JuliaLang / julia / #37311
70%

DEFAULT BRANCH: master
Ran
Jobs 1
Files 383
Run time 15s
Badge
Embed ▾
README BADGES
x

If you need to use a raster PNG badge, change the '.svg' to '.png' in the link

Markdown

Textile

RDoc

HTML

Rst
#37311

push

local

web-flow 
concrete-eval: Use concrete eval information even if the result is too large (#47283)

When we originally implemented concrete-eval, we decided not to create `Const`
lattice elements for constants that are too large, on the fear that these
would end up in the IR and blowing up the size. Now that we have some
experience with this, I think that decision was incorrect for several reasons:

1. We've already performed the concrete evaluation (and allocated the big
   object), so we're just throwing away precision here that we could
   have otherwise used (Although if the call result is unused, we probably
   shouldn't do concrete eval at all - see #46774).
2. There's a number of other places in the compiler where we read large
   values into `Const`. Unless we add these kinds of check there too,
   we need to have appropriate guards in the optimizer and the cache
   anyway, to prevent the IR size blowup.
3. It turns out that throwing away this precision actually causes
   significant performance problems for code that is just over the line.
   Consider for example a lookup of a small struct inside a large,
   multi-level constant structure. The final result might be quite
   tiny, but if we refuse to propagate the intermediate levels,
   we might end up doing an (expensive) full-constprop when propagating
   the constant information could have given us a much cheaper
   concrete evaluation.

This commit simply removes that check. If we see any regressions
as a result of this, we should see if there are additional guards
needed in the optimizer.

80654 of 86432 relevant lines covered (93.31%)

32591982.75 hits per line

Jobs
ID Job ID Ran Files Coverage
1 #37311.1 0
93.31
Source Files on build #37311
Detailed source file information is not available for this build.