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

[Eli Friedman via cfe-commits]

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@@ -24,9 +27,140 @@ 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());
+}
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efriedma-quic wrote:

I don't buy the reasoning of "`mlir::Location` exists, therefore it's the right representation".  We're losing information which is likely to be important for many users of CIR.  Not saying this is something we need to solve right now, but it will eventually become problematic.

Converting a SourceLocation to line/column is also sort of slow (we compute line numbers lazily), but not sure how slow relative to other stuff CIR lowering needs to do anyway.

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