From c4befe280a15ec27c4a64a4c28294b66b1ece1d2 Mon Sep 17 00:00:00 2001
From: Matthias Springer <springerm@google.com>
Date: Wed, 6 Dec 2023 11:49:01 +0900
Subject: [PATCH] [mlir][SparseTensor] Fix insertion point in `createQuickSort`

`createQuickSort` used to generate invalid IR:
```
"func.func"() <{function_type = (index, index, memref<?xindex>, memref<?xf32>, memref<?xi32>) -> (), sym_name = "_sparse_qsort_0_1_index_coo_1_f32_i32", sym_visibility = "private"}> ({
^bb0(%arg0: index, %arg1: index, %arg2: memref<?xindex>, %arg3: memref<?xf32>, %arg4: memref<?xi32>):
  %0:2 = "scf.while"(%arg0, %arg1) ({
  ^bb0(%arg5: index, %arg6: index):
    %1 = "arith.constant"() <{value = 1 : index}> : () -> index
    %2 = "arith.addi"(%arg5, %1) : (index, index) -> index
    %3 = "arith.cmpi"(%2, %arg6) <{predicate = 6 : i64}> : (index, index) -> i1
    "scf.condition"(%3, %arg5, %arg6) : (i1, index, index) -> ()
  }, {
  ^bb0(%arg5: index, %arg6: index):
    %1 = "func.call"(%arg5, %arg6, %arg2, %arg3, %arg4) <{callee = @_sparse_partition_0_1_index_coo_1_f32_i32}> : (index, index, memref<?xindex>, memref<?xf32>, memref<?xi32>) -> index
    %2 = "arith.subi"(%1, %arg5) : (index, index) -> index
    %3 = "arith.subi"(%arg6, %1) : (index, index) -> index
    %4 = "arith.constant"() <{value = 2 : index}> : () -> index
    %5 = "arith.subi"(%arg6, %arg5) : (index, index) -> index
    %6 = "arith.cmpi"(%5, %4) <{predicate = 8 : i64}> : (index, index) -> i1
    %7:2 = "scf.if"(%6) ({
      %8 = "arith.cmpi"(%2, %3) <{predicate = 7 : i64}> : (index, index) -> i1
      // ...
      "scf.yield"(%9#0, %9#1) : (index, index) -> ()
      %10 = "arith.constant"() <{value = 0 : index}> : () -> index
    }, {
      "scf.yield"(%arg5, %arg5) : (index, index) -> ()
    }) : (i1) -> (index, index)
    "scf.yield"(%7#0, %7#1) : (index, index) -> ()
  }) : (index, index) -> (index, index)
  "func.return"() : () -> ()
}) : () -> ()
within split at mlir/test/Dialect/SparseTensor/buffer_rewriting.mlir:76 offset :11:1: error: 'scf.yield' op must be the last operation in the parent block
```

This commit fixes tests such as `mlir/test/Dialect/SparseTensor/buffer_rewriting.mlir` when verifying the IR after each pattern application (#74270).
---
 .../Dialect/SparseTensor/Transforms/SparseBufferRewriting.cpp   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mlir/lib/Dialect/SparseTensor/Transforms/SparseBufferRewriting.cpp b/mlir/lib/Dialect/SparseTensor/Transforms/SparseBufferRewriting.cpp
index 463a49f52283a..cdbf4f048a00f 100644
--- a/mlir/lib/Dialect/SparseTensor/Transforms/SparseBufferRewriting.cpp
+++ b/mlir/lib/Dialect/SparseTensor/Transforms/SparseBufferRewriting.cpp
@@ -952,9 +952,9 @@ createQuickSort(OpBuilder &builder, ModuleOp module, func::FuncOp func,
   Value cond = builder.create<arith::CmpIOp>(loc, arith::CmpIPredicate::ule,
                                              lenLow, lenHigh);
 
+  Value c0 = constantIndex(builder, loc, 0);
   scf::IfOp ifOp = builder.create<scf::IfOp>(loc, types, cond, /*else=*/true);
 
-  Value c0 = constantIndex(builder, loc, 0);
   auto mayRecursion = [&](Value low, Value high, Value len) {
     Value cond =
         builder.create<arith::CmpIOp>(loc, arith::CmpIPredicate::ne, len, c0);