Verifier: Diagnose an instruction using its own result values.

cranelift/filetests/verifier/defs_dominates_uses.cton

@@ -0,0 +1,16 @@
+test verifier
+
+; Test verification that uses properly dominate defs.
+
+function %non_dominating(i32) -> i32 native {
+ebb0(v0: i32):
+    v1 = iadd.i32 v2, v0   ; error: uses value from non-dominating
+    v2 = iadd.i32 v1, v0
+    return v2
+}
+
+function %inst_uses_its_own_values(i32) -> i32 native {
+ebb0(v0: i32):
+    v1 = iadd.i32 v1, v0   ; error: uses value from itself
+    return v1
+}