extend example, add doc

zokrates_core/src/static_analysis/propagation.rs

@@ -1,5 +1,11 @@
 //! Module containing constant propagation for the typed AST
 //!
+//! On top of the usual behavior of removing statements which assign a constant to a variable (as the variable can simply be
+//! substituted for the constant whenever used), we provide a `verbose` mode which does not remove such statements. This is done
+//! as for partial passes which do not visit the whole program, the variables being defined may be be used in parts of the program
+//! that are not visited. Keeping the statements is semantically equivalent and enables rebuilding the set of constants at the
+//! next pass.
+//!
 //! @file propagation.rs
 //! @author Thibaut Schaeffer <thibaut@schaeff.fr>
 //! @date 2018
@@ -16,7 +22,7 @@ pub struct Propagator<'ast, T: Field> {
     // we currently do not support partially constant expressions: `field [x, 1][1]` is not considered constant, `field [0, 1][1]` is
     constants: HashMap<TypedAssignee<'ast, T>, TypedExpression<'ast, T>>,
     // the verbose mode doesn't remove statements which assign constants to variables
-    // it required when using propagation in combination with unrolling
+    // it's required when using propagation in combination with unrolling
     verbose: bool,
 }
 

zokrates_core_test/tests/tests/nested_loop.json

@@ -7,7 +7,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["4838400", "10"]
+					"values": ["4838400", "10", "25"]
 				}
 			}
 		},
@@ -17,7 +17,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["0", "10"]
+					"values": ["0", "10", "25"]
 				}
 			}
 		}

zokrates_core_test/tests/tests/nested_loop.zok

@@ -1,4 +1,4 @@
-def main(field[4] values) -> (field, field):
+def main(field[4] values) -> (field, field, field):
     field res0 = 1
     field res1 = 0
 
@@ -15,4 +15,13 @@ def main(field[4] values) -> (field, field):
         res1 = res1 + 1
     endfor
 
-    return res0, res1
+    field res2 = 0
+    field i = 0
+    for field i in i..5 do
+        i = 5
+        for field i in 0..i do
+            res2 = res2 + 1
+        endfor
+    endfor
+
+    return res0, res1, res2