Cache LDE from Round 1 to skip recomputation in Rounds 2-4 (#492)

* Cache LDE from Round 1 to skip recomputation in Rounds 2-4

* Remove timing profile script (moved to separate PR)

* Document memory trade-off, fix expect messages

* Fix stale trace_lde comment in prove_rounds_2_to_4

* Remove dead trace_lde telemetry field

* Remove LDE column pool, commit functions own their buffers (#498)

* Simplification (#500)

* Simplification

* Rename metadata -> cache

* Rework

* CacheLDE -> LDE

* Drop has_aux_trace param from build_round1

* Route reconstruct_round1 through build_round1

* Revert "Drop has_aux_trace param from build_round1"

This reverts commit 164c7c0.

* Pass has_aux_trace to build_round1 from reconstruct_round1

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Co-authored-by: gabrielbosio <gabrielbosio95@gmail.com>

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Co-authored-by: Mauro Toscano <12560266+MauroToscano@users.noreply.github.com>

Author: 2 people

crypto/math/src/fft/polynomial.rs

@@ -215,7 +215,7 @@ impl<E: IsField> Polynomial<FieldElement<E>> {
     ///
     /// Unlike [`coset_lde_full_into`], this skips the `clear + extend_from_slice` step
     /// since data is already in the buffer. Used for transpose elimination: columns are
-    /// extracted directly into pool buffers, then expanded in-place.
+    /// extracted directly into owned buffers, then expanded in-place.
     pub fn coset_lde_full_expand<F: IsFFTField + IsSubFieldOf<E> + Send + Sync>(
         buffer: &mut Vec<FieldElement<E>>,
         blowup_factor: usize,

crypto/stark/src/instruments.rs

@@ -5,8 +5,6 @@ use std::time::Duration;
 /// Sub-operation timing breakdown for a single table in Rounds 2-4.
 #[derive(Clone, Debug, Default)]
 pub struct TableSubOps {
-    /// reconstruct_round1 (expand_pool_to_lde)
-    pub trace_lde: Duration,
     /// evaluator.evaluate()
     pub constraints: Duration,
     /// decompose_and_extend_d2
@@ -28,11 +26,11 @@ pub struct TableSubOps {
 /// Sub-operation breakdown for Round 1 aux commit pass.
 #[derive(Clone, Debug, Default)]
 pub struct Round1SubOps {
-    /// Main trace: expand_pool_to_lde (LDE/FFT)
+    /// Main trace: expand_columns_to_lde (LDE/FFT)
     pub main_lde: Duration,
     /// Main trace: commit_columns_bit_reversed (Merkle)
     pub main_merkle: Duration,
-    /// Aux trace: expand_pool_to_lde (LDE/FFT)
+    /// Aux trace: expand_columns_to_lde (LDE/FFT)
     pub aux_lde: Duration,
     /// Aux trace: commit_columns_bit_reversed (Merkle)
     pub aux_merkle: Duration,