Unnecessary movzx instruction?

Ian Lance Taylor iant@google.com
Mon Nov 8 15:07:00 GMT 2010


Jeff Law <law@redhat.com> writes:

> The pass which typically tracks zero/nonzero information and tries to
> eliminate redundant zero/sign extensions is combine which only
> operates on insns found within a single basic block.  In this case the
> instructions at 0x10 and 0x23 are in different basic blocks and
> combine makes a worst case assumption.

Mainline also has the implicit_zee pass  but it doesn't seem to help
with this test case.

Ian



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