[Cranelift] (-X) * C = X * (-C)

Author: bongjunj

cranelift/codegen/src/opts/arithmetic.isle

@@ -500,3 +500,6 @@
 (rule (simplify (ugt ty x (umax ty y x))) (iconst_u ty 0))
 (rule (simplify (ult ty (umax ty x y) x)) (iconst_u ty 0))
 (rule (simplify (ult ty (umax ty y x) x)) (iconst_u ty 0))
+
+;; (-X) * C = X * (-C)
+(rule (simplify (imul (fits_in_64 ty) (ineg ty x) (iconst ty y))) (imul ty x (iconst ty (imm64_neg ty y))))