[clang] [CIR] Mark globals as constants (PR #168463)

[Bruno Cardoso Lopes via cfe-commits]

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@@ -675,7 +675,9 @@ CIRGenModule::getOrCreateCIRGlobal(StringRef mangledName, mlir::Type ty,
       errorNYI(d->getSourceRange(), "OpenMP target global variable");
 
     gv.setAlignmentAttr(getSize(astContext.getDeclAlign(d)));
-    assert(!cir::MissingFeatures::opGlobalConstant());
+    // FIXME: This code is overly simple and should be merged with other global
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bcardosolopes wrote:

Keeping the CIR ones as FIXME(cir) or similar is what I find to be most helpful, but it's frustrating when you see a FIXME and you are not sure whether it's cargo cult. I'd be fine with a best effort `FIXME(ogcg)` if folks want to make it a bit more obvious

https://github.com/llvm/llvm-project/pull/168463