[clang] [CIR] Call code gen; create empty cir.func op (PR #113483)

[Aaron Ballman via cfe-commits]

================
@@ -24,9 +27,135 @@ CIRGenModule::CIRGenModule(mlir::MLIRContext &context,
                            clang::ASTContext &astctx,
                            const clang::CodeGenOptions &cgo,
                            DiagnosticsEngine &diags)
-    : astCtx(astctx), langOpts(astctx.getLangOpts()),
-      theModule{mlir::ModuleOp::create(mlir::UnknownLoc())},
-      target(astCtx.getTargetInfo()) {}
+    : builder(&context), astCtx(astctx), langOpts(astctx.getLangOpts()),
+      theModule{mlir::ModuleOp::create(mlir::UnknownLoc::get(&context))},
+      diags(diags), target(astCtx.getTargetInfo()) {}
+
+mlir::Location CIRGenModule::getLoc(SourceLocation cLoc) {
+  assert(cLoc.isValid() && "expected valid source location");
+  const SourceManager &sm = astCtx.getSourceManager();
+  PresumedLoc pLoc = sm.getPresumedLoc(cLoc);
+  StringRef filename = pLoc.getFilename();
+  return mlir::FileLineColLoc::get(builder.getStringAttr(filename),
+                                   pLoc.getLine(), pLoc.getColumn());
+}
+
+mlir::Location CIRGenModule::getLoc(SourceRange cRange) {
+  assert(cRange.isValid() && "expected a valid source range");
+  mlir::Location begin = getLoc(cRange.getBegin());
+  mlir::Location end = getLoc(cRange.getEnd());
+  mlir::Attribute metadata;
+  return mlir::FusedLoc::get({begin, end}, metadata, builder.getContext());
+}
+
+void CIRGenModule::buildGlobal(clang::GlobalDecl gd) {
+  const auto *global = cast<ValueDecl>(gd.getDecl());
+
+  if (const auto *fd = dyn_cast<FunctionDecl>(global)) {
+    // Update deferred annotations with the latest declaration if the function
+    // was already used or defined.
+    if (fd->hasAttr<AnnotateAttr>()) {
+      errorNYI(fd->getSourceRange(), "defferedAnnotations");
+    }
+    if (!fd->doesThisDeclarationHaveABody()) {
+      if (!fd->doesDeclarationForceExternallyVisibleDefinition())
+        return;
+
+      errorNYI(fd->getSourceRange(),
+               "function declaration that forces code gen");
+      return;
+    }
+  } else {
+    errorNYI(global->getSourceRange(), "global variable declaration");
+  }
+
+  // TODO(CIR): Defer emitting some global definitions until later
+  buildGlobalDefinition(gd);
+}
+
+void CIRGenModule::buildGlobalFunctionDefinition(clang::GlobalDecl gd,
+                                                 mlir::Operation *op) {
+  auto const *funcDecl = cast<FunctionDecl>(gd.getDecl());
+  auto funcOp = builder.create<mlir::cir::FuncOp>(
+      getLoc(funcDecl->getSourceRange()), funcDecl->getIdentifier()->getName());
----------------
AaronBallman wrote:

Leaving that for follow-up work makes sense to me, thanks!

For these sort of questions, I think it might make sense to stub in a test case with a FIXME comment and doing the bare minimum to ensure the test doesn't crash. Then we don't accidentally forget to cover those cases again in the future when we're not looking at what was discussed in much earlier reviews. WDYT?

https://github.com/llvm/llvm-project/pull/113483