llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: Timm Baeder (tbaederr) <details> <summary>Changes</summary> Union members get the same address, so we can't just use `Pointer::getByteOffset()`. --- Full diff: https://github.com/llvm/llvm-project/pull/133852.diff 4 Files Affected: - (modified) clang/lib/AST/ByteCode/Interp.h (+10-1) - (modified) clang/lib/AST/ByteCode/Pointer.cpp (+31) - (modified) clang/lib/AST/ByteCode/Pointer.h (+3-1) - (modified) clang/test/AST/ByteCode/unions.cpp (+38) ``````````diff diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h index 938077a9f10ae..6fe1d4b1f95ae 100644 --- a/clang/lib/AST/ByteCode/Interp.h +++ b/clang/lib/AST/ByteCode/Interp.h @@ -1070,9 +1070,18 @@ inline bool CmpHelperEQ<Pointer>(InterpState &S, CodePtr OpPC, CompareFn Fn) { } if (Pointer::hasSameBase(LHS, RHS)) { + if (LHS.inUnion() && RHS.inUnion()) { + // If the pointers point into a union, things are a little more + // complicated since the offset we save in interp::Pointer can't be used + // to compare the pointers directly. + size_t A = LHS.computeOffsetForComparison(); + size_t B = RHS.computeOffsetForComparison(); + S.Stk.push<BoolT>(BoolT::from(Fn(Compare(A, B)))); + return true; + } + unsigned VL = LHS.getByteOffset(); unsigned VR = RHS.getByteOffset(); - // In our Pointer class, a pointer to an array and a pointer to the first // element in the same array are NOT equal. They have the same Base value, // but a different Offset. This is a pretty rare case, so we fix this here diff --git a/clang/lib/AST/ByteCode/Pointer.cpp b/clang/lib/AST/ByteCode/Pointer.cpp index 79b47c26992ae..7ccefd6aeb9e1 100644 --- a/clang/lib/AST/ByteCode/Pointer.cpp +++ b/clang/lib/AST/ByteCode/Pointer.cpp @@ -339,6 +339,37 @@ void Pointer::print(llvm::raw_ostream &OS) const { } } +/// Compute an integer that can be used to compare this pointer to +/// another one. +size_t Pointer::computeOffsetForComparison() const { + if (!isBlockPointer()) + return Offset; + + size_t Result = 0; + Pointer P = *this; + while (!P.isRoot()) { + if (P.isArrayRoot()) { + P = P.getBase(); + continue; + } + if (P.isArrayElement()) { + Result += (P.getIndex() * P.elemSize()); + P = P.getArray(); + } + + if (const Record *R = P.getBase().getRecord(); R && R->isUnion()) { + // Direct child of a union - all have offset 0. + P = P.getBase(); + continue; + } + + Result += P.getInlineDesc()->Offset; + P = P.getBase(); + } + + return Result; +} + std::string Pointer::toDiagnosticString(const ASTContext &Ctx) const { if (isZero()) return "nullptr"; diff --git a/clang/lib/AST/ByteCode/Pointer.h b/clang/lib/AST/ByteCode/Pointer.h index fd33ee9955f55..988237d39fff4 100644 --- a/clang/lib/AST/ByteCode/Pointer.h +++ b/clang/lib/AST/ByteCode/Pointer.h @@ -417,7 +417,7 @@ class Pointer { return false; } bool inUnion() const { - if (isBlockPointer()) + if (isBlockPointer() && asBlockPointer().Base >= sizeof(InlineDescriptor)) return getInlineDesc()->InUnion; return false; }; @@ -727,6 +727,8 @@ class Pointer { /// Prints the pointer. void print(llvm::raw_ostream &OS) const; + size_t computeOffsetForComparison() const; + private: friend class Block; friend class DeadBlock; diff --git a/clang/test/AST/ByteCode/unions.cpp b/clang/test/AST/ByteCode/unions.cpp index 66b8389606b85..3911a2b2f7dde 100644 --- a/clang/test/AST/ByteCode/unions.cpp +++ b/clang/test/AST/ByteCode/unions.cpp @@ -600,3 +600,41 @@ namespace MoveOrAssignOp { static_assert(foo()); } #endif + +namespace AddressComparison { + union { + int a; + int c; + } U; + static_assert(__builtin_addressof(U.a) == (void*)__builtin_addressof(U.c)); + static_assert(&U.a == &U.c); + + + struct { + union { + struct { + int a; + int b; + } a; + struct { + int b; + int a; + }b; + } u; + int b; + } S; + + static_assert(&S.u.a.a == &S.u.b.b); + static_assert(&S.u.a.b != &S.u.b.b); + static_assert(&S.u.a.b == &S.u.b.b); // both-error {{failed}} + + + union { + int a[2]; + int b[2]; + } U2; + + static_assert(&U2.a[0] == &U2.b[0]); + static_assert(&U2.a[0] != &U2.b[1]); + static_assert(&U2.a[0] == &U2.b[1]); // both-error {{failed}} +} `````````` </details> https://github.com/llvm/llvm-project/pull/133852 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
