Use two rules for 'select' to avoid if-then-else on valstack (#655)

* Use two rules for 'select' to avoid if-then-else on valstack


---------

Co-authored-by: devops <[email protected]>
Co-authored-by: Burak Bilge Yalçınkaya <[email protected]>

Author: 3 people

package/version

@@ -1 +1 @@
-0.1.68
+0.1.69

pykwasm/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "poetry.core.masonry.api"
 
 [tool.poetry]
 name = "pykwasm"
-version = "0.1.68"
+version = "0.1.69"
 description = ""
 authors = [
     "Runtime Verification, Inc. <[email protected]>",

pykwasm/src/pykwasm/kdist/wasm-semantics/wasm.md

@@ -449,11 +449,16 @@ The `select` operator picks one of the second or third stack values based on the
          <valstack> _ : VALSTACK => VALSTACK </valstack>
 
     rule <instrs> select => .K ... </instrs>
-         <valstack> < i32 > C : V2 : V1                  : VALSTACK
-                 => #if C =/=Int 0 #then V1 #else V2 #fi : VALSTACK
+         <valstack> < i32 > C : V2 : V1 : VALSTACK
+                 =>             V2      : VALSTACK
          </valstack>
-      requires #sameType(V1, V2)
+      requires C ==Int 0 andBool #sameType(V1, V2)
 
+    rule <instrs> select => .K ... </instrs>
+         <valstack> < i32 > C : V2 : V1 : VALSTACK
+                 =>                  V1 : VALSTACK
+         </valstack>
+      requires C =/=Int 0 andBool #sameType(V1, V2)
 ```
 
 Structured Control Flow