ARMBaseRegisterInfo::estimateRSStackSizeLimit() could return prematurely with a too large limit.
ARMBaseRegisterInfo::estimateRSStackSizeLimit() could return prematurely with a
too large limit.

The function would return immediately when finding an addrmode 3/5 instruction.
It needs to keep scanning in case there is an addrmode 6 instruction which drops
the limit to 0.

A test case is very difficult to produce because it will only fail when the
scavenger is used.

rdar://problem/7894847

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@103995 91177308-0d34-0410-b5e6-96231b3b80d8

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