[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:

I don't expect the incubator project to have tested all the weird scenarios we come up with during PR review, and I don't expect reviewers to remember test cases from earlier reviews once they become more relevant, AND I don't expect CIR folks to handle every test case up front because that likely involves doing/undoing a bunch of work and makes upstreaming harder.

How about this for a compromise: as we think of test cases during PR review, the patch author either verifies the incubator project has test coverage for that already or adds the test coverage to the incubator project, and then fixes issues wherever it makes the most sense (either as part of the PR, a separate upstream PR, or in the incubator side which then gets upstreamed in a future PR)?

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