Add support for __builtin_verbose_trap (#79230)

The builtin causes the program to stop its execution abnormally and
shows a human-readable description of the reason for the termination
when a debugger is attached or in a symbolicated crash log.

The motivation for the builtin is explained in the following RFC:

https://discourse.llvm.org/t/rfc-adding-builtin-verbose-trap-string-literal/75845

clang's CodeGen lowers the builtin to `llvm.trap` and emits debugging
information that represents an artificial inline frame whose name
encodes the category and reason strings passed to the builtin.

1 files changed, 32 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 8798851..bce941c 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -183,6 +183,33 @@ bool Sema::checkArgCount(CallExpr *Call, unsigned DesiredArgCount) {
          << /*is non object*/ 0 << Call->getArg(1)->getSourceRange();
 }
 
+static bool checkBuiltinVerboseTrap(CallExpr *Call, Sema &S) {
+  bool HasError = false;
+
+  for (unsigned I = 0; I < Call->getNumArgs(); ++I) {
+    Expr *Arg = Call->getArg(I);
+
+    if (Arg->isValueDependent())
+      continue;
+
+    std::optional<std::string> ArgString = Arg->tryEvaluateString(S.Context);
+    int DiagMsgKind = -1;
+    // Arguments must be pointers to constant strings and cannot use '$'.
+    if (!ArgString.has_value())
+      DiagMsgKind = 0;
+    else if (ArgString->find('$') != std::string::npos)
+      DiagMsgKind = 1;
+
+    if (DiagMsgKind >= 0) {
+      S.Diag(Arg->getBeginLoc(), diag::err_builtin_verbose_trap_arg)
+          << DiagMsgKind << Arg->getSourceRange();
+      HasError = true;
+    }
+  }
+
+  return !HasError;
+}
+
 static bool convertArgumentToType(Sema &S, Expr *&Value, QualType Ty) {
   if (Value->isTypeDependent())
     return false;
@@ -3351,6 +3378,11 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
   case Builtin::BI__builtin_matrix_column_major_store:
     return BuiltinMatrixColumnMajorStore(TheCall, TheCallResult);
 
+  case Builtin::BI__builtin_verbose_trap:
+    if (!checkBuiltinVerboseTrap(TheCall, *this))
+      return ExprError();
+    break;
+
   case Builtin::BI__builtin_get_device_side_mangled_name: {
     auto Check = [](CallExpr *TheCall) {
       if (TheCall->getNumArgs() != 1)