I don't know why the original test tests that fused mult-add is not emitted for these pieces, while at the same time specifying "fast" math on the operations.
When certain attributes are applied to the calling function, like "unsafe-fp-math", the inlined inlineIR function has to have the same attributes otherwise the calling function attribute will be reset to the safe merge of the two: "false". Because the same inlineIR function can be called in different functions using an alias definition, a new function (with possibly different attributes) has to be instantiated upon every call.
Related GH issue #1438