Don't bother sign/zext_inreg'ing the result of an and operation if we know
the result does change as a result of the extend.
This improves codegen for Alpha on this testcase:
int %a(ushort* %i) {
%tmp.1 = load ushort* %i
%tmp.2 = cast ushort %tmp.1 to int
%tmp.4 = and int %tmp.2, 1
ret int %tmp.4
}
Generating:
a:
ldgp $29, 0($27)
ldwu $0,0($16)
and $0,1,$0
ret $31,($26),1
instead of:
a:
ldgp $29, 0($27)
ldwu $0,0($16)
and $0,1,$0
addl $0,0,$0
ret $31,($26),1
btw, alpha really should switch to livein/outs for args :)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21213
91177308-0d34-0410-b5e6-
96231b3b80d8