Remove extra truncs/exts around i32 bit operations on PPC64
This generalizes the code to eliminate extra truncs/exts around i1 bit operations to also do the same on PPC64 for i32 bit operations. This eliminates a fairly prevalent code wart: int foo(int a) { return a == 5 ? 7 : 8; } On PPC64, because of the extension implied by the ABI, this would generate: cmplwi 0, 3, 5 li 12, 8 li 4, 7 isel 3, 4, 12, 2 rldicl 3, 3, 0, 32 blr where the 'rldicl 3, 3, 0, 32', the extension, is completely unnecessary. At least for the single-BB case (which is all that the DAG combine mechanism can handle), this unnecessary extension is no longer generated. llvm-svn: 202600
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