[LLVMdev] RegAllocFast uses too much stack
gohman at apple.com
Mon Jul 11 15:41:00 PDT 2011
On Jul 11, 2011, at 3:06 PM, Eli Friedman wrote:
> On Mon, Jul 11, 2011 at 2:44 PM, Eric Christopher <echristo at apple.com> wrote:
>> On Jul 11, 2011, at 1:48 PM, Nick Lewycky wrote:
>> This seems odd. I'd think that fast-isel should be able to materialize the constants when we want them rather than at the beginning of the block.
> I'm not entirely sure why, but FastISel does intentionally materialize
> constants at the beginning of the block. See
> FastISel::enterLocalValueArea etc. Maybe Dan knows why?
Going bottom-up, FastISel doesn't know when it'll see the first use of a value
in a block. Cleverer schemes are possible.
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