[llvm-commits] [llvm][commits] r162603

[Jakob Stoklund Olesen]

On Nov 12, 2012, at 2:31 AM, "Silviu Baranga" <silbar01 at arm.com> wrote:

> Hi Jakob,
> 
> Why is the LEApcrel marked as having side effects?
> This is preventing it from being hoisted by the MachineLICM pass.

Hi Silviu,

As the commit message says, hoisting the lea breaks the pass that forms tbb instructions for jump tables.

Patches welcome, it's the constant island pass IIRC.

/jakob

>> Explicitly mark LEApcrel pseudos with hasSideEffects.
>> 
>> It's not clear that they should be marked as such, but tbb formation
> fails if t2LEApcrelJT is hoisted of of a loop.
>> 
>> This doesn't change the flags on these instructions,
>> UnmodeledSideEffects was already inferred from the missing pattern.
> 
> 
>