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[clang][bytecode] Handle __builtin_strncmp #119208

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Merged
merged 1 commit into from
Dec 9, 2024
Merged

[clang][bytecode] Handle __builtin_strncmp #119208

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20 changes: 18 additions & 2 deletions clang/lib/AST/ByteCode/InterpBuiltin.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -197,9 +197,19 @@ static bool interp__builtin_strcmp(InterpState &S, CodePtr OpPC,
const Pointer &A = getParam<Pointer>(Frame, 0);
const Pointer &B = getParam<Pointer>(Frame, 1);

if (ID == Builtin::BIstrcmp)
if (ID == Builtin::BIstrcmp || ID == Builtin::BIstrncmp)
diagnoseNonConstexprBuiltin(S, OpPC, ID);

uint64_t Limit = ~static_cast<uint64_t>(0);
if (ID == Builtin::BIstrncmp || ID == Builtin::BI__builtin_strncmp)
Limit = peekToAPSInt(S.Stk, *S.getContext().classify(Call->getArg(2)))
.getZExtValue();

if (Limit == 0) {
pushInteger(S, 0, Call->getType());
return true;
}

if (!CheckLive(S, OpPC, A, AK_Read) || !CheckLive(S, OpPC, B, AK_Read))
return false;

Expand All @@ -212,7 +222,11 @@ static bool interp__builtin_strcmp(InterpState &S, CodePtr OpPC,
unsigned IndexA = A.getIndex();
unsigned IndexB = B.getIndex();
int32_t Result = 0;
for (;; ++IndexA, ++IndexB) {
uint64_t Steps = 0;
for (;; ++IndexA, ++IndexB, ++Steps) {

if (Steps >= Limit)
break;
const Pointer &PA = A.atIndex(IndexA);
const Pointer &PB = B.atIndex(IndexB);
if (!CheckRange(S, OpPC, PA, AK_Read) ||
Expand Down Expand Up @@ -1873,6 +1887,8 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
break;
case Builtin::BI__builtin_strcmp:
case Builtin::BIstrcmp:
case Builtin::BI__builtin_strncmp:
case Builtin::BIstrncmp:
if (!interp__builtin_strcmp(S, OpPC, Frame, F, Call))
return false;
break;
Expand Down
9 changes: 9 additions & 0 deletions clang/test/AST/ByteCode/builtin-functions.cpp
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Expand Up @@ -51,6 +51,15 @@ namespace strcmp {
return __builtin_strcmp(buffer, "mutable") == 0;
}
static_assert(char_memchr_mutable(), "");

static_assert(__builtin_strncmp("abaa", "abba", 5) == -1);
static_assert(__builtin_strncmp("abaa", "abba", 4) == -1);
static_assert(__builtin_strncmp("abaa", "abba", 3) == -1);
static_assert(__builtin_strncmp("abaa", "abba", 2) == 0);
static_assert(__builtin_strncmp("abaa", "abba", 1) == 0);
static_assert(__builtin_strncmp("abaa", "abba", 0) == 0);
static_assert(__builtin_strncmp(0, 0, 0) == 0);
static_assert(__builtin_strncmp("abab\0banana", "abab\0canada", 100) == 0);
}

/// Copied from constant-expression-cxx11.cpp
Expand Down
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