885180 - isLoopBackedge doesn't work after critical edge unsplitting

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement)

Description

[Dan Gohman [:sunfish]]

After the fix for bug 881412, debugging/printing routines which call isLoopBackedge don't work, because its assertions assume that critical edges are split.

Comment 1

[Dan Gohman [:sunfish]]

Attachment: a proposed fix

Comment 2

[Brian Hackett [Laid off!]]

Comment on attachment 765173 [details] [diff] [review]
a proposed fix

Review of attachment 765173 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/ion/MIRGraph.h
@@ +312,5 @@
>          return kind_ == LOOP_HEADER;
>      }
> +    bool hasUniqueBackedge() const {
> +        JS_ASSERT(isLoopHeader());
> +        return numPredecessors() == 2;

Could this assert numPredecessors() >= 2?  I think the numPredecessors() == 1 bit in the assertion you removed is antiquated, and now that we prune dead code from the graph it should (at least after that pass) be the case there are at least two predecessors.

Comment 3

[Dan Gohman [:sunfish]]

I added numPredecessors() >= 2 as you suggested.

https://hg.mozilla.org/integration/mozilla-inbound/rev/f7c30b1d5c35

Comment 4

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/f7c30b1d5c35