[llvm-dev] Look up table in function section

[Krzysztof Parzyszek via llvm-dev]

On 5/4/2017 1:51 PM, Tim Northover via llvm-dev wrote:
> 
> It's not usually that useful though: more gadgets to exploit and in
> the RISCy targets I know of you still have to address them as a
> full-on global to ensure they're in range.
> 
> If at all possible, I wouldn't recommend going the ARMConstantIslands
> route and putting the tables in the middle of a function. That pass is
> a constant source of bugs.

For us this is to keep the jump table/lookup table in the tightly 
coupled memory.  For functions that are not in TCM it doesn't matter 
that much, but functions in TCM may suffer a long delay on loads from 
non-TCM.  We need to be able to put both tables in the same section as 
the function.  The hook you mentioned works for jump tables, but we need 
some mechanism to do the same for lookup tables.

-Krzysztof

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