=instcombine -S -data-layout="e" | FileCheck %s --check-prefixes=LE
7
8declare i32 @memcmp(ptr, ptr, i64)
9
10@ia16a = constant [4 x i16] [i16 24930, i16 25444, i16 25958, i16 26472]
11@ia16b = constant [5 x i16] [i16 24930, i16 25444, i16 25958, i16 26472, i16 26992]
12@ia16c = constant [6 x i16] [i16 24930, i16 25444, i16 25958, i16 26472, i16 26993, i16 29042]
13
14
15; Fold calls with a count in excess of the size of one of the arrays that
16; differ.  They're strictly undefined but folding the result to the expected
17; value (analogous to strncmp) is safer than letting a SIMD library
18; implementation return a bogus value.
19
20define void @fold_memcmp_mismatch_too_big(ptr %pcmp) {
21; BE-LABEL: @fold_memcmp_mismatch_too_big(
22; BE-NEXT:    store i32 -1, ptr [[PCMP:%.*]], align 4
23; BE-NEXT:    [[PSTOR_CB:%.*]] = getelementptr i8, ptr [[PCMP]], i64 4
24; BE-NEXT:    store i32 1, ptr [[PSTOR_CB]], align 4
25; BE-NEXT:    ret void
26;
27; LE-LABEL: @fold_memcmp_mismatch_too_big(
28; LE-NEXT:    store i32 -1, ptr [[PCMP:%.*]], align 4
29; LE-NEXT:    [[PSTOR_CB:%.*]] = getelementptr i8, ptr [[PCMP]], i64 4
30; LE-NEXT:    store i32 1, ptr [[PSTOR_CB]], align 4
31; LE-NEXT:    ret void
32;
33
34  %cmp_bc = call i32 @memcmp(ptr @ia16b, ptr @ia16c, i64 12)
35  store i32 %cmp_bc, ptr %pcmp
36
37  %cmp_cb = call i32 @memcmp(ptr @ia16c, ptr @ia16b, i64 12)
38  %pstor_cb = getelementptr i32, ptr %pcmp, i64 1
39  store i32 %cmp_cb, ptr %pstor_cb
40
41  ret void
42}
43
44
45; Fold even calls with excessive byte counts of arrays with matching bytes.
46; Like in the instances above, this is preferable to letting the undefined
47; calls take place, although it does prevent sanitizers from detecting them.
48
49define void @fold_memcmp_match_too_big(ptr %pcmp) {
50; BE-LABEL: @fold_memcmp_match_too_big(
51; BE-NEXT:    store i32 0, ptr [[PCMP:%.*]], align 4
52; BE-NEXT:    [[PSTOR_AB_M1:%.*]] = getelementptr i8, ptr [[PCMP]], i64 4
53; BE-NEXT:    store i32 0, ptr [[PSTOR_AB_M1]], align 4
54; BE-NEXT:    ret void
55;
56; LE-LABEL: @fold_memcmp_match_too_big(
57; LE-NEXT:    store i32 0, ptr [[PCMP:%.*]], align 4
58; LE-NEXT:    [[PSTOR_AB_M1:%.*]] = getelementptr i8, ptr [[PCMP]], i64 4
59; LE-NEXT:    store i32 0, ptr [[PSTOR_AB_M1]], align 4
60; LE-NEXT:    ret void
61;
62
63  %cmp_ab_9 = call i32 @memcmp(ptr @ia16a, ptr @ia16b, i64 9)
64  store i32 %cmp_ab_9, ptr %pcmp
65
66  %cmp_ab_m1 = call i32 @memcmp(ptr @ia16a, ptr @ia16b, i64 -1)
67  %pstor_ab_m1 = getelementptr i32, ptr %pcmp, i64 1
68  store i32 %cmp_ab_m1, ptr %pstor_ab_m1
69
70  ret void
71}
72