llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: Yingwei Zheng (dtcxzyw) <details> <summary>Changes</summary> It is an alternative to https://github.com/llvm/llvm-project/pull/127525. Close https://github.com/llvm/llvm-project/issues/127475. --- Full diff: https://github.com/llvm/llvm-project/pull/128409.diff 3 Files Affected: - (modified) clang/lib/AST/ExprConstant.cpp (+12-2) - (modified) clang/lib/CodeGen/CGExprConstant.cpp (+5-1) - (added) clang/test/CodeGenCXX/cxx23-p2280r4.cpp (+15) ``````````diff diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index 6ccb6e23f8d2f..42801dc4e18fa 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -3628,8 +3628,6 @@ static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E, if (AllowConstexprUnknown) { if (!Result) Result = &Info.CurrentCall->createConstexprUnknownAPValues(VD, Base); - else - Result->setConstexprUnknown(); } return true; } @@ -17000,6 +16998,18 @@ bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx, if (!Info.discardCleanups()) llvm_unreachable("Unhandled cleanup; missing full expression marker?"); + + if (Value.allowConstexprUnknown()) { + assert(Value.isLValue() && "Expected an lvalue"); + auto Base = Value.getLValueBase(); + const auto *NewVD = Base.dyn_cast<const ValueDecl *>(); + if (!NewVD) + NewVD = VD; + Info.FFDiag(getExprLoc(), diag::note_constexpr_var_init_non_constant, 1) + << NewVD; + NoteLValueLocation(Info, Base); + return false; + } } return CheckConstantExpression(Info, DeclLoc, DeclTy, Value, diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp index ee5874b26f534..0295f703b9061 100644 --- a/clang/lib/CodeGen/CGExprConstant.cpp +++ b/clang/lib/CodeGen/CGExprConstant.cpp @@ -1883,8 +1883,12 @@ llvm::Constant *ConstantEmitter::tryEmitPrivateForVarInit(const VarDecl &D) { // Try to emit the initializer. Note that this can allow some things that // are not allowed by tryEmitPrivateForMemory alone. - if (APValue *value = D.evaluateValue()) + // Bail out on constexpr-unknown values since they are invalid in CodeGen. + if (APValue *value = D.evaluateValue()) { + assert(!value->allowConstexprUnknown() && + "Constexpr unknown values are not allowed in CodeGen"); return tryEmitPrivateForMemory(*value, destType); + } return nullptr; } diff --git a/clang/test/CodeGenCXX/cxx23-p2280r4.cpp b/clang/test/CodeGenCXX/cxx23-p2280r4.cpp new file mode 100644 index 0000000000000..d5409be451df0 --- /dev/null +++ b/clang/test/CodeGenCXX/cxx23-p2280r4.cpp @@ -0,0 +1,15 @@ +// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++23 %s -emit-llvm -o - | FileCheck %s +// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20 %s -emit-llvm -o - | FileCheck %s +// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++17 %s -emit-llvm -o - | FileCheck %s + +extern int& s; + +// CHECK: @_Z4testv() +// CHECK-NEXT: entry: +// CHECK-NEXT: [[I:%.*]] = alloca ptr, align {{.*}} +// CHECK-NEXT: [[X:%.*]] = load ptr, ptr @s, align {{.*}} +// CHECK-NEXT: store ptr [[X]], ptr [[I]], align {{.*}} +int& test() { + auto &i = s; + return i; +} `````````` </details> https://github.com/llvm/llvm-project/pull/128409 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
