(MUL x (MOVDconst [1])) => x
(MUL x (MOVDconst [c])) && isPowerOfTwo64(c) => (SLLconst [log64(c)] x)
(MUL x (MOVDconst [c])) && isPowerOfTwo64(c-1) && c >= 3 => (ADDshiftLL x x [log64(c-1)])
(MUL x (MOVDconst [c])) && isPowerOfTwo64(c+1) && c >= 7 => (ADDshiftLL (NEG <x.Type> x) x [log64(c+1)])
(MUL x (MOVDconst [c])) && c%3 == 0 && isPowerOfTwo64(c/3) => (SLLconst [log64(c/3)] (ADDshiftLL <x.Type> x x [1]))

(Mul16 <t> n (Const16 [c])) && isPowerOfTwo16(c) => (Lsh16x64 <t> n (Const64 <typ.UInt64> [log16(c)]))
(Mul32 <t> n (Const32 [c])) && isPowerOfTwo32(c) => (Lsh32x64 <t> n (Const64 <typ.UInt64> [log32(c)]))
(Mul64 <t> n (Const64 [c])) && isPowerOfTwo64(c) => (Lsh64x64 <t> n (Const64 <typ.UInt64> [log64(c)]))
(Mul8  <t> n (Const8  [c])) && t.IsSigned() && isPowerOfTwo8(-c)  => (Neg8  (Lsh8x64  <t> n (Const64 <typ.UInt64> [log8(-c)])))