[LLVMdev] Prevent sizeof being replaced by a constant in IR

[Krzysztof Parzyszek]

On 4/14/2014 8:35 AM, Peter Conn wrote:
> Hello,
>
> Using the following command:
>
> clang -O0 -S -emit-llvm size.c
>
> Will generate an LLVM IR file where uses of 'sizeof' have been replaced
> by constants. Is there any way to prevent this, and perhaps leave the
> 'sizeof's replaced by GEPs as detailed here:
> http://nondot.org/sabre/LLVMNotes/SizeOf-OffsetOf-VariableSizedStructs.txt

"sizeof" _is_ a constant.

The technique from the note only works for aggregates that end with an 
array (or arrays themselves).

-Krzysztof

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