[LLVMdev] [cfe-dev] RFC: Codifying (but not formalizing) the optimization levels in LLVM and Clang

Krzysztof Parzyszek
Sat, 19 Jan 2013 17:21:14 -0000

On 1/19/2013 1:55 AM, Chandler Carruth wrote:
>
> -ffast-math is *totally* different from these attributes, and in fact
> -ffast-math is specifically not modeled as a function attribute because
> it changes the fundamental semantics of an operation.
>
> These attributes have zero semantic impact on the function, and so it is
> always functionally correct to change them, replace them, merge them,
> remove them, or inline code from one to the other.

I just thought of this example: attribute "section".  It has zero
semantic impact on the function, and yet it is not correct to change it,
replace it, remove it, etc.

-Krzysztof


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