reuse lhs frag strategy (#132)

crates/cubecl-linalg/src/matmul/cmma/compute_loop/accumulators_first.rs

@@ -27,21 +27,33 @@ impl ComputeLoop for AllAccumulatorsFirstComputeLoop {
         let num_accumulators = comptime_info.num_accumulators;
         let num_buffers = block_size_k / tile_size;
         let num_coop_per_row = (block_size_n / tile_size) / num_accumulators;
+        let reuse_lhs_fragment = comptime_info.reuse_lhs_fragment;
 
         // Runtime values
         let tile_row = ids.coop / num_coop_per_row;
         let tile_col_base = (ids.coop % num_coop_per_row) * num_accumulators;
 
         #[unroll(unroll)]
         for buffer_iter in 0..num_buffers {
-            #[unroll]
-            for accumulator_iter in 0..num_accumulators {
+            if reuse_lhs_fragment {
                 load_into_fragment(
                     tile_row * num_buffers + buffer_iter,
                     shared_memories.lhs,
                     &fragments.lhs,
                     comptime_info,
                 );
+            }
+
+            #[unroll]
+            for accumulator_iter in 0..num_accumulators {
+                if !reuse_lhs_fragment {
+                    load_into_fragment(
+                        tile_row * num_buffers + buffer_iter,
+                        shared_memories.lhs,
+                        &fragments.lhs,
+                        comptime_info,
+                    );
+                }
 
                 load_into_fragment(
                     (tile_col_base + accumulator_iter) * num_buffers + buffer_iter,

crates/cubecl-linalg/src/matmul/cmma/config.rs

@@ -52,14 +52,16 @@ pub enum ComputeLoopOrderStrategy {
     /// Accumulators for one warp are put concurrently in a shared memory large enough to contain them all
     AllBuffersFirst,
     /// Accumulators for one warp are put sequentially in a shared memory with only one reusable spot
-    AllAccumulatorsFirst,
+    AllAccumulatorsFirst { reuse_lhs_fragment: bool },
 }
 
-impl From<ComputeLoopOrderStrategy> for u32 {
+impl From<ComputeLoopOrderStrategy> for (u32, bool) {
     fn from(value: ComputeLoopOrderStrategy) -> Self {
         match value {
-            ComputeLoopOrderStrategy::AllBuffersFirst => 0,
-            ComputeLoopOrderStrategy::AllAccumulatorsFirst => 1,
+            ComputeLoopOrderStrategy::AllBuffersFirst => (0, false),
+            ComputeLoopOrderStrategy::AllAccumulatorsFirst { reuse_lhs_fragment } => {
+                (1, reuse_lhs_fragment)
+            }
         }
     }
 }
@@ -116,6 +118,8 @@ impl CmmaConfig {
 
     pub(crate) fn comptime_info(&self, m: usize, k: usize, n: usize) -> ComptimeCmmaInfo {
         let num_coops = self.b_mn * self.b_k / (CMMA_TILE_SIZE * CMMA_TILE_SIZE);
+        let (compute_loop_order_strategy, reuse_lhs_fragment) =
+            self.compute_loop_order_strategy.into();
 
         ComptimeCmmaInfo {
             block_size_m: self.b_mn as u32,
@@ -131,7 +135,8 @@ impl CmmaConfig {
             num_accumulators: (self.b_mn / self.b_k) as u32,
             write_out_strategy: self.write_out_strategy.into(),
             cube_dispatch_strategy: self.cube_dispatch_strategy.into(),
-            compute_loop_order_strategy: self.compute_loop_order_strategy.into(),
+            compute_loop_order_strategy,
+            reuse_lhs_fragment,
         }
     }
 
@@ -205,6 +210,9 @@ pub struct ComptimeCmmaInfo {
     pub write_out_strategy: u32,
     /// 0 = RowMajor, 1 = ColMajor, 2 = Swizzle
     pub cube_dispatch_strategy: u32,
-    /// 0 = buffer inner, 1 = buffer outer
+    /// 0 = all buffers first, 1 = all accumulators first
     pub compute_loop_order_strategy: u32,
+    /// Whether to reuse lhs fragment (true) or to reload it (false)
+    /// Available only with all accumulators first compute loop order
+    pub reuse_lhs_fragment: bool,
 }