LookupCnsE needs a catch block

Reviewed By: @alexmalyshev

Differential Revision: D1381275
Fix bug in preOptimizeAssertTypeOp, tighten up typeMightRelax logic

Summary: preOptimizeAssertTypeOp has some logic to avoiding inserting redundant
AssertTypeOps when the source value comes from an AssertTypeOp with an
appropriate typeParam. It was looking at the dest type instead of the typeParam
of the new Assert op and missing out on lots of cases.

typeMightRelax would previously only return false if guard relaxation was off
or if the value was a constant. I've extended it to do the right thing for each
dest type in the opcode table. This prevents us from doing silly things like
keeping around "AssertType<Cell> t4:Str" when t4 comes from a Concat operation.

Together, these two fixes drastically reduce the number of AsssertTypes we end
up emitting into the initial translation. This eliminates some O(n^2) guard
relaxation crap we were running into in the new test. It looks like there's
still something superlinear going on in a different part of the jit so I'll dig
into that next.

Reviewed By: @bertmaher

Differential Revision: D1380326
Add InterpOne support for multiple profile translations with same SrcKey in translateRegion

Summary: We want to support Optimize regions that contain arbitrary
shapes. These regions may be formed from multiple Profile translations
that contain the same bytecode instruction ranges.  The set of
instructions to be InterpOne'd was keyed by SrcKey, and this diff
generalizes it by keying it by ProfSrcKey, which is a pair of
profiling TransID and SrcKey.

Reviewed By: @bertmaher

Differential Revision: D1380158
Fix assert in cse

Summary: The simplifier removes Movs as instruction sources as
it goes along, and as it processes later instructions, it asserts
that this has been done to all previous instructions. But if the
result of simplification is a Mov, and the dst is different from
the input, it would generate a Mov, causing the assert to fire.

Reviewed By: @bertmaher

Differential Revision: D1380875
Fix link.

Summary: Closes #2928

Reviewed By: @ptarjan

Differential Revision: D1381819

Pulled By: @JoelMarcey