Remove branch isolation

changelogs/unreleased/1353-dark64

@@ -0,0 +1 @@
+Remove expensive and buggy branch isolation

zokrates_analysis/src/lib.rs

@@ -6,7 +6,6 @@
 
 mod assembly_transformer;
 mod boolean_array_comparator;
-mod branch_isolator;
 mod condition_redefiner;
 mod constant_argument_checker;
 mod constant_resolver;
@@ -25,7 +24,6 @@ mod variable_write_remover;
 mod zir_propagation;
 
 use self::boolean_array_comparator::BooleanArrayComparator;
-use self::branch_isolator::Isolator;
 use self::condition_redefiner::ConditionRedefiner;
 use self::constant_argument_checker::ConstantArgumentChecker;
 use self::flatten_complex_types::Flattener;
@@ -132,17 +130,6 @@ pub fn analyse<'ast, T: Field>(
     let r = ConstantResolver::inline(p);
     log::trace!("\n{}", r);
 
-    // isolate branches
-    let r = if config.isolate_branches {
-        log::debug!("Static analyser: Isolate branches");
-        let r = Isolator::isolate(r);
-        log::trace!("\n{}", r);
-        r
-    } else {
-        log::debug!("Static analyser: Branch isolation skipped");
-        r
-    };
-
     // include logs
     let r = if config.debug {
         log::debug!("Static analyser: Include logs");

zokrates_ast/src/ir/mod.rs

@@ -74,7 +74,7 @@ impl<T: Field> fmt::Display for ConstraintStatement<T> {
             self.error
                 .as_ref()
                 .map(|e| format!(" // {}", e))
-                .unwrap_or_else(|| "".to_string())
+                .unwrap_or_default()
         )
     }
 }

zokrates_ast/src/lib.rs

@@ -1,3 +1,6 @@
+// see https://github.com/mcarton/rust-derivative/issues/115
+#![allow(clippy::incorrect_partial_ord_impl_on_ord_type)]
+
 pub mod common;
 pub mod flat;
 pub mod ir;

zokrates_ast/src/untyped/mod.rs

@@ -543,11 +543,8 @@ impl<'ast> fmt::Display for Range<'ast> {
             self.from
                 .as_ref()
                 .map(|e| e.to_string())
-                .unwrap_or_else(|| "".to_string()),
-            self.to
-                .as_ref()
-                .map(|e| e.to_string())
-                .unwrap_or_else(|| "".to_string())
+                .unwrap_or_default(),
+            self.to.as_ref().map(|e| e.to_string()).unwrap_or_default()
         )
     }
 }

zokrates_book/src/language/control_flow.md

@@ -47,9 +47,8 @@ Now the two caveats:
 ```zokrates
 {{#include ../../../zokrates_cli/examples/book/conditional_panic.zok}}
 ```
-The experimental flag `--branch-isolation` can be activated in the CLI in order to restrict any unsatisfied constraint to make the execution fail only if it is in a logically executed branch. This way, the execution of the program above will always succeed.
 
->The reason for these caveats is that the program is compiled down to an arithmetic circuit. This construct does not support jumping to a branch depending on a condition as you could do on traditional architectures. Instead, all branches are inlined as if they were printed on a circuit board. The `branch-isolation` feature comes with overhead for each assertion in each branch, and this overhead compounds when deeply nesting conditionals.
+>The reason for these caveats is that the program is compiled down to an arithmetic circuit. This construct does not support jumping to a branch depending on a condition as you could do on traditional architectures. Instead, all branches are inlined as if they were printed on a circuit board.
 
 ### For loops
 

zokrates_cli/src/ops/check.rs

@@ -44,11 +44,6 @@ pub fn subcommand() -> App<'static, 'static> {
                 .possible_values(cli_constants::CURVES)
                 .default_value(BN128),
         )
-        .arg(Arg::with_name("isolate-branches")
-            .long("isolate-branches")
-            .help("Isolate the execution of branches: a panic in a branch only makes the program panic if this branch is being logically executed")
-            .required(false)
-        )
 }
 
 pub fn exec(sub_matches: &ArgMatches) -> Result<(), String> {
@@ -94,17 +89,13 @@ fn cli_check<T: Field>(sub_matches: &ArgMatches) -> Result<(), String> {
         )),
     }?;
 
-    let config =
-        CompileConfig::default().isolate_branches(sub_matches.is_present("isolate-branches"));
-
+    let config = CompileConfig::default();
     let resolver = FileSystemResolver::with_stdlib_root(stdlib_path);
+
     check::<T, _>(source, path, Some(&resolver), &config).map_err(|e| {
         format!(
             "Check failed:\n\n{}",
-            e.0.iter()
-                .map(|e| fmt_error(e))
-                .collect::<Vec<_>>()
-                .join("\n\n")
+            e.0.iter().map(fmt_error).collect::<Vec<_>>().join("\n\n")
         )
     })?;
 

