[clang] [CIR] Upstream support for emitting ignored statements (PR #130869)

[Andy Kaylor via cfe-commits]

================
@@ -55,10 +55,154 @@ mlir::LogicalResult CIRGenFunction::emitStmt(const Stmt *s,
   if (mlir::succeeded(emitSimpleStmt(s, useCurrentScope)))
     return mlir::success();
 
-  // Only a subset of simple statements are supported at the moment.  When more
-  // kinds of statements are supported, a
-  //     switch (s->getStmtClass()) {
-  // will be added here.
+  switch (s->getStmtClass()) {
+
+#define STMT(Type, Base)
+#define ABSTRACT_STMT(Op)
+#define EXPR(Type, Base) case Stmt::Type##Class:
+#include "clang/AST/StmtNodes.inc"
+    {
+      // Remember the block we came in on.
+      mlir::Block *incoming = builder.getInsertionBlock();
+      assert(incoming && "expression emission must have an insertion point");
+
+      emitIgnoredExpr(cast<Expr>(s));
----------------
andykaylor wrote:

Yes, this is far from obvious. StmtNodes.inc uses a system of macros and preprocessors statements, so when it is included what you get for each one is somewhat determined by which of the macros the client has defined. In this case, we're getting expressions that are neither statements or abstract statements (because we define STMT and ABSTRACT_STMT but do nothing with them). The exact list, of course, depends on what's in StmtNodes.td and how things are defined there.

FWIW, this matches the handling in the classic codegen (https://github.com/llvm/llvm-project/blob/1a626e63b5a009075eea87c01f0661144b1ec010/clang/lib/CodeGen/CGStmt.cpp#L130).

https://github.com/llvm/llvm-project/pull/130869