Legalize unsigned-to-float conversions for Intel 64.

Also make sure we generate type checks for the controlling type variable
in legalization patterns. This is not needed for encodings since the
encoding tables are already keyed on the controlling type variable.

cranelift/filetests/wasm/conversions.cton

@@ -49,25 +49,47 @@ ebb0(v0: i32):
     return v1
 }
 
+function %f32_convert_u_i32(i32) -> f32 {
+ebb0(v0: i32):
+    v1 = fcvt_from_uint.f32 v0
+    return v1
+}
+
 function %f64_convert_s_i32(i32) -> f64 {
 ebb0(v0: i32):
     v1 = fcvt_from_sint.f64 v0
     return v1
 }
 
+function %f64_convert_u_i32(i32) -> f64 {
+ebb0(v0: i32):
+    v1 = fcvt_from_uint.f64 v0
+    return v1
+}
+
 function %f32_convert_s_i64(i64) -> f32 {
 ebb0(v0: i64):
     v1 = fcvt_from_sint.f32 v0
     return v1
 }
 
+function %f32_convert_u_i64(i64) -> f32 {
+ebb0(v0: i64):
+    v1 = fcvt_from_uint.f32 v0
+    return v1
+}
+
 function %f64_convert_s_i64(i64) -> f64 {
 ebb0(v0: i64):
     v1 = fcvt_from_sint.f64 v0
     return v1
 }
 
-; TODO: f*_convert_u_i* (Don't exist on Intel).
+function %f64_convert_u_i64(i64) -> f64 {
+ebb0(v0: i64):
+    v1 = fcvt_from_uint.f64 v0
+    return v1
+}
 
 function %i32_reinterpret_f32(f32) -> i32 {
 ebb0(v0: f32):