Fix Alpha/2005-07-12-TwoMallocCalls.ll and PR593.
Fix Alpha/2005-07-12-TwoMallocCalls.ll and PR593.

It is not safe to call LegalizeOp on something that has already been legalized.
Instead, just force another iteration of legalization.

This could affect all platforms but X86, as this codepath is dynamically
dead on X86 (ISD::MEMSET and friends are legal).


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@22419 91177308-0d34-0410-b5e6-96231b3b80d8

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