[clang] [clang][bytecode] Fix new overflow behavior tests (PR #183761)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr updated https://github.com/llvm/llvm-project/pull/183761

>From a42fc169d00aa2bb7adae380790042474f409607 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Fri, 27 Feb 2026 16:54:14 +0100
Subject: [PATCH] obt

---
 clang/lib/AST/ByteCode/Context.cpp                   |  3 +++
 clang/lib/AST/ByteCode/Interp.h                      | 12 ++++++++++++
 clang/test/Sema/attr-overflow-behavior-constexpr.cpp |  4 ++++
 clang/test/Sema/attr-overflow-behavior-templates.cpp |  1 +
 clang/test/Sema/attr-overflow-behavior.c             |  1 +
 clang/test/Sema/attr-overflow-behavior.cpp           |  1 +
 6 files changed, 22 insertions(+)

diff --git a/clang/lib/AST/ByteCode/Context.cpp b/clang/lib/AST/ByteCode/Context.cpp
index 879d51e6a2c3e..c811fac384fd4 100644
--- a/clang/lib/AST/ByteCode/Context.cpp
+++ b/clang/lib/AST/ByteCode/Context.cpp
@@ -470,6 +470,9 @@ OptPrimType Context::classify(QualType T) const {
   if (const auto *DT = dyn_cast<DecltypeType>(T))
     return classify(DT->getUnderlyingType());
 
+  if (const auto *OBT = T.getCanonicalType()->getAs<OverflowBehaviorType>())
+    return classify(OBT->getUnderlyingType());
+
   if (T->isObjCObjectPointerType() || T->isBlockPointerType())
     return PT_Ptr;
 
diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h
index 7f30def20cc36..bec6560a4020c 100644
--- a/clang/lib/AST/ByteCode/Interp.h
+++ b/clang/lib/AST/ByteCode/Interp.h
@@ -296,6 +296,10 @@ bool AddSubMulHelper(InterpState &S, CodePtr OpPC, unsigned Bits, const T &LHS,
   if constexpr (std::is_same_v<T, FixedPoint>)
     return handleFixedPointOverflow(S, OpPC, Result);
 
+  // If wrapping is enabled, the new value is fine.
+  if (S.Current->getExpr(OpPC)->getType().isWrapType())
+    return true;
+
   // Slow path - compute the result using another bit of precision.
   APSInt Value = OpAP<APSInt>()(LHS.toAPSInt(Bits), RHS.toAPSInt(Bits));
 
@@ -708,6 +712,9 @@ bool Neg(InterpState &S, CodePtr OpPC) {
            "don't expect other types to fail at constexpr negation");
     S.Stk.push<T>(Result);
 
+    if (S.Current->getExpr(OpPC)->getType().isWrapType())
+      return true;
+
     APSInt NegatedValue = -Value.toAPSInt(Value.bitWidth() + 1);
     if (S.checkingForUndefinedBehavior()) {
       const Expr *E = S.Current->getExpr(OpPC);
@@ -776,6 +783,11 @@ bool IncDecHelper(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
   }
   assert(CanOverflow);
 
+  if (S.Current->getExpr(OpPC)->getType().isWrapType()) {
+    Ptr.deref<T>() = Result;
+    return true;
+  }
+
   // Something went wrong with the previous operation. Compute the
   // result with another bit of precision.
   unsigned Bits = Value.bitWidth() + 1;
diff --git a/clang/test/Sema/attr-overflow-behavior-constexpr.cpp b/clang/test/Sema/attr-overflow-behavior-constexpr.cpp
index 1d81d3a243c1e..403ea319a61ae 100644
--- a/clang/test/Sema/attr-overflow-behavior-constexpr.cpp
+++ b/clang/test/Sema/attr-overflow-behavior-constexpr.cpp
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -triple x86_64-linux-gnu %s -fexperimental-overflow-behavior-types -verify -fsyntax-only -std=c++14
+// RUN: %clang_cc1 -triple x86_64-linux-gnu %s -fexperimental-overflow-behavior-types -verify -fsyntax-only -std=c++14 -fexperimental-new-constant-interpreter
 
 #define __wrap __attribute__((overflow_behavior(wrap)))
 #define __no_trap __attribute__((overflow_behavior(trap)))
@@ -35,6 +36,9 @@ void constexpr_test() {
 
   static_assert(preinc(max) == -2147483648, "preinc wrapping failed");
   static_assert(postinc(max) == -2147483648, "postinc wrapping failed");
+
+  constexpr wrap_int M = -2147483648;
+  constexpr wrap_int A = -M;
 }
 
 template <typename T>
diff --git a/clang/test/Sema/attr-overflow-behavior-templates.cpp b/clang/test/Sema/attr-overflow-behavior-templates.cpp
index 09242f6f9ab3a..40c7310b78e53 100644
--- a/clang/test/Sema/attr-overflow-behavior-templates.cpp
+++ b/clang/test/Sema/attr-overflow-behavior-templates.cpp
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 %s -fexperimental-overflow-behavior-types -verify -fsyntax-only -Wimplicit-overflow-behavior-conversion
+// RUN: %clang_cc1 %s -fexperimental-overflow-behavior-types -verify -fsyntax-only -Wimplicit-overflow-behavior-conversion -fexperimental-new-constant-interpreter
 
 template<typename T>
 constexpr int template_overload_test(T) {
diff --git a/clang/test/Sema/attr-overflow-behavior.c b/clang/test/Sema/attr-overflow-behavior.c
index 6ce876f09d802..7f2312537516d 100644
--- a/clang/test/Sema/attr-overflow-behavior.c
+++ b/clang/test/Sema/attr-overflow-behavior.c
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 %s -Winteger-overflow -Wno-unused-value -fexperimental-overflow-behavior-types -Woverflow-behavior-conversion -Wconstant-conversion -verify -fsyntax-only -std=c11 -Wno-pointer-sign
+// RUN: %clang_cc1 %s -Winteger-overflow -Wno-unused-value -fexperimental-overflow-behavior-types -Woverflow-behavior-conversion -Wconstant-conversion -verify -fsyntax-only -std=c11 -Wno-pointer-sign -fexperimental-new-constant-interpreter
 
 typedef int __attribute__((overflow_behavior)) bad_arg_count; // expected-error {{'overflow_behavior' attribute takes one argument}}
 typedef int __attribute__((overflow_behavior(not_real))) bad_arg_spec; // expected-error {{'not_real' is not a valid argument to attribute 'overflow_behavior'}}
diff --git a/clang/test/Sema/attr-overflow-behavior.cpp b/clang/test/Sema/attr-overflow-behavior.cpp
index 1dfe00ab47ae2..a69eb83e591f5 100644
--- a/clang/test/Sema/attr-overflow-behavior.cpp
+++ b/clang/test/Sema/attr-overflow-behavior.cpp
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 %s -Winteger-overflow -Wno-unused-value -fexperimental-overflow-behavior-types -Wconstant-conversion -Woverflow-behavior-conversion -verify -fsyntax-only
+// RUN: %clang_cc1 %s -Winteger-overflow -Wno-unused-value -fexperimental-overflow-behavior-types -Wconstant-conversion -Woverflow-behavior-conversion -verify -fsyntax-only -fexperimental-new-constant-interpreter
 
 typedef int __attribute__((overflow_behavior)) bad_arg_count; // expected-error {{'overflow_behavior' attribute takes one argument}}
 typedef int __attribute__((overflow_behavior(not_real))) bad_arg_spec; // expected-error {{'not_real' is not a valid argument to attribute 'overflow_behavior'}}