Author: Timm Baeder Date: 2024-12-12T10:57:39+01:00 New Revision: 98470c0b2e0eef52e6900bf2d524a390edac9d58
URL: https://github.com/llvm/llvm-project/commit/98470c0b2e0eef52e6900bf2d524a390edac9d58 DIFF: https://github.com/llvm/llvm-project/commit/98470c0b2e0eef52e6900bf2d524a390edac9d58.diff LOG: [clang][bytecode] Handle __builtin_bcmp (#119678) ... the same as `__builtin_memcmp`. Also fix a bug we still had when we couldn't find a difference in the two inputs after `Size` bytes. Added: Modified: clang/lib/AST/ByteCode/InterpBuiltin.cpp clang/test/AST/ByteCode/builtin-functions.cpp Removed: ################################################################################ diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp index a343280b5ce50f..21baedf832eeac 100644 --- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp +++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp @@ -1917,7 +1917,7 @@ static bool interp__builtin_memcmp(InterpState &S, CodePtr OpPC, const APSInt &Size = peekToAPSInt(S.Stk, *S.getContext().classify(Call->getArg(2))); - if (ID == Builtin::BImemcmp) + if (ID == Builtin::BImemcmp || ID == Builtin::BIbcmp) diagnoseNonConstexprBuiltin(S, OpPC, ID); if (Size.isZero()) { @@ -1952,15 +1952,34 @@ static bool interp__builtin_memcmp(InterpState &S, CodePtr OpPC, BufferB.byteSize().getQuantity()); size_t CmpSize = std::min(MinBufferSize, static_cast<size_t>(Size.getZExtValue())); - int Result = std::memcmp(BufferA.Data.get(), BufferB.Data.get(), CmpSize); - if (Result == 0) + + for (size_t I = 0; I != CmpSize; ++I) { + std::byte A = BufferA.Data[I]; + std::byte B = BufferB.Data[I]; + + if (A < B) { + pushInteger(S, -1, Call->getType()); + return true; + } else if (A > B) { + pushInteger(S, 1, Call->getType()); + return true; + } + } + + // We compared CmpSize bytes above. If the limiting factor was the Size + // passed, we're done and the result is equality (0). + if (Size.getZExtValue() <= CmpSize) { pushInteger(S, 0, Call->getType()); - else if (Result < 0) - pushInteger(S, -1, Call->getType()); - else - pushInteger(S, 1, Call->getType()); + return true; + } - return true; + // However, if we read all the available bytes but were instructed to read + // even more, diagnose this as a "read of dereferenced one-past-the-end + // pointer". This is what would happen if we called CheckRead() on every array + // element. + S.FFDiag(S.Current->getSource(OpPC), diag::note_constexpr_access_past_end) + << AK_Read << S.Current->getRange(OpPC); + return false; } bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F, @@ -2438,6 +2457,8 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F, case Builtin::BI__builtin_memcmp: case Builtin::BImemcmp: + case Builtin::BI__builtin_bcmp: + case Builtin::BIbcmp: if (!interp__builtin_memcmp(S, OpPC, Frame, F, Call)) return false; break; diff --git a/clang/test/AST/ByteCode/builtin-functions.cpp b/clang/test/AST/ByteCode/builtin-functions.cpp index 83caa1d03df3a3..4ee24646286fa8 100644 --- a/clang/test/AST/ByteCode/builtin-functions.cpp +++ b/clang/test/AST/ByteCode/builtin-functions.cpp @@ -1255,4 +1255,19 @@ namespace Memcmp { // both-note {{not supported}} static_assert(__builtin_memcmp("", &incomplete, 1u) == 42); // both-error {{not an integral constant}} \ // both-note {{not supported}} + + static_assert(__builtin_memcmp(u8"abab\0banana", u8"abab\0banana", 100) == 0); // both-error {{not an integral constant}} \ + // both-note {{dereferenced one-past-the-end}} + + static_assert(__builtin_bcmp("abaa", "abba", 3) != 0); + static_assert(__builtin_bcmp("abaa", "abba", 2) == 0); + static_assert(__builtin_bcmp("a\203", "a", 2) != 0); + static_assert(__builtin_bcmp("a\203", "a\003", 2) != 0); + static_assert(__builtin_bcmp(0, 0, 0) == 0); + static_assert(__builtin_bcmp("abab\0banana", "abab\0banana", 100) == 0); // both-error {{not an integral constant}}\ + // both-note {{dereferenced one-past-the-end}} + static_assert(__builtin_bcmp("abab\0banana", "abab\0canada", 100) != 0); // FIXME: Should we reject this? + static_assert(__builtin_bcmp("abab\0banana", "abab\0canada", 7) != 0); + static_assert(__builtin_bcmp("abab\0banana", "abab\0canada", 6) != 0); + static_assert(__builtin_bcmp("abab\0banana", "abab\0canada", 5) == 0); } _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
