[Mlir-commits] [mlir] [mlir][ArmSME] Use liveness information in the tile allocator (PR #90448)

[Benjamin Maxwell]

================
@@ -109,18 +112,16 @@ func.func @use_too_many_tiles() {
 /// Note: In this example an entire tile swap is inserted before/after the
 /// `arm_sme.load_tile_slice` operation. Really, this only needs to spill a
 /// single tile slice (and can omit the initial load, like in the previous example).
-func.func @very_excessive_spills(%memref : memref<?x?xf32>) -> vector<[4]x[4]xf32> {
-  %useAllTiles = arm_sme.get_tile : vector<[16]x[16]xi8>
+func.func @very_excessive_spills(%useAllTiles : vector<[16]x[16]xi8>, %memref: memref<?x?xf32>) -> vector<[4]x[4]xf32> {
   %c0 = arith.constant 0 : index
-  // expected-warning @below {{failed to allocate SME virtual tile to operation, all tile operations will go through memory, expect degraded performance}}
   %tile = arm_sme.get_tile : vector<[4]x[4]xf32>
   %mask = vector.constant_mask [4] : vector<[4]xi1>
+  // expected-warning @below {{failed to allocate SME virtual tile to operation, all tile operations will go through memory, expect degraded performance}}
   %loadSlice = arm_sme.load_tile_slice %memref[%c0, %c0], %mask, %tile, %c0 : memref<?x?xf32>, vector<[4]xi1>, vector<[4]x[4]xf32>
+  "test.some_use"(%useAllTiles) : (vector<[16]x[16]xi8>) -> ()
   return %loadSlice : vector<[4]x[4]xf32>
 }
 // AFTER-TILE-ALLOC-LABEL: @very_excessive_spills
-//      AFTER-TILE-ALLOC: arm_sme.get_tile
-// AFTER-TILE-ALLOC-SAME:   tile_id = 0
----------------
MacDue wrote:

I made that `get_tile` into a `%useAllTiles` function argument to prevent the tile allocator from being clever. 

https://github.com/llvm/llvm-project/pull/90448