T783 regresses severely in allocations with new pattern match checker

The new pattern match checker (Phab:D1535) allocates 115% more than the previous checker on the T783 testcase,

bytes allocated value is too high:
    Expected    T783(normal) bytes allocated:  526230456 +/-10%
    Lower bound T783(normal) bytes allocated:  473607410 
    Upper bound T783(normal) bytes allocated:  578853502 
    Actual      T783(normal) bytes allocated: 1134085384 
    Deviation   T783(normal) bytes allocated:      115.5 %
*** unexpected stat test failure for T783(normal)

I suspect this isn't avoidable as this testcase consists of nothing more than 500 guarded equations, so exercises the checker quite thoroughly. That being said, perhaps it's worth a closer look.

Trac metadata

Trac field	Value
Version	7.10.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
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Blocking
CC	gkaracha
Operating system
Architecture