feat: speed up transformation of debug messages (#3815)

# Description
Same as #3814 but with a different
approach, by building the map of old to new inside AcirTransformationMap
## Problem\*

Resolves #3809

## Summary\*



## Additional Context



## Documentation\*

Check one:
- [ ] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[Exceptional Case]** Documentation to be submitted in a separate
PR.

# PR Checklist\*

- [ ] I have tested the changes locally.
- [ ] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

acvm-repo/acvm/src/compiler/mod.rs

@@ -1,3 +1,5 @@
+use std::collections::HashMap;
+
 use acir::{
     circuit::{opcodes::UnsupportedMemoryOpcode, Circuit, Opcode, OpcodeLocation},
     BlackBoxFunc,
@@ -27,12 +29,22 @@ pub enum CompileError {
 /// metadata they had about the opcodes to the new opcode structure generated after the transformation.
 #[derive(Debug)]
 pub struct AcirTransformationMap {
-    /// This is a vector of pointers to the old acir opcodes. The index of the vector is the new opcode index.
-    /// The value of the vector is the old opcode index pointed.
-    acir_opcode_positions: Vec<usize>,
+    /// Maps the old acir indices to the new acir indices
+    old_indices_to_new_indices: HashMap<usize, Vec<usize>>,
 }
 
 impl AcirTransformationMap {
+    /// Builds a map from a vector of pointers to the old acir opcodes.
+    /// The index of the vector is the new opcode index.
+    /// The value of the vector is the old opcode index pointed.
+    fn new(acir_opcode_positions: Vec<usize>) -> Self {
+        let mut old_indices_to_new_indices = HashMap::with_capacity(acir_opcode_positions.len());
+        for (new_index, old_index) in acir_opcode_positions.into_iter().enumerate() {
+            old_indices_to_new_indices.entry(old_index).or_insert_with(Vec::new).push(new_index);
+        }
+        AcirTransformationMap { old_indices_to_new_indices }
+    }
+
     pub fn new_locations(
         &self,
         old_location: OpcodeLocation,
@@ -42,16 +54,16 @@ impl AcirTransformationMap {
             OpcodeLocation::Brillig { acir_index, .. } => acir_index,
         };
 
-        self.acir_opcode_positions
-            .iter()
-            .enumerate()
-            .filter(move |(_, &old_index)| old_index == old_acir_index)
-            .map(move |(new_index, _)| match old_location {
-                OpcodeLocation::Acir(_) => OpcodeLocation::Acir(new_index),
-                OpcodeLocation::Brillig { brillig_index, .. } => {
-                    OpcodeLocation::Brillig { acir_index: new_index, brillig_index }
-                }
-            })
+        self.old_indices_to_new_indices.get(&old_acir_index).into_iter().flat_map(
+            move |new_indices| {
+                new_indices.iter().map(move |new_index| match old_location {
+                    OpcodeLocation::Acir(_) => OpcodeLocation::Acir(*new_index),
+                    OpcodeLocation::Brillig { brillig_index, .. } => {
+                        OpcodeLocation::Brillig { acir_index: *new_index, brillig_index }
+                    }
+                })
+            },
+        )
     }
 }
 
@@ -74,11 +86,13 @@ pub fn compile(
     np_language: Language,
     is_opcode_supported: impl Fn(&Opcode) -> bool,
 ) -> Result<(Circuit, AcirTransformationMap), CompileError> {
-    let (acir, AcirTransformationMap { acir_opcode_positions }) = optimize_internal(acir);
+    let (acir, acir_opcode_positions) = optimize_internal(acir);
 
-    let (mut acir, transformation_map) =
+    let (mut acir, acir_opcode_positions) =
         transform_internal(acir, np_language, is_opcode_supported, acir_opcode_positions)?;
 
+    let transformation_map = AcirTransformationMap::new(acir_opcode_positions);
+
     acir.assert_messages = transform_assert_messages(acir.assert_messages, &transformation_map);
 
     Ok((acir, transformation_map))

acvm-repo/acvm/src/compiler/optimizers/mod.rs

@@ -13,15 +13,17 @@ use super::{transform_assert_messages, AcirTransformationMap};
 
 /// Applies [`ProofSystemCompiler`][crate::ProofSystemCompiler] independent optimizations to a [`Circuit`].
 pub fn optimize(acir: Circuit) -> (Circuit, AcirTransformationMap) {
-    let (mut acir, transformation_map) = optimize_internal(acir);
+    let (mut acir, new_opcode_positions) = optimize_internal(acir);
+
+    let transformation_map = AcirTransformationMap::new(new_opcode_positions);
 
     acir.assert_messages = transform_assert_messages(acir.assert_messages, &transformation_map);
 
     (acir, transformation_map)
 }
 
 /// Applies [`ProofSystemCompiler`][crate::ProofSystemCompiler] independent optimizations to a [`Circuit`].
-pub(super) fn optimize_internal(acir: Circuit) -> (Circuit, AcirTransformationMap) {
+pub(super) fn optimize_internal(acir: Circuit) -> (Circuit, Vec<usize>) {
     log::trace!("Start circuit optimization");
 
     // General optimizer pass
@@ -52,9 +54,7 @@ pub(super) fn optimize_internal(acir: Circuit) -> (Circuit, AcirTransformationMa
     let (acir, acir_opcode_positions) =
         range_optimizer.replace_redundant_ranges(acir_opcode_positions);
 
-    let transformation_map = AcirTransformationMap { acir_opcode_positions };
-
     log::trace!("Finish circuit optimization");
 
-    (acir, transformation_map)
+    (acir, acir_opcode_positions)
 }

acvm-repo/acvm/src/compiler/transformers/mod.rs

@@ -27,9 +27,11 @@ pub fn transform(
     // by applying the modifications done to the circuit opcodes and also to the opcode_positions (delete and insert)
     let acir_opcode_positions = acir.opcodes.iter().enumerate().map(|(i, _)| i).collect();
 
-    let (mut acir, transformation_map) =
+    let (mut acir, acir_opcode_positions) =
         transform_internal(acir, np_language, is_opcode_supported, acir_opcode_positions)?;
 
+    let transformation_map = AcirTransformationMap::new(acir_opcode_positions);
+
     acir.assert_messages = transform_assert_messages(acir.assert_messages, &transformation_map);
 
     Ok((acir, transformation_map))
@@ -43,7 +45,7 @@ pub(super) fn transform_internal(
     np_language: Language,
     is_opcode_supported: impl Fn(&Opcode) -> bool,
     acir_opcode_positions: Vec<usize>,
-) -> Result<(Circuit, AcirTransformationMap), CompileError> {
+) -> Result<(Circuit, Vec<usize>), CompileError> {
     log::trace!("Start circuit transformation");
 
     // Fallback transformer pass
@@ -52,9 +54,8 @@ pub(super) fn transform_internal(
 
     let mut transformer = match &np_language {
         crate::Language::R1CS => {
-            let transformation_map = AcirTransformationMap { acir_opcode_positions };
             let transformer = R1CSTransformer::new(acir);
-            return Ok((transformer.transform(), transformation_map));
+            return Ok((transformer.transform(), acir_opcode_positions));
         }
         crate::Language::PLONKCSat { width } => {
             let mut csat = CSatTransformer::new(*width);
@@ -216,10 +217,7 @@ pub(super) fn transform_internal(
         ..acir
     };
 
-    let transformation_map =
-        AcirTransformationMap { acir_opcode_positions: new_acir_opcode_positions };
-
     log::trace!("Finish circuit transformation");
 
-    Ok((acir, transformation_map))
+    Ok((acir, new_acir_opcode_positions))
 }