[Mlir-commits] [mlir] [mlir][RemoveDeadValues] Simplify branch op handling using ub.poison (PR #182711)

[Matthias Springer]

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@@ -35,20 +35,26 @@ module @named_module_acceptable {
 func.func @acceptable_ir_has_cleanable_loop_of_conditional_and_branch_op(%arg0: i1) {
   %non_live = arith.constant 0 : i32
   // CHECK-NOT: arith.constant
+  // CHECK-CANONICALIZE-NOT: arith.constant
   cf.br ^bb1(%non_live : i32)
-  // CHECK: cf.br ^[[BB1:bb[0-9]+]]
+  // CHECK: cf.br ^[[BB1:bb[0-9]+]](%{{.*}} : i32)
+  // CHECK-CANONICALIZE: cf.br ^[[BB1:bb[0-9]+]](%{{.*}} : i32)
 ^bb1(%non_live_1 : i32):
-  // CHECK: ^[[BB1]]:
+  // CHECK: ^[[BB1]](%{{.*}}: i32):
+  // CHECK-CANONICALIZE: ^[[BB1]](%{{.*}}: i32):
   %non_live_5 = arith.constant 1 : i32
   cf.br ^bb3(%non_live_1, %non_live_5 : i32, i32)
-  // CHECK: cf.br ^[[BB3:bb[0-9]+]]
-  // CHECK-NOT: i32
+  // CHECK: cf.br ^[[BB3:bb[0-9]+]](%{{.*}}, %{{.*}} : i32, i32)
+  // CHECK-CANONICALIZE: cf.br ^[[BB3:bb[0-9]+]](%{{.*}}, %{{.*}} : i32, i32)
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matthias-springer wrote:

Exactly, that's what I meant. We do the [same for region-branch control flow](https://github.com/llvm/llvm-project/pull/174094): the `MakeRegionBranchOpSuccessorInputsDead` performs that kind of canonicalization for region-based ops.

You picked a kind of tricky issue from the bug tracker here. It took me about a month to implement + merge all this for region-based ops. But on the bright side, you can learn a lot from this issue.

https://github.com/llvm/llvm-project/pull/182711