Speedup Function::getIntrinsicID() with caching of result

[Duncan Sands]

Hi Jean-Luc,

On 28/02/13 02:16, Jean-Luc Duprat wrote:
> The attached patch caches the result of Function::getIntrinsicID() in a DenseMap attached to the LLVMContext.  This reduces the time actually spent doing string to ID conversion and shows a 10% improvement in compile time for a particularly bad case that involves ARM Neon intrinsics (these have many overloads).
>
> This changes passes the regression tests and the nightly tests suite.

if you delete an intrinsic function declaration from the module, don't you get a
stale pointer to freed memory in the cache?  To avoid all such issues, maybe it
is simpler to have the cache map the name (a StringRef) to the intrinsic ID,
rather than mapping the function pointer to the intrinsic ID.  You probably lose
some of the speedup then though.

Ciao, Duncan.