zokrates_cli/src/ops/compile.rs

@@ -18,62 +18,71 @@ use zokrates_fs_resolver::FileSystemResolver;
 pub fn subcommand() -> App<'static, 'static> {
     SubCommand::with_name("compile")
         .about("Compiles into a runnable constraint system")
-        .arg(Arg::with_name("input")
-            .short("i")
-            .long("input")
-            .help("Path of the source code")
-            .value_name("FILE")
-            .takes_value(true)
-            .required(true)
-        ).arg(Arg::with_name("stdlib-path")
-        .long("stdlib-path")
-        .help("Path to the standard library")
-        .value_name("PATH")
-        .takes_value(true)
-        .required(false)
-        .env("ZOKRATES_STDLIB")
-        .default_value(cli_constants::DEFAULT_STDLIB_PATH.as_str())
-    ).arg(Arg::with_name("abi-spec")
-        .short("s")
-        .long("abi-spec")
-        .help("Path of the ABI specification")
-        .value_name("FILE")
-        .takes_value(true)
-        .required(false)
-        .default_value(cli_constants::ABI_SPEC_DEFAULT_PATH)
-    ).arg(Arg::with_name("output")
-        .short("o")
-        .long("output")
-        .help("Path of the output binary")
-        .value_name("FILE")
-        .takes_value(true)
-        .required(false)
-        .default_value(cli_constants::FLATTENED_CODE_DEFAULT_PATH)
-    ).arg(Arg::with_name("r1cs")
-    .short("r1cs")
-    .long("r1cs")
-    .help("Path of the output r1cs file")
-    .value_name("FILE")
-    .takes_value(true)
-    .required(false)
-    .default_value(cli_constants::CIRCOM_R1CS_DEFAULT_PATH)
-).arg(Arg::with_name("curve")
-        .short("c")
-        .long("curve")
-        .help("Curve to be used in the compilation")
-        .takes_value(true)
-        .required(false)
-        .possible_values(cli_constants::CURVES)
-        .default_value(BN128)
-    ).arg(Arg::with_name("isolate-branches")
-        .long("isolate-branches")
-        .help("Isolate the execution of branches: a panic in a branch only makes the program panic if this branch is being logically executed")
-        .required(false)
-    ).arg(Arg::with_name("debug")
-        .long("debug")
-        .help("Include logs")
-        .required(false)
-)
+        .arg(
+            Arg::with_name("input")
+                .short("i")
+                .long("input")
+                .help("Path of the source code")
+                .value_name("FILE")
+                .takes_value(true)
+                .required(true),
+        )
+        .arg(
+            Arg::with_name("stdlib-path")
+                .long("stdlib-path")
+                .help("Path to the standard library")
+                .value_name("PATH")
+                .takes_value(true)
+                .required(false)
+                .env("ZOKRATES_STDLIB")
+                .default_value(cli_constants::DEFAULT_STDLIB_PATH.as_str()),
+        )
+        .arg(
+            Arg::with_name("abi-spec")
+                .short("s")
+                .long("abi-spec")
+                .help("Path of the ABI specification")
+                .value_name("FILE")
+                .takes_value(true)
+                .required(false)
+                .default_value(cli_constants::ABI_SPEC_DEFAULT_PATH),
+        )
+        .arg(
+            Arg::with_name("output")
+                .short("o")
+                .long("output")
+                .help("Path of the output binary")
+                .value_name("FILE")
+                .takes_value(true)
+                .required(false)
+                .default_value(cli_constants::FLATTENED_CODE_DEFAULT_PATH),
+        )
+        .arg(
+            Arg::with_name("r1cs")
+                .short("r1cs")
+                .long("r1cs")
+                .help("Path of the output r1cs file")
+                .value_name("FILE")
+                .takes_value(true)
+                .required(false)
+                .default_value(cli_constants::CIRCOM_R1CS_DEFAULT_PATH),
+        )
+        .arg(
+            Arg::with_name("curve")
+                .short("c")
+                .long("curve")
+                .help("Curve to be used in the compilation")
+                .takes_value(true)
+                .required(false)
+                .possible_values(cli_constants::CURVES)
+                .default_value(BN128),
+        )
+        .arg(
+            Arg::with_name("debug")
+                .long("debug")
+                .help("Include logs")
+                .required(false),
+        )
 }
 
 pub fn exec(sub_matches: &ArgMatches) -> Result<(), String> {
@@ -124,10 +133,7 @@ fn cli_compile<T: Field>(sub_matches: &ArgMatches) -> Result<(), String> {
         )),
     }?;
 
-    let config = CompileConfig::default()
-        .isolate_branches(sub_matches.is_present("isolate-branches"))
-        .debug(sub_matches.is_present("debug"));
-
+    let config = CompileConfig::default().debug(sub_matches.is_present("debug"));
     let resolver = FileSystemResolver::with_stdlib_root(stdlib_path);
 
     log::debug!("Compile");
@@ -138,10 +144,7 @@ fn cli_compile<T: Field>(sub_matches: &ArgMatches) -> Result<(), String> {
         .map_err(|e| {
             format!(
                 "Compilation failed:\n\n{}",
-                e.0.iter()
-                    .map(|e| fmt_error(e))
-                    .collect::<Vec<_>>()
-                    .join("\n\n")
+                e.0.iter().map(fmt_error).collect::<Vec<_>>().join("\n\n")
             )
         })?;