perf: eager resize for ´load_data´ (#1117)

lambdaclass · May 5, 2023 · e284753 · e284753
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,7 +2,9 @@
 
 #### Upcoming Changes
 
-* Add `CairoRunner::get_program method` [#1123](https://github.com/lambdaclass/cairo-rs/pull/1123):
+* perf: insert elements from the tail in `load_data` so reallocation happens only once [#1117](https://github.com/lambdaclass/cairo-rs/pull/1117)
+
+* Add `CairoRunner::get_program method` [#1123](https://github.com/lambdaclass/cairo-rs/pull/1123)
 
 * Use to_signed_felt as function for felt252 as BigInt within [-P/2, P/2] range and use to_bigint as function for representation as BigInt. [#1100](https://github.com/lambdaclass/cairo-rs/pull/1100)
 

diff --git a/src/vm/vm_memory/memory_segments.rs b/src/vm/vm_memory/memory_segments.rs
@@ -55,7 +55,9 @@ impl MemorySegmentManager {
         ptr: Relocatable,
         data: &Vec<MaybeRelocatable>,
     ) -> Result<Relocatable, MemoryError> {
-        for (num, value) in data.iter().enumerate() {
+        // Starting from the end ensures any necessary resize
+        // is performed once with enough room for everything
+        for (num, value) in data.iter().enumerate().rev() {
             self.memory.insert((ptr + num)?, value)?;
         }
         (ptr + data.len()).map_err(MemoryError::Math